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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
  * All Rights Reserved.
  */
 #include <linux/iversion.h>
 
 #include "xfs.h"
 #include "xfs_fs.h"
 #include "xfs_shared.h"
 #include "xfs_format.h"
 #include "xfs_log_format.h"
 #include "xfs_trans_resv.h"
 #include "xfs_mount.h"
 #include "xfs_defer.h"
 #include "xfs_inode.h"
 #include "xfs_dir2.h"
 #include "xfs_attr.h"
 #include "xfs_trans_space.h"
 #include "xfs_trans.h"
 #include "xfs_buf_item.h"
 #include "xfs_inode_item.h"
 #include "xfs_iunlink_item.h"
 #include "xfs_ialloc.h"
 #include "xfs_bmap.h"
 #include "xfs_bmap_util.h"
 #include "xfs_errortag.h"
 #include "xfs_error.h"
 #include "xfs_quota.h"
 #include "xfs_filestream.h"
 #include "xfs_trace.h"
 #include "xfs_icache.h"
 #include "xfs_symlink.h"
 #include "xfs_trans_priv.h"
 #include "xfs_log.h"
 #include "xfs_bmap_btree.h"
 #include "xfs_reflink.h"
 #include "xfs_ag.h"
 #include "xfs_log_priv.h"
 
 struct kmem_cache *xfs_inode_cache;
 
 /*
  * Used in xfs_itruncate_extents().  This is the maximum number of extents
  * freed from a file in a single transaction.
  */
 #define XFS_ITRUNC_MAX_EXTENTS  2
 
 STATIC int xfs_iunlink(struct xfs_trans *, struct xfs_inode *);
 STATIC int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag,
     struct xfs_inode *);
 
 /*
  * helper function to extract extent size hint from inode
  */
 xfs_extlen_t
 xfs_get_extsz_hint(
     struct xfs_inode    *ip)
 {
     /*
      * No point in aligning allocations if we need to COW to actually
      * write to them.
      */
     if (xfs_is_always_cow_inode(ip))
         return 0;
     if ((ip->i_diflags & XFS_DIFLAG_EXTSIZE) && ip->i_extsize)
         return ip->i_extsize;
     if (XFS_IS_REALTIME_INODE(ip))
         return ip->i_mount->m_sb.sb_rextsize;
     return 0;
 }
 
 /*
  * Helper function to extract CoW extent size hint from inode.
  * Between the extent size hint and the CoW extent size hint, we
  * return the greater of the two.  If the value is zero (automatic),
  * use the default size.
  */
 xfs_extlen_t
 xfs_get_cowextsz_hint(
     struct xfs_inode    *ip)
 {
     xfs_extlen_t        a, b;
 
     a = 0;
     if (ip->i_diflags2 & XFS_DIFLAG2_COWEXTSIZE)
         a = ip->i_cowextsize;
     b = xfs_get_extsz_hint(ip);
 
     a = max(a, b);
     if (a == 0)
         return XFS_DEFAULT_COWEXTSZ_HINT;
     return a;
 }
 
 /*
  * These two are wrapper routines around the xfs_ilock() routine used to
  * centralize some grungy code.  They are used in places that wish to lock the
  * inode solely for reading the extents.  The reason these places can't just
  * call xfs_ilock(ip, XFS_ILOCK_SHARED) is that the inode lock also guards to
  * bringing in of the extents from disk for a file in b-tree format.  If the
  * inode is in b-tree format, then we need to lock the inode exclusively until
  * the extents are read in.  Locking it exclusively all the time would limit
  * our parallelism unnecessarily, though.  What we do instead is check to see
  * if the extents have been read in yet, and only lock the inode exclusively
  * if they have not.
  *
  * The functions return a value which should be given to the corresponding
  * xfs_iunlock() call.
  */
 uint
 xfs_ilock_data_map_shared(
     struct xfs_inode    *ip)
 {
     uint            lock_mode = XFS_ILOCK_SHARED;
 
     if (xfs_need_iread_extents(&ip->i_df))
         lock_mode = XFS_ILOCK_EXCL;
     xfs_ilock(ip, lock_mode);
     return lock_mode;
 }
 
 uint
 xfs_ilock_attr_map_shared(
     struct xfs_inode    *ip)
 {
     uint            lock_mode = XFS_ILOCK_SHARED;
 
     if (xfs_inode_has_attr_fork(ip) && xfs_need_iread_extents(&ip->i_af))
         lock_mode = XFS_ILOCK_EXCL;
     xfs_ilock(ip, lock_mode);
     return lock_mode;
 }
 
 /*
  * You can't set both SHARED and EXCL for the same lock,
  * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_MMAPLOCK_SHARED,
  * XFS_MMAPLOCK_EXCL, XFS_ILOCK_SHARED, XFS_ILOCK_EXCL are valid values
  * to set in lock_flags.
  */
 static inline void
 xfs_lock_flags_assert(
     uint        lock_flags)
 {
     ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
         (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
     ASSERT((lock_flags & (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL)) !=
         (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL));
     ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
         (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
     ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0);
     ASSERT(lock_flags != 0);
 }
 
 /*
  * In addition to i_rwsem in the VFS inode, the xfs inode contains 2
  * multi-reader locks: invalidate_lock and the i_lock.  This routine allows
  * various combinations of the locks to be obtained.
  *
  * The 3 locks should always be ordered so that the IO lock is obtained first,
  * the mmap lock second and the ilock last in order to prevent deadlock.
  *
  * Basic locking order:
  *
  * i_rwsem -> invalidate_lock -> page_lock -> i_ilock
  *
  * mmap_lock locking order:
  *
  * i_rwsem -> page lock -> mmap_lock
  * mmap_lock -> invalidate_lock -> page_lock
  *
  * The difference in mmap_lock locking order mean that we cannot hold the
  * invalidate_lock over syscall based read(2)/write(2) based IO. These IO paths
  * can fault in pages during copy in/out (for buffered IO) or require the
  * mmap_lock in get_user_pages() to map the user pages into the kernel address
  * space for direct IO. Similarly the i_rwsem cannot be taken inside a page
  * fault because page faults already hold the mmap_lock.
  *
  * Hence to serialise fully against both syscall and mmap based IO, we need to
  * take both the i_rwsem and the invalidate_lock. These locks should *only* be
  * both taken in places where we need to invalidate the page cache in a race
  * free manner (e.g. truncate, hole punch and other extent manipulation
  * functions).
  */
 void
 xfs_ilock(
     xfs_inode_t     *ip,
     uint            lock_flags)
 {
     trace_xfs_ilock(ip, lock_flags, _RET_IP_);
 
     xfs_lock_flags_assert(lock_flags);
 
     if (lock_flags & XFS_IOLOCK_EXCL) {
         down_write_nested(&VFS_I(ip)->i_rwsem,
                   XFS_IOLOCK_DEP(lock_flags));
     } else if (lock_flags & XFS_IOLOCK_SHARED) {
         down_read_nested(&VFS_I(ip)->i_rwsem,
                  XFS_IOLOCK_DEP(lock_flags));
     }
 
     if (lock_flags & XFS_MMAPLOCK_EXCL) {
         down_write_nested(&VFS_I(ip)->i_mapping->invalidate_lock,
                   XFS_MMAPLOCK_DEP(lock_flags));
     } else if (lock_flags & XFS_MMAPLOCK_SHARED) {
         down_read_nested(&VFS_I(ip)->i_mapping->invalidate_lock,
                  XFS_MMAPLOCK_DEP(lock_flags));
     }
 
     if (lock_flags & XFS_ILOCK_EXCL)
         mrupdate_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
     else if (lock_flags & XFS_ILOCK_SHARED)
         mraccess_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
 }
 
 /*
  * This is just like xfs_ilock(), except that the caller
  * is guaranteed not to sleep.  It returns 1 if it gets
  * the requested locks and 0 otherwise.  If the IO lock is
  * obtained but the inode lock cannot be, then the IO lock
  * is dropped before returning.
  *
  * ip -- the inode being locked
  * lock_flags -- this parameter indicates the inode's locks to be
  *       to be locked.  See the comment for xfs_ilock() for a list
  *   of valid values.
  */
 int
 xfs_ilock_nowait(
     xfs_inode_t     *ip,
     uint            lock_flags)
 {
     trace_xfs_ilock_nowait(ip, lock_flags, _RET_IP_);
 
     xfs_lock_flags_assert(lock_flags);
 
     if (lock_flags & XFS_IOLOCK_EXCL) {
         if (!down_write_trylock(&VFS_I(ip)->i_rwsem))
             goto out;
     } else if (lock_flags & XFS_IOLOCK_SHARED) {
         if (!down_read_trylock(&VFS_I(ip)->i_rwsem))
             goto out;
     }
 
     if (lock_flags & XFS_MMAPLOCK_EXCL) {
         if (!down_write_trylock(&VFS_I(ip)->i_mapping->invalidate_lock))
             goto out_undo_iolock;
     } else if (lock_flags & XFS_MMAPLOCK_SHARED) {
         if (!down_read_trylock(&VFS_I(ip)->i_mapping->invalidate_lock))
             goto out_undo_iolock;
     }
 
     if (lock_flags & XFS_ILOCK_EXCL) {
         if (!mrtryupdate(&ip->i_lock))
             goto out_undo_mmaplock;
     } else if (lock_flags & XFS_ILOCK_SHARED) {
         if (!mrtryaccess(&ip->i_lock))
             goto out_undo_mmaplock;
     }
     return 1;
 
 out_undo_mmaplock:
     if (lock_flags & XFS_MMAPLOCK_EXCL)
         up_write(&VFS_I(ip)->i_mapping->invalidate_lock);
     else if (lock_flags & XFS_MMAPLOCK_SHARED)
         up_read(&VFS_I(ip)->i_mapping->invalidate_lock);
 out_undo_iolock:
     if (lock_flags & XFS_IOLOCK_EXCL)
         up_write(&VFS_I(ip)->i_rwsem);
     else if (lock_flags & XFS_IOLOCK_SHARED)
         up_read(&VFS_I(ip)->i_rwsem);
 out:
     return 0;
 }
 
 /*
  * xfs_iunlock() is used to drop the inode locks acquired with
  * xfs_ilock() and xfs_ilock_nowait().  The caller must pass
  * in the flags given to xfs_ilock() or xfs_ilock_nowait() so
  * that we know which locks to drop.
  *
  * ip -- the inode being unlocked
  * lock_flags -- this parameter indicates the inode's locks to be
  *       to be unlocked.  See the comment for xfs_ilock() for a list
  *   of valid values for this parameter.
  *
  */
 void
 xfs_iunlock(
     xfs_inode_t     *ip,
     uint            lock_flags)
 {
     xfs_lock_flags_assert(lock_flags);
 
     if (lock_flags & XFS_IOLOCK_EXCL)
         up_write(&VFS_I(ip)->i_rwsem);
     else if (lock_flags & XFS_IOLOCK_SHARED)
         up_read(&VFS_I(ip)->i_rwsem);
 
     if (lock_flags & XFS_MMAPLOCK_EXCL)
         up_write(&VFS_I(ip)->i_mapping->invalidate_lock);
     else if (lock_flags & XFS_MMAPLOCK_SHARED)
         up_read(&VFS_I(ip)->i_mapping->invalidate_lock);
 
     if (lock_flags & XFS_ILOCK_EXCL)
         mrunlock_excl(&ip->i_lock);
     else if (lock_flags & XFS_ILOCK_SHARED)
         mrunlock_shared(&ip->i_lock);
 
     trace_xfs_iunlock(ip, lock_flags, _RET_IP_);
 }
 
 /*
  * give up write locks.  the i/o lock cannot be held nested
  * if it is being demoted.
  */
 void
 xfs_ilock_demote(
     xfs_inode_t     *ip,
     uint            lock_flags)
 {
     ASSERT(lock_flags & (XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL|XFS_ILOCK_EXCL));
     ASSERT((lock_flags &
         ~(XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL|XFS_ILOCK_EXCL)) == 0);
 
     if (lock_flags & XFS_ILOCK_EXCL)
         mrdemote(&ip->i_lock);
     if (lock_flags & XFS_MMAPLOCK_EXCL)
         downgrade_write(&VFS_I(ip)->i_mapping->invalidate_lock);
     if (lock_flags & XFS_IOLOCK_EXCL)
         downgrade_write(&VFS_I(ip)->i_rwsem);
 
     trace_xfs_ilock_demote(ip, lock_flags, _RET_IP_);
 }
 
 #if defined(DEBUG) || defined(XFS_WARN)
 static inline bool
 __xfs_rwsem_islocked(
     struct rw_semaphore *rwsem,
     bool            shared)
 {
     if (!debug_locks)
         return rwsem_is_locked(rwsem);
 
     if (!shared)
         return lockdep_is_held_type(rwsem, 0);
 
     /*
      * We are checking that the lock is held at least in shared
      * mode but don't care that it might be held exclusively
      * (i.e. shared | excl). Hence we check if the lock is held
      * in any mode rather than an explicit shared mode.
      */
     return lockdep_is_held_type(rwsem, -1);
 }
 
 bool
 xfs_isilocked(
     struct xfs_inode    *ip,
     uint            lock_flags)
 {
     if (lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) {
         if (!(lock_flags & XFS_ILOCK_SHARED))
             return !!ip->i_lock.mr_writer;
         return rwsem_is_locked(&ip->i_lock.mr_lock);
     }
 
     if (lock_flags & (XFS_MMAPLOCK_EXCL|XFS_MMAPLOCK_SHARED)) {
         return __xfs_rwsem_islocked(&VFS_I(ip)->i_mapping->invalidate_lock,
                 (lock_flags & XFS_MMAPLOCK_SHARED));
     }
 
     if (lock_flags & (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED)) {
         return __xfs_rwsem_islocked(&VFS_I(ip)->i_rwsem,
                 (lock_flags & XFS_IOLOCK_SHARED));
     }
 
     ASSERT(0);
     return false;
 }
 #endif
 
 /*
  * xfs_lockdep_subclass_ok() is only used in an ASSERT, so is only called when
  * DEBUG or XFS_WARN is set. And MAX_LOCKDEP_SUBCLASSES is then only defined
  * when CONFIG_LOCKDEP is set. Hence the complex define below to avoid build
  * errors and warnings.
  */
 #if (defined(DEBUG) || defined(XFS_WARN)) && defined(CONFIG_LOCKDEP)
 static bool
 xfs_lockdep_subclass_ok(
     int subclass)
 {
     return subclass < MAX_LOCKDEP_SUBCLASSES;
 }
 #else
 #define xfs_lockdep_subclass_ok(subclass)   (true)
 #endif
 
 /*
  * Bump the subclass so xfs_lock_inodes() acquires each lock with a different
  * value. This can be called for any type of inode lock combination, including
  * parent locking. Care must be taken to ensure we don't overrun the subclass
  * storage fields in the class mask we build.
  */
 static inline uint
 xfs_lock_inumorder(
     uint    lock_mode,
     uint    subclass)
 {
     uint    class = 0;
 
