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Merge patch series "btrfs: stop duplicating VFS code for subvolume/snapshot dentry"

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Filipe Manana <fdmanana@suse.com> says:

Currently btrfs has copies of two unexported functions from fs/namei.c
used in the snapshot/subvolume creation and deletion. This patchset
exports those functions and makes btrfs use them, to avoid duplication
and the burden of keeping the copies up to date.

* patches from https://patch.msgid.link/cover.1768307858.git.fdmanana@suse.com:
  btrfs: use may_create_dentry() in btrfs_mksubvol()
  btrfs: use may_delete_dentry() in btrfs_ioctl_snap_destroy()
  fs: export may_create() as may_create_dentry()
  fs: export may_delete() as may_delete_dentry()

Link: https://patch.msgid.link/cover.1768307858.git.fdmanana@suse.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2026-01-14 17:17:53 +01:00
commit f97f020075
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GPG Key ID: 91C61BC06578DCA2
3 changed files with 26 additions and 88 deletions
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73
fs/btrfs/ioctl.c
View File

@ -815,75 +815,6 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
return ret;
}
/* copy of may_delete in fs/namei.c()
* Check whether we can remove a link victim from directory dir, check
* whether the type of victim is right.
* 1. We can't do it if dir is read-only (done in permission())
* 2. We should have write and exec permissions on dir
* 3. We can't remove anything from append-only dir
* 4. We can't do anything with immutable dir (done in permission())
* 5. If the sticky bit on dir is set we should either
* a. be owner of dir, or
* b. be owner of victim, or
* c. have CAP_FOWNER capability
* 6. If the victim is append-only or immutable we can't do anything with
* links pointing to it.
* 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
* 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
* 9. We can't remove a root or mountpoint.
* 10. We don't allow removal of NFS sillyrenamed files; it's handled by
* nfs_async_unlink().
*/
static int btrfs_may_delete(struct mnt_idmap *idmap,
struct inode *dir, struct dentry *victim, int isdir)
{
int ret;
if (d_really_is_negative(victim))
return -ENOENT;
/* The @victim is not inside @dir. */
if (d_inode(victim->d_parent) != dir)
return -EINVAL;
audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
ret = inode_permission(idmap, dir, MAY_WRITE | MAY_EXEC);
if (ret)
return ret;
if (IS_APPEND(dir))
return -EPERM;
if (check_sticky(idmap, dir, d_inode(victim)) ||
IS_APPEND(d_inode(victim)) || IS_IMMUTABLE(d_inode(victim)) ||
IS_SWAPFILE(d_inode(victim)))
return -EPERM;
if (isdir) {
if (!d_is_dir(victim))
return -ENOTDIR;
if (IS_ROOT(victim))
return -EBUSY;
} else if (d_is_dir(victim))
return -EISDIR;
if (IS_DEADDIR(dir))
return -ENOENT;
if (victim->d_flags & DCACHE_NFSFS_RENAMED)
return -EBUSY;
return 0;
}
/* copy of may_create in fs/namei.c() */
static inline int btrfs_may_create(struct mnt_idmap *idmap,
struct inode *dir, const struct dentry *child)
{
if (d_really_is_positive(child))
return -EEXIST;
if (IS_DEADDIR(dir))
return -ENOENT;
if (!fsuidgid_has_mapping(dir->i_sb, idmap))
return -EOVERFLOW;
return inode_permission(idmap, dir, MAY_WRITE | MAY_EXEC);
}
/*
* Create a new subvolume below @parent. This is largely modeled after
* sys_mkdirat and vfs_mkdir, but we only do a single component lookup
@ -905,7 +836,7 @@ static noinline int btrfs_mksubvol(struct dentry *parent,
if (IS_ERR(dentry))
return PTR_ERR(dentry);
ret = btrfs_may_create(idmap, dir, dentry);
ret = may_create_dentry(idmap, dir, dentry);
if (ret)
goto out_dput;
@ -2420,7 +2351,7 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
}
/* check if subvolume may be deleted by a user */
ret = btrfs_may_delete(idmap, dir, dentry, 1);
ret = may_delete_dentry(idmap, dir, dentry, true);
if (ret)
goto out_end_removing;

