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From:   "NeilBrown" <neilb@suse.de>
To:     Trond Myklebust <trondmy@hammerspace.com>,
        Anna Schumaker <anna@kernel.org>
Cc:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: [PATCH] NFS: unlink/rmdir shouldn't call d_delete() twice on ENOENT
Date:   Tue, 16 Aug 2022 16:35:34 +1000
Message-id: <166063173439.5425.8345694210902041629@noble.neil.brown.name>
Precedence: bulk


nfs_unlink() calls d_delete() twice if it receives ENOENT from the
server - once in nfs_dentry_handle_enoent() from nfs_safe_remove and
once in nfs_dentry_remove_handle_error().

nfs_rmddir() also calls it twice - the nfs_dentry_handle_enoent() call
is direct and inside a region locked with ->rmdir_sem

It is safe to call d_delete() twice if the refcount > 1 as the dentry is
simply unhashed.
If the refcount is 1, the first call sets d_inode to NULL and the second
call crashes.

Refcount is almost always 1 in nfs_unlink() so this must almost never
happen else we would have seen crashes before.

This patch removes the d_delete() call from nfs_dentry_handle_enoent()
so as to leave the one under ->remdir_sem in case that is important.

Fixes: 9019fb391de0 ("NFS: Label the dentry with a verifier in nfs_rmdir() an=
d nfs_unlink()")
Signed-off-by: NeilBrown <neilb@suse.de>
---
 fs/nfs/dir.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index dbab3caa15ed..4648b421025c 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -2382,7 +2382,6 @@ static void nfs_dentry_remove_handle_error(struct inode=
 *dir,
 {
 	switch (error) {
 	case -ENOENT:
-		d_delete(dentry);
 		nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
 		break;
 	case 0:
--=20
2.37.1