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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) 2000-2005 Silicon Graphics, Inc.
  * All Rights Reserved.
  */
 #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_inode.h"
 #include "xfs_trans.h"
 #include "xfs_inode_item.h"
 #include "xfs_bmap.h"
 #include "xfs_bmap_util.h"
 #include "xfs_dir2.h"
 #include "xfs_dir2_priv.h"
 #include "xfs_ioctl.h"
 #include "xfs_trace.h"
 #include "xfs_log.h"
 #include "xfs_icache.h"
 #include "xfs_pnfs.h"
 #include "xfs_iomap.h"
 #include "xfs_reflink.h"
 
 #include <linux/dax.h>
 #include <linux/falloc.h>
 #include <linux/backing-dev.h>
 #include <linux/mman.h>
 #include <linux/fadvise.h>
 #include <linux/mount.h>
 
 static const struct vm_operations_struct xfs_file_vm_ops;
 
 /*
  * Decide if the given file range is aligned to the size of the fundamental
  * allocation unit for the file.
  */
 static bool
 xfs_is_falloc_aligned(
     struct xfs_inode    *ip,
     loff_t          pos,
     long long int       len)
 {
     struct xfs_mount    *mp = ip->i_mount;
     uint64_t        mask;
 
     if (XFS_IS_REALTIME_INODE(ip)) {
         if (!is_power_of_2(mp->m_sb.sb_rextsize)) {
             u64 rextbytes;
             u32 mod;
 
             rextbytes = XFS_FSB_TO_B(mp, mp->m_sb.sb_rextsize);
             div_u64_rem(pos, rextbytes, &mod);
             if (mod)
                 return false;
             div_u64_rem(len, rextbytes, &mod);
             return mod == 0;
         }
         mask = XFS_FSB_TO_B(mp, mp->m_sb.sb_rextsize) - 1;
     } else {
         mask = mp->m_sb.sb_blocksize - 1;
     }
 
     return !((pos | len) & mask);
 }
 
 /*
  * Fsync operations on directories are much simpler than on regular files,
  * as there is no file data to flush, and thus also no need for explicit
  * cache flush operations, and there are no non-transaction metadata updates
  * on directories either.
  */
 STATIC int
 xfs_dir_fsync(
     struct file     *file,
     loff_t          start,
     loff_t          end,
     int         datasync)
 {
     struct xfs_inode    *ip = XFS_I(file->f_mapping->host);
 
     trace_xfs_dir_fsync(ip);
     return xfs_log_force_inode(ip);
 }
 
 static xfs_csn_t
 xfs_fsync_seq(
     struct xfs_inode    *ip,
     bool            datasync)
 {
     if (!xfs_ipincount(ip))
         return 0;
     if (datasync && !(ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
         return 0;
     return ip->i_itemp->ili_commit_seq;
 }
 
 /*
  * All metadata updates are logged, which means that we just have to flush the
  * log up to the latest LSN that touched the inode.
  *
  * If we have concurrent fsync/fdatasync() calls, we need them to all block on
  * the log force before we clear the ili_fsync_fields field. This ensures that
  * we don't get a racing sync operation that does not wait for the metadata to
  * hit the journal before returning.  If we race with clearing ili_fsync_fields,
  * then all that will happen is the log force will do nothing as the lsn will
  * already be on disk.  We can't race with setting ili_fsync_fields because that
  * is done under XFS_ILOCK_EXCL, and that can't happen because we hold the lock
  * shared until after the ili_fsync_fields is cleared.
  */
 static  int
 xfs_fsync_flush_log(
     struct xfs_inode    *ip,
     bool            datasync,
     int         *log_flushed)
 {
     int         error = 0;
     xfs_csn_t       seq;
 
     xfs_ilock(ip, XFS_ILOCK_SHARED);
     seq = xfs_fsync_seq(ip, datasync);
     if (seq) {
         error = xfs_log_force_seq(ip->i_mount, seq, XFS_LOG_SYNC,
                       log_flushed);
 
         spin_lock(&ip->i_itemp->ili_lock);
         ip->i_itemp->ili_fsync_fields = 0;
         spin_unlock(&ip->i_itemp->ili_lock);
     }
     xfs_iunlock(ip, XFS_ILOCK_SHARED);
     return error;
 }
 
 STATIC int
 xfs_file_fsync(
     struct file     *file,
     loff_t          start,
     loff_t          end,
     int         datasync)
 {
     struct xfs_inode    *ip = XFS_I(file->f_mapping->host);
     struct xfs_mount    *mp = ip->i_mount;
     int         error, err2;
     int         log_flushed = 0;
 
     trace_xfs_file_fsync(ip);
 
     error = file_write_and_wait_range(file, start, end);
     if (error)
         return error;
 
     if (xfs_is_shutdown(mp))
         return -EIO;
 
     xfs_iflags_clear(ip, XFS_ITRUNCATED);
 
     /*
      * If we have an RT and/or log subvolume we need to make sure to flush
      * the write cache the device used for file data first.  This is to
      * ensure newly written file data make it to disk before logging the new
      * inode size in case of an extending write.
      */
     if (XFS_IS_REALTIME_INODE(ip))
         error = blkdev_issue_flush(mp->m_rtdev_targp->bt_bdev);
     else if (mp->m_logdev_targp != mp->m_ddev_targp)
         error = blkdev_issue_flush(mp->m_ddev_targp->bt_bdev);
 
     /*
      * Any inode that has dirty modifications in the log is pinned.  The
      * racy check here for a pinned inode will not catch modifications
      * that happen concurrently to the fsync call, but fsync semantics
      * only require to sync previously completed I/O.
      */
     if (xfs_ipincount(ip)) {
         err2 = xfs_fsync_flush_log(ip, datasync, &log_flushed);
         if (err2 && !error)
             error = err2;
     }
 