36
fs/namei.c
View File

@ -3604,7 +3604,7 @@ EXPORT_SYMBOL(__check_sticky);
* 11. We don't allow removal of NFS sillyrenamed files; it's handled by
* nfs_async_unlink().
*/
static int may_delete(struct mnt_idmap *idmap, struct inode *dir,
int may_delete_dentry(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *victim, bool isdir)
{
struct inode *inode = d_backing_inode(victim);
@ -3646,6 +3646,7 @@ static int may_delete(struct mnt_idmap *idmap, struct inode *dir,
return -EBUSY;
return 0;
}
EXPORT_SYMBOL(may_delete_dentry);
/* Check whether we can create an object with dentry child in directory
* dir.
@ -3656,8 +3657,8 @@ static int may_delete(struct mnt_idmap *idmap, struct inode *dir,
* 4. We should have write and exec permissions on dir
* 5. We can't do it if dir is immutable (done in permission())
*/
static inline int may_create(struct mnt_idmap *idmap,
struct inode *dir, struct dentry *child)
int may_create_dentry(struct mnt_idmap *idmap,
struct inode *dir, struct dentry *child)
{
audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE);
if (child->d_inode)
@ -3669,6 +3670,7 @@ static inline int may_create(struct mnt_idmap *idmap,
return inode_permission(idmap, dir, MAY_WRITE | MAY_EXEC);
}
EXPORT_SYMBOL(may_create_dentry);
// p1 != p2, both are on the same filesystem, ->s_vfs_rename_mutex is held
static struct dentry *lock_two_directories(struct dentry *p1, struct dentry *p2)
@ -4115,7 +4117,7 @@ int vfs_create(struct mnt_idmap *idmap, struct dentry *dentry, umode_t mode,
struct inode *dir = d_inode(dentry->d_parent);
int error;
error = may_create(idmap, dir, dentry);
error = may_create_dentry(idmap, dir, dentry);
if (error)
return error;
@ -4141,7 +4143,7 @@ int vfs_mkobj(struct dentry *dentry, umode_t mode,
void *arg)
{
struct inode *dir = dentry->d_parent->d_inode;
int error = may_create(&nop_mnt_idmap, dir, dentry);
int error = may_create_dentry(&nop_mnt_idmap, dir, dentry);
if (error)
return error;
@ -4960,7 +4962,7 @@ int vfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
struct delegated_inode *delegated_inode)
{
bool is_whiteout = S_ISCHR(mode) && dev == WHITEOUT_DEV;
int error = may_create(idmap, dir, dentry);
int error = may_create_dentry(idmap, dir, dentry);
if (error)
return error;
@ -5106,7 +5108,7 @@ struct dentry *vfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
unsigned max_links = dir->i_sb->s_max_links;
struct dentry *de;
error = may_create(idmap, dir, dentry);
error = may_create_dentry(idmap, dir, dentry);
if (error)
goto err;
@ -5209,7 +5211,7 @@ SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
int vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, struct delegated_inode *delegated_inode)
{
int error = may_delete(idmap, dir, dentry, 1);
int error = may_delete_dentry(idmap, dir, dentry, true);
if (error)
return error;
@ -5344,7 +5346,7 @@ int vfs_unlink(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, struct delegated_inode *delegated_inode)
{
struct inode *target = dentry->d_inode;
int error = may_delete(idmap, dir, dentry, 0);
int error = may_delete_dentry(idmap, dir, dentry, false);
if (error)
return error;
@ -5496,7 +5498,7 @@ int vfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
{
int error;
error = may_create(idmap, dir, dentry);
error = may_create_dentry(idmap, dir, dentry);
if (error)
return error;
@ -5604,7 +5606,7 @@ int vfs_link(struct dentry *old_dentry, struct mnt_idmap *idmap,
if (!inode)
return -ENOENT;
error = may_create(idmap, dir, new_dentry);
error = may_create_dentry(idmap, dir, new_dentry);
if (error)
return error;
@ -5816,21 +5818,21 @@ int vfs_rename(struct renamedata *rd)
if (source == target)
return 0;
error = may_delete(rd->mnt_idmap, old_dir, old_dentry, is_dir);
error = may_delete_dentry(rd->mnt_idmap, old_dir, old_dentry, is_dir);
if (error)
return error;
if (!target) {
error = may_create(rd->mnt_idmap, new_dir, new_dentry);
error = may_create_dentry(rd->mnt_idmap, new_dir, new_dentry);
} else {
new_is_dir = d_is_dir(new_dentry);
if (!(flags & RENAME_EXCHANGE))
error = may_delete(rd->mnt_idmap, new_dir,
new_dentry, is_dir);
error = may_delete_dentry(rd->mnt_idmap, new_dir,
new_dentry, is_dir);
else
error = may_delete(rd->mnt_idmap, new_dir,
new_dentry, new_is_dir);
error = may_delete_dentry(rd->mnt_idmap, new_dir,
new_dentry, new_is_dir);
}
if (error)
return error;

5
include/linux/fs.h
View File

@ -2657,6 +2657,11 @@ static inline int path_permission(const struct path *path, int mask)
int __check_sticky(struct mnt_idmap *idmap, struct inode *dir,
struct inode *inode);
int may_delete_dentry(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *victim, bool isdir);
int may_create_dentry(struct mnt_idmap *idmap,
struct inode *dir, struct dentry *child);
static inline bool execute_ok(struct inode *inode)
{
return (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode);