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

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 bbe6a7c899e7 ("bch2_ioctl_subvolume_destroy(): fix locking")

Signed-off-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20250217003020.3170652-2-neilb@suse.de
Acked-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
index 1639e78..2ead47e 100644 (file)
--- a/Documentation/filesystems/porting.rst
+++ b/Documentation/filesystems/porting.rst
@@ -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.

diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index b848764..c9e3484 100644 (file)
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -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;
-       }
+       if (d_inode(dentry)->i_private == &thread)
+               err = vfs_rmdir(&nop_mnt_idmap, d_inode(parent.dentry),
+                               dentry);
+       else
+               err = -EPERM;
+
        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;
 
@@ -317,32 +316,28 @@ 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};
-               err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
-                                 AT_STATX_SYNC_AS_STAT);
-               if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
-                       struct iattr newattrs;
-                       /*
-                        * before unlinking this node, reset permissions
-                        * of possible references like hardlinks
-                        */
-                       newattrs.ia_uid = GLOBAL_ROOT_UID;
-                       newattrs.ia_gid = GLOBAL_ROOT_GID;
-                       newattrs.ia_mode = stat.mode & ~0777;
-                       newattrs.ia_valid =
-                               ATTR_UID|ATTR_GID|ATTR_MODE;
-                       inode_lock(d_inode(dentry));
-                       notify_change(&nop_mnt_idmap, dentry, &newattrs, NULL);
-                       inode_unlock(d_inode(dentry));
-                       err = vfs_unlink(&nop_mnt_idmap, d_inode(parent.dentry),
-                                        dentry, NULL);
-                       if (!err || err == -ENOENT)
-                               deleted = 1;
-               }
-       } else {
-               err = -ENOENT;
+       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)) {
+               struct iattr newattrs;
+               /*
+                * before unlinking this node, reset permissions
+                * of possible references like hardlinks
+                */
+               newattrs.ia_uid = GLOBAL_ROOT_UID;
+               newattrs.ia_gid = GLOBAL_ROOT_GID;
+               newattrs.ia_mode = stat.mode & ~0777;
+               newattrs.ia_valid =
+                       ATTR_UID|ATTR_GID|ATTR_MODE;
+               inode_lock(d_inode(dentry));
+               notify_change(&nop_mnt_idmap, dentry, &newattrs, NULL);
+               inode_unlock(d_inode(dentry));
+               err = vfs_unlink(&nop_mnt_idmap, d_inode(parent.dentry),
+                                dentry, NULL);
+               if (!err || err == -ENOENT)
+                       deleted = 1;
        }
        dput(dentry);
        inode_unlock(d_inode(parent.dentry));

diff --git a/fs/bcachefs/fs-ioctl.c b/fs/bcachefs/fs-ioctl.c
index 15725b4..595b57f 100644 (file)
--- a/fs/bcachefs/fs-ioctl.c
+++ b/fs/bcachefs/fs-ioctl.c
@@ -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);

diff --git a/fs/namei.c b/fs/namei.c
index 3ab9440..fb6da3c 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -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);

diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
index 7f35874..367eaf2 100644 (file)
--- a/kernel/audit_watch.c
+++ b/kernel/audit_watch.c
@@ -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;
-       }
+       /* 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));