     ASSERT(!(lock_mode & (XFS_ILOCK_PARENT | XFS_ILOCK_RTBITMAP |
                   XFS_ILOCK_RTSUM)));
     ASSERT(xfs_lockdep_subclass_ok(subclass));
 
     if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)) {
         ASSERT(subclass <= XFS_IOLOCK_MAX_SUBCLASS);
         class += subclass << XFS_IOLOCK_SHIFT;
     }
 
     if (lock_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) {
         ASSERT(subclass <= XFS_MMAPLOCK_MAX_SUBCLASS);
         class += subclass << XFS_MMAPLOCK_SHIFT;
     }
 
     if (lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)) {
         ASSERT(subclass <= XFS_ILOCK_MAX_SUBCLASS);
         class += subclass << XFS_ILOCK_SHIFT;
     }
 
     return (lock_mode & ~XFS_LOCK_SUBCLASS_MASK) | class;
 }
 
 /*
  * The following routine will lock n inodes in exclusive mode.  We assume the
  * caller calls us with the inodes in i_ino order.
  *
  * We need to detect deadlock where an inode that we lock is in the AIL and we
  * start waiting for another inode that is locked by a thread in a long running
  * transaction (such as truncate). This can result in deadlock since the long
  * running trans might need to wait for the inode we just locked in order to
  * push the tail and free space in the log.
  *
  * xfs_lock_inodes() can only be used to lock one type of lock at a time -
  * the iolock, the mmaplock or the ilock, but not more than one at a time. If we
  * lock more than one at a time, lockdep will report false positives saying we
  * have violated locking orders.
  */
 static void
 xfs_lock_inodes(
     struct xfs_inode    **ips,
     int         inodes,
     uint            lock_mode)
 {
     int         attempts = 0;
     uint            i;
     int         j;
     bool            try_lock;
     struct xfs_log_item *lp;
 
     /*
      * Currently supports between 2 and 5 inodes with exclusive locking.  We
      * support an arbitrary depth of locking here, but absolute limits on
      * inodes depend on the type of locking and the limits placed by
      * lockdep annotations in xfs_lock_inumorder.  These are all checked by
      * the asserts.
      */
     ASSERT(ips && inodes >= 2 && inodes <= 5);
     ASSERT(lock_mode & (XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL |
                 XFS_ILOCK_EXCL));
     ASSERT(!(lock_mode & (XFS_IOLOCK_SHARED | XFS_MMAPLOCK_SHARED |
                   XFS_ILOCK_SHARED)));
     ASSERT(!(lock_mode & XFS_MMAPLOCK_EXCL) ||
         inodes <= XFS_MMAPLOCK_MAX_SUBCLASS + 1);
     ASSERT(!(lock_mode & XFS_ILOCK_EXCL) ||
         inodes <= XFS_ILOCK_MAX_SUBCLASS + 1);
 
     if (lock_mode & XFS_IOLOCK_EXCL) {
         ASSERT(!(lock_mode & (XFS_MMAPLOCK_EXCL | XFS_ILOCK_EXCL)));
     } else if (lock_mode & XFS_MMAPLOCK_EXCL)
         ASSERT(!(lock_mode & XFS_ILOCK_EXCL));
 
 again:
     try_lock = false;
     i = 0;
     for (; i < inodes; i++) {
         ASSERT(ips[i]);
 
         if (i && (ips[i] == ips[i - 1]))    /* Already locked */
             continue;
 
         /*
          * If try_lock is not set yet, make sure all locked inodes are
          * not in the AIL.  If any are, set try_lock to be used later.
          */
         if (!try_lock) {
             for (j = (i - 1); j >= 0 && !try_lock; j--) {
                 lp = &ips[j]->i_itemp->ili_item;
                 if (lp && test_bit(XFS_LI_IN_AIL, &lp->li_flags))
                     try_lock = true;
             }
         }
 
         /*
          * If any of the previous locks we have locked is in the AIL,
          * we must TRY to get the second and subsequent locks. If
          * we can't get any, we must release all we have
          * and try again.
          */
         if (!try_lock) {
             xfs_ilock(ips[i], xfs_lock_inumorder(lock_mode, i));
             continue;
         }
 
         /* try_lock means we have an inode locked that is in the AIL. */
         ASSERT(i != 0);
         if (xfs_ilock_nowait(ips[i], xfs_lock_inumorder(lock_mode, i)))
             continue;
 
         /*
          * Unlock all previous guys and try again.  xfs_iunlock will try
          * to push the tail if the inode is in the AIL.
          */
         attempts++;
         for (j = i - 1; j >= 0; j--) {
             /*
              * Check to see if we've already unlocked this one.  Not
              * the first one going back, and the inode ptr is the
              * same.
              */
             if (j != (i - 1) && ips[j] == ips[j + 1])
                 continue;
 
             xfs_iunlock(ips[j], lock_mode);
         }
 
         if ((attempts % 5) == 0) {
             delay(1); /* Don't just spin the CPU */
         }
         goto again;
     }
 }
 
 /*
  * xfs_lock_two_inodes() can only be used to lock ilock. The iolock and
  * mmaplock must be double-locked separately since we use i_rwsem and
  * invalidate_lock for that. We now support taking one lock EXCL and the
  * other SHARED.
  */
 void
 xfs_lock_two_inodes(
     struct xfs_inode    *ip0,
     uint            ip0_mode,
     struct xfs_inode    *ip1,
     uint            ip1_mode)
 {
     int         attempts = 0;
     struct xfs_log_item *lp;
 
     ASSERT(hweight32(ip0_mode) == 1);
     ASSERT(hweight32(ip1_mode) == 1);
     ASSERT(!(ip0_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)));
     ASSERT(!(ip1_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)));
     ASSERT(!(ip0_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)));
     ASSERT(!(ip1_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)));
     ASSERT(ip0->i_ino != ip1->i_ino);
 
     if (ip0->i_ino > ip1->i_ino) {
         swap(ip0, ip1);
         swap(ip0_mode, ip1_mode);
     }
 
  again:
     xfs_ilock(ip0, xfs_lock_inumorder(ip0_mode, 0));
 
     /*
      * If the first lock we have locked is in the AIL, we must TRY to get
      * the second lock. If we can't get it, we must release the first one
      * and try again.
      */
     lp = &ip0->i_itemp->ili_item;
     if (lp && test_bit(XFS_LI_IN_AIL, &lp->li_flags)) {
         if (!xfs_ilock_nowait(ip1, xfs_lock_inumorder(ip1_mode, 1))) {
             xfs_iunlock(ip0, ip0_mode);
             if ((++attempts % 5) == 0)
                 delay(1); /* Don't just spin the CPU */
             goto again;
         }
     } else {
         xfs_ilock(ip1, xfs_lock_inumorder(ip1_mode, 1));
     }
 }
 
 uint
 xfs_ip2xflags(
     struct xfs_inode    *ip)
 {
     uint            flags = 0;
 
     if (ip->i_diflags & XFS_DIFLAG_ANY) {
         if (ip->i_diflags & XFS_DIFLAG_REALTIME)
             flags |= FS_XFLAG_REALTIME;
         if (ip->i_diflags & XFS_DIFLAG_PREALLOC)
             flags |= FS_XFLAG_PREALLOC;
         if (ip->i_diflags & XFS_DIFLAG_IMMUTABLE)
             flags |= FS_XFLAG_IMMUTABLE;
         if (ip->i_diflags & XFS_DIFLAG_APPEND)
             flags |= FS_XFLAG_APPEND;
         if (ip->i_diflags & XFS_DIFLAG_SYNC)
             flags |= FS_XFLAG_SYNC;
         if (ip->i_diflags & XFS_DIFLAG_NOATIME)
             flags |= FS_XFLAG_NOATIME;
         if (ip->i_diflags & XFS_DIFLAG_NODUMP)
             flags |= FS_XFLAG_NODUMP;
         if (ip->i_diflags & XFS_DIFLAG_RTINHERIT)
             flags |= FS_XFLAG_RTINHERIT;
         if (ip->i_diflags & XFS_DIFLAG_PROJINHERIT)
             flags |= FS_XFLAG_PROJINHERIT;
         if (ip->i_diflags & XFS_DIFLAG_NOSYMLINKS)
             flags |= FS_XFLAG_NOSYMLINKS;
         if (ip->i_diflags & XFS_DIFLAG_EXTSIZE)
             flags |= FS_XFLAG_EXTSIZE;
         if (ip->i_diflags & XFS_DIFLAG_EXTSZINHERIT)
             flags |= FS_XFLAG_EXTSZINHERIT;
         if (ip->i_diflags & XFS_DIFLAG_NODEFRAG)
             flags |= FS_XFLAG_NODEFRAG;
         if (ip->i_diflags & XFS_DIFLAG_FILESTREAM)
             flags |= FS_XFLAG_FILESTREAM;
     }
 
     if (ip->i_diflags2 & XFS_DIFLAG2_ANY) {
         if (ip->i_diflags2 & XFS_DIFLAG2_DAX)
             flags |= FS_XFLAG_DAX;
         if (ip->i_diflags2 & XFS_DIFLAG2_COWEXTSIZE)
             flags |= FS_XFLAG_COWEXTSIZE;
     }
 
     if (xfs_inode_has_attr_fork(ip))
         flags |= FS_XFLAG_HASATTR;
     return flags;
 }
 
 /*
  * Lookups up an inode from "name". If ci_name is not NULL, then a CI match
  * is allowed, otherwise it has to be an exact match. If a CI match is found,
  * ci_name->name will point to a the actual name (caller must free) or
  * will be set to NULL if an exact match is found.
  */
 int
 xfs_lookup(
     struct xfs_inode    *dp,
     const struct xfs_name   *name,
     struct xfs_inode    **ipp,
     struct xfs_name     *ci_name)
 {
     xfs_ino_t       inum;
     int         error;
 
     trace_xfs_lookup(dp, name);
 
     if (xfs_is_shutdown(dp->i_mount))
         return -EIO;
 
     error = xfs_dir_lookup(NULL, dp, name, &inum, ci_name);
     if (error)
         goto out_unlock;
 
     error = xfs_iget(dp->i_mount, NULL, inum, 0, 0, ipp);
     if (error)
         goto out_free_name;
 
     return 0;
 
 out_free_name:
     if (ci_name)
         kmem_free(ci_name->name);
 out_unlock:
     *ipp = NULL;
     return error;
 }
 
 /* Propagate di_flags from a parent inode to a child inode. */
 static void
 xfs_inode_inherit_flags(
     struct xfs_inode    *ip,
     const struct xfs_inode  *pip)
 {
     unsigned int        di_flags = 0;
     xfs_failaddr_t      failaddr;
     umode_t         mode = VFS_I(ip)->i_mode;
 
     if (S_ISDIR(mode)) {
         if (pip->i_diflags & XFS_DIFLAG_RTINHERIT)
             di_flags |= XFS_DIFLAG_RTINHERIT;
         if (pip->i_diflags & XFS_DIFLAG_EXTSZINHERIT) {
             di_flags |= XFS_DIFLAG_EXTSZINHERIT;
             ip->i_extsize = pip->i_extsize;
         }
         if (pip->i_diflags & XFS_DIFLAG_PROJINHERIT)
             di_flags |= XFS_DIFLAG_PROJINHERIT;
     } else if (S_ISREG(mode)) {
         if ((pip->i_diflags & XFS_DIFLAG_RTINHERIT) &&
             xfs_has_realtime(ip->i_mount))
             di_flags |= XFS_DIFLAG_REALTIME;
         if (pip->i_diflags & XFS_DIFLAG_EXTSZINHERIT) {
             di_flags |= XFS_DIFLAG_EXTSIZE;
             ip->i_extsize = pip->i_extsize;
         }
     }
     if ((pip->i_diflags & XFS_DIFLAG_NOATIME) &&
         xfs_inherit_noatime)
         di_flags |= XFS_DIFLAG_NOATIME;
     if ((pip->i_diflags & XFS_DIFLAG_NODUMP) &&
         xfs_inherit_nodump)
         di_flags |= XFS_DIFLAG_NODUMP;
     if ((pip->i_diflags & XFS_DIFLAG_SYNC) &&
         xfs_inherit_sync)
         di_flags |= XFS_DIFLAG_SYNC;
     if ((pip->i_diflags & XFS_DIFLAG_NOSYMLINKS) &&
         xfs_inherit_nosymlinks)
         di_flags |= XFS_DIFLAG_NOSYMLINKS;
     if ((pip->i_diflags & XFS_DIFLAG_NODEFRAG) &&
         xfs_inherit_nodefrag)
         di_flags |= XFS_DIFLAG_NODEFRAG;
     if (pip->i_diflags & XFS_DIFLAG_FILESTREAM)
         di_flags |= XFS_DIFLAG_FILESTREAM;
 
     ip->i_diflags |= di_flags;
 
     /*
      * Inode verifiers on older kernels only check that the extent size
      * hint is an integer multiple of the rt extent size on realtime files.
      * They did not check the hint alignment on a directory with both
      * rtinherit and extszinherit flags set.  If the misaligned hint is
      * propagated from a directory into a new realtime file, new file
      * allocations will fail due to math errors in the rt allocator and/or
      * trip the verifiers.  Validate the hint settings in the new file so
      * that we don't let broken hints propagate.
      */
     failaddr = xfs_inode_validate_extsize(ip->i_mount, ip->i_extsize,
             VFS_I(ip)->i_mode, ip->i_diflags);
     if (failaddr) {
         ip->i_diflags &= ~(XFS_DIFLAG_EXTSIZE |
                    XFS_DIFLAG_EXTSZINHERIT);
         ip->i_extsize = 0;
     }
 }
 
 /* Propagate di_flags2 from a parent inode to a child inode. */
 static void
 xfs_inode_inherit_flags2(
     struct xfs_inode    *ip,
     const struct xfs_inode  *pip)
 {
     xfs_failaddr_t      failaddr;
 
     if (pip->i_diflags2 & XFS_DIFLAG2_COWEXTSIZE) {
         ip->i_diflags2 |= XFS_DIFLAG2_COWEXTSIZE;
         ip->i_cowextsize = pip->i_cowextsize;
     }
     if (pip->i_diflags2 & XFS_DIFLAG2_DAX)
         ip->i_diflags2 |= XFS_DIFLAG2_DAX;
 
     /* Don't let invalid cowextsize hints propagate. */
     failaddr = xfs_inode_validate_cowextsize(ip->i_mount, ip->i_cowextsize,
             VFS_I(ip)->i_mode, ip->i_diflags, ip->i_diflags2);
     if (failaddr) {
         ip->i_diflags2 &= ~XFS_DIFLAG2_COWEXTSIZE;
         ip->i_cowextsize = 0;
     }
 }
 
 /*
  * Initialise a newly allocated inode and return the in-core inode to the
  * caller locked exclusively.
  */
 int
 xfs_init_new_inode(
     struct user_namespace   *mnt_userns,
     struct xfs_trans    *tp,
     struct xfs_inode    *pip,
     xfs_ino_t       ino,
     umode_t         mode,
     xfs_nlink_t     nlink,
     dev_t           rdev,
     prid_t          prid,
     bool            init_xattrs,
     struct xfs_inode    **ipp)
 {
     struct inode        *dir = pip ? VFS_I(pip) : NULL;
     struct xfs_mount    *mp = tp->t_mountp;
     struct xfs_inode    *ip;
     unsigned int        flags;
     int         error;
     struct timespec64   tv;
     struct inode        *inode;
 
