OSCL-LXR linux-6.0.1/​fs/​overlayfs/​util.c	Source navigation Diff markup Identifier search General search
	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-only
 /*
  * Copyright (C) 2011 Novell Inc.
  * Copyright (C) 2016 Red Hat, Inc.
  */
 
 #include <linux/fs.h>
 #include <linux/mount.h>
 #include <linux/slab.h>
 #include <linux/cred.h>
 #include <linux/xattr.h>
 #include <linux/exportfs.h>
 #include <linux/fileattr.h>
 #include <linux/uuid.h>
 #include <linux/namei.h>
 #include <linux/ratelimit.h>
 #include "overlayfs.h"
 
 int ovl_want_write(struct dentry *dentry)
 {
     struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
     return mnt_want_write(ovl_upper_mnt(ofs));
 }
 
 void ovl_drop_write(struct dentry *dentry)
 {
     struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
     mnt_drop_write(ovl_upper_mnt(ofs));
 }
 
 struct dentry *ovl_workdir(struct dentry *dentry)
 {
     struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
     return ofs->workdir;
 }
 
 const struct cred *ovl_override_creds(struct super_block *sb)
 {
     struct ovl_fs *ofs = sb->s_fs_info;
 
     return override_creds(ofs->creator_cred);
 }
 
 /*
  * Check if underlying fs supports file handles and try to determine encoding
  * type, in order to deduce maximum inode number used by fs.
  *
  * Return 0 if file handles are not supported.
  * Return 1 (FILEID_INO32_GEN) if fs uses the default 32bit inode encoding.
  * Return -1 if fs uses a non default encoding with unknown inode size.
  */
 int ovl_can_decode_fh(struct super_block *sb)
 {
     if (!capable(CAP_DAC_READ_SEARCH))
         return 0;
 
     if (!sb->s_export_op || !sb->s_export_op->fh_to_dentry)
         return 0;
 
     return sb->s_export_op->encode_fh ? -1 : FILEID_INO32_GEN;
 }
 
 struct dentry *ovl_indexdir(struct super_block *sb)
 {
     struct ovl_fs *ofs = sb->s_fs_info;
 
     return ofs->indexdir;
 }
 
 /* Index all files on copy up. For now only enabled for NFS export */
 bool ovl_index_all(struct super_block *sb)
 {
     struct ovl_fs *ofs = sb->s_fs_info;
 
     return ofs->config.nfs_export && ofs->config.index;
 }
 
 /* Verify lower origin on lookup. For now only enabled for NFS export */
 bool ovl_verify_lower(struct super_block *sb)
 {
     struct ovl_fs *ofs = sb->s_fs_info;
 
     return ofs->config.nfs_export && ofs->config.index;
 }
 
 struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
 {
     size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
     struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
 
     if (oe)
         oe->numlower = numlower;
 
     return oe;
 }
 
 bool ovl_dentry_remote(struct dentry *dentry)
 {
     return dentry->d_flags &
         (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
 }
 
 void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
                  unsigned int mask)
 {
     struct ovl_entry *oe = OVL_E(dentry);
     unsigned int i, flags = 0;
 
     if (upperdentry)
         flags |= upperdentry->d_flags;
     for (i = 0; i < oe->numlower; i++)
         flags |= oe->lowerstack[i].dentry->d_flags;
 
     spin_lock(&dentry->d_lock);
     dentry->d_flags &= ~mask;
     dentry->d_flags |= flags & mask;
     spin_unlock(&dentry->d_lock);
 }
 
 bool ovl_dentry_weird(struct dentry *dentry)
 {
     return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
                   DCACHE_MANAGE_TRANSIT |
                   DCACHE_OP_HASH |
                   DCACHE_OP_COMPARE);
 }
 
 enum ovl_path_type ovl_path_type(struct dentry *dentry)
 {
     struct ovl_entry *oe = dentry->d_fsdata;
     enum ovl_path_type type = 0;
 
     if (ovl_dentry_upper(dentry)) {
         type = __OVL_PATH_UPPER;
 