     /*
      * If we only have a single device, and the log force about was
      * a no-op we might have to flush the data device cache here.
      * This can only happen for fdatasync/O_DSYNC if we were overwriting
      * an already allocated file and thus do not have any metadata to
      * commit.
      */
     if (!log_flushed && !XFS_IS_REALTIME_INODE(ip) &&
         mp->m_logdev_targp == mp->m_ddev_targp) {
         err2 = blkdev_issue_flush(mp->m_ddev_targp->bt_bdev);
         if (err2 && !error)
             error = err2;
     }
 
     return error;
 }
 
 static int
 xfs_ilock_iocb(
     struct kiocb        *iocb,
     unsigned int        lock_mode)
 {
     struct xfs_inode    *ip = XFS_I(file_inode(iocb->ki_filp));
 
     if (iocb->ki_flags & IOCB_NOWAIT) {
         if (!xfs_ilock_nowait(ip, lock_mode))
             return -EAGAIN;
     } else {
         xfs_ilock(ip, lock_mode);
     }
 
     return 0;
 }
 
 STATIC ssize_t
 xfs_file_dio_read(
     struct kiocb        *iocb,
     struct iov_iter     *to)
 {
     struct xfs_inode    *ip = XFS_I(file_inode(iocb->ki_filp));
     ssize_t         ret;
 
     trace_xfs_file_direct_read(iocb, to);
 
     if (!iov_iter_count(to))
         return 0; /* skip atime */
 
     file_accessed(iocb->ki_filp);
 
     ret = xfs_ilock_iocb(iocb, XFS_IOLOCK_SHARED);
     if (ret)
         return ret;
     ret = iomap_dio_rw(iocb, to, &xfs_read_iomap_ops, NULL, 0, NULL, 0);
     xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 
     return ret;
 }
 
 static noinline ssize_t
 xfs_file_dax_read(
     struct kiocb        *iocb,
     struct iov_iter     *to)
 {
     struct xfs_inode    *ip = XFS_I(iocb->ki_filp->f_mapping->host);
     ssize_t         ret = 0;
 
     trace_xfs_file_dax_read(iocb, to);
 
     if (!iov_iter_count(to))
         return 0; /* skip atime */
 
     ret = xfs_ilock_iocb(iocb, XFS_IOLOCK_SHARED);
     if (ret)
         return ret;
     ret = dax_iomap_rw(iocb, to, &xfs_read_iomap_ops);
     xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 
     file_accessed(iocb->ki_filp);
     return ret;
 }
 
 STATIC ssize_t
 xfs_file_buffered_read(
     struct kiocb        *iocb,
     struct iov_iter     *to)
 {
     struct xfs_inode    *ip = XFS_I(file_inode(iocb->ki_filp));
     ssize_t         ret;
 
     trace_xfs_file_buffered_read(iocb, to);
 
     ret = xfs_ilock_iocb(iocb, XFS_IOLOCK_SHARED);
     if (ret)
         return ret;
     ret = generic_file_read_iter(iocb, to);
     xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 
     return ret;
 }
 
 STATIC ssize_t
 xfs_file_read_iter(
     struct kiocb        *iocb,
     struct iov_iter     *to)
 {
     struct inode        *inode = file_inode(iocb->ki_filp);
     struct xfs_mount    *mp = XFS_I(inode)->i_mount;
     ssize_t         ret = 0;
 
     XFS_STATS_INC(mp, xs_read_calls);
 
     if (xfs_is_shutdown(mp))
         return -EIO;
 
     if (IS_DAX(inode))
         ret = xfs_file_dax_read(iocb, to);
     else if (iocb->ki_flags & IOCB_DIRECT)
         ret = xfs_file_dio_read(iocb, to);
     else
         ret = xfs_file_buffered_read(iocb, to);
 
     if (ret > 0)
         XFS_STATS_ADD(mp, xs_read_bytes, ret);
     return ret;
 }
 
 /*
  * Common pre-write limit and setup checks.
  *
  * Called with the iolocked held either shared and exclusive according to
  * @iolock, and returns with it held.  Might upgrade the iolock to exclusive
  * if called for a direct write beyond i_size.
  */
 STATIC ssize_t
 xfs_file_write_checks(
     struct kiocb        *iocb,
     struct iov_iter     *from,
     unsigned int        *iolock)
 {
     struct file     *file = iocb->ki_filp;
     struct inode        *inode = file->f_mapping->host;
     struct xfs_inode    *ip = XFS_I(inode);
     ssize_t         error = 0;
     size_t          count = iov_iter_count(from);
     bool            drained_dio = false;
     loff_t          isize;
 
 restart:
     error = generic_write_checks(iocb, from);
     if (error <= 0)
         return error;
 
     if (iocb->ki_flags & IOCB_NOWAIT) {
         error = break_layout(inode, false);
         if (error == -EWOULDBLOCK)
             error = -EAGAIN;
     } else {
         error = xfs_break_layouts(inode, iolock, BREAK_WRITE);
     }
 
     if (error)
         return error;
 
     /*
      * For changing security info in file_remove_privs() we need i_rwsem
      * exclusively.
      */
     if (*iolock == XFS_IOLOCK_SHARED && !IS_NOSEC(inode)) {
         xfs_iunlock(ip, *iolock);
         *iolock = XFS_IOLOCK_EXCL;
         error = xfs_ilock_iocb(iocb, *iolock);
         if (error) {
             *iolock = 0;
             return error;
         }
         goto restart;
     }
 
