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

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>

3 files changed, 26 insertions, 88 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index acb484546b1d..d1ab03691606 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -815,75 +815,6 @@ free_pending:
 	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;
 
diff --git a/fs/namei.c b/fs/namei.c
index bf0f66f0e9b9..676b8c016839 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -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;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 04ceeca12a0d..2d28eff6eb6a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -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);