     /*
      * Protect against obviously corrupt allocation btree records. Later
      * xfs_iget checks will catch re-allocation of other active in-memory
      * and on-disk inodes. If we don't catch reallocating the parent inode
      * here we will deadlock in xfs_iget() so we have to do these checks
      * first.
      */
     if ((pip && ino == pip->i_ino) || !xfs_verify_dir_ino(mp, ino)) {
         xfs_alert(mp, "Allocated a known in-use inode 0x%llx!", ino);
         return -EFSCORRUPTED;
     }
 
     /*
      * Get the in-core inode with the lock held exclusively to prevent
      * others from looking at until we're done.
      */
     error = xfs_iget(mp, tp, ino, XFS_IGET_CREATE, XFS_ILOCK_EXCL, &ip);
     if (error)
         return error;
 
     ASSERT(ip != NULL);
     inode = VFS_I(ip);
     set_nlink(inode, nlink);
     inode->i_rdev = rdev;
     ip->i_projid = prid;
 
     if (dir && !(dir->i_mode & S_ISGID) && xfs_has_grpid(mp)) {
         inode_fsuid_set(inode, mnt_userns);
         inode->i_gid = dir->i_gid;
         inode->i_mode = mode;
     } else {
         inode_init_owner(mnt_userns, inode, dir, mode);
     }
 
     /*
      * If the group ID of the new file does not match the effective group
      * ID or one of the supplementary group IDs, the S_ISGID bit is cleared
      * (and only if the irix_sgid_inherit compatibility variable is set).
      */
     if (irix_sgid_inherit &&
         (inode->i_mode & S_ISGID) &&
         !in_group_p(i_gid_into_mnt(mnt_userns, inode)))
         inode->i_mode &= ~S_ISGID;
 
     ip->i_disk_size = 0;
     ip->i_df.if_nextents = 0;
     ASSERT(ip->i_nblocks == 0);
 
     tv = current_time(inode);
     inode->i_mtime = tv;
     inode->i_atime = tv;
     inode->i_ctime = tv;
 
     ip->i_extsize = 0;
     ip->i_diflags = 0;
 
     if (xfs_has_v3inodes(mp)) {
         inode_set_iversion(inode, 1);
         ip->i_cowextsize = 0;
         ip->i_crtime = tv;
     }
 
     flags = XFS_ILOG_CORE;
     switch (mode & S_IFMT) {
     case S_IFIFO:
     case S_IFCHR:
     case S_IFBLK:
     case S_IFSOCK:
         ip->i_df.if_format = XFS_DINODE_FMT_DEV;
         flags |= XFS_ILOG_DEV;
         break;
     case S_IFREG:
     case S_IFDIR:
         if (pip && (pip->i_diflags & XFS_DIFLAG_ANY))
             xfs_inode_inherit_flags(ip, pip);
         if (pip && (pip->i_diflags2 & XFS_DIFLAG2_ANY))
             xfs_inode_inherit_flags2(ip, pip);
         fallthrough;
     case S_IFLNK:
         ip->i_df.if_format = XFS_DINODE_FMT_EXTENTS;
         ip->i_df.if_bytes = 0;
         ip->i_df.if_u1.if_root = NULL;
         break;
     default:
         ASSERT(0);
     }
 
     /*
      * If we need to create attributes immediately after allocating the
      * inode, initialise an empty attribute fork right now. We use the
      * default fork offset for attributes here as we don't know exactly what
      * size or how many attributes we might be adding. We can do this
      * safely here because we know the data fork is completely empty and
      * this saves us from needing to run a separate transaction to set the
      * fork offset in the immediate future.
      */
     if (init_xattrs && xfs_has_attr(mp)) {
         ip->i_forkoff = xfs_default_attroffset(ip) >> 3;
         xfs_ifork_init_attr(ip, XFS_DINODE_FMT_EXTENTS, 0);
     }
 
     /*
      * Log the new values stuffed into the inode.
      */
     xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
     xfs_trans_log_inode(tp, ip, flags);
 
     /* now that we have an i_mode we can setup the inode structure */
     xfs_setup_inode(ip);
 
     *ipp = ip;
     return 0;
 }
 
 /*
  * Decrement the link count on an inode & log the change.  If this causes the
  * link count to go to zero, move the inode to AGI unlinked list so that it can
  * be freed when the last active reference goes away via xfs_inactive().
  */
 static int          /* error */
 xfs_droplink(
     xfs_trans_t *tp,
     xfs_inode_t *ip)
 {
     xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
 
     drop_nlink(VFS_I(ip));
     xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 
     if (VFS_I(ip)->i_nlink)
         return 0;
 
     return xfs_iunlink(tp, ip);
 }
 
 /*
  * Increment the link count on an inode & log the change.
  */
 static void
 xfs_bumplink(
     xfs_trans_t *tp,
     xfs_inode_t *ip)
 {
     xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
 
     inc_nlink(VFS_I(ip));
     xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 }
 
 int
 xfs_create(
     struct user_namespace   *mnt_userns,
     xfs_inode_t     *dp,
     struct xfs_name     *name,
     umode_t         mode,
     dev_t           rdev,
     bool            init_xattrs,
     xfs_inode_t     **ipp)
 {
     int         is_dir = S_ISDIR(mode);
     struct xfs_mount    *mp = dp->i_mount;
     struct xfs_inode    *ip = NULL;
     struct xfs_trans    *tp = NULL;
     int         error;
     bool                    unlock_dp_on_error = false;
     prid_t          prid;
     struct xfs_dquot    *udqp = NULL;
     struct xfs_dquot    *gdqp = NULL;
     struct xfs_dquot    *pdqp = NULL;
     struct xfs_trans_res    *tres;
     uint            resblks;
     xfs_ino_t       ino;
 
     trace_xfs_create(dp, name);
 
     if (xfs_is_shutdown(mp))
         return -EIO;
 
     prid = xfs_get_initial_prid(dp);
 
     /*
      * Make sure that we have allocated dquot(s) on disk.
      */
     error = xfs_qm_vop_dqalloc(dp, mapped_fsuid(mnt_userns, &init_user_ns),
             mapped_fsgid(mnt_userns, &init_user_ns), prid,
             XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
             &udqp, &gdqp, &pdqp);
     if (error)
         return error;
 
     if (is_dir) {
         resblks = XFS_MKDIR_SPACE_RES(mp, name->len);
         tres = &M_RES(mp)->tr_mkdir;
     } else {
         resblks = XFS_CREATE_SPACE_RES(mp, name->len);
         tres = &M_RES(mp)->tr_create;
     }
 
     /*
      * Initially assume that the file does not exist and
      * reserve the resources for that case.  If that is not
      * the case we'll drop the one we have and get a more
      * appropriate transaction later.
      */
     error = xfs_trans_alloc_icreate(mp, tres, udqp, gdqp, pdqp, resblks,
             &tp);
     if (error == -ENOSPC) {
         /* flush outstanding delalloc blocks and retry */
         xfs_flush_inodes(mp);
         error = xfs_trans_alloc_icreate(mp, tres, udqp, gdqp, pdqp,
                 resblks, &tp);
     }
     if (error)
         goto out_release_dquots;
 
     xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
     unlock_dp_on_error = true;
 
     /*
      * A newly created regular or special file just has one directory
      * entry pointing to them, but a directory also the "." entry
      * pointing to itself.
      */
     error = xfs_dialloc(&tp, dp->i_ino, mode, &ino);
     if (!error)
         error = xfs_init_new_inode(mnt_userns, tp, dp, ino, mode,
                 is_dir ? 2 : 1, rdev, prid, init_xattrs, &ip);
     if (error)
         goto out_trans_cancel;
 
     /*
      * Now we join the directory inode to the transaction.  We do not do it
      * earlier because xfs_dialloc might commit the previous transaction
      * (and release all the locks).  An error from here on will result in
      * the transaction cancel unlocking dp so don't do it explicitly in the
      * error path.
      */
     xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
     unlock_dp_on_error = false;
 
     error = xfs_dir_createname(tp, dp, name, ip->i_ino,
                     resblks - XFS_IALLOC_SPACE_RES(mp));
     if (error) {
         ASSERT(error != -ENOSPC);
         goto out_trans_cancel;
     }
     xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
     xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
 
     if (is_dir) {
         error = xfs_dir_init(tp, ip, dp);
         if (error)
             goto out_trans_cancel;
 
         xfs_bumplink(tp, dp);
     }
 
     /*
      * If this is a synchronous mount, make sure that the
      * create transaction goes to disk before returning to
      * the user.
      */
     if (xfs_has_wsync(mp) || xfs_has_dirsync(mp))
         xfs_trans_set_sync(tp);
 
     /*
      * Attach the dquot(s) to the inodes and modify them incore.
      * These ids of the inode couldn't have changed since the new
      * inode has been locked ever since it was created.
      */
     xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
 
     error = xfs_trans_commit(tp);
     if (error)
         goto out_release_inode;
 
     xfs_qm_dqrele(udqp);
     xfs_qm_dqrele(gdqp);
     xfs_qm_dqrele(pdqp);
 
     *ipp = ip;
     return 0;
 
  out_trans_cancel:
     xfs_trans_cancel(tp);
  out_release_inode:
     /*
      * Wait until after the current transaction is aborted to finish the
      * setup of the inode and release the inode.  This prevents recursive
      * transactions and deadlocks from xfs_inactive.
      */
     if (ip) {
         xfs_finish_inode_setup(ip);
         xfs_irele(ip);
     }
  out_release_dquots:
     xfs_qm_dqrele(udqp);
     xfs_qm_dqrele(gdqp);
     xfs_qm_dqrele(pdqp);
 
     if (unlock_dp_on_error)
         xfs_iunlock(dp, XFS_ILOCK_EXCL);
     return error;
 }
 
 int
 xfs_create_tmpfile(
     struct user_namespace   *mnt_userns,
     struct xfs_inode    *dp,
     umode_t         mode,
     struct xfs_inode    **ipp)
 {
     struct xfs_mount    *mp = dp->i_mount;
     struct xfs_inode    *ip = NULL;
     struct xfs_trans    *tp = NULL;
     int         error;
     prid_t                  prid;
     struct xfs_dquot    *udqp = NULL;
     struct xfs_dquot    *gdqp = NULL;
     struct xfs_dquot    *pdqp = NULL;
     struct xfs_trans_res    *tres;
     uint            resblks;
     xfs_ino_t       ino;
 
     if (xfs_is_shutdown(mp))
         return -EIO;
 
     prid = xfs_get_initial_prid(dp);
 
     /*
      * Make sure that we have allocated dquot(s) on disk.
      */
     error = xfs_qm_vop_dqalloc(dp, mapped_fsuid(mnt_userns, &init_user_ns),
             mapped_fsgid(mnt_userns, &init_user_ns), prid,
             XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
             &udqp, &gdqp, &pdqp);
     if (error)
         return error;
 
     resblks = XFS_IALLOC_SPACE_RES(mp);
     tres = &M_RES(mp)->tr_create_tmpfile;
 
     error = xfs_trans_alloc_icreate(mp, tres, udqp, gdqp, pdqp, resblks,
             &tp);
     if (error)
         goto out_release_dquots;
 
     error = xfs_dialloc(&tp, dp->i_ino, mode, &ino);
     if (!error)
         error = xfs_init_new_inode(mnt_userns, tp, dp, ino, mode,
                 0, 0, prid, false, &ip);
     if (error)
         goto out_trans_cancel;
 
     if (xfs_has_wsync(mp))
         xfs_trans_set_sync(tp);
 
     /*
      * Attach the dquot(s) to the inodes and modify them incore.
      * These ids of the inode couldn't have changed since the new
      * inode has been locked ever since it was created.
      */
     xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
 
     error = xfs_iunlink(tp, ip);
     if (error)
         goto out_trans_cancel;
 
     error = xfs_trans_commit(tp);
     if (error)
         goto out_release_inode;
 
     xfs_qm_dqrele(udqp);
     xfs_qm_dqrele(gdqp);
     xfs_qm_dqrele(pdqp);
 
     *ipp = ip;
     return 0;
 
  out_trans_cancel:
     xfs_trans_cancel(tp);
  out_release_inode:
     /*
      * Wait until after the current transaction is aborted to finish the
      * setup of the inode and release the inode.  This prevents recursive
      * transactions and deadlocks from xfs_inactive.
      */
     if (ip) {
         xfs_finish_inode_setup(ip);
         xfs_irele(ip);
     }
  out_release_dquots:
     xfs_qm_dqrele(udqp);
     xfs_qm_dqrele(gdqp);
     xfs_qm_dqrele(pdqp);
 
     return error;
 }
 
 int
 xfs_link(
     xfs_inode_t     *tdp,
     xfs_inode_t     *sip,
     struct xfs_name     *target_name)
 {
     xfs_mount_t     *mp = tdp->i_mount;
     xfs_trans_t     *tp;
     int         error, nospace_error = 0;
     int         resblks;
 
     trace_xfs_link(tdp, target_name);
 
     ASSERT(!S_ISDIR(VFS_I(sip)->i_mode));
 
     if (xfs_is_shutdown(mp))
         return -EIO;
 
     error = xfs_qm_dqattach(sip);
     if (error)
         goto std_return;
 
     error = xfs_qm_dqattach(tdp);
     if (error)
         goto std_return;
 
     resblks = XFS_LINK_SPACE_RES(mp, target_name->len);
     error = xfs_trans_alloc_dir(tdp, &M_RES(mp)->tr_link, sip, &resblks,
             &tp, &nospace_error);
     if (error)
         goto std_return;
 
     /*
      * If we are using project inheritance, we only allow hard link
      * creation in our tree when the project IDs are the same; else
      * the tree quota mechanism could be circumvented.
      */
     if (unlikely((tdp->i_diflags & XFS_DIFLAG_PROJINHERIT) &&
              tdp->i_projid != sip->i_projid)) {
         error = -EXDEV;
         goto error_return;
     }
 
     if (!resblks) {
         error = xfs_dir_canenter(tp, tdp, target_name);
         if (error)
             goto error_return;
     }
 
     /*
      * Handle initial link state of O_TMPFILE inode
      */
     if (VFS_I(sip)->i_nlink == 0) {
         struct xfs_perag    *pag;
 
         pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, sip->i_ino));
         error = xfs_iunlink_remove(tp, pag, sip);
         xfs_perag_put(pag);
         if (error)
             goto error_return;
     }
 
     error = xfs_dir_createname(tp, tdp, target_name, sip->i_ino,
                    resblks);
     if (error)
         goto error_return;
     xfs_trans_ichgtime(tp, tdp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
     xfs_trans_log_inode(tp, tdp, XFS_ILOG_CORE);
 
     xfs_bumplink(tp, sip);
 
     /*
      * If this is a synchronous mount, make sure that the
      * link transaction goes to disk before returning to
      * the user.
      */
     if (xfs_has_wsync(mp) || xfs_has_dirsync(mp))
         xfs_trans_set_sync(tp);
 
     return xfs_trans_commit(tp);
 
  error_return:
     xfs_trans_cancel(tp);
  std_return:
     if (error == -ENOSPC && nospace_error)
         error = nospace_error;
     return error;
 }
 
 /* Clear the reflink flag and the cowblocks tag if possible. */
 static void
 xfs_itruncate_clear_reflink_flags(
     struct xfs_inode    *ip)
 {
     struct xfs_ifork    *dfork;
     struct xfs_ifork    *cfork;
 
     if (!xfs_is_reflink_inode(ip))
         return;
     dfork = xfs_ifork_ptr(ip, XFS_DATA_FORK);
     cfork = xfs_ifork_ptr(ip, XFS_COW_FORK);
     if (dfork->if_bytes == 0 && cfork->if_bytes == 0)
         ip->i_diflags2 &= ~XFS_DIFLAG2_REFLINK;
     if (cfork->if_bytes == 0)
         xfs_inode_clear_cowblocks_tag(ip);
 }
 
 /*
  * Free up the underlying blocks past new_size.  The new size must be smaller
  * than the current size.  This routine can be used both for the attribute and
  * data fork, and does not modify the inode size, which is left to the caller.
  *
  * The transaction passed to this routine must have made a permanent log
  * reservation of at least XFS_ITRUNCATE_LOG_RES.  This routine may commit the
  * given transaction and start new ones, so make sure everything involved in
  * the transaction is tidy before calling here.  Some transaction will be
  * returned to the caller to be committed.  The incoming transaction must
  * already include the inode, and both inode locks must be held exclusively.
  * The inode must also be "held" within the transaction.  On return the inode
  * will be "held" within the returned transaction.  This routine does NOT
  * require any disk space to be reserved for it within the transaction.
  *
  * If we get an error, we must return with the inode locked and linked into the
  * current transaction. This keeps things simple for the higher level code,
  * because it always knows that the inode is locked and held in the transaction
  * that returns to it whether errors occur or not.  We don't mark the inode
  * dirty on error so that transactions can be easily aborted if possible.
  */
 int
 xfs_itruncate_extents_flags(
     struct xfs_trans    **tpp,
     struct xfs_inode    *ip,
     int         whichfork,
     xfs_fsize_t     new_size,
     int         flags)
 {
     struct xfs_mount    *mp = ip->i_mount;
     struct xfs_trans    *tp = *tpp;
     xfs_fileoff_t       first_unmap_block;
     xfs_filblks_t       unmap_len;
     int         error = 0;
 
     ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
     ASSERT(!atomic_read(&VFS_I(ip)->i_count) ||
            xfs_isilocked(ip, XFS_IOLOCK_EXCL));
     ASSERT(new_size <= XFS_ISIZE(ip));
     ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
     ASSERT(ip->i_itemp != NULL);
     ASSERT(ip->i_itemp->ili_lock_flags == 0);
     ASSERT(!XFS_NOT_DQATTACHED(mp, ip));
 
     trace_xfs_itruncate_extents_start(ip, new_size);
 
     flags |= xfs_bmapi_aflag(whichfork);
 
     /*
      * Since it is possible for space to become allocated beyond
      * the end of the file (in a crash where the space is allocated
      * but the inode size is not yet updated), simply remove any
      * blocks which show up between the new EOF and the maximum
      * possible file size.
      *
      * We have to free all the blocks to the bmbt maximum offset, even if
      * the page cache can't scale that far.
      */
     first_unmap_block = XFS_B_TO_FSB(mp, (xfs_ufsize_t)new_size);
     if (!xfs_verify_fileoff(mp, first_unmap_block)) {
         WARN_ON_ONCE(first_unmap_block > XFS_MAX_FILEOFF);
         return 0;
     }
 
     unmap_len = XFS_MAX_FILEOFF - first_unmap_block + 1;
     while (unmap_len > 0) {
         ASSERT(tp->t_firstblock == NULLFSBLOCK);
         error = __xfs_bunmapi(tp, ip, first_unmap_block, &unmap_len,
                 flags, XFS_ITRUNC_MAX_EXTENTS);
         if (error)
             goto out;
 
         /* free the just unmapped extents */
         error = xfs_defer_finish(&tp);
         if (error)
             goto out;
     }
 
     if (whichfork == XFS_DATA_FORK) {
         /* Remove all pending CoW reservations. */
         error = xfs_reflink_cancel_cow_blocks(ip, &tp,
                 first_unmap_block, XFS_MAX_FILEOFF, true);
         if (error)
             goto out;
 
         xfs_itruncate_clear_reflink_flags(ip);
     }
 
     /*
      * Always re-log the inode so that our permanent transaction can keep
      * on rolling it forward in the log.
      */
     xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 
     trace_xfs_itruncate_extents_end(ip, new_size);
 
 out:
     *tpp = tp;
     return error;
 }
 
 int
 xfs_release(
     xfs_inode_t *ip)
 {
     xfs_mount_t *mp = ip->i_mount;
     int     error = 0;
 
     if (!S_ISREG(VFS_I(ip)->i_mode) || (VFS_I(ip)->i_mode == 0))
         return 0;
 
     /* If this is a read-only mount, don't do this (would generate I/O) */
     if (xfs_is_readonly(mp))
         return 0;
 
     if (!xfs_is_shutdown(mp)) {
         int truncated;
 
         /*
          * If we previously truncated this file and removed old data
          * in the process, we want to initiate "early" writeout on
          * the last close.  This is an attempt to combat the notorious
          * NULL files problem which is particularly noticeable from a
          * truncate down, buffered (re-)write (delalloc), followed by
          * a crash.  What we are effectively doing here is
          * significantly reducing the time window where we'd otherwise
          * be exposed to that problem.
          */
         truncated = xfs_iflags_test_and_clear(ip, XFS_ITRUNCATED);
         if (truncated) {
             xfs_iflags_clear(ip, XFS_IDIRTY_RELEASE);
             if (ip->i_delayed_blks > 0) {
                 error = filemap_flush(VFS_I(ip)->i_mapping);
                 if (error)
                     return error;
             }
         }
     }
 
     if (VFS_I(ip)->i_nlink == 0)
         return 0;
 
     /*
      * If we can't get the iolock just skip truncating the blocks past EOF
      * because we could deadlock with the mmap_lock otherwise. We'll get
      * another chance to drop them once the last reference to the inode is
      * dropped, so we'll never leak blocks permanently.
      */
     if (!xfs_ilock_nowait(ip, XFS_IOLOCK_EXCL))
         return 0;
 
     if (xfs_can_free_eofblocks(ip, false)) {
         /*
          * Check if the inode is being opened, written and closed
          * frequently and we have delayed allocation blocks outstanding
          * (e.g. streaming writes from the NFS server), truncating the
          * blocks past EOF will cause fragmentation to occur.
          *
          * In this case don't do the truncation, but we have to be
          * careful how we detect this case. Blocks beyond EOF show up as
          * i_delayed_blks even when the inode is clean, so we need to
          * truncate them away first before checking for a dirty release.
          * Hence on the first dirty close we will still remove the
          * speculative allocation, but after that we will leave it in
          * place.
          */
         if (xfs_iflags_test(ip, XFS_IDIRTY_RELEASE))
             goto out_unlock;
 
         error = xfs_free_eofblocks(ip);
         if (error)
             goto out_unlock;
 
         /* delalloc blocks after truncation means it really is dirty */
         if (ip->i_delayed_blks)
             xfs_iflags_set(ip, XFS_IDIRTY_RELEASE);
     }
 
 out_unlock:
     xfs_iunlock(ip, XFS_IOLOCK_EXCL);
     return error;
 }
 
 /*
  * xfs_inactive_truncate
  *
  * Called to perform a truncate when an inode becomes unlinked.
  */
 STATIC int
 xfs_inactive_truncate(
     struct xfs_inode *ip)
 {
     struct xfs_mount    *mp = ip->i_mount;
     struct xfs_trans    *tp;
     int         error;
 
     error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
     if (error) {
         ASSERT(xfs_is_shutdown(mp));
         return error;
     }
     xfs_ilock(ip, XFS_ILOCK_EXCL);
     xfs_trans_ijoin(tp, ip, 0);
 
     /*
      * Log the inode size first to prevent stale data exposure in the event
      * of a system crash before the truncate completes. See the related
      * comment in xfs_vn_setattr_size() for details.
      */
     ip->i_disk_size = 0;
     xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 
     error = xfs_itruncate_extents(&tp, ip, XFS_DATA_FORK, 0);
     if (error)
         goto error_trans_cancel;
 
     ASSERT(ip->i_df.if_nextents == 0);
 
     error = xfs_trans_commit(tp);
     if (error)
         goto error_unlock;
 
     xfs_iunlock(ip, XFS_ILOCK_EXCL);
     return 0;
 
 error_trans_cancel:
     xfs_trans_cancel(tp);
 error_unlock:
     xfs_iunlock(ip, XFS_ILOCK_EXCL);
     return error;
 }
 
 /*
  * xfs_inactive_ifree()
  *
  * Perform the inode free when an inode is unlinked.
  */
 STATIC int
 xfs_inactive_ifree(
     struct xfs_inode *ip)
 {
     struct xfs_mount    *mp = ip->i_mount;
     struct xfs_trans    *tp;
     int         error;
 
     /*
      * We try to use a per-AG reservation for any block needed by the finobt
      * tree, but as the finobt feature predates the per-AG reservation
      * support a degraded file system might not have enough space for the
      * reservation at mount time.  In that case try to dip into the reserved
      * pool and pray.
      *
      * Send a warning if the reservation does happen to fail, as the inode
      * now remains allocated and sits on the unlinked list until the fs is
      * repaired.
      */
     if (unlikely(mp->m_finobt_nores)) {
         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ifree,
                 XFS_IFREE_SPACE_RES(mp), 0, XFS_TRANS_RESERVE,
                 &tp);
     } else {
         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ifree, 0, 0, 0, &tp);
     }
     if (error) {
         if (error == -ENOSPC) {
             xfs_warn_ratelimited(mp,
             "Failed to remove inode(s) from unlinked list. "
             "Please free space, unmount and run xfs_repair.");
         } else {
             ASSERT(xfs_is_shutdown(mp));
         }
         return error;
     }
 
     /*
      * We do not hold the inode locked across the entire rolling transaction
      * here. We only need to hold it for the first transaction that
      * xfs_ifree() builds, which may mark the inode XFS_ISTALE if the
      * underlying cluster buffer is freed. Relogging an XFS_ISTALE inode
      * here breaks the relationship between cluster buffer invalidation and
      * stale inode invalidation on cluster buffer item journal commit
      * completion, and can result in leaving dirty stale inodes hanging
      * around in memory.
      *
      * We have no need for serialising this inode operation against other
      * operations - we freed the inode and hence reallocation is required
      * and that will serialise on reallocating the space the deferops need
      * to free. Hence we can unlock the inode on the first commit of
      * the transaction rather than roll it right through the deferops. This
      * avoids relogging the XFS_ISTALE inode.
      *
      * We check that xfs_ifree() hasn't grown an internal transaction roll
      * by asserting that the inode is still locked when it returns.
      */
     xfs_ilock(ip, XFS_ILOCK_EXCL);
     xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 
     error = xfs_ifree(tp, ip);
     ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
     if (error) {
         /*
          * If we fail to free the inode, shut down.  The cancel
          * might do that, we need to make sure.  Otherwise the
          * inode might be lost for a long time or forever.
          */
         if (!xfs_is_shutdown(mp)) {
             xfs_notice(mp, "%s: xfs_ifree returned error %d",
                 __func__, error);
             xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
         }
         xfs_trans_cancel(tp);
         return error;
     }
 
     /*
      * Credit the quota account(s). The inode is gone.
      */
     xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_ICOUNT, -1);
 
     /*
      * Just ignore errors at this point.  There is nothing we can do except
      * to try to keep going. Make sure it's not a silent error.
      */
     error = xfs_trans_commit(tp);
     if (error)
         xfs_notice(mp, "%s: xfs_trans_commit returned error %d",
             __func__, error);
 
     return 0;
 }
 
 /*
  * Returns true if we need to update the on-disk metadata before we can free
  * the memory used by this inode.  Updates include freeing post-eof
  * preallocations; freeing COW staging extents; and marking the inode free in
  * the inobt if it is on the unlinked list.
  */
 bool
 xfs_inode_needs_inactive(
     struct xfs_inode    *ip)
 {
     struct xfs_mount    *mp = ip->i_mount;
     struct xfs_ifork    *cow_ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
 
     /*
      * If the inode is already free, then there can be nothing
      * to clean up here.
      */
     if (VFS_I(ip)->i_mode == 0)
         return false;
 
     /* If this is a read-only mount, don't do this (would generate I/O) */
     if (xfs_is_readonly(mp))
         return false;
 
     /* If the log isn't running, push inodes straight to reclaim. */
     if (xfs_is_shutdown(mp) || xfs_has_norecovery(mp))
         return false;
 
     /* Metadata inodes require explicit resource cleanup. */
     if (xfs_is_metadata_inode(ip))
         return false;
 
     /* Want to clean out the cow blocks if there are any. */
     if (cow_ifp && cow_ifp->if_bytes > 0)
         return true;
 
     /* Unlinked files must be freed. */
     if (VFS_I(ip)->i_nlink == 0)
         return true;
 
     /*
      * This file isn't being freed, so check if there are post-eof blocks
      * to free.  @force is true because we are evicting an inode from the
      * cache.  Post-eof blocks must be freed, lest we end up with broken
      * free space accounting.
      *
      * Note: don't bother with iolock here since lockdep complains about
      * acquiring it in reclaim context. We have the only reference to the
      * inode at this point anyways.
      */
     return xfs_can_free_eofblocks(ip, true);
 }
 
 /*
  * xfs_inactive
  *
  * This is called when the vnode reference count for the vnode
  * goes to zero.  If the file has been unlinked, then it must
  * now be truncated.  Also, we clear all of the read-ahead state
  * kept for the inode here since the file is now closed.
  */
 void
 xfs_inactive(
     xfs_inode_t *ip)
 {
     struct xfs_mount    *mp;
     int         error;
     int         truncate = 0;
 
     /*
      * If the inode is already free, then there can be nothing
      * to clean up here.
      */
     if (VFS_I(ip)->i_mode == 0) {
         ASSERT(ip->i_df.if_broot_bytes == 0);
         goto out;
     }
 
     mp = ip->i_mount;
     ASSERT(!xfs_iflags_test(ip, XFS_IRECOVERY));
 
     /* If this is a read-only mount, don't do this (would generate I/O) */
     if (xfs_is_readonly(mp))
         goto out;
 
     /* Metadata inodes require explicit resource cleanup. */
     if (xfs_is_metadata_inode(ip))
         goto out;
 
     /* Try to clean out the cow blocks if there are any. */
     if (xfs_inode_has_cow_data(ip))
         xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF, true);
 
     if (VFS_I(ip)->i_nlink != 0) {
         /*
          * force is true because we are evicting an inode from the
          * cache. Post-eof blocks must be freed, lest we end up with
          * broken free space accounting.
          *
          * Note: don't bother with iolock here since lockdep complains
          * about acquiring it in reclaim context. We have the only
          * reference to the inode at this point anyways.
          */
         if (xfs_can_free_eofblocks(ip, true))
             xfs_free_eofblocks(ip);
 
         goto out;
     }
 
     if (S_ISREG(VFS_I(ip)->i_mode) &&
         (ip->i_disk_size != 0 || XFS_ISIZE(ip) != 0 ||
          ip->i_df.if_nextents > 0 || ip->i_delayed_blks > 0))
         truncate = 1;
 
     error = xfs_qm_dqattach(ip);
     if (error)
         goto out;
 
     if (S_ISLNK(VFS_I(ip)->i_mode))
         error = xfs_inactive_symlink(ip);
     else if (truncate)
         error = xfs_inactive_truncate(ip);
     if (error)
         goto out;
 
     /*
      * If there are attributes associated with the file then blow them away
      * now.  The code calls a routine that recursively deconstructs the
      * attribute fork. If also blows away the in-core attribute fork.
      */
     if (xfs_inode_has_attr_fork(ip)) {
         error = xfs_attr_inactive(ip);
         if (error)
             goto out;
     }
 
     ASSERT(ip->i_forkoff == 0);
 
     /*
      * Free the inode.
      */
     xfs_inactive_ifree(ip);
 
 out:
     /*
      * We're done making metadata updates for this inode, so we can release
      * the attached dquots.
      */
     xfs_qm_dqdetach(ip);
 }
 
 /*
  * In-Core Unlinked List Lookups
  * =============================
  *
  * Every inode is supposed to be reachable from some other piece of metadata
  * with the exception of the root directory.  Inodes with a connection to a
  * file descriptor but not linked from anywhere in the on-disk directory tree
  * are collectively known as unlinked inodes, though the filesystem itself
  * maintains links to these inodes so that on-disk metadata are consistent.
  *
  * XFS implements a per-AG on-disk hash table of unlinked inodes.  The AGI
  * header contains a number of buckets that point to an inode, and each inode
  * record has a pointer to the next inode in the hash chain.  This
  * singly-linked list causes scaling problems in the iunlink remove function
  * because we must walk that list to find the inode that points to the inode
  * being removed from the unlinked hash bucket list.
  *
  * Hence we keep an in-memory double linked list to link each inode on an
  * unlinked list. Because there are 64 unlinked lists per AGI, keeping pointer
  * based lists would require having 64 list heads in the perag, one for each
  * list. This is expensive in terms of memory (think millions of AGs) and cache
  * misses on lookups. Instead, use the fact that inodes on the unlinked list
  * must be referenced at the VFS level to keep them on the list and hence we
  * have an existence guarantee for inodes on the unlinked list.
  *
  * Given we have an existence guarantee, we can use lockless inode cache lookups
  * to resolve aginos to xfs inodes. This means we only need 8 bytes per inode
  * for the double linked unlinked list, and we don't need any extra locking to
  * keep the list safe as all manipulations are done under the AGI buffer lock.
  * Keeping the list up to date does not require memory allocation, just finding
  * the XFS inode and updating the next/prev unlinked list aginos.
  */
 
 /*
  * Find an inode on the unlinked list. This does not take references to the
  * inode as we have existence guarantees by holding the AGI buffer lock and that
  * only unlinked, referenced inodes can be on the unlinked inode list.  If we
  * don't find the inode in cache, then let the caller handle the situation.
  */
 static struct xfs_inode *
 xfs_iunlink_lookup(
     struct xfs_perag    *pag,
     xfs_agino_t     agino)
 {
     struct xfs_inode    *ip;
 
     rcu_read_lock();
     ip = radix_tree_lookup(&pag->pag_ici_root, agino);
 
     /*
      * Inode not in memory or in RCU freeing limbo should not happen.
      * Warn about this and let the caller handle the failure.
      */
     if (WARN_ON_ONCE(!ip || !ip->i_ino)) {
         rcu_read_unlock();
         return NULL;
     }
     ASSERT(!xfs_iflags_test(ip, XFS_IRECLAIMABLE | XFS_IRECLAIM));
     rcu_read_unlock();
     return ip;
 }
 
 /* Update the prev pointer of the next agino. */
 static int
 xfs_iunlink_update_backref(
     struct xfs_perag    *pag,
     xfs_agino_t     prev_agino,
     xfs_agino_t     next_agino)
 {
     struct xfs_inode    *ip;
 
     /* No update necessary if we are at the end of the list. */
     if (next_agino == NULLAGINO)
         return 0;
 
     ip = xfs_iunlink_lookup(pag, next_agino);
     if (!ip)
         return -EFSCORRUPTED;
     ip->i_prev_unlinked = prev_agino;
     return 0;
 }
 
 /*
  * Point the AGI unlinked bucket at an inode and log the results.  The caller
  * is responsible for validating the old value.
  */
 STATIC int
 xfs_iunlink_update_bucket(
     struct xfs_trans    *tp,
     struct xfs_perag    *pag,
     struct xfs_buf      *agibp,
     unsigned int        bucket_index,
     xfs_agino_t     new_agino)
 {
     struct xfs_agi      *agi = agibp->b_addr;
     xfs_agino_t     old_value;
     int         offset;
 
     ASSERT(xfs_verify_agino_or_null(pag, new_agino));
 
     old_value = be32_to_cpu(agi->agi_unlinked[bucket_index]);
     trace_xfs_iunlink_update_bucket(tp->t_mountp, pag->pag_agno, bucket_index,
             old_value, new_agino);
 
     /*
      * We should never find the head of the list already set to the value
      * passed in because either we're adding or removing ourselves from the
      * head of the list.
      */
     if (old_value == new_agino) {
         xfs_buf_mark_corrupt(agibp);
         return -EFSCORRUPTED;
     }
 
     agi->agi_unlinked[bucket_index] = cpu_to_be32(new_agino);
     offset = offsetof(struct xfs_agi, agi_unlinked) +
             (sizeof(xfs_agino_t) * bucket_index);
     xfs_trans_log_buf(tp, agibp, offset, offset + sizeof(xfs_agino_t) - 1);
     return 0;
 }
 
 static int
 xfs_iunlink_insert_inode(
     struct xfs_trans    *tp,
     struct xfs_perag    *pag,
     struct xfs_buf      *agibp,
     struct xfs_inode    *ip)
 {
     struct xfs_mount    *mp = tp->t_mountp;
     struct xfs_agi      *agi = agibp->b_addr;
     xfs_agino_t     next_agino;
     xfs_agino_t     agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
     short           bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
     int         error;
 
     /*
      * Get the index into the agi hash table for the list this inode will
      * go on.  Make sure the pointer isn't garbage and that this inode
      * isn't already on the list.
      */
     next_agino = be32_to_cpu(agi->agi_unlinked[bucket_index]);
     if (next_agino == agino ||
         !xfs_verify_agino_or_null(pag, next_agino)) {
         xfs_buf_mark_corrupt(agibp);
         return -EFSCORRUPTED;
     }
 
     /*
      * Update the prev pointer in the next inode to point back to this
      * inode.
      */
     error = xfs_iunlink_update_backref(pag, agino, next_agino);
     if (error)
         return error;
 
     if (next_agino != NULLAGINO) {
         /*
          * There is already another inode in the bucket, so point this
          * inode to the current head of the list.
          */
         error = xfs_iunlink_log_inode(tp, ip, pag, next_agino);
         if (error)
             return error;
         ip->i_next_unlinked = next_agino;
     }
 
     /* Point the head of the list to point to this inode. */
     return xfs_iunlink_update_bucket(tp, pag, agibp, bucket_index, agino);
 }
 
 /*
  * This is called when the inode's link count has gone to 0 or we are creating
  * a tmpfile via O_TMPFILE.  The inode @ip must have nlink == 0.
  *
  * We place the on-disk inode on a list in the AGI.  It will be pulled from this
  * list when the inode is freed.
  */
 STATIC int
 xfs_iunlink(
     struct xfs_trans    *tp,
     struct xfs_inode    *ip)
 {
     struct xfs_mount    *mp = tp->t_mountp;
     struct xfs_perag    *pag;
     struct xfs_buf      *agibp;
     int         error;
 
     ASSERT(VFS_I(ip)->i_nlink == 0);
     ASSERT(VFS_I(ip)->i_mode != 0);
     trace_xfs_iunlink(ip);
 
     pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
 
     /* Get the agi buffer first.  It ensures lock ordering on the list. */
     error = xfs_read_agi(pag, tp, &agibp);
     if (error)
         goto out;
 
     error = xfs_iunlink_insert_inode(tp, pag, agibp, ip);
 out:
     xfs_perag_put(pag);
     return error;
 }
 
 static int
 xfs_iunlink_remove_inode(
     struct xfs_trans    *tp,
     struct xfs_perag    *pag,
     struct xfs_buf      *agibp,
     struct xfs_inode    *ip)
 {
     struct xfs_mount    *mp = tp->t_mountp;
     struct xfs_agi      *agi = agibp->b_addr;
     xfs_agino_t     agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
     xfs_agino_t     head_agino;
     short           bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
     int         error;
 
     trace_xfs_iunlink_remove(ip);
 
     /*
      * Get the index into the agi hash table for the list this inode will
      * go on.  Make sure the head pointer isn't garbage.
      */
     head_agino = be32_to_cpu(agi->agi_unlinked[bucket_index]);
     if (!xfs_verify_agino(pag, head_agino)) {
         XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
                 agi, sizeof(*agi));
         return -EFSCORRUPTED;
     }
 
     /*
      * Set our inode's next_unlinked pointer to NULL and then return
      * the old pointer value so that we can update whatever was previous
      * to us in the list to point to whatever was next in the list.
      */
     error = xfs_iunlink_log_inode(tp, ip, pag, NULLAGINO);
     if (error)
         return error;
 
     /*
      * Update the prev pointer in the next inode to point back to previous
      * inode in the chain.
      */
     error = xfs_iunlink_update_backref(pag, ip->i_prev_unlinked,
             ip->i_next_unlinked);
     if (error)
         return error;
 
     if (head_agino != agino) {
         struct xfs_inode    *prev_ip;
 
         prev_ip = xfs_iunlink_lookup(pag, ip->i_prev_unlinked);
         if (!prev_ip)
             return -EFSCORRUPTED;
 
         error = xfs_iunlink_log_inode(tp, prev_ip, pag,
                 ip->i_next_unlinked);
         prev_ip->i_next_unlinked = ip->i_next_unlinked;
     } else {
         /* Point the head of the list to the next unlinked inode. */
         error = xfs_iunlink_update_bucket(tp, pag, agibp, bucket_index,
                 ip->i_next_unlinked);
     }
 
     ip->i_next_unlinked = NULLAGINO;
     ip->i_prev_unlinked = NULLAGINO;
     return error;
 }
 
 /*
  * Pull the on-disk inode from the AGI unlinked list.
  */
 STATIC int
 xfs_iunlink_remove(
     struct xfs_trans    *tp,
     struct xfs_perag    *pag,
     struct xfs_inode    *ip)
 {
     struct xfs_buf      *agibp;
     int         error;
 
     trace_xfs_iunlink_remove(ip);
 
     /* Get the agi buffer first.  It ensures lock ordering on the list. */
     error = xfs_read_agi(pag, tp, &agibp);
     if (error)
         return error;
 
     return xfs_iunlink_remove_inode(tp, pag, agibp, ip);
 }
 
 /*
  * Look up the inode number specified and if it is not already marked XFS_ISTALE
  * mark it stale. We should only find clean inodes in this lookup that aren't
  * already stale.
  */
 static void
 xfs_ifree_mark_inode_stale(
     struct xfs_perag    *pag,
     struct xfs_inode    *free_ip,
     xfs_ino_t       inum)
 {
     struct xfs_mount    *mp = pag->pag_mount;
     struct xfs_inode_log_item *iip;
     struct xfs_inode    *ip;
 
 retry:
     rcu_read_lock();
     ip = radix_tree_lookup(&pag->pag_ici_root, XFS_INO_TO_AGINO(mp, inum));
 
     /* Inode not in memory, nothing to do */
     if (!ip) {
         rcu_read_unlock();
         return;
     }
 
     /*
      * because this is an RCU protected lookup, we could find a recently
      * freed or even reallocated inode during the lookup. We need to check
      * under the i_flags_lock for a valid inode here. Skip it if it is not
      * valid, the wrong inode or stale.
      */
     spin_lock(&ip->i_flags_lock);
     if (ip->i_ino != inum || __xfs_iflags_test(ip, XFS_ISTALE))
         goto out_iflags_unlock;
 
     /*
      * Don't try to lock/unlock the current inode, but we _cannot_ skip the
      * other inodes that we did not find in the list attached to the buffer
      * and are not already marked stale. If we can't lock it, back off and
      * retry.
      */
     if (ip != free_ip) {
         if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL)) {
             spin_unlock(&ip->i_flags_lock);
             rcu_read_unlock();
             delay(1);
             goto retry;
         }
     }
     ip->i_flags |= XFS_ISTALE;
 
     /*
      * If the inode is flushing, it is already attached to the buffer.  All
      * we needed to do here is mark the inode stale so buffer IO completion
      * will remove it from the AIL.
      */
     iip = ip->i_itemp;
     if (__xfs_iflags_test(ip, XFS_IFLUSHING)) {
         ASSERT(!list_empty(&iip->ili_item.li_bio_list));
         ASSERT(iip->ili_last_fields);
         goto out_iunlock;
     }
 
     /*
      * Inodes not attached to the buffer can be released immediately.
      * Everything else has to go through xfs_iflush_abort() on journal
      * commit as the flock synchronises removal of the inode from the
      * cluster buffer against inode reclaim.
      */
     if (!iip || list_empty(&iip->ili_item.li_bio_list))
         goto out_iunlock;
 
     __xfs_iflags_set(ip, XFS_IFLUSHING);
     spin_unlock(&ip->i_flags_lock);
     rcu_read_unlock();
 
     /* we have a dirty inode in memory that has not yet been flushed. */
     spin_lock(&iip->ili_lock);
     iip->ili_last_fields = iip->ili_fields;
     iip->ili_fields = 0;
     iip->ili_fsync_fields = 0;
     spin_unlock(&iip->ili_lock);
     ASSERT(iip->ili_last_fields);
 
     if (ip != free_ip)
         xfs_iunlock(ip, XFS_ILOCK_EXCL);
     return;
 
 out_iunlock:
     if (ip != free_ip)
         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 out_iflags_unlock:
     spin_unlock(&ip->i_flags_lock);
     rcu_read_unlock();
 }
 
 /*
  * A big issue when freeing the inode cluster is that we _cannot_ skip any
  * inodes that are in memory - they all must be marked stale and attached to
  * the cluster buffer.
  */
 static int
 xfs_ifree_cluster(
     struct xfs_trans    *tp,
     struct xfs_perag    *pag,
     struct xfs_inode    *free_ip,
     struct xfs_icluster *xic)
 {
     struct xfs_mount    *mp = free_ip->i_mount;
     struct xfs_ino_geometry *igeo = M_IGEO(mp);
     struct xfs_buf      *bp;
     xfs_daddr_t     blkno;
     xfs_ino_t       inum = xic->first_ino;
     int         nbufs;
     int         i, j;
     int         ioffset;
     int         error;
 
     nbufs = igeo->ialloc_blks / igeo->blocks_per_cluster;
 
     for (j = 0; j < nbufs; j++, inum += igeo->inodes_per_cluster) {
         /*
          * The allocation bitmap tells us which inodes of the chunk were
          * physically allocated. Skip the cluster if an inode falls into
          * a sparse region.
          */
         ioffset = inum - xic->first_ino;
         if ((xic->alloc & XFS_INOBT_MASK(ioffset)) == 0) {
             ASSERT(ioffset % igeo->inodes_per_cluster == 0);
             continue;
         }
 
         blkno = XFS_AGB_TO_DADDR(mp, XFS_INO_TO_AGNO(mp, inum),
                      XFS_INO_TO_AGBNO(mp, inum));
 