         /*
          * Non-dir dentry can hold lower dentry of its copy up origin.
          */
         if (oe->numlower) {
             if (ovl_test_flag(OVL_CONST_INO, d_inode(dentry)))
                 type |= __OVL_PATH_ORIGIN;
             if (d_is_dir(dentry) ||
                 !ovl_has_upperdata(d_inode(dentry)))
                 type |= __OVL_PATH_MERGE;
         }
     } else {
         if (oe->numlower > 1)
             type |= __OVL_PATH_MERGE;
     }
     return type;
 }
 
 void ovl_path_upper(struct dentry *dentry, struct path *path)
 {
     struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
 
     path->mnt = ovl_upper_mnt(ofs);
     path->dentry = ovl_dentry_upper(dentry);
 }
 
 void ovl_path_lower(struct dentry *dentry, struct path *path)
 {
     struct ovl_entry *oe = dentry->d_fsdata;
 
     if (oe->numlower) {
         path->mnt = oe->lowerstack[0].layer->mnt;
         path->dentry = oe->lowerstack[0].dentry;
     } else {
         *path = (struct path) { };
     }
 }
 
 void ovl_path_lowerdata(struct dentry *dentry, struct path *path)
 {
     struct ovl_entry *oe = dentry->d_fsdata;
 
     if (oe->numlower) {
         path->mnt = oe->lowerstack[oe->numlower - 1].layer->mnt;
         path->dentry = oe->lowerstack[oe->numlower - 1].dentry;
     } else {
         *path = (struct path) { };
     }
 }
 
 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
 {
     enum ovl_path_type type = ovl_path_type(dentry);
 
     if (!OVL_TYPE_UPPER(type))
         ovl_path_lower(dentry, path);
     else
         ovl_path_upper(dentry, path);
 
     return type;
 }
 
 enum ovl_path_type ovl_path_realdata(struct dentry *dentry, struct path *path)
 {
     enum ovl_path_type type = ovl_path_type(dentry);
 
     WARN_ON_ONCE(d_is_dir(dentry));
 
     if (!OVL_TYPE_UPPER(type) || OVL_TYPE_MERGE(type))
         ovl_path_lowerdata(dentry, path);
     else
         ovl_path_upper(dentry, path);
 
     return type;
 }
 
 struct dentry *ovl_dentry_upper(struct dentry *dentry)
 {
     return ovl_upperdentry_dereference(OVL_I(d_inode(dentry)));
 }
 
 struct dentry *ovl_dentry_lower(struct dentry *dentry)
 {
     struct ovl_entry *oe = dentry->d_fsdata;
 
     return oe->numlower ? oe->lowerstack[0].dentry : NULL;
 }
 
 const struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
 {
     struct ovl_entry *oe = dentry->d_fsdata;
 
     return oe->numlower ? oe->lowerstack[0].layer : NULL;
 }
 
 /*
  * ovl_dentry_lower() could return either a data dentry or metacopy dentry
  * depending on what is stored in lowerstack[0]. At times we need to find
  * lower dentry which has data (and not metacopy dentry). This helper
  * returns the lower data dentry.
  */
 struct dentry *ovl_dentry_lowerdata(struct dentry *dentry)
 {
     struct ovl_entry *oe = dentry->d_fsdata;
 
     return oe->numlower ? oe->lowerstack[oe->numlower - 1].dentry : NULL;
 }
 
 struct dentry *ovl_dentry_real(struct dentry *dentry)
 {
     return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);
 }
 
 struct dentry *ovl_i_dentry_upper(struct inode *inode)
 {
     return ovl_upperdentry_dereference(OVL_I(inode));
 }
 
 void ovl_i_path_real(struct inode *inode, struct path *path)
 {
     path->dentry = ovl_i_dentry_upper(inode);
     if (!path->dentry) {
         path->dentry = OVL_I(inode)->lowerpath.dentry;
         path->mnt = OVL_I(inode)->lowerpath.layer->mnt;
     } else {
         path->mnt = ovl_upper_mnt(OVL_FS(inode->i_sb));
     }
 }
 
 struct inode *ovl_inode_upper(struct inode *inode)
 {
     struct dentry *upperdentry = ovl_i_dentry_upper(inode);
 
     return upperdentry ? d_inode(upperdentry) : NULL;
 }
 
 struct inode *ovl_inode_lower(struct inode *inode)
 {
     struct dentry *lowerdentry = OVL_I(inode)->lowerpath.dentry;
 
     return lowerdentry ? d_inode(lowerdentry) : NULL;
 }
 
 struct inode *ovl_inode_real(struct inode *inode)
 {
     return ovl_inode_upper(inode) ?: ovl_inode_lower(inode);
 }
 