     /*
      * If the offset is beyond the size of the file, we need to zero any
      * blocks that fall between the existing EOF and the start of this
      * write.  If zeroing is needed and we are currently holding the iolock
      * shared, we need to update it to exclusive which implies having to
      * redo all checks before.
      *
      * We need to serialise against EOF updates that occur in IO completions
      * here. We want to make sure that nobody is changing the size while we
      * do this check until we have placed an IO barrier (i.e.  hold the
      * XFS_IOLOCK_EXCL) that prevents new IO from being dispatched.  The
      * spinlock effectively forms a memory barrier once we have the
      * XFS_IOLOCK_EXCL so we are guaranteed to see the latest EOF value and
      * hence be able to correctly determine if we need to run zeroing.
      *
      * We can do an unlocked check here safely as IO completion can only
      * extend EOF. Truncate is locked out at this point, so the EOF can
      * not move backwards, only forwards. Hence we only need to take the
      * slow path and spin locks when we are at or beyond the current EOF.
      */
     if (iocb->ki_pos <= i_size_read(inode))
         goto out;
 
     spin_lock(&ip->i_flags_lock);
     isize = i_size_read(inode);
     if (iocb->ki_pos > isize) {
         spin_unlock(&ip->i_flags_lock);
 
         if (iocb->ki_flags & IOCB_NOWAIT)
             return -EAGAIN;
 
         if (!drained_dio) {
             if (*iolock == XFS_IOLOCK_SHARED) {
                 xfs_iunlock(ip, *iolock);
                 *iolock = XFS_IOLOCK_EXCL;
                 xfs_ilock(ip, *iolock);
                 iov_iter_reexpand(from, count);
             }
             /*
              * We now have an IO submission barrier in place, but
              * AIO can do EOF updates during IO completion and hence
              * we now need to wait for all of them to drain. Non-AIO
              * DIO will have drained before we are given the
              * XFS_IOLOCK_EXCL, and so for most cases this wait is a
              * no-op.
              */
             inode_dio_wait(inode);
             drained_dio = true;
             goto restart;
         }
 
         trace_xfs_zero_eof(ip, isize, iocb->ki_pos - isize);
         error = xfs_zero_range(ip, isize, iocb->ki_pos - isize, NULL);
         if (error)
             return error;
     } else
         spin_unlock(&ip->i_flags_lock);
 
 out:
     return kiocb_modified(iocb);
 }
 
 static int
 xfs_dio_write_end_io(
     struct kiocb        *iocb,
     ssize_t         size,
     int         error,
     unsigned        flags)
 {
     struct inode        *inode = file_inode(iocb->ki_filp);
     struct xfs_inode    *ip = XFS_I(inode);
     loff_t          offset = iocb->ki_pos;
     unsigned int        nofs_flag;
 
     trace_xfs_end_io_direct_write(ip, offset, size);
 
     if (xfs_is_shutdown(ip->i_mount))
         return -EIO;
 
     if (error)
         return error;
     if (!size)
         return 0;
 
     /*
      * Capture amount written on completion as we can't reliably account
      * for it on submission.
      */
     XFS_STATS_ADD(ip->i_mount, xs_write_bytes, size);
 
     /*
      * We can allocate memory here while doing writeback on behalf of
      * memory reclaim.  To avoid memory allocation deadlocks set the
      * task-wide nofs context for the following operations.
      */
     nofs_flag = memalloc_nofs_save();
 
     if (flags & IOMAP_DIO_COW) {
         error = xfs_reflink_end_cow(ip, offset, size);
         if (error)
             goto out;
     }
 
     /*
      * Unwritten conversion updates the in-core isize after extent
      * conversion but before updating the on-disk size. Updating isize any
      * earlier allows a racing dio read to find unwritten extents before
      * they are converted.
      */
     if (flags & IOMAP_DIO_UNWRITTEN) {
         error = xfs_iomap_write_unwritten(ip, offset, size, true);
         goto out;
     }
 
     /*
      * We need to update the in-core inode size here so that we don't end up
      * with the on-disk inode size being outside the in-core inode size. We
      * have no other method of updating EOF for AIO, so always do it here
      * if necessary.
      *
      * We need to lock the test/set EOF update as we can be racing with
      * other IO completions here to update the EOF. Failing to serialise
      * here can result in EOF moving backwards and Bad Things Happen when
      * that occurs.
      *
      * As IO completion only ever extends EOF, we can do an unlocked check
      * here to avoid taking the spinlock. If we land within the current EOF,
      * then we do not need to do an extending update at all, and we don't
      * need to take the lock to check this. If we race with an update moving
      * EOF, then we'll either still be beyond EOF and need to take the lock,
      * or we'll be within EOF and we don't need to take it at all.
      */
     if (offset + size <= i_size_read(inode))
         goto out;
 
     spin_lock(&ip->i_flags_lock);
     if (offset + size > i_size_read(inode)) {
         i_size_write(inode, offset + size);
         spin_unlock(&ip->i_flags_lock);
         error = xfs_setfilesize(ip, offset, size);
     } else {
         spin_unlock(&ip->i_flags_lock);
     }
 
 out:
     memalloc_nofs_restore(nofs_flag);
     return error;
 }
 
 static const struct iomap_dio_ops xfs_dio_write_ops = {
     .end_io     = xfs_dio_write_end_io,
 };
 
 /*
  * Handle block aligned direct I/O writes
  */
 static noinline ssize_t
 xfs_file_dio_write_aligned(
     struct xfs_inode    *ip,
     struct kiocb        *iocb,
     struct iov_iter     *from)
 {
     unsigned int        iolock = XFS_IOLOCK_SHARED;
     ssize_t         ret;
 
     ret = xfs_ilock_iocb(iocb, iolock);
     if (ret)
         return ret;
     ret = xfs_file_write_checks(iocb, from, &iolock);
     if (ret)
         goto out_unlock;
 
     /*
      * We don't need to hold the IOLOCK exclusively across the IO, so demote
      * the iolock back to shared if we had to take the exclusive lock in
      * xfs_file_write_checks() for other reasons.
      */
     if (iolock == XFS_IOLOCK_EXCL) {
         xfs_ilock_demote(ip, XFS_IOLOCK_EXCL);
         iolock = XFS_IOLOCK_SHARED;
     }
     trace_xfs_file_direct_write(iocb, from);
     ret = iomap_dio_rw(iocb, from, &xfs_direct_write_iomap_ops,
                &xfs_dio_write_ops, 0, NULL, 0);
 out_unlock:
     if (iolock)
         xfs_iunlock(ip, iolock);
     return ret;
 }
 