         /*
          * We obtain and lock the backing buffer first in the process
          * here to ensure dirty inodes attached to the buffer remain in
          * the flushing state while we mark them stale.
          *
          * If we scan the in-memory inodes first, then buffer IO can
          * complete before we get a lock on it, and hence we may fail
          * to mark all the active inodes on the buffer stale.
          */
         error = xfs_trans_get_buf(tp, mp->m_ddev_targp, blkno,
                 mp->m_bsize * igeo->blocks_per_cluster,
                 XBF_UNMAPPED, &bp);
         if (error)
             return error;
 
         /*
          * This buffer may not have been correctly initialised as we
          * didn't read it from disk. That's not important because we are
          * only using to mark the buffer as stale in the log, and to
          * attach stale cached inodes on it. That means it will never be
          * dispatched for IO. If it is, we want to know about it, and we
          * want it to fail. We can acheive this by adding a write
          * verifier to the buffer.
          */
         bp->b_ops = &xfs_inode_buf_ops;
 
         /*
          * Now we need to set all the cached clean inodes as XFS_ISTALE,
          * too. This requires lookups, and will skip inodes that we've
          * already marked XFS_ISTALE.
          */
         for (i = 0; i < igeo->inodes_per_cluster; i++)
             xfs_ifree_mark_inode_stale(pag, free_ip, inum + i);
 
         xfs_trans_stale_inode_buf(tp, bp);
         xfs_trans_binval(tp, bp);
     }
     return 0;
 }
 
 /*
  * This is called to return an inode to the inode free list.  The inode should
  * already be truncated to 0 length and have no pages associated with it.  This
  * routine also assumes that the inode is already a part of the transaction.
  *
  * The on-disk copy of the inode will have been added to the list of unlinked
  * inodes in the AGI. We need to remove the inode from that list atomically with
  * respect to freeing it here.
  */
 int
 xfs_ifree(
     struct xfs_trans    *tp,
     struct xfs_inode    *ip)
 {
     struct xfs_mount    *mp = ip->i_mount;
     struct xfs_perag    *pag;
     struct xfs_icluster xic = { 0 };
     struct xfs_inode_log_item *iip = ip->i_itemp;
     int         error;
 
     ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
     ASSERT(VFS_I(ip)->i_nlink == 0);
     ASSERT(ip->i_df.if_nextents == 0);
     ASSERT(ip->i_disk_size == 0 || !S_ISREG(VFS_I(ip)->i_mode));
     ASSERT(ip->i_nblocks == 0);
 
     pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
 
     /*
      * Free the inode first so that we guarantee that the AGI lock is going
      * to be taken before we remove the inode from the unlinked list. This
      * makes the AGI lock -> unlinked list modification order the same as
      * used in O_TMPFILE creation.
      */
     error = xfs_difree(tp, pag, ip->i_ino, &xic);
     if (error)
         goto out;
 
     error = xfs_iunlink_remove(tp, pag, ip);
     if (error)
         goto out;
 
     /*
      * Free any local-format data sitting around before we reset the
      * data fork to extents format.  Note that the attr fork data has
      * already been freed by xfs_attr_inactive.
      */
     if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL) {
         kmem_free(ip->i_df.if_u1.if_data);
         ip->i_df.if_u1.if_data = NULL;
         ip->i_df.if_bytes = 0;
     }
 
     VFS_I(ip)->i_mode = 0;      /* mark incore inode as free */
     ip->i_diflags = 0;
     ip->i_diflags2 = mp->m_ino_geo.new_diflags2;
     ip->i_forkoff = 0;      /* mark the attr fork not in use */
     ip->i_df.if_format = XFS_DINODE_FMT_EXTENTS;
     if (xfs_iflags_test(ip, XFS_IPRESERVE_DM_FIELDS))
         xfs_iflags_clear(ip, XFS_IPRESERVE_DM_FIELDS);
 
     /* Don't attempt to replay owner changes for a deleted inode */
     spin_lock(&iip->ili_lock);
     iip->ili_fields &= ~(XFS_ILOG_AOWNER | XFS_ILOG_DOWNER);
     spin_unlock(&iip->ili_lock);
 
     /*
      * Bump the generation count so no one will be confused
      * by reincarnations of this inode.
      */
     VFS_I(ip)->i_generation++;
     xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 
     if (xic.deleted)
         error = xfs_ifree_cluster(tp, pag, ip, &xic);
 out:
     xfs_perag_put(pag);
     return error;
 }
 
 /*
  * This is called to unpin an inode.  The caller must have the inode locked
  * in at least shared mode so that the buffer cannot be subsequently pinned
  * once someone is waiting for it to be unpinned.
  */
 static void
 xfs_iunpin(
     struct xfs_inode    *ip)
 {
     ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
 
     trace_xfs_inode_unpin_nowait(ip, _RET_IP_);
 
     /* Give the log a push to start the unpinning I/O */
     xfs_log_force_seq(ip->i_mount, ip->i_itemp->ili_commit_seq, 0, NULL);
 
 }
 
 static void
 __xfs_iunpin_wait(
     struct xfs_inode    *ip)
 {
     wait_queue_head_t *wq = bit_waitqueue(&ip->i_flags, __XFS_IPINNED_BIT);
     DEFINE_WAIT_BIT(wait, &ip->i_flags, __XFS_IPINNED_BIT);
 
     xfs_iunpin(ip);
 
     do {
         prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
         if (xfs_ipincount(ip))
             io_schedule();
     } while (xfs_ipincount(ip));
     finish_wait(wq, &wait.wq_entry);
 }
 
 void
 xfs_iunpin_wait(
     struct xfs_inode    *ip)
 {
     if (xfs_ipincount(ip))
         __xfs_iunpin_wait(ip);
 }
 
 /*
  * Removing an inode from the namespace involves removing the directory entry
  * and dropping the link count on the inode. Removing the directory entry can
  * result in locking an AGF (directory blocks were freed) and removing a link
  * count can result in placing the inode on an unlinked list which results in
  * locking an AGI.
  *
  * The big problem here is that we have an ordering constraint on AGF and AGI
  * locking - inode allocation locks the AGI, then can allocate a new extent for
  * new inodes, locking the AGF after the AGI. Similarly, freeing the inode
  * removes the inode from the unlinked list, requiring that we lock the AGI
  * first, and then freeing the inode can result in an inode chunk being freed
  * and hence freeing disk space requiring that we lock an AGF.
  *
  * Hence the ordering that is imposed by other parts of the code is AGI before
  * AGF. This means we cannot remove the directory entry before we drop the inode
  * reference count and put it on the unlinked list as this results in a lock
  * order of AGF then AGI, and this can deadlock against inode allocation and
  * freeing. Therefore we must drop the link counts before we remove the
  * directory entry.
  *
  * This is still safe from a transactional point of view - it is not until we
  * get to xfs_defer_finish() that we have the possibility of multiple
  * transactions in this operation. Hence as long as we remove the directory
  * entry and drop the link count in the first transaction of the remove
  * operation, there are no transactional constraints on the ordering here.
  */
 int
 xfs_remove(
     xfs_inode_t             *dp,
     struct xfs_name     *name,
     xfs_inode_t     *ip)
 {
     xfs_mount_t     *mp = dp->i_mount;
     xfs_trans_t             *tp = NULL;
     int         is_dir = S_ISDIR(VFS_I(ip)->i_mode);
     int         dontcare;
     int                     error = 0;
     uint            resblks;
 
     trace_xfs_remove(dp, name);
 
     if (xfs_is_shutdown(mp))
         return -EIO;
 
     error = xfs_qm_dqattach(dp);
     if (error)
         goto std_return;
 
     error = xfs_qm_dqattach(ip);
     if (error)
         goto std_return;
 
     /*
      * We try to get the real space reservation first, allowing for
      * directory btree deletion(s) implying possible bmap insert(s).  If we
      * can't get the space reservation then we use 0 instead, and avoid the
      * bmap btree insert(s) in the directory code by, if the bmap insert
      * tries to happen, instead trimming the LAST block from the directory.
      *
      * Ignore EDQUOT and ENOSPC being returned via nospace_error because
      * the directory code can handle a reservationless update and we don't
      * want to prevent a user from trying to free space by deleting things.
      */
     resblks = XFS_REMOVE_SPACE_RES(mp);
     error = xfs_trans_alloc_dir(dp, &M_RES(mp)->tr_remove, ip, &resblks,
             &tp, &dontcare);
     if (error) {
         ASSERT(error != -ENOSPC);
         goto std_return;
     }
 
     /*
      * If we're removing a directory perform some additional validation.
      */
     if (is_dir) {
         ASSERT(VFS_I(ip)->i_nlink >= 2);
         if (VFS_I(ip)->i_nlink != 2) {
             error = -ENOTEMPTY;
             goto out_trans_cancel;
         }
         if (!xfs_dir_isempty(ip)) {
             error = -ENOTEMPTY;
             goto out_trans_cancel;
         }
 
         /* Drop the link from ip's "..".  */
         error = xfs_droplink(tp, dp);
         if (error)
             goto out_trans_cancel;
 
         /* Drop the "." link from ip to self.  */
         error = xfs_droplink(tp, ip);
         if (error)
             goto out_trans_cancel;
 
         /*
          * Point the unlinked child directory's ".." entry to the root
          * directory to eliminate back-references to inodes that may
          * get freed before the child directory is closed.  If the fs
          * gets shrunk, this can lead to dirent inode validation errors.
          */
         if (dp->i_ino != tp->t_mountp->m_sb.sb_rootino) {
             error = xfs_dir_replace(tp, ip, &xfs_name_dotdot,
                     tp->t_mountp->m_sb.sb_rootino, 0);
             if (error)
                 return error;
         }
     } else {
         /*
          * When removing a non-directory we need to log the parent
          * inode here.  For a directory this is done implicitly
          * by the xfs_droplink call for the ".." entry.
          */
         xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
     }
     xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 
     /* Drop the link from dp to ip. */
     error = xfs_droplink(tp, ip);
     if (error)
         goto out_trans_cancel;
 
     error = xfs_dir_removename(tp, dp, name, ip->i_ino, resblks);
     if (error) {
         ASSERT(error != -ENOENT);
         goto out_trans_cancel;
     }
 
     /*
      * If this is a synchronous mount, make sure that the
      * remove transaction goes to disk before returning to
      * the user.
      */
     if (xfs_has_wsync(mp) || xfs_has_dirsync(mp))
         xfs_trans_set_sync(tp);
 
     error = xfs_trans_commit(tp);
     if (error)
         goto std_return;
 
     if (is_dir && xfs_inode_is_filestream(ip))
         xfs_filestream_deassociate(ip);
 
     return 0;
 
  out_trans_cancel:
     xfs_trans_cancel(tp);
  std_return:
     return error;
 }
 
 /*
  * Enter all inodes for a rename transaction into a sorted array.
  */
 #define __XFS_SORT_INODES   5
 STATIC void
 xfs_sort_for_rename(
     struct xfs_inode    *dp1,   /* in: old (source) directory inode */
     struct xfs_inode    *dp2,   /* in: new (target) directory inode */
     struct xfs_inode    *ip1,   /* in: inode of old entry */
     struct xfs_inode    *ip2,   /* in: inode of new entry */
     struct xfs_inode    *wip,   /* in: whiteout inode */
     struct xfs_inode    **i_tab,/* out: sorted array of inodes */
     int         *num_inodes)  /* in/out: inodes in array */
 {
     int         i, j;
 
     ASSERT(*num_inodes == __XFS_SORT_INODES);
     memset(i_tab, 0, *num_inodes * sizeof(struct xfs_inode *));
 
     /*
      * i_tab contains a list of pointers to inodes.  We initialize
      * the table here & we'll sort it.  We will then use it to
      * order the acquisition of the inode locks.
      *
      * Note that the table may contain duplicates.  e.g., dp1 == dp2.
      */
     i = 0;
     i_tab[i++] = dp1;
     i_tab[i++] = dp2;
     i_tab[i++] = ip1;
     if (ip2)
         i_tab[i++] = ip2;
     if (wip)
         i_tab[i++] = wip;
     *num_inodes = i;
 
     /*
      * Sort the elements via bubble sort.  (Remember, there are at
      * most 5 elements to sort, so this is adequate.)
      */
     for (i = 0; i < *num_inodes; i++) {
         for (j = 1; j < *num_inodes; j++) {
             if (i_tab[j]->i_ino < i_tab[j-1]->i_ino) {
                 struct xfs_inode *temp = i_tab[j];
                 i_tab[j] = i_tab[j-1];
                 i_tab[j-1] = temp;
             }
         }
     }
 }
 
 static int
 xfs_finish_rename(
     struct xfs_trans    *tp)
 {
     /*
      * If this is a synchronous mount, make sure that the rename transaction
      * goes to disk before returning to the user.
      */
     if (xfs_has_wsync(tp->t_mountp) || xfs_has_dirsync(tp->t_mountp))
         xfs_trans_set_sync(tp);
 
     return xfs_trans_commit(tp);
 }
 
 /*
  * xfs_cross_rename()
  *
  * responsible for handling RENAME_EXCHANGE flag in renameat2() syscall
  */
 STATIC int
 xfs_cross_rename(
     struct xfs_trans    *tp,
     struct xfs_inode    *dp1,
     struct xfs_name     *name1,
     struct xfs_inode    *ip1,
     struct xfs_inode    *dp2,
     struct xfs_name     *name2,
     struct xfs_inode    *ip2,
     int         spaceres)
 {
     int     error = 0;
     int     ip1_flags = 0;
     int     ip2_flags = 0;
     int     dp2_flags = 0;
 
     /* Swap inode number for dirent in first parent */
     error = xfs_dir_replace(tp, dp1, name1, ip2->i_ino, spaceres);
     if (error)
         goto out_trans_abort;
 
     /* Swap inode number for dirent in second parent */
     error = xfs_dir_replace(tp, dp2, name2, ip1->i_ino, spaceres);
     if (error)
         goto out_trans_abort;
 
     /*
      * If we're renaming one or more directories across different parents,
      * update the respective ".." entries (and link counts) to match the new
      * parents.
      */
     if (dp1 != dp2) {
         dp2_flags = XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;
 
         if (S_ISDIR(VFS_I(ip2)->i_mode)) {
             error = xfs_dir_replace(tp, ip2, &xfs_name_dotdot,
                         dp1->i_ino, spaceres);
             if (error)
                 goto out_trans_abort;
 
             /* transfer ip2 ".." reference to dp1 */
             if (!S_ISDIR(VFS_I(ip1)->i_mode)) {
                 error = xfs_droplink(tp, dp2);
                 if (error)
                     goto out_trans_abort;
                 xfs_bumplink(tp, dp1);
             }
 