 /* Return inode which contains lower data. Do not return metacopy */
 struct inode *ovl_inode_lowerdata(struct inode *inode)
 {
     if (WARN_ON(!S_ISREG(inode->i_mode)))
         return NULL;
 
     return OVL_I(inode)->lowerdata ?: ovl_inode_lower(inode);
 }
 
 /* Return real inode which contains data. Does not return metacopy inode */
 struct inode *ovl_inode_realdata(struct inode *inode)
 {
     struct inode *upperinode;
 
     upperinode = ovl_inode_upper(inode);
     if (upperinode && ovl_has_upperdata(inode))
         return upperinode;
 
     return ovl_inode_lowerdata(inode);
 }
 
 struct ovl_dir_cache *ovl_dir_cache(struct inode *inode)
 {
     return OVL_I(inode)->cache;
 }
 
 void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache)
 {
     OVL_I(inode)->cache = cache;
 }
 
 void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry)
 {
     set_bit(flag, &OVL_E(dentry)->flags);
 }
 
 void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry)
 {
     clear_bit(flag, &OVL_E(dentry)->flags);
 }
 
 bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry)
 {
     return test_bit(flag, &OVL_E(dentry)->flags);
 }
 
 bool ovl_dentry_is_opaque(struct dentry *dentry)
 {
     return ovl_dentry_test_flag(OVL_E_OPAQUE, dentry);
 }
 
 bool ovl_dentry_is_whiteout(struct dentry *dentry)
 {
     return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
 }
 
 void ovl_dentry_set_opaque(struct dentry *dentry)
 {
     ovl_dentry_set_flag(OVL_E_OPAQUE, dentry);
 }
 
 /*
  * For hard links and decoded file handles, it's possible for ovl_dentry_upper()
  * to return positive, while there's no actual upper alias for the inode.
  * Copy up code needs to know about the existence of the upper alias, so it
  * can't use ovl_dentry_upper().
  */
 bool ovl_dentry_has_upper_alias(struct dentry *dentry)
 {
     return ovl_dentry_test_flag(OVL_E_UPPER_ALIAS, dentry);
 }
 
 void ovl_dentry_set_upper_alias(struct dentry *dentry)
 {
     ovl_dentry_set_flag(OVL_E_UPPER_ALIAS, dentry);
 }
 
 static bool ovl_should_check_upperdata(struct inode *inode)
 {
     if (!S_ISREG(inode->i_mode))
         return false;
 
     if (!ovl_inode_lower(inode))
         return false;
 
     return true;
 }
 
 bool ovl_has_upperdata(struct inode *inode)
 {
     if (!ovl_should_check_upperdata(inode))
         return true;
 
     if (!ovl_test_flag(OVL_UPPERDATA, inode))
         return false;
     /*
      * Pairs with smp_wmb() in ovl_set_upperdata(). Main user of
      * ovl_has_upperdata() is ovl_copy_up_meta_inode_data(). Make sure
      * if setting of OVL_UPPERDATA is visible, then effects of writes
      * before that are visible too.
      */
     smp_rmb();
     return true;
 }
 
 void ovl_set_upperdata(struct inode *inode)
 {
     /*
      * Pairs with smp_rmb() in ovl_has_upperdata(). Make sure
      * if OVL_UPPERDATA flag is visible, then effects of write operations
      * before it are visible as well.
      */
     smp_wmb();
     ovl_set_flag(OVL_UPPERDATA, inode);
 }
 
 /* Caller should hold ovl_inode->lock */
 bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags)
 {
     if (!ovl_open_flags_need_copy_up(flags))
         return false;
 
     return !ovl_test_flag(OVL_UPPERDATA, d_inode(dentry));
 }
 
 bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags)
 {
     if (!ovl_open_flags_need_copy_up(flags))
         return false;
 
     return !ovl_has_upperdata(d_inode(dentry));
 }
 
 bool ovl_redirect_dir(struct super_block *sb)
 {
     struct ovl_fs *ofs = sb->s_fs_info;
 
     return ofs->config.redirect_dir && !ofs->noxattr;
 }
 
 const char *ovl_dentry_get_redirect(struct dentry *dentry)
 {
     return OVL_I(d_inode(dentry))->redirect;
 }
 
 void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect)
 {
     struct ovl_inode *oi = OVL_I(d_inode(dentry));
 
     kfree(oi->redirect);
     oi->redirect = redirect;
 }
 
 void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
 {
     struct inode *upperinode = d_inode(upperdentry);
 
     WARN_ON(OVL_I(inode)->__upperdentry);
 
