fuse: do not use start_removing_noperm()

Revert the fuse part of commit c9ba789dad15 ("VFS: introduce
start_creating_noperm() and start_removing_noperm()").

Commit c9ba789dad15 ("VFS: introduce start_creating_noperm() and
start_removing_noperm()") caused a regression in FUSE_NOTIFY_INVAL_ENTRY,
which failed to invalidate negative dentries.

This manifests in the filesystem returning -ENOENT for operations on an
existing file.

Fixing it properly while still keeping the start_removing* infrastructure
would add much additional complexity.

Instead revert to the original simple implementation.

The start_removing* infrastructure is needed in VFS to abstract the
filesystem locking.  However filesystem code can still safely use the raw
locking primitives without affacting other filesystems.

This is part two of the revert.

Reported-by: Артем Лабазов <123321artyom@gmail.com>
Closes: https://lore.kernel.org/all/CAFbF8N7++zopZuEcsKRxBV_sgOGCbzCY0hOyMw1SiGAtuzGhyQ@mail.gmail.com/
Fixes: c9ba789dad15 ("VFS: introduce start_creating_noperm() and start_removing_noperm()")
Cc: stable@vger.kernel.org # 6.19
Cc: NeilBrown <neilb@ownmail.net>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 6b05846c9bed26a7a5c650af2ab9bafae2f963be..97751bacb79ce8f9823c45e1f9ab544956983a23 100644 (file)
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1594,25 +1594,27 @@ int fuse_reverse_inval_entry(struct fuse_conn *fc, u64 parent_nodeid,
        if (!parent)
                return -ENOENT;
 
+       inode_lock_nested(parent, I_MUTEX_PARENT);
        if (!S_ISDIR(parent->i_mode))
-               goto put_parent;
+               goto unlock;
 
        err = -ENOENT;
        dir = d_find_alias(parent);
        if (!dir)
-               goto put_parent;
+               goto unlock;
 
-       entry = start_removing_noperm(dir, name);
+       name->hash = full_name_hash(dir, name->name, name->len);
+       entry = d_lookup(dir, name);
        dput(dir);
-       if (IS_ERR(entry))
-               goto put_parent;
+       if (!entry)
+               goto unlock;
 
        fuse_dir_changed(parent);
        if (!(flags & FUSE_EXPIRE_ONLY))
                d_invalidate(entry);
        fuse_invalidate_entry_cache(entry);
 
-       if (child_nodeid != 0) {
+       if (child_nodeid != 0 && d_really_is_positive(entry)) {
                inode_lock(d_inode(entry));
                if (get_node_id(d_inode(entry)) != child_nodeid) {
                        err = -ENOENT;
@@ -1640,9 +1642,10 @@ int fuse_reverse_inval_entry(struct fuse_conn *fc, u64 parent_nodeid,
        } else {
                err = 0;
        }
+       dput(entry);
 
-       end_removing(entry);
- put_parent:
+ unlock:
+       inode_unlock(parent);
        iput(parent);
        return err;
 }