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ovl: narrow locking in ovl_check_rename_whiteout()

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ovl_check_rename_whiteout() now only holds the directory lock when
needed, and takes it again if necessary.

This makes way for future changes where locks are taken on individual
dentries rather than the whole directory.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://lore.kernel.org/20250716004725.1206467-20-neil@brown.name
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
NeilBrown 2025-07-16 10:44:30 +10:00 committed by Christian Brauner
parent 8afa0a7367
commit 09d56cc88c
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
1 changed files with 7 additions and 8 deletions
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15
fs/overlayfs/super.c
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@ -556,7 +556,6 @@ static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
static int ovl_check_rename_whiteout(struct ovl_fs *ofs)
{
struct dentry *workdir = ofs->workdir;
struct inode *dir = d_inode(workdir);
struct dentry *temp;
struct dentry *dest;
struct dentry *whiteout;
@ -577,19 +576,22 @@ static int ovl_check_rename_whiteout(struct ovl_fs *ofs)
err = PTR_ERR(dest);
if (IS_ERR(dest)) {
dput(temp);
goto out_unlock;
ovl_parent_unlock(workdir);
return err;
}
/* Name is inline and stable - using snapshot as a copy helper */
take_dentry_name_snapshot(&name, temp);
err = ovl_do_rename(ofs, workdir, temp, workdir, dest, RENAME_WHITEOUT);
ovl_parent_unlock(workdir);
if (err) {
if (err == -EINVAL)
err = 0;
goto cleanup_temp;
}
whiteout = ovl_lookup_upper(ofs, name.name.name, workdir, name.name.len);
whiteout = ovl_lookup_upper_unlocked(ofs, name.name.name,
workdir, name.name.len);
err = PTR_ERR(whiteout);
if (IS_ERR(whiteout))
goto cleanup_temp;
@ -598,18 +600,15 @@ static int ovl_check_rename_whiteout(struct ovl_fs *ofs)
/* Best effort cleanup of whiteout and temp file */
if (err)
ovl_cleanup(ofs, dir, whiteout);
ovl_cleanup_unlocked(ofs, workdir, whiteout);
dput(whiteout);
cleanup_temp:
ovl_cleanup(ofs, dir, temp);
ovl_cleanup_unlocked(ofs, workdir, temp);
release_dentry_name_snapshot(&name);
dput(temp);
dput(dest);
out_unlock:
ovl_parent_unlock(workdir);
return err;
}