     /*
      * Make sure upperdentry is consistent before making it visible
      */
     smp_wmb();
     OVL_I(inode)->__upperdentry = upperdentry;
     if (inode_unhashed(inode)) {
         inode->i_private = upperinode;
         __insert_inode_hash(inode, (unsigned long) upperinode);
     }
 }
 
 static void ovl_dir_version_inc(struct dentry *dentry, bool impurity)
 {
     struct inode *inode = d_inode(dentry);
 
     WARN_ON(!inode_is_locked(inode));
     WARN_ON(!d_is_dir(dentry));
     /*
      * Version is used by readdir code to keep cache consistent.
      * For merge dirs (or dirs with origin) all changes need to be noted.
      * For non-merge dirs, cache contains only impure entries (i.e. ones
      * which have been copied up and have origins), so only need to note
      * changes to impure entries.
      */
     if (!ovl_dir_is_real(dentry) || impurity)
         OVL_I(inode)->version++;
 }
 
 void ovl_dir_modified(struct dentry *dentry, bool impurity)
 {
     /* Copy mtime/ctime */
     ovl_copyattr(d_inode(dentry));
 
     ovl_dir_version_inc(dentry, impurity);
 }
 
 u64 ovl_dentry_version_get(struct dentry *dentry)
 {
     struct inode *inode = d_inode(dentry);
 
     WARN_ON(!inode_is_locked(inode));
     return OVL_I(inode)->version;
 }
 
 bool ovl_is_whiteout(struct dentry *dentry)
 {
     struct inode *inode = dentry->d_inode;
 
     return inode && IS_WHITEOUT(inode);
 }
 
 struct file *ovl_path_open(struct path *path, int flags)
 {
     struct inode *inode = d_inode(path->dentry);
     struct user_namespace *real_mnt_userns = mnt_user_ns(path->mnt);
     int err, acc_mode;
 
     if (flags & ~(O_ACCMODE | O_LARGEFILE))
         BUG();
 
     switch (flags & O_ACCMODE) {
     case O_RDONLY:
         acc_mode = MAY_READ;
         break;
     case O_WRONLY:
         acc_mode = MAY_WRITE;
         break;
     default:
         BUG();
     }
 
     err = inode_permission(real_mnt_userns, inode, acc_mode | MAY_OPEN);
     if (err)
         return ERR_PTR(err);
 
     /* O_NOATIME is an optimization, don't fail if not permitted */
     if (inode_owner_or_capable(real_mnt_userns, inode))
         flags |= O_NOATIME;
 
     return dentry_open(path, flags, current_cred());
 }
 
 /* Caller should hold ovl_inode->lock */
 static bool ovl_already_copied_up_locked(struct dentry *dentry, int flags)
 {
     bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
 
     if (ovl_dentry_upper(dentry) &&
         (ovl_dentry_has_upper_alias(dentry) || disconnected) &&
         !ovl_dentry_needs_data_copy_up_locked(dentry, flags))
         return true;
 
     return false;
 }
 
 bool ovl_already_copied_up(struct dentry *dentry, int flags)
 {
     bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
 
     /*
      * Check if copy-up has happened as well as for upper alias (in
      * case of hard links) is there.
      *
      * Both checks are lockless:
      *  - false negatives: will recheck under oi->lock
      *  - false positives:
      *    + ovl_dentry_upper() uses memory barriers to ensure the
      *      upper dentry is up-to-date
      *    + ovl_dentry_has_upper_alias() relies on locking of
      *      upper parent i_rwsem to prevent reordering copy-up
      *      with rename.
      */
     if (ovl_dentry_upper(dentry) &&
         (ovl_dentry_has_upper_alias(dentry) || disconnected) &&
         !ovl_dentry_needs_data_copy_up(dentry, flags))
         return true;
 
     return false;
 }
 
 int ovl_copy_up_start(struct dentry *dentry, int flags)
 {
     struct inode *inode = d_inode(dentry);
     int err;
 
     err = ovl_inode_lock_interruptible(inode);
     if (!err && ovl_already_copied_up_locked(dentry, flags)) {
         err = 1; /* Already copied up */
         ovl_inode_unlock(inode);
     }
 
     return err;
 }
 
 void ovl_copy_up_end(struct dentry *dentry)
 {
     ovl_inode_unlock(d_inode(dentry));
 }
 
 bool ovl_path_check_origin_xattr(struct ovl_fs *ofs, struct path *path)
 {
     int res;
 
     res = ovl_path_getxattr(ofs, path, OVL_XATTR_ORIGIN, NULL, 0);
 
     /* Zero size value means "copied up but origin unknown" */
     if (res >= 0)
         return true;
 
     return false;
 }
 
 bool ovl_path_check_dir_xattr(struct ovl_fs *ofs, struct path *path,
                    enum ovl_xattr ox)
 {
     int res;
     char val;
 
     if (!d_is_dir(path->dentry))
         return false;
 
     res = ovl_path_getxattr(ofs, path, ox, &val, 1);
     if (res == 1 && val == 'y')
         return true;
 
     return false;
 }
 
 #define OVL_XATTR_OPAQUE_POSTFIX    "opaque"
 #define OVL_XATTR_REDIRECT_POSTFIX  "redirect"
 #define OVL_XATTR_ORIGIN_POSTFIX    "origin"
 #define OVL_XATTR_IMPURE_POSTFIX    "impure"
 #define OVL_XATTR_NLINK_POSTFIX     "nlink"
 #define OVL_XATTR_UPPER_POSTFIX     "upper"
 #define OVL_XATTR_METACOPY_POSTFIX  "metacopy"
 #define OVL_XATTR_PROTATTR_POSTFIX  "protattr"
 
 #define OVL_XATTR_TAB_ENTRY(x) \
     [x] = { [false] = OVL_XATTR_TRUSTED_PREFIX x ## _POSTFIX, \
         [true] = OVL_XATTR_USER_PREFIX x ## _POSTFIX }
 
 const char *const ovl_xattr_table[][2] = {
     OVL_XATTR_TAB_ENTRY(OVL_XATTR_OPAQUE),
     OVL_XATTR_TAB_ENTRY(OVL_XATTR_REDIRECT),
     OVL_XATTR_TAB_ENTRY(OVL_XATTR_ORIGIN),
     OVL_XATTR_TAB_ENTRY(OVL_XATTR_IMPURE),
     OVL_XATTR_TAB_ENTRY(OVL_XATTR_NLINK),
     OVL_XATTR_TAB_ENTRY(OVL_XATTR_UPPER),
     OVL_XATTR_TAB_ENTRY(OVL_XATTR_METACOPY),
     OVL_XATTR_TAB_ENTRY(OVL_XATTR_PROTATTR),
 };
 
 int ovl_check_setxattr(struct ovl_fs *ofs, struct dentry *upperdentry,
                enum ovl_xattr ox, const void *value, size_t size,
                int xerr)
 {
     int err;
 
     if (ofs->noxattr)
         return xerr;
 
     err = ovl_setxattr(ofs, upperdentry, ox, value, size);
 
     if (err == -EOPNOTSUPP) {
         pr_warn("cannot set %s xattr on upper\n", ovl_xattr(ofs, ox));
         ofs->noxattr = true;
         return xerr;
     }
 
     return err;
 }
 
 int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry)
 {
     struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
     int err;
 
     if (ovl_test_flag(OVL_IMPURE, d_inode(dentry)))
         return 0;
 
     /*
      * Do not fail when upper doesn't support xattrs.
      * Upper inodes won't have origin nor redirect xattr anyway.
      */
     err = ovl_check_setxattr(ofs, upperdentry, OVL_XATTR_IMPURE, "y", 1, 0);
     if (!err)
         ovl_set_flag(OVL_IMPURE, d_inode(dentry));
 
     return err;
 }
 
 
 #define OVL_PROTATTR_MAX 32 /* Reserved for future flags */
 
 void ovl_check_protattr(struct inode *inode, struct dentry *upper)
 {
     struct ovl_fs *ofs = OVL_FS(inode->i_sb);
     u32 iflags = inode->i_flags & OVL_PROT_I_FLAGS_MASK;
     char buf[OVL_PROTATTR_MAX+1];
     int res, n;
 
     res = ovl_getxattr_upper(ofs, upper, OVL_XATTR_PROTATTR, buf,
                  OVL_PROTATTR_MAX);
     if (res < 0)
         return;
 
     /*
      * Initialize inode flags from overlay.protattr xattr and upper inode
      * flags.  If upper inode has those fileattr flags set (i.e. from old
      * kernel), we do not clear them on ovl_get_inode(), but we will clear
      * them on next fileattr_set().
      */
     for (n = 0; n < res; n++) {
         if (buf[n] == 'a')
             iflags |= S_APPEND;
         else if (buf[n] == 'i')
             iflags |= S_IMMUTABLE;
         else
             break;
     }
 
     if (!res || n < res) {
         pr_warn_ratelimited("incompatible overlay.protattr format (%pd2, len=%d)\n",
                     upper, res);
     } else {
         inode_set_flags(inode, iflags, OVL_PROT_I_FLAGS_MASK);
     }
 }
 
 int ovl_set_protattr(struct inode *inode, struct dentry *upper,
               struct fileattr *fa)
 {
     struct ovl_fs *ofs = OVL_FS(inode->i_sb);
     char buf[OVL_PROTATTR_MAX];
     int len = 0, err = 0;
     u32 iflags = 0;
 