 /*
  * Handle block unaligned direct I/O writes
  *
  * In most cases direct I/O writes will be done holding IOLOCK_SHARED, allowing
  * them to be done in parallel with reads and other direct I/O writes.  However,
  * if the I/O is not aligned to filesystem blocks, the direct I/O layer may need
  * to do sub-block zeroing and that requires serialisation against other direct
  * I/O to the same block.  In this case we need to serialise the submission of
  * the unaligned I/O so that we don't get racing block zeroing in the dio layer.
  * In the case where sub-block zeroing is not required, we can do concurrent
  * sub-block dios to the same block successfully.
  *
  * Optimistically submit the I/O using the shared lock first, but use the
  * IOMAP_DIO_OVERWRITE_ONLY flag to tell the lower layers to return -EAGAIN
  * if block allocation or partial block zeroing would be required.  In that case
  * we try again with the exclusive lock.
  */
 static noinline ssize_t
 xfs_file_dio_write_unaligned(
     struct xfs_inode    *ip,
     struct kiocb        *iocb,
     struct iov_iter     *from)
 {
     size_t          isize = i_size_read(VFS_I(ip));
     size_t          count = iov_iter_count(from);
     unsigned int        iolock = XFS_IOLOCK_SHARED;
     unsigned int        flags = IOMAP_DIO_OVERWRITE_ONLY;
     ssize_t         ret;
 
     /*
      * Extending writes need exclusivity because of the sub-block zeroing
      * that the DIO code always does for partial tail blocks beyond EOF, so
      * don't even bother trying the fast path in this case.
      */
     if (iocb->ki_pos > isize || iocb->ki_pos + count >= isize) {
         if (iocb->ki_flags & IOCB_NOWAIT)
             return -EAGAIN;
 retry_exclusive:
         iolock = XFS_IOLOCK_EXCL;
         flags = IOMAP_DIO_FORCE_WAIT;
     }
 
     ret = xfs_ilock_iocb(iocb, iolock);
     if (ret)
         return ret;
 
     /*
      * We can't properly handle unaligned direct I/O to reflink files yet,
      * as we can't unshare a partial block.
      */
     if (xfs_is_cow_inode(ip)) {
         trace_xfs_reflink_bounce_dio_write(iocb, from);
         ret = -ENOTBLK;
         goto out_unlock;
     }
 
     ret = xfs_file_write_checks(iocb, from, &iolock);
     if (ret)
         goto out_unlock;
 
     /*
      * If we are doing exclusive unaligned I/O, this must be the only I/O
      * in-flight.  Otherwise we risk data corruption due to unwritten extent
      * conversions from the AIO end_io handler.  Wait for all other I/O to
      * drain first.
      */
     if (flags & IOMAP_DIO_FORCE_WAIT)
         inode_dio_wait(VFS_I(ip));
 
     trace_xfs_file_direct_write(iocb, from);
     ret = iomap_dio_rw(iocb, from, &xfs_direct_write_iomap_ops,
                &xfs_dio_write_ops, flags, NULL, 0);
 
     /*
      * Retry unaligned I/O with exclusive blocking semantics if the DIO
      * layer rejected it for mapping or locking reasons. If we are doing
      * nonblocking user I/O, propagate the error.
      */
     if (ret == -EAGAIN && !(iocb->ki_flags & IOCB_NOWAIT)) {
         ASSERT(flags & IOMAP_DIO_OVERWRITE_ONLY);
         xfs_iunlock(ip, iolock);
         goto retry_exclusive;
     }
 
 out_unlock:
     if (iolock)
         xfs_iunlock(ip, iolock);
     return ret;
 }
 
 static ssize_t
 xfs_file_dio_write(
     struct kiocb        *iocb,
     struct iov_iter     *from)
 {
     struct xfs_inode    *ip = XFS_I(file_inode(iocb->ki_filp));
     struct xfs_buftarg      *target = xfs_inode_buftarg(ip);
     size_t          count = iov_iter_count(from);
 
     /* direct I/O must be aligned to device logical sector size */
     if ((iocb->ki_pos | count) & target->bt_logical_sectormask)
         return -EINVAL;
     if ((iocb->ki_pos | count) & ip->i_mount->m_blockmask)
         return xfs_file_dio_write_unaligned(ip, iocb, from);
     return xfs_file_dio_write_aligned(ip, iocb, from);
 }
 
 static noinline ssize_t
 xfs_file_dax_write(
     struct kiocb        *iocb,
     struct iov_iter     *from)
 {
     struct inode        *inode = iocb->ki_filp->f_mapping->host;
     struct xfs_inode    *ip = XFS_I(inode);
     unsigned int        iolock = XFS_IOLOCK_EXCL;
     ssize_t         ret, error = 0;
     loff_t          pos;
 
     ret = xfs_ilock_iocb(iocb, iolock);
     if (ret)
         return ret;
     ret = xfs_file_write_checks(iocb, from, &iolock);
     if (ret)
         goto out;
 
     pos = iocb->ki_pos;
 
     trace_xfs_file_dax_write(iocb, from);
     ret = dax_iomap_rw(iocb, from, &xfs_dax_write_iomap_ops);
     if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
         i_size_write(inode, iocb->ki_pos);
         error = xfs_setfilesize(ip, pos, ret);
     }
 out:
     if (iolock)
         xfs_iunlock(ip, iolock);
     if (error)
         return error;
 
     if (ret > 0) {
         XFS_STATS_ADD(ip->i_mount, xs_write_bytes, ret);
 
         /* Handle various SYNC-type writes */
         ret = generic_write_sync(iocb, ret);
     }
     return ret;
 }
 
 STATIC ssize_t
 xfs_file_buffered_write(
     struct kiocb        *iocb,
     struct iov_iter     *from)
 {
     struct inode        *inode = iocb->ki_filp->f_mapping->host;
     struct xfs_inode    *ip = XFS_I(inode);
     ssize_t         ret;
     bool            cleared_space = false;
     unsigned int        iolock;
 
 write_retry:
     iolock = XFS_IOLOCK_EXCL;
     ret = xfs_ilock_iocb(iocb, iolock);
     if (ret)
         return ret;
 
     ret = xfs_file_write_checks(iocb, from, &iolock);
     if (ret)
         goto out;
 