             /*
              * Although ip1 isn't changed here, userspace needs
              * to be warned about the change, so that applications
              * relying on it (like backup ones), will properly
              * notify the change
              */
             ip1_flags |= XFS_ICHGTIME_CHG;
             ip2_flags |= XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;
         }
 
         if (S_ISDIR(VFS_I(ip1)->i_mode)) {
             error = xfs_dir_replace(tp, ip1, &xfs_name_dotdot,
                         dp2->i_ino, spaceres);
             if (error)
                 goto out_trans_abort;
 
             /* transfer ip1 ".." reference to dp2 */
             if (!S_ISDIR(VFS_I(ip2)->i_mode)) {
                 error = xfs_droplink(tp, dp1);
                 if (error)
                     goto out_trans_abort;
                 xfs_bumplink(tp, dp2);
             }
 
             /*
              * Although ip2 isn't changed here, userspace needs
              * to be warned about the change, so that applications
              * relying on it (like backup ones), will properly
              * notify the change
              */
             ip1_flags |= XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;
             ip2_flags |= XFS_ICHGTIME_CHG;
         }
     }
 
     if (ip1_flags) {
         xfs_trans_ichgtime(tp, ip1, ip1_flags);
         xfs_trans_log_inode(tp, ip1, XFS_ILOG_CORE);
     }
     if (ip2_flags) {
         xfs_trans_ichgtime(tp, ip2, ip2_flags);
         xfs_trans_log_inode(tp, ip2, XFS_ILOG_CORE);
     }
     if (dp2_flags) {
         xfs_trans_ichgtime(tp, dp2, dp2_flags);
         xfs_trans_log_inode(tp, dp2, XFS_ILOG_CORE);
     }
     xfs_trans_ichgtime(tp, dp1, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
     xfs_trans_log_inode(tp, dp1, XFS_ILOG_CORE);
     return xfs_finish_rename(tp);
 
 out_trans_abort:
     xfs_trans_cancel(tp);
     return error;
 }
 
 /*
  * xfs_rename_alloc_whiteout()
  *
  * Return a referenced, unlinked, unlocked inode that can be used as a
  * whiteout in a rename transaction. We use a tmpfile inode here so that if we
  * crash between allocating the inode and linking it into the rename transaction
  * recovery will free the inode and we won't leak it.
  */
 static int
 xfs_rename_alloc_whiteout(
     struct user_namespace   *mnt_userns,
     struct xfs_name     *src_name,
     struct xfs_inode    *dp,
     struct xfs_inode    **wip)
 {
     struct xfs_inode    *tmpfile;
     struct qstr     name;
     int         error;
 
     error = xfs_create_tmpfile(mnt_userns, dp, S_IFCHR | WHITEOUT_MODE,
                    &tmpfile);
     if (error)
         return error;
 
     name.name = src_name->name;
     name.len = src_name->len;
     error = xfs_inode_init_security(VFS_I(tmpfile), VFS_I(dp), &name);
     if (error) {
         xfs_finish_inode_setup(tmpfile);
         xfs_irele(tmpfile);
         return error;
     }
 
     /*
      * Prepare the tmpfile inode as if it were created through the VFS.
      * Complete the inode setup and flag it as linkable.  nlink is already
      * zero, so we can skip the drop_nlink.
      */
     xfs_setup_iops(tmpfile);
     xfs_finish_inode_setup(tmpfile);
     VFS_I(tmpfile)->i_state |= I_LINKABLE;
 
     *wip = tmpfile;
     return 0;
 }
 
 /*
  * xfs_rename
  */
 int
 xfs_rename(
     struct user_namespace   *mnt_userns,
     struct xfs_inode    *src_dp,
     struct xfs_name     *src_name,
     struct xfs_inode    *src_ip,
     struct xfs_inode    *target_dp,
     struct xfs_name     *target_name,
     struct xfs_inode    *target_ip,
     unsigned int        flags)
 {
     struct xfs_mount    *mp = src_dp->i_mount;
     struct xfs_trans    *tp;
     struct xfs_inode    *wip = NULL;        /* whiteout inode */
     struct xfs_inode    *inodes[__XFS_SORT_INODES];
     int         i;
     int         num_inodes = __XFS_SORT_INODES;
     bool            new_parent = (src_dp != target_dp);
     bool            src_is_directory = S_ISDIR(VFS_I(src_ip)->i_mode);
     int         spaceres;
     bool            retried = false;
     int         error, nospace_error = 0;
 
     trace_xfs_rename(src_dp, target_dp, src_name, target_name);
 
     if ((flags & RENAME_EXCHANGE) && !target_ip)
         return -EINVAL;
 
     /*
      * If we are doing a whiteout operation, allocate the whiteout inode
      * we will be placing at the target and ensure the type is set
      * appropriately.
      */
     if (flags & RENAME_WHITEOUT) {
         error = xfs_rename_alloc_whiteout(mnt_userns, src_name,
                           target_dp, &wip);
         if (error)
             return error;
 
         /* setup target dirent info as whiteout */
         src_name->type = XFS_DIR3_FT_CHRDEV;
     }
 
     xfs_sort_for_rename(src_dp, target_dp, src_ip, target_ip, wip,
                 inodes, &num_inodes);
 
 retry:
     nospace_error = 0;
     spaceres = XFS_RENAME_SPACE_RES(mp, target_name->len);
     error = xfs_trans_alloc(mp, &M_RES(mp)->tr_rename, spaceres, 0, 0, &tp);
     if (error == -ENOSPC) {
         nospace_error = error;
         spaceres = 0;
         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_rename, 0, 0, 0,
                 &tp);
     }
     if (error)
         goto out_release_wip;
 
     /*
      * Attach the dquots to the inodes
      */
     error = xfs_qm_vop_rename_dqattach(inodes);
     if (error)
         goto out_trans_cancel;
 
     /*
      * Lock all the participating inodes. Depending upon whether
      * the target_name exists in the target directory, and
      * whether the target directory is the same as the source
      * directory, we can lock from 2 to 4 inodes.
      */
     xfs_lock_inodes(inodes, num_inodes, XFS_ILOCK_EXCL);
 
     /*
      * Join all the inodes to the transaction. From this point on,
      * we can rely on either trans_commit or trans_cancel to unlock
      * them.
      */
     xfs_trans_ijoin(tp, src_dp, XFS_ILOCK_EXCL);
     if (new_parent)
         xfs_trans_ijoin(tp, target_dp, XFS_ILOCK_EXCL);
     xfs_trans_ijoin(tp, src_ip, XFS_ILOCK_EXCL);
     if (target_ip)
         xfs_trans_ijoin(tp, target_ip, XFS_ILOCK_EXCL);
     if (wip)
         xfs_trans_ijoin(tp, wip, XFS_ILOCK_EXCL);
 
     /*
      * If we are using project inheritance, we only allow renames
      * into our tree when the project IDs are the same; else the
      * tree quota mechanism would be circumvented.
      */
     if (unlikely((target_dp->i_diflags & XFS_DIFLAG_PROJINHERIT) &&
              target_dp->i_projid != src_ip->i_projid)) {
         error = -EXDEV;
         goto out_trans_cancel;
     }
 
     /* RENAME_EXCHANGE is unique from here on. */
     if (flags & RENAME_EXCHANGE)
         return xfs_cross_rename(tp, src_dp, src_name, src_ip,
                     target_dp, target_name, target_ip,
                     spaceres);
 
     /*
      * Try to reserve quota to handle an expansion of the target directory.
      * We'll allow the rename to continue in reservationless mode if we hit
      * a space usage constraint.  If we trigger reservationless mode, save
      * the errno if there isn't any free space in the target directory.
      */
     if (spaceres != 0) {
         error = xfs_trans_reserve_quota_nblks(tp, target_dp, spaceres,
                 0, false);
         if (error == -EDQUOT || error == -ENOSPC) {
             if (!retried) {
                 xfs_trans_cancel(tp);
                 xfs_blockgc_free_quota(target_dp, 0);
                 retried = true;
                 goto retry;
             }
 
             nospace_error = error;
             spaceres = 0;
             error = 0;
         }
         if (error)
             goto out_trans_cancel;
     }
 
     /*
      * Check for expected errors before we dirty the transaction
      * so we can return an error without a transaction abort.
      */
     if (target_ip == NULL) {
         /*
          * If there's no space reservation, check the entry will
          * fit before actually inserting it.
          */
         if (!spaceres) {
             error = xfs_dir_canenter(tp, target_dp, target_name);
             if (error)
                 goto out_trans_cancel;
         }
     } else {
         /*
          * If target exists and it's a directory, check that whether
          * it can be destroyed.
          */
         if (S_ISDIR(VFS_I(target_ip)->i_mode) &&
             (!xfs_dir_isempty(target_ip) ||
              (VFS_I(target_ip)->i_nlink > 2))) {
             error = -EEXIST;
             goto out_trans_cancel;
         }
     }
 
     /*
      * Lock the AGI buffers we need to handle bumping the nlink of the
      * whiteout inode off the unlinked list and to handle dropping the
      * nlink of the target inode.  Per locking order rules, do this in
      * increasing AG order and before directory block allocation tries to
      * grab AGFs because we grab AGIs before AGFs.
      *
      * The (vfs) caller must ensure that if src is a directory then
      * target_ip is either null or an empty directory.
      */
     for (i = 0; i < num_inodes && inodes[i] != NULL; i++) {
         if (inodes[i] == wip ||
             (inodes[i] == target_ip &&
              (VFS_I(target_ip)->i_nlink == 1 || src_is_directory))) {
             struct xfs_perag    *pag;
             struct xfs_buf      *bp;
 
             pag = xfs_perag_get(mp,
                     XFS_INO_TO_AGNO(mp, inodes[i]->i_ino));
             error = xfs_read_agi(pag, tp, &bp);
             xfs_perag_put(pag);
             if (error)
                 goto out_trans_cancel;
         }
     }
 
     /*
      * Directory entry creation below may acquire the AGF. Remove
      * the whiteout from the unlinked list first to preserve correct
      * AGI/AGF locking order. This dirties the transaction so failures
      * after this point will abort and log recovery will clean up the
      * mess.
      *
      * For whiteouts, we need to bump the link count on the whiteout
      * inode. After this point, we have a real link, clear the tmpfile
      * state flag from the inode so it doesn't accidentally get misused
      * in future.
      */
     if (wip) {
         struct xfs_perag    *pag;
 
         ASSERT(VFS_I(wip)->i_nlink == 0);
 
         pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, wip->i_ino));
         error = xfs_iunlink_remove(tp, pag, wip);
         xfs_perag_put(pag);
         if (error)
             goto out_trans_cancel;
 
         xfs_bumplink(tp, wip);
         VFS_I(wip)->i_state &= ~I_LINKABLE;
     }
 
     /*
      * Set up the target.
      */
     if (target_ip == NULL) {
         /*
          * If target does not exist and the rename crosses
          * directories, adjust the target directory link count
          * to account for the ".." reference from the new entry.
          */
         error = xfs_dir_createname(tp, target_dp, target_name,
                        src_ip->i_ino, spaceres);
         if (error)
             goto out_trans_cancel;
 
         xfs_trans_ichgtime(tp, target_dp,
                     XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 
         if (new_parent && src_is_directory) {
             xfs_bumplink(tp, target_dp);
         }
     } else { /* target_ip != NULL */
         /*
          * Link the source inode under the target name.
          * If the source inode is a directory and we are moving
          * it across directories, its ".." entry will be
          * inconsistent until we replace that down below.
          *
          * In case there is already an entry with the same
          * name at the destination directory, remove it first.
          */
         error = xfs_dir_replace(tp, target_dp, target_name,
                     src_ip->i_ino, spaceres);
         if (error)
             goto out_trans_cancel;
 
         xfs_trans_ichgtime(tp, target_dp,
                     XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 
         /*
          * Decrement the link count on the target since the target
          * dir no longer points to it.
          */
         error = xfs_droplink(tp, target_ip);
         if (error)
             goto out_trans_cancel;
 
         if (src_is_directory) {
             /*
              * Drop the link from the old "." entry.
              */
             error = xfs_droplink(tp, target_ip);
             if (error)
                 goto out_trans_cancel;
         }
     } /* target_ip != NULL */
 
     /*
      * Remove the source.
      */
     if (new_parent && src_is_directory) {
         /*
          * Rewrite the ".." entry to point to the new
          * directory.
          */
         error = xfs_dir_replace(tp, src_ip, &xfs_name_dotdot,
                     target_dp->i_ino, spaceres);
         ASSERT(error != -EEXIST);
         if (error)
             goto out_trans_cancel;
     }
 
     /*
      * We always want to hit the ctime on the source inode.
      *
      * This isn't strictly required by the standards since the source
      * inode isn't really being changed, but old unix file systems did
      * it and some incremental backup programs won't work without it.
      */
     xfs_trans_ichgtime(tp, src_ip, XFS_ICHGTIME_CHG);
     xfs_trans_log_inode(tp, src_ip, XFS_ILOG_CORE);
 
     /*
      * Adjust the link count on src_dp.  This is necessary when
      * renaming a directory, either within one parent when
      * the target existed, or across two parent directories.
      */
     if (src_is_directory && (new_parent || target_ip != NULL)) {
 
         /*
          * Decrement link count on src_directory since the
          * entry that's moved no longer points to it.
          */
         error = xfs_droplink(tp, src_dp);
         if (error)
             goto out_trans_cancel;
     }
 
     /*
      * For whiteouts, we only need to update the source dirent with the
      * inode number of the whiteout inode rather than removing it
      * altogether.
      */
     if (wip)
         error = xfs_dir_replace(tp, src_dp, src_name, wip->i_ino,
                     spaceres);
     else
         error = xfs_dir_removename(tp, src_dp, src_name, src_ip->i_ino,
                        spaceres);
 
     if (error)
         goto out_trans_cancel;
 
     xfs_trans_ichgtime(tp, src_dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
     xfs_trans_log_inode(tp, src_dp, XFS_ILOG_CORE);
     if (new_parent)
         xfs_trans_log_inode(tp, target_dp, XFS_ILOG_CORE);
 
     error = xfs_finish_rename(tp);
     if (wip)
         xfs_irele(wip);
     return error;
 
 out_trans_cancel:
     xfs_trans_cancel(tp);
 out_release_wip:
     if (wip)
         xfs_irele(wip);
     if (error == -ENOSPC && nospace_error)
         error = nospace_error;
     return error;
 }
 
 static int
 xfs_iflush(
     struct xfs_inode    *ip,
     struct xfs_buf      *bp)
 {
     struct xfs_inode_log_item *iip = ip->i_itemp;
     struct xfs_dinode   *dip;
     struct xfs_mount    *mp = ip->i_mount;
     int         error;
 
     ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
     ASSERT(xfs_iflags_test(ip, XFS_IFLUSHING));
     ASSERT(ip->i_df.if_format != XFS_DINODE_FMT_BTREE ||
            ip->i_df.if_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));
     ASSERT(iip->ili_item.li_buf == bp);
 
     dip = xfs_buf_offset(bp, ip->i_imap.im_boffset);
 