     BUILD_BUG_ON(HWEIGHT32(OVL_PROT_FS_FLAGS_MASK) > OVL_PROTATTR_MAX);
 
     if (fa->flags & FS_APPEND_FL) {
         buf[len++] = 'a';
         iflags |= S_APPEND;
     }
     if (fa->flags & FS_IMMUTABLE_FL) {
         buf[len++] = 'i';
         iflags |= S_IMMUTABLE;
     }
 
     /*
      * Do not allow to set protection flags when upper doesn't support
      * xattrs, because we do not set those fileattr flags on upper inode.
      * Remove xattr if it exist and all protection flags are cleared.
      */
     if (len) {
         err = ovl_check_setxattr(ofs, upper, OVL_XATTR_PROTATTR,
                      buf, len, -EPERM);
     } else if (inode->i_flags & OVL_PROT_I_FLAGS_MASK) {
         err = ovl_removexattr(ofs, upper, OVL_XATTR_PROTATTR);
         if (err == -EOPNOTSUPP || err == -ENODATA)
             err = 0;
     }
     if (err)
         return err;
 
     inode_set_flags(inode, iflags, OVL_PROT_I_FLAGS_MASK);
 
     /* Mask out the fileattr flags that should not be set in upper inode */
     fa->flags &= ~OVL_PROT_FS_FLAGS_MASK;
     fa->fsx_xflags &= ~OVL_PROT_FSX_FLAGS_MASK;
 
     return 0;
 }
 
 /**
  * Caller must hold a reference to inode to prevent it from being freed while
  * it is marked inuse.
  */
 bool ovl_inuse_trylock(struct dentry *dentry)
 {
     struct inode *inode = d_inode(dentry);
     bool locked = false;
 
     spin_lock(&inode->i_lock);
     if (!(inode->i_state & I_OVL_INUSE)) {
         inode->i_state |= I_OVL_INUSE;
         locked = true;
     }
     spin_unlock(&inode->i_lock);
 
     return locked;
 }
 
 void ovl_inuse_unlock(struct dentry *dentry)
 {
     if (dentry) {
         struct inode *inode = d_inode(dentry);
 
         spin_lock(&inode->i_lock);
         WARN_ON(!(inode->i_state & I_OVL_INUSE));
         inode->i_state &= ~I_OVL_INUSE;
         spin_unlock(&inode->i_lock);
     }
 }
 
 bool ovl_is_inuse(struct dentry *dentry)
 {
     struct inode *inode = d_inode(dentry);
     bool inuse;
 
     spin_lock(&inode->i_lock);
     inuse = (inode->i_state & I_OVL_INUSE);
     spin_unlock(&inode->i_lock);
 
     return inuse;
 }
 
 /*
  * Does this overlay dentry need to be indexed on copy up?
  */
 bool ovl_need_index(struct dentry *dentry)
 {
     struct dentry *lower = ovl_dentry_lower(dentry);
 
     if (!lower || !ovl_indexdir(dentry->d_sb))
         return false;
 
     /* Index all files for NFS export and consistency verification */
     if (ovl_index_all(dentry->d_sb))
         return true;
 
     /* Index only lower hardlinks on copy up */
     if (!d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
         return true;
 
     return false;
 }
 
 /* Caller must hold OVL_I(inode)->lock */
 static void ovl_cleanup_index(struct dentry *dentry)
 {
     struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
     struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
     struct inode *dir = indexdir->d_inode;
     struct dentry *lowerdentry = ovl_dentry_lower(dentry);
     struct dentry *upperdentry = ovl_dentry_upper(dentry);
     struct dentry *index = NULL;
     struct inode *inode;
     struct qstr name = { };
     int err;
 
     err = ovl_get_index_name(ofs, lowerdentry, &name);
     if (err)
         goto fail;
 
