Unverified Commit 1c3cb50b authored by NeilBrown's avatar NeilBrown Committed by Christian Brauner
Browse files

VFS: change kern_path_locked() and user_path_locked_at() to never return negative dentry 



No callers of kern_path_locked() or user_path_locked_at() want a
negative dentry.  So change them to return -ENOENT instead.  This
simplifies callers.

This results in a subtle change to bcachefs in that an ioctl will now
return -ENOENT in preference to -EXDEV.  I believe this restores the
behaviour to what it was prior to
 Commit bbe6a7c8 ("bch2_ioctl_subvolume_destroy(): fix locking")

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20250217003020.3170652-2-neilb@suse.de


Acked-by: default avatarPaul Moore <paul@paul-moore.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 2c3230fb

Documentation/filesystems/porting.rst

+8 −0
Original line number Diff line number Diff line
@@ -1157,3 +1157,11 @@ in normal case it points into the pathname being looked up. 
NOTE: if you need something like full path from the root of filesystem,

you are still on your own - this assists with simple cases, but it's not

magic.



---



** recommended**



kern_path_locked() and user_path_locked() no longer return a negative

dentry so this doesn't need to be checked.  If the name cannot be found,

ERR_PTR(-ENOENT) is returned.

drivers/base/devtmpfs.c

+30 −35
Original line number Diff line number Diff line
@@ -245,15 +245,12 @@ static int dev_rmdir(const char *name) 
	dentry = kern_path_locked(name, &parent);

	if (IS_ERR(dentry))

		return PTR_ERR(dentry);

	if (d_really_is_positive(dentry)) {

	if (d_inode(dentry)->i_private == &thread)

		err = vfs_rmdir(&nop_mnt_idmap, d_inode(parent.dentry),

				dentry);

	else

		err = -EPERM;

	} else {

		err = -ENOENT;

	}



	dput(dentry);

	inode_unlock(d_inode(parent.dentry));

	path_put(&parent);
@@ -310,6 +307,8 @@ static int handle_remove(const char *nodename, struct device *dev) 
{

	struct path parent;

	struct dentry *dentry;

	struct kstat stat;

	struct path p;

	int deleted = 0;

	int err;
@@ -317,9 +316,8 @@ static int handle_remove(const char *nodename, struct device *dev) 
	if (IS_ERR(dentry))

		return PTR_ERR(dentry);



	if (d_really_is_positive(dentry)) {

		struct kstat stat;

		struct path p = {.mnt = parent.mnt, .dentry = dentry};

	p.mnt = parent.mnt;

	p.dentry = dentry;

	err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,

			  AT_STATX_SYNC_AS_STAT);

	if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
@@ -341,9 +339,6 @@ static int handle_remove(const char *nodename, struct device *dev) 
		if (!err || err == -ENOENT)

			deleted = 1;

	}

	} else {

		err = -ENOENT;

	}

	dput(dentry);

	inode_unlock(d_inode(parent.dentry));

fs/bcachefs/fs-ioctl.c

+0 −4
Original line number Diff line number Diff line
@@ -511,10 +511,6 @@ static long bch2_ioctl_subvolume_destroy(struct bch_fs *c, struct file *filp, 
		ret = -EXDEV;

		goto err;

	}

	if (!d_is_positive(victim)) {

		ret = -ENOENT;

		goto err;

	}

	ret = __bch2_unlink(dir, victim, true);

	if (!ret) {

		fsnotify_rmdir(dir, victim);

fs/namei.c

+4 −0
Original line number Diff line number Diff line
@@ -2741,6 +2741,10 @@ static struct dentry *__kern_path_locked(int dfd, struct filename *name, struct 
	}

	inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);

	d = lookup_one_qstr_excl(&last, path->dentry, 0);

	if (!IS_ERR(d) && d_is_negative(d)) {

		dput(d);

		d = ERR_PTR(-ENOENT);

	}

	if (IS_ERR(d)) {

		inode_unlock(path->dentry->d_inode);

		path_put(path);

kernel/audit_watch.c

+6 −6
Original line number Diff line number Diff line
@@ -350,11 +350,10 @@ static int audit_get_nd(struct audit_watch *watch, struct path *parent) 
	struct dentry *d = kern_path_locked(watch->path, parent);

	if (IS_ERR(d))

		return PTR_ERR(d);

	if (d_is_positive(d)) {

	/* update watch filter fields */

	watch->dev = d->d_sb->s_dev;

	watch->ino = d_backing_inode(d)->i_ino;

	}



	inode_unlock(d_backing_inode(parent->dentry));

	dput(d);

	return 0;
@@ -419,10 +418,11 @@ int audit_add_watch(struct audit_krule *krule, struct list_head **list) 
	/* caller expects mutex locked */

	mutex_lock(&audit_filter_mutex);



	if (ret) {

	if (ret && ret != -ENOENT) {

		audit_put_watch(watch);

		return ret;

	}

	ret = 0;



	/* either find an old parent or attach a new one */

	parent = audit_find_parent(d_backing_inode(parent_path.dentry));