     /* We can write back this queue in page reclaim */
     current->backing_dev_info = inode_to_bdi(inode);
 
     trace_xfs_file_buffered_write(iocb, from);
     ret = iomap_file_buffered_write(iocb, from,
             &xfs_buffered_write_iomap_ops);
     if (likely(ret >= 0))
         iocb->ki_pos += ret;
 
     /*
      * If we hit a space limit, try to free up some lingering preallocated
      * space before returning an error. In the case of ENOSPC, first try to
      * write back all dirty inodes to free up some of the excess reserved
      * metadata space. This reduces the chances that the eofblocks scan
      * waits on dirty mappings. Since xfs_flush_inodes() is serialized, this
      * also behaves as a filter to prevent too many eofblocks scans from
      * running at the same time.  Use a synchronous scan to increase the
      * effectiveness of the scan.
      */
     if (ret == -EDQUOT && !cleared_space) {
         xfs_iunlock(ip, iolock);
         xfs_blockgc_free_quota(ip, XFS_ICWALK_FLAG_SYNC);
         cleared_space = true;
         goto write_retry;
     } else if (ret == -ENOSPC && !cleared_space) {
         struct xfs_icwalk   icw = {0};
 
         cleared_space = true;
         xfs_flush_inodes(ip->i_mount);
 
         xfs_iunlock(ip, iolock);
         icw.icw_flags = XFS_ICWALK_FLAG_SYNC;
         xfs_blockgc_free_space(ip->i_mount, &icw);
         goto write_retry;
     }
 
     current->backing_dev_info = NULL;
 out:
     if (iolock)
         xfs_iunlock(ip, iolock);
 
     if (ret > 0) {
         XFS_STATS_ADD(ip->i_mount, xs_write_bytes, ret);
         /* Handle various SYNC-type writes */
         ret = generic_write_sync(iocb, ret);
     }
     return ret;
 }
 
 STATIC ssize_t
 xfs_file_write_iter(
     struct kiocb        *iocb,
     struct iov_iter     *from)
 {
     struct inode        *inode = iocb->ki_filp->f_mapping->host;
     struct xfs_inode    *ip = XFS_I(inode);
     ssize_t         ret;
     size_t          ocount = iov_iter_count(from);
 
     XFS_STATS_INC(ip->i_mount, xs_write_calls);
 
     if (ocount == 0)
         return 0;
 
     if (xfs_is_shutdown(ip->i_mount))
         return -EIO;
 
     if (IS_DAX(inode))
         return xfs_file_dax_write(iocb, from);
 
     if (iocb->ki_flags & IOCB_DIRECT) {
         /*
          * Allow a directio write to fall back to a buffered
          * write *only* in the case that we're doing a reflink
          * CoW.  In all other directio scenarios we do not
          * allow an operation to fall back to buffered mode.
          */
         ret = xfs_file_dio_write(iocb, from);
         if (ret != -ENOTBLK)
             return ret;
     }
 
     return xfs_file_buffered_write(iocb, from);
 }
 
 static void
 xfs_wait_dax_page(
     struct inode        *inode)
 {
     struct xfs_inode        *ip = XFS_I(inode);
 
     xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
     schedule();
     xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
 }
 
 int
 xfs_break_dax_layouts(
     struct inode        *inode,
     bool            *retry)
 {
     struct page     *page;
 
     ASSERT(xfs_isilocked(XFS_I(inode), XFS_MMAPLOCK_EXCL));
 
     page = dax_layout_busy_page(inode->i_mapping);
     if (!page)
         return 0;
 
     *retry = true;
     return ___wait_var_event(&page->_refcount,
             atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE,
             0, 0, xfs_wait_dax_page(inode));
 }
 
 int
 xfs_break_layouts(
     struct inode        *inode,
     uint            *iolock,
     enum layout_break_reason reason)
 {
     bool            retry;
     int         error;
 
     ASSERT(xfs_isilocked(XFS_I(inode), XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL));
 
     do {
         retry = false;
         switch (reason) {
         case BREAK_UNMAP:
             error = xfs_break_dax_layouts(inode, &retry);
             if (error || retry)
                 break;
             fallthrough;
         case BREAK_WRITE:
             error = xfs_break_leased_layouts(inode, iolock, &retry);
             break;
         default:
             WARN_ON_ONCE(1);
             error = -EINVAL;
         }
     } while (error == 0 && retry);
 
     return error;
 }
 
 /* Does this file, inode, or mount want synchronous writes? */
 static inline bool xfs_file_sync_writes(struct file *filp)
 {
     struct xfs_inode    *ip = XFS_I(file_inode(filp));
 
     if (xfs_has_wsync(ip->i_mount))
         return true;
     if (filp->f_flags & (__O_SYNC | O_DSYNC))
         return true;
     if (IS_SYNC(file_inode(filp)))
         return true;
 
     return false;
 }
 
 #define XFS_FALLOC_FL_SUPPORTED                     \
         (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |       \
          FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE |  \
          FALLOC_FL_INSERT_RANGE | FALLOC_FL_UNSHARE_RANGE)
 
 STATIC long
 xfs_file_fallocate(
     struct file     *file,
     int         mode,
     loff_t          offset,
     loff_t          len)
 {
     struct inode        *inode = file_inode(file);
     struct xfs_inode    *ip = XFS_I(inode);
     long            error;
     uint            iolock = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL;
     loff_t          new_size = 0;
     bool            do_file_insert = false;
 
     if (!S_ISREG(inode->i_mode))
         return -EINVAL;
     if (mode & ~XFS_FALLOC_FL_SUPPORTED)
         return -EOPNOTSUPP;
 
     xfs_ilock(ip, iolock);
     error = xfs_break_layouts(inode, &iolock, BREAK_UNMAP);
     if (error)
         goto out_unlock;
 
     /*
      * Must wait for all AIO to complete before we continue as AIO can
      * change the file size on completion without holding any locks we
      * currently hold. We must do this first because AIO can update both
      * the on disk and in memory inode sizes, and the operations that follow
      * require the in-memory size to be fully up-to-date.
      */
     inode_dio_wait(inode);
 
     /*
      * Now AIO and DIO has drained we flush and (if necessary) invalidate
      * the cached range over the first operation we are about to run.
      *
      * We care about zero and collapse here because they both run a hole
      * punch over the range first. Because that can zero data, and the range
      * of invalidation for the shift operations is much larger, we still do
      * the required flush for collapse in xfs_prepare_shift().
      *
      * Insert has the same range requirements as collapse, and we extend the
      * file first which can zero data. Hence insert has the same
      * flush/invalidate requirements as collapse and so they are both
      * handled at the right time by xfs_prepare_shift().
      */
     if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE |
             FALLOC_FL_COLLAPSE_RANGE)) {
         error = xfs_flush_unmap_range(ip, offset, len);
         if (error)
             goto out_unlock;
     }
 
     error = file_modified(file);
     if (error)
         goto out_unlock;
 
     if (mode & FALLOC_FL_PUNCH_HOLE) {
         error = xfs_free_file_space(ip, offset, len);
         if (error)
             goto out_unlock;
     } else if (mode & FALLOC_FL_COLLAPSE_RANGE) {
         if (!xfs_is_falloc_aligned(ip, offset, len)) {
             error = -EINVAL;
             goto out_unlock;
         }
 
         /*
          * There is no need to overlap collapse range with EOF,
          * in which case it is effectively a truncate operation
          */
         if (offset + len >= i_size_read(inode)) {
             error = -EINVAL;
             goto out_unlock;
         }
 
         new_size = i_size_read(inode) - len;
 
         error = xfs_collapse_file_space(ip, offset, len);
         if (error)
             goto out_unlock;
     } else if (mode & FALLOC_FL_INSERT_RANGE) {
         loff_t      isize = i_size_read(inode);
 
         if (!xfs_is_falloc_aligned(ip, offset, len)) {
             error = -EINVAL;
             goto out_unlock;
         }
 
         /*
          * New inode size must not exceed ->s_maxbytes, accounting for
          * possible signed overflow.
          */
         if (inode->i_sb->s_maxbytes - isize < len) {
             error = -EFBIG;
             goto out_unlock;
         }
         new_size = isize + len;
 
         /* Offset should be less than i_size */
         if (offset >= isize) {
             error = -EINVAL;
             goto out_unlock;
         }
         do_file_insert = true;
     } else {
         if (!(mode & FALLOC_FL_KEEP_SIZE) &&
             offset + len > i_size_read(inode)) {
             new_size = offset + len;
             error = inode_newsize_ok(inode, new_size);
             if (error)
                 goto out_unlock;
         }
 
         if (mode & FALLOC_FL_ZERO_RANGE) {
             /*
              * Punch a hole and prealloc the range.  We use a hole
              * punch rather than unwritten extent conversion for two
              * reasons:
              *
              *   1.) Hole punch handles partial block zeroing for us.
              *   2.) If prealloc returns ENOSPC, the file range is
              *       still zero-valued by virtue of the hole punch.
              */
             unsigned int blksize = i_blocksize(inode);
 
             trace_xfs_zero_file_space(ip);
 
             error = xfs_free_file_space(ip, offset, len);
             if (error)
                 goto out_unlock;
 
             len = round_up(offset + len, blksize) -
                   round_down(offset, blksize);
             offset = round_down(offset, blksize);
         } else if (mode & FALLOC_FL_UNSHARE_RANGE) {
             error = xfs_reflink_unshare(ip, offset, len);
             if (error)
                 goto out_unlock;
         } else {
             /*
              * If always_cow mode we can't use preallocations and
              * thus should not create them.
              */
             if (xfs_is_always_cow_inode(ip)) {
                 error = -EOPNOTSUPP;
                 goto out_unlock;
             }
         }
 
         if (!xfs_is_always_cow_inode(ip)) {
             error = xfs_alloc_file_space(ip, offset, len);
             if (error)
                 goto out_unlock;
         }
     }
 
     /* Change file size if needed */
     if (new_size) {
         struct iattr iattr;
 
         iattr.ia_valid = ATTR_SIZE;
         iattr.ia_size = new_size;
         error = xfs_vn_setattr_size(file_mnt_user_ns(file),
                         file_dentry(file), &iattr);
         if (error)
             goto out_unlock;
     }
 
     /*
      * Perform hole insertion now that the file size has been
      * updated so that if we crash during the operation we don't
      * leave shifted extents past EOF and hence losing access to
      * the data that is contained within them.
      */
     if (do_file_insert) {
         error = xfs_insert_file_space(ip, offset, len);
         if (error)
             goto out_unlock;
     }
 
     if (xfs_file_sync_writes(file))
         error = xfs_log_force_inode(ip);
 
 out_unlock:
     xfs_iunlock(ip, iolock);
     return error;
 }
 
 STATIC int
 xfs_file_fadvise(
     struct file *file,
     loff_t      start,
     loff_t      end,
     int     advice)
 {
     struct xfs_inode *ip = XFS_I(file_inode(file));
     int ret;
     int lockflags = 0;
 
     /*
      * Operations creating pages in page cache need protection from hole
      * punching and similar ops
      */
     if (advice == POSIX_FADV_WILLNEED) {
         lockflags = XFS_IOLOCK_SHARED;
         xfs_ilock(ip, lockflags);
     }
     ret = generic_fadvise(file, start, end, advice);
     if (lockflags)
         xfs_iunlock(ip, lockflags);
     return ret;
 }
 
 STATIC loff_t
 xfs_file_remap_range(
     struct file     *file_in,
     loff_t          pos_in,
     struct file     *file_out,
     loff_t          pos_out,
     loff_t          len,
     unsigned int        remap_flags)
 {
     struct inode        *inode_in = file_inode(file_in);
     struct xfs_inode    *src = XFS_I(inode_in);
     struct inode        *inode_out = file_inode(file_out);
     struct xfs_inode    *dest = XFS_I(inode_out);
     struct xfs_mount    *mp = src->i_mount;
     loff_t          remapped = 0;
     xfs_extlen_t        cowextsize;
     int         ret;
 
     if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
         return -EINVAL;
 
     if (!xfs_has_reflink(mp))
         return -EOPNOTSUPP;
 
     if (xfs_is_shutdown(mp))
         return -EIO;
 
     /* Prepare and then clone file data. */
     ret = xfs_reflink_remap_prep(file_in, pos_in, file_out, pos_out,
             &len, remap_flags);
     if (ret || len == 0)
         return ret;
 
     trace_xfs_reflink_remap_range(src, pos_in, len, dest, pos_out);
 
     ret = xfs_reflink_remap_blocks(src, pos_in, dest, pos_out, len,
             &remapped);
     if (ret)
         goto out_unlock;
 
     /*
      * Carry the cowextsize hint from src to dest if we're sharing the
      * entire source file to the entire destination file, the source file
      * has a cowextsize hint, and the destination file does not.
      */
     cowextsize = 0;
     if (pos_in == 0 && len == i_size_read(inode_in) &&
         (src->i_diflags2 & XFS_DIFLAG2_COWEXTSIZE) &&
         pos_out == 0 && len >= i_size_read(inode_out) &&
         !(dest->i_diflags2 & XFS_DIFLAG2_COWEXTSIZE))
         cowextsize = src->i_cowextsize;
 
     ret = xfs_reflink_update_dest(dest, pos_out + len, cowextsize,
             remap_flags);
     if (ret)
         goto out_unlock;
 
     if (xfs_file_sync_writes(file_in) || xfs_file_sync_writes(file_out))
         xfs_log_force_inode(dest);
 out_unlock:
     xfs_iunlock2_io_mmap(src, dest);
     if (ret)
         trace_xfs_reflink_remap_range_error(dest, ret, _RET_IP_);
     return remapped > 0 ? remapped : ret;
 }
 
 STATIC int
 xfs_file_open(
     struct inode    *inode,
     struct file *file)
 {
     if (xfs_is_shutdown(XFS_M(inode->i_sb)))
         return -EIO;
     file->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC | FMODE_BUF_WASYNC;
     return generic_file_open(inode, file);
 }
 
 STATIC int
 xfs_dir_open(
     struct inode    *inode,
     struct file *file)
 {
     struct xfs_inode *ip = XFS_I(inode);
     unsigned int    mode;
     int     error;
 
     error = xfs_file_open(inode, file);
     if (error)
         return error;
 
     /*
      * If there are any blocks, read-ahead block 0 as we're almost
      * certain to have the next operation be a read there.
      */
     mode = xfs_ilock_data_map_shared(ip);
     if (ip->i_df.if_nextents > 0)
         error = xfs_dir3_data_readahead(ip, 0, 0);
     xfs_iunlock(ip, mode);
     return error;
 }
 
 STATIC int
 xfs_file_release(
     struct inode    *inode,
     struct file *filp)
 {
     return xfs_release(XFS_I(inode));
 }
 
 STATIC int
 xfs_file_readdir(
     struct file *file,
     struct dir_context *ctx)
 {
     struct inode    *inode = file_inode(file);
     xfs_inode_t *ip = XFS_I(inode);
     size_t      bufsize;
 
     /*
      * The Linux API doesn't pass down the total size of the buffer
      * we read into down to the filesystem.  With the filldir concept
      * it's not needed for correct information, but the XFS dir2 leaf
      * code wants an estimate of the buffer size to calculate it's
      * readahead window and size the buffers used for mapping to
      * physical blocks.
      *
      * Try to give it an estimate that's good enough, maybe at some
      * point we can change the ->readdir prototype to include the
      * buffer size.  For now we use the current glibc buffer size.
      */
     bufsize = (size_t)min_t(loff_t, XFS_READDIR_BUFSIZE, ip->i_disk_size);
 
     return xfs_readdir(NULL, ip, ctx, bufsize);
 }
 
 STATIC loff_t
 xfs_file_llseek(
     struct file *file,
     loff_t      offset,
     int     whence)
 {
     struct inode        *inode = file->f_mapping->host;
 
     if (xfs_is_shutdown(XFS_I(inode)->i_mount))
         return -EIO;
 
     switch (whence) {
     default:
         return generic_file_llseek(file, offset, whence);
     case SEEK_HOLE:
         offset = iomap_seek_hole(inode, offset, &xfs_seek_iomap_ops);
         break;
     case SEEK_DATA:
         offset = iomap_seek_data(inode, offset, &xfs_seek_iomap_ops);
         break;
     }
 
     if (offset < 0)
         return offset;
     return vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
 }
 
 #ifdef CONFIG_FS_DAX
 static int
 xfs_dax_fault(
     struct vm_fault     *vmf,
     enum page_entry_size    pe_size,
     bool            write_fault,
     pfn_t           *pfn)
 {
     return dax_iomap_fault(vmf, pe_size, pfn, NULL,
             (write_fault && !vmf->cow_page) ?
                 &xfs_dax_write_iomap_ops :
                 &xfs_read_iomap_ops);
 }
 #else
 static int
 xfs_dax_fault(
     struct vm_fault     *vmf,
     enum page_entry_size    pe_size,
     bool            write_fault,
     pfn_t           *pfn)
 {
     return 0;
 }
 #endif
 
 /*
  * Locking for serialisation of IO during page faults. This results in a lock
  * ordering of:
  *
  * mmap_lock (MM)
  *   sb_start_pagefault(vfs, freeze)
  *     invalidate_lock (vfs/XFS_MMAPLOCK - truncate serialisation)
  *       page_lock (MM)
  *         i_lock (XFS - extent map serialisation)
  */
 static vm_fault_t
 __xfs_filemap_fault(
     struct vm_fault     *vmf,
     enum page_entry_size    pe_size,
     bool            write_fault)
 {
     struct inode        *inode = file_inode(vmf->vma->vm_file);
     struct xfs_inode    *ip = XFS_I(inode);
     vm_fault_t      ret;
 
     trace_xfs_filemap_fault(ip, pe_size, write_fault);
 
     if (write_fault) {
         sb_start_pagefault(inode->i_sb);
         file_update_time(vmf->vma->vm_file);
     }
 
     if (IS_DAX(inode)) {
         pfn_t pfn;
 
         xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
         ret = xfs_dax_fault(vmf, pe_size, write_fault, &pfn);
         if (ret & VM_FAULT_NEEDDSYNC)
             ret = dax_finish_sync_fault(vmf, pe_size, pfn);
         xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
     } else {
         if (write_fault) {
             xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
             ret = iomap_page_mkwrite(vmf,
                     &xfs_buffered_write_iomap_ops);
             xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
         } else {
             ret = filemap_fault(vmf);
         }
     }
 
     if (write_fault)
         sb_end_pagefault(inode->i_sb);
     return ret;
 }
 
 static inline bool
 xfs_is_write_fault(
     struct vm_fault     *vmf)
 {
     return (vmf->flags & FAULT_FLAG_WRITE) &&
            (vmf->vma->vm_flags & VM_SHARED);
 }
 
 static vm_fault_t
 xfs_filemap_fault(
     struct vm_fault     *vmf)
 {
     /* DAX can shortcut the normal fault path on write faults! */
     return __xfs_filemap_fault(vmf, PE_SIZE_PTE,
             IS_DAX(file_inode(vmf->vma->vm_file)) &&
             xfs_is_write_fault(vmf));
 }
 
 static vm_fault_t
 xfs_filemap_huge_fault(
     struct vm_fault     *vmf,
     enum page_entry_size    pe_size)
 {
     if (!IS_DAX(file_inode(vmf->vma->vm_file)))
         return VM_FAULT_FALLBACK;
 
     /* DAX can shortcut the normal fault path on write faults! */
     return __xfs_filemap_fault(vmf, pe_size,
             xfs_is_write_fault(vmf));
 }
 
 static vm_fault_t
 xfs_filemap_page_mkwrite(
     struct vm_fault     *vmf)
 {
     return __xfs_filemap_fault(vmf, PE_SIZE_PTE, true);
 }
 
 /*
  * pfn_mkwrite was originally intended to ensure we capture time stamp updates
  * on write faults. In reality, it needs to serialise against truncate and
  * prepare memory for writing so handle is as standard write fault.
  */
 static vm_fault_t
 xfs_filemap_pfn_mkwrite(
     struct vm_fault     *vmf)
 {
 
     return __xfs_filemap_fault(vmf, PE_SIZE_PTE, true);
 }
 
 static vm_fault_t
 xfs_filemap_map_pages(
     struct vm_fault     *vmf,
     pgoff_t         start_pgoff,
     pgoff_t         end_pgoff)
 {
     struct inode        *inode = file_inode(vmf->vma->vm_file);
     vm_fault_t ret;
 
     xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
     ret = filemap_map_pages(vmf, start_pgoff, end_pgoff);
     xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
     return ret;
 }
 
 static const struct vm_operations_struct xfs_file_vm_ops = {
     .fault      = xfs_filemap_fault,
     .huge_fault = xfs_filemap_huge_fault,
     .map_pages  = xfs_filemap_map_pages,
     .page_mkwrite   = xfs_filemap_page_mkwrite,
     .pfn_mkwrite    = xfs_filemap_pfn_mkwrite,
 };
 
 STATIC int
 xfs_file_mmap(
     struct file     *file,
     struct vm_area_struct   *vma)
 {
     struct inode        *inode = file_inode(file);
     struct xfs_buftarg  *target = xfs_inode_buftarg(XFS_I(inode));
 
     /*
      * We don't support synchronous mappings for non-DAX files and
      * for DAX files if underneath dax_device is not synchronous.
      */
     if (!daxdev_mapping_supported(vma, target->bt_daxdev))
         return -EOPNOTSUPP;
 
     file_accessed(file);
     vma->vm_ops = &xfs_file_vm_ops;
     if (IS_DAX(inode))
         vma->vm_flags |= VM_HUGEPAGE;
     return 0;
 }
 
 const struct file_operations xfs_file_operations = {
     .llseek     = xfs_file_llseek,
     .read_iter  = xfs_file_read_iter,
     .write_iter = xfs_file_write_iter,
     .splice_read    = generic_file_splice_read,
     .splice_write   = iter_file_splice_write,
     .iopoll     = iocb_bio_iopoll,
     .unlocked_ioctl = xfs_file_ioctl,
 #ifdef CONFIG_COMPAT
     .compat_ioctl   = xfs_file_compat_ioctl,
 #endif
     .mmap       = xfs_file_mmap,
     .mmap_supported_flags = MAP_SYNC,
     .open       = xfs_file_open,
     .release    = xfs_file_release,
     .fsync      = xfs_file_fsync,
     .get_unmapped_area = thp_get_unmapped_area,
     .fallocate  = xfs_file_fallocate,
     .fadvise    = xfs_file_fadvise,
     .remap_file_range = xfs_file_remap_range,
 };
 
 const struct file_operations xfs_dir_file_operations = {
     .open       = xfs_dir_open,
     .read       = generic_read_dir,
     .iterate_shared = xfs_file_readdir,
     .llseek     = generic_file_llseek,
     .unlocked_ioctl = xfs_file_ioctl,
 #ifdef CONFIG_COMPAT
     .compat_ioctl   = xfs_file_compat_ioctl,
 #endif
     .fsync      = xfs_dir_fsync,
 };

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