     inode = d_inode(upperdentry);
     if (!S_ISDIR(inode->i_mode) && inode->i_nlink != 1) {
         pr_warn_ratelimited("cleanup linked index (%pd2, ino=%lu, nlink=%u)\n",
                     upperdentry, inode->i_ino, inode->i_nlink);
         /*
          * We either have a bug with persistent union nlink or a lower
          * hardlink was added while overlay is mounted. Adding a lower
          * hardlink and then unlinking all overlay hardlinks would drop
          * overlay nlink to zero before all upper inodes are unlinked.
          * As a safety measure, when that situation is detected, set
          * the overlay nlink to the index inode nlink minus one for the
          * index entry itself.
          */
         set_nlink(d_inode(dentry), inode->i_nlink - 1);
         ovl_set_nlink_upper(dentry);
         goto out;
     }
 
     inode_lock_nested(dir, I_MUTEX_PARENT);
     index = ovl_lookup_upper(ofs, name.name, indexdir, name.len);
     err = PTR_ERR(index);
     if (IS_ERR(index)) {
         index = NULL;
     } else if (ovl_index_all(dentry->d_sb)) {
         /* Whiteout orphan index to block future open by handle */
         err = ovl_cleanup_and_whiteout(OVL_FS(dentry->d_sb),
                            dir, index);
     } else {
         /* Cleanup orphan index entries */
         err = ovl_cleanup(ofs, dir, index);
     }
 
     inode_unlock(dir);
     if (err)
         goto fail;
 
 out:
     kfree(name.name);
     dput(index);
     return;
 
 fail:
     pr_err("cleanup index of '%pd2' failed (%i)\n", dentry, err);
     goto out;
 }
 
 /*
  * Operations that change overlay inode and upper inode nlink need to be
  * synchronized with copy up for persistent nlink accounting.
  */
 int ovl_nlink_start(struct dentry *dentry)
 {
     struct inode *inode = d_inode(dentry);
     const struct cred *old_cred;
     int err;
 
     if (WARN_ON(!inode))
         return -ENOENT;
 
     /*
      * With inodes index is enabled, we store the union overlay nlink
      * in an xattr on the index inode. When whiting out an indexed lower,
      * we need to decrement the overlay persistent nlink, but before the
      * first copy up, we have no upper index inode to store the xattr.
      *
      * As a workaround, before whiteout/rename over an indexed lower,
      * copy up to create the upper index. Creating the upper index will
      * initialize the overlay nlink, so it could be dropped if unlink
      * or rename succeeds.
      *
      * TODO: implement metadata only index copy up when called with
      *       ovl_copy_up_flags(dentry, O_PATH).
      */
     if (ovl_need_index(dentry) && !ovl_dentry_has_upper_alias(dentry)) {
         err = ovl_copy_up(dentry);
         if (err)
             return err;
     }
 
     err = ovl_inode_lock_interruptible(inode);
     if (err)
         return err;
 
     if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode))
         goto out;
 
     old_cred = ovl_override_creds(dentry->d_sb);
     /*
      * The overlay inode nlink should be incremented/decremented IFF the
      * upper operation succeeds, along with nlink change of upper inode.
      * Therefore, before link/unlink/rename, we store the union nlink
      * value relative to the upper inode nlink in an upper inode xattr.
      */
     err = ovl_set_nlink_upper(dentry);
     revert_creds(old_cred);
 
 out:
     if (err)
         ovl_inode_unlock(inode);
 
     return err;
 }
 
 void ovl_nlink_end(struct dentry *dentry)
 {
     struct inode *inode = d_inode(dentry);
 
     if (ovl_test_flag(OVL_INDEX, inode) && inode->i_nlink == 0) {
         const struct cred *old_cred;
 
         old_cred = ovl_override_creds(dentry->d_sb);
         ovl_cleanup_index(dentry);
         revert_creds(old_cred);
     }
 
     ovl_inode_unlock(inode);
 }
 
 int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
 {
     /* Workdir should not be the same as upperdir */
     if (workdir == upperdir)
         goto err;
 
     /* Workdir should not be subdir of upperdir and vice versa */
     if (lock_rename(workdir, upperdir) != NULL)
         goto err_unlock;
 
     return 0;
 
 err_unlock:
     unlock_rename(workdir, upperdir);
 err:
     pr_err("failed to lock workdir+upperdir\n");
     return -EIO;
 }
 
 /* err < 0, 0 if no metacopy xattr, 1 if metacopy xattr found */
 int ovl_check_metacopy_xattr(struct ovl_fs *ofs, struct path *path)
 {
     int res;
 
     /* Only regular files can have metacopy xattr */
     if (!S_ISREG(d_inode(path->dentry)->i_mode))
         return 0;
 
     res = ovl_path_getxattr(ofs, path, OVL_XATTR_METACOPY, NULL, 0);
     if (res < 0) {
         if (res == -ENODATA || res == -EOPNOTSUPP)
             return 0;
         /*
          * getxattr on user.* may fail with EACCES in case there's no
          * read permission on the inode.  Not much we can do, other than
          * tell the caller that this is not a metacopy inode.
          */
         if (ofs->config.userxattr && res == -EACCES)
             return 0;
         goto out;
     }
 
     return 1;
 out:
     pr_warn_ratelimited("failed to get metacopy (%i)\n", res);
     return res;
 }
 
 bool ovl_is_metacopy_dentry(struct dentry *dentry)
 {
     struct ovl_entry *oe = dentry->d_fsdata;
 
     if (!d_is_reg(dentry))
         return false;
 
     if (ovl_dentry_upper(dentry)) {
         if (!ovl_has_upperdata(d_inode(dentry)))
             return true;
         return false;
     }
 
     return (oe->numlower > 1);
 }
 
 char *ovl_get_redirect_xattr(struct ovl_fs *ofs, struct path *path, int padding)
 {
     int res;
     char *s, *next, *buf = NULL;
 
     res = ovl_path_getxattr(ofs, path, OVL_XATTR_REDIRECT, NULL, 0);
     if (res == -ENODATA || res == -EOPNOTSUPP)
         return NULL;
     if (res < 0)
         goto fail;
     if (res == 0)
         goto invalid;
 
     buf = kzalloc(res + padding + 1, GFP_KERNEL);
     if (!buf)
         return ERR_PTR(-ENOMEM);
 
     res = ovl_path_getxattr(ofs, path, OVL_XATTR_REDIRECT, buf, res);
     if (res < 0)
         goto fail;
     if (res == 0)
         goto invalid;
 
     if (buf[0] == '/') {
         for (s = buf; *s++ == '/'; s = next) {
             next = strchrnul(s, '/');
             if (s == next)
                 goto invalid;
         }
     } else {
         if (strchr(buf, '/') != NULL)
             goto invalid;
     }
 
     return buf;
 invalid:
     pr_warn_ratelimited("invalid redirect (%s)\n", buf);
     res = -EINVAL;
     goto err_free;
 fail:
     pr_warn_ratelimited("failed to get redirect (%i)\n", res);
 err_free:
     kfree(buf);
     return ERR_PTR(res);
 }
 
 /*
  * ovl_sync_status() - Check fs sync status for volatile mounts
  *
  * Returns 1 if this is not a volatile mount and a real sync is required.
  *
  * Returns 0 if syncing can be skipped because mount is volatile, and no errors
  * have occurred on the upperdir since the mount.
  *
  * Returns -errno if it is a volatile mount, and the error that occurred since
  * the last mount. If the error code changes, it'll return the latest error
  * code.
  */
 
 int ovl_sync_status(struct ovl_fs *ofs)
 {
     struct vfsmount *mnt;
 
     if (ovl_should_sync(ofs))
         return 1;
 
     mnt = ovl_upper_mnt(ofs);
     if (!mnt)
         return 0;
 
     return errseq_check(&mnt->mnt_sb->s_wb_err, ofs->errseq);
 }
 
 /*
  * ovl_copyattr() - copy inode attributes from layer to ovl inode
  *
  * When overlay copies inode information from an upper or lower layer to the
  * relevant overlay inode it will apply the idmapping of the upper or lower
  * layer when doing so ensuring that the ovl inode ownership will correctly
  * reflect the ownership of the idmapped upper or lower layer. For example, an
  * idmapped upper or lower layer mapping id 1001 to id 1000 will take care to
  * map any lower or upper inode owned by id 1001 to id 1000. These mapping
  * helpers are nops when the relevant layer isn't idmapped.
  */
 void ovl_copyattr(struct inode *inode)
 {
     struct path realpath;
     struct inode *realinode;
     struct user_namespace *real_mnt_userns;
 
     ovl_i_path_real(inode, &realpath);
     realinode = d_inode(realpath.dentry);
     real_mnt_userns = mnt_user_ns(realpath.mnt);
 
     inode->i_uid = i_uid_into_mnt(real_mnt_userns, realinode);
     inode->i_gid = i_gid_into_mnt(real_mnt_userns, realinode);
     inode->i_mode = realinode->i_mode;
     inode->i_atime = realinode->i_atime;
     inode->i_mtime = realinode->i_mtime;
     inode->i_ctime = realinode->i_ctime;
     i_size_write(inode, i_size_read(realinode));
 }

This page was automatically generated by the 2.1.0 LXR engine. The LXR team