     /*
      * We don't flush the inode if any of the following checks fail, but we
      * do still update the log item and attach to the backing buffer as if
      * the flush happened. This is a formality to facilitate predictable
      * error handling as the caller will shutdown and fail the buffer.
      */
     error = -EFSCORRUPTED;
     if (XFS_TEST_ERROR(dip->di_magic != cpu_to_be16(XFS_DINODE_MAGIC),
                    mp, XFS_ERRTAG_IFLUSH_1)) {
         xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
             "%s: Bad inode %Lu magic number 0x%x, ptr "PTR_FMT,
             __func__, ip->i_ino, be16_to_cpu(dip->di_magic), dip);
         goto flush_out;
     }
     if (S_ISREG(VFS_I(ip)->i_mode)) {
         if (XFS_TEST_ERROR(
             ip->i_df.if_format != XFS_DINODE_FMT_EXTENTS &&
             ip->i_df.if_format != XFS_DINODE_FMT_BTREE,
             mp, XFS_ERRTAG_IFLUSH_3)) {
             xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
                 "%s: Bad regular inode %Lu, ptr "PTR_FMT,
                 __func__, ip->i_ino, ip);
             goto flush_out;
         }
     } else if (S_ISDIR(VFS_I(ip)->i_mode)) {
         if (XFS_TEST_ERROR(
             ip->i_df.if_format != XFS_DINODE_FMT_EXTENTS &&
             ip->i_df.if_format != XFS_DINODE_FMT_BTREE &&
             ip->i_df.if_format != XFS_DINODE_FMT_LOCAL,
             mp, XFS_ERRTAG_IFLUSH_4)) {
             xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
                 "%s: Bad directory inode %Lu, ptr "PTR_FMT,
                 __func__, ip->i_ino, ip);
             goto flush_out;
         }
     }
     if (XFS_TEST_ERROR(ip->i_df.if_nextents + xfs_ifork_nextents(&ip->i_af) >
                 ip->i_nblocks, mp, XFS_ERRTAG_IFLUSH_5)) {
         xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
             "%s: detected corrupt incore inode %llu, "
             "total extents = %llu nblocks = %lld, ptr "PTR_FMT,
             __func__, ip->i_ino,
             ip->i_df.if_nextents + xfs_ifork_nextents(&ip->i_af),
             ip->i_nblocks, ip);
         goto flush_out;
     }
     if (XFS_TEST_ERROR(ip->i_forkoff > mp->m_sb.sb_inodesize,
                 mp, XFS_ERRTAG_IFLUSH_6)) {
         xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
             "%s: bad inode %Lu, forkoff 0x%x, ptr "PTR_FMT,
             __func__, ip->i_ino, ip->i_forkoff, ip);
         goto flush_out;
     }
 
     /*
      * Inode item log recovery for v2 inodes are dependent on the flushiter
      * count for correct sequencing.  We bump the flush iteration count so
      * we can detect flushes which postdate a log record during recovery.
      * This is redundant as we now log every change and hence this can't
      * happen but we need to still do it to ensure backwards compatibility
      * with old kernels that predate logging all inode changes.
      */
     if (!xfs_has_v3inodes(mp))
         ip->i_flushiter++;
 
     /*
      * If there are inline format data / attr forks attached to this inode,
      * make sure they are not corrupt.
      */
     if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL &&
         xfs_ifork_verify_local_data(ip))
         goto flush_out;
     if (xfs_inode_has_attr_fork(ip) &&
         ip->i_af.if_format == XFS_DINODE_FMT_LOCAL &&
         xfs_ifork_verify_local_attr(ip))
         goto flush_out;
 
     /*
      * Copy the dirty parts of the inode into the on-disk inode.  We always
      * copy out the core of the inode, because if the inode is dirty at all
      * the core must be.
      */
     xfs_inode_to_disk(ip, dip, iip->ili_item.li_lsn);
 
     /* Wrap, we never let the log put out DI_MAX_FLUSH */
     if (!xfs_has_v3inodes(mp)) {
         if (ip->i_flushiter == DI_MAX_FLUSH)
             ip->i_flushiter = 0;
     }
 
     xfs_iflush_fork(ip, dip, iip, XFS_DATA_FORK);
     if (xfs_inode_has_attr_fork(ip))
         xfs_iflush_fork(ip, dip, iip, XFS_ATTR_FORK);
 
     /*
      * We've recorded everything logged in the inode, so we'd like to clear
      * the ili_fields bits so we don't log and flush things unnecessarily.
      * However, we can't stop logging all this information until the data
      * we've copied into the disk buffer is written to disk.  If we did we
      * might overwrite the copy of the inode in the log with all the data
      * after re-logging only part of it, and in the face of a crash we
      * wouldn't have all the data we need to recover.
      *
      * What we do is move the bits to the ili_last_fields field.  When
      * logging the inode, these bits are moved back to the ili_fields field.
      * In the xfs_buf_inode_iodone() routine we clear ili_last_fields, since
      * we know that the information those bits represent is permanently on
      * disk.  As long as the flush completes before the inode is logged
      * again, then both ili_fields and ili_last_fields will be cleared.
      */
     error = 0;
 flush_out:
     spin_lock(&iip->ili_lock);
     iip->ili_last_fields = iip->ili_fields;
     iip->ili_fields = 0;
     iip->ili_fsync_fields = 0;
     spin_unlock(&iip->ili_lock);
 
     /*
      * Store the current LSN of the inode so that we can tell whether the
      * item has moved in the AIL from xfs_buf_inode_iodone().
      */
     xfs_trans_ail_copy_lsn(mp->m_ail, &iip->ili_flush_lsn,
                 &iip->ili_item.li_lsn);
 
     /* generate the checksum. */
     xfs_dinode_calc_crc(mp, dip);
     return error;
 }
 
 /*
  * Non-blocking flush of dirty inode metadata into the backing buffer.
  *
  * The caller must have a reference to the inode and hold the cluster buffer
  * locked. The function will walk across all the inodes on the cluster buffer it
  * can find and lock without blocking, and flush them to the cluster buffer.
  *
  * On successful flushing of at least one inode, the caller must write out the
  * buffer and release it. If no inodes are flushed, -EAGAIN will be returned and
  * the caller needs to release the buffer. On failure, the filesystem will be
  * shut down, the buffer will have been unlocked and released, and EFSCORRUPTED
  * will be returned.
  */
 int
 xfs_iflush_cluster(
     struct xfs_buf      *bp)
 {
     struct xfs_mount    *mp = bp->b_mount;
     struct xfs_log_item *lip, *n;
     struct xfs_inode    *ip;
     struct xfs_inode_log_item *iip;
     int         clcount = 0;
     int         error = 0;
 
     /*
      * We must use the safe variant here as on shutdown xfs_iflush_abort()
      * will remove itself from the list.
      */
     list_for_each_entry_safe(lip, n, &bp->b_li_list, li_bio_list) {
         iip = (struct xfs_inode_log_item *)lip;
         ip = iip->ili_inode;
 
         /*
          * Quick and dirty check to avoid locks if possible.
          */
         if (__xfs_iflags_test(ip, XFS_IRECLAIM | XFS_IFLUSHING))
             continue;
         if (xfs_ipincount(ip))
             continue;
 
         /*
          * The inode is still attached to the buffer, which means it is
          * dirty but reclaim might try to grab it. Check carefully for
          * that, and grab the ilock while still holding the i_flags_lock
          * to guarantee reclaim will not be able to reclaim this inode
          * once we drop the i_flags_lock.
          */
         spin_lock(&ip->i_flags_lock);
         ASSERT(!__xfs_iflags_test(ip, XFS_ISTALE));
         if (__xfs_iflags_test(ip, XFS_IRECLAIM | XFS_IFLUSHING)) {
             spin_unlock(&ip->i_flags_lock);
             continue;
         }
 
         /*
          * ILOCK will pin the inode against reclaim and prevent
          * concurrent transactions modifying the inode while we are
          * flushing the inode. If we get the lock, set the flushing
          * state before we drop the i_flags_lock.
          */
         if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED)) {
             spin_unlock(&ip->i_flags_lock);
             continue;
         }
         __xfs_iflags_set(ip, XFS_IFLUSHING);
         spin_unlock(&ip->i_flags_lock);
 
         /*
          * Abort flushing this inode if we are shut down because the
          * inode may not currently be in the AIL. This can occur when
          * log I/O failure unpins the inode without inserting into the
          * AIL, leaving a dirty/unpinned inode attached to the buffer
          * that otherwise looks like it should be flushed.
          */
         if (xlog_is_shutdown(mp->m_log)) {
             xfs_iunpin_wait(ip);
             xfs_iflush_abort(ip);
             xfs_iunlock(ip, XFS_ILOCK_SHARED);
             error = -EIO;
             continue;
         }
 
         /* don't block waiting on a log force to unpin dirty inodes */
         if (xfs_ipincount(ip)) {
             xfs_iflags_clear(ip, XFS_IFLUSHING);
             xfs_iunlock(ip, XFS_ILOCK_SHARED);
             continue;
         }
 
         if (!xfs_inode_clean(ip))
             error = xfs_iflush(ip, bp);
         else
             xfs_iflags_clear(ip, XFS_IFLUSHING);
         xfs_iunlock(ip, XFS_ILOCK_SHARED);
         if (error)
             break;
         clcount++;
     }
 
     if (error) {
         /*
          * Shutdown first so we kill the log before we release this
          * buffer. If it is an INODE_ALLOC buffer and pins the tail
          * of the log, failing it before the _log_ is shut down can
          * result in the log tail being moved forward in the journal
          * on disk because log writes can still be taking place. Hence
          * unpinning the tail will allow the ICREATE intent to be
          * removed from the log an recovery will fail with uninitialised
          * inode cluster buffers.
          */
         xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
         bp->b_flags |= XBF_ASYNC;
         xfs_buf_ioend_fail(bp);
         return error;
     }
 
     if (!clcount)
         return -EAGAIN;
 
     XFS_STATS_INC(mp, xs_icluster_flushcnt);
     XFS_STATS_ADD(mp, xs_icluster_flushinode, clcount);
     return 0;
 
 }
 
 /* Release an inode. */
 void
 xfs_irele(
     struct xfs_inode    *ip)
 {
     trace_xfs_irele(ip, _RET_IP_);
     iput(VFS_I(ip));
 }
 
 /*
  * Ensure all commited transactions touching the inode are written to the log.
  */
 int
 xfs_log_force_inode(
     struct xfs_inode    *ip)
 {
     xfs_csn_t       seq = 0;
 
     xfs_ilock(ip, XFS_ILOCK_SHARED);
     if (xfs_ipincount(ip))
         seq = ip->i_itemp->ili_commit_seq;
     xfs_iunlock(ip, XFS_ILOCK_SHARED);
 
     if (!seq)
         return 0;
     return xfs_log_force_seq(ip->i_mount, seq, XFS_LOG_SYNC, NULL);
 }
 
 /*
  * Grab the exclusive iolock for a data copy from src to dest, making sure to
  * abide vfs locking order (lowest pointer value goes first) and breaking the
  * layout leases before proceeding.  The loop is needed because we cannot call
  * the blocking break_layout() with the iolocks held, and therefore have to
  * back out both locks.
  */
 static int
 xfs_iolock_two_inodes_and_break_layout(
     struct inode        *src,
     struct inode        *dest)
 {
     int         error;
 
     if (src > dest)
         swap(src, dest);
 
 retry:
     /* Wait to break both inodes' layouts before we start locking. */
     error = break_layout(src, true);
     if (error)
         return error;
     if (src != dest) {
         error = break_layout(dest, true);
         if (error)
             return error;
     }
 
     /* Lock one inode and make sure nobody got in and leased it. */
     inode_lock(src);
     error = break_layout(src, false);
     if (error) {
         inode_unlock(src);
         if (error == -EWOULDBLOCK)
             goto retry;
         return error;
     }
 
     if (src == dest)
         return 0;
 
     /* Lock the other inode and make sure nobody got in and leased it. */
     inode_lock_nested(dest, I_MUTEX_NONDIR2);
     error = break_layout(dest, false);
     if (error) {
         inode_unlock(src);
         inode_unlock(dest);
         if (error == -EWOULDBLOCK)
             goto retry;
         return error;
     }
 
     return 0;
 }
 
 static int
 xfs_mmaplock_two_inodes_and_break_dax_layout(
     struct xfs_inode    *ip1,
     struct xfs_inode    *ip2)
 {
     int         error;
     bool            retry;
     struct page     *page;
 
     if (ip1->i_ino > ip2->i_ino)
         swap(ip1, ip2);
 
 again:
     retry = false;
     /* Lock the first inode */
     xfs_ilock(ip1, XFS_MMAPLOCK_EXCL);
     error = xfs_break_dax_layouts(VFS_I(ip1), &retry);
     if (error || retry) {
         xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL);
         if (error == 0 && retry)
             goto again;
         return error;
     }
 
     if (ip1 == ip2)
         return 0;
 
     /* Nested lock the second inode */
     xfs_ilock(ip2, xfs_lock_inumorder(XFS_MMAPLOCK_EXCL, 1));
     /*
      * We cannot use xfs_break_dax_layouts() directly here because it may
      * need to unlock & lock the XFS_MMAPLOCK_EXCL which is not suitable
      * for this nested lock case.
      */
     page = dax_layout_busy_page(VFS_I(ip2)->i_mapping);
     if (page && page_ref_count(page) != 1) {
         xfs_iunlock(ip2, XFS_MMAPLOCK_EXCL);
         xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL);
         goto again;
     }
 
     return 0;
 }
 
 /*
  * Lock two inodes so that userspace cannot initiate I/O via file syscalls or
  * mmap activity.
  */
 int
 xfs_ilock2_io_mmap(
     struct xfs_inode    *ip1,
     struct xfs_inode    *ip2)
 {
     int         ret;
 
     ret = xfs_iolock_two_inodes_and_break_layout(VFS_I(ip1), VFS_I(ip2));
     if (ret)
         return ret;
 
     if (IS_DAX(VFS_I(ip1)) && IS_DAX(VFS_I(ip2))) {
         ret = xfs_mmaplock_two_inodes_and_break_dax_layout(ip1, ip2);
         if (ret) {
             inode_unlock(VFS_I(ip2));
             if (ip1 != ip2)
                 inode_unlock(VFS_I(ip1));
             return ret;
         }
     } else
         filemap_invalidate_lock_two(VFS_I(ip1)->i_mapping,
                         VFS_I(ip2)->i_mapping);
 
     return 0;
 }
 
 /* Unlock both inodes to allow IO and mmap activity. */
 void
 xfs_iunlock2_io_mmap(
     struct xfs_inode    *ip1,
     struct xfs_inode    *ip2)
 {
     if (IS_DAX(VFS_I(ip1)) && IS_DAX(VFS_I(ip2))) {
         xfs_iunlock(ip2, XFS_MMAPLOCK_EXCL);
         if (ip1 != ip2)
             xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL);
     } else
         filemap_invalidate_unlock_two(VFS_I(ip1)->i_mapping,
                           VFS_I(ip2)->i_mapping);
 
     inode_unlock(VFS_I(ip2));
     if (ip1 != ip2)
         inode_unlock(VFS_I(ip1));
 }