This is a note to let you know that I've just added the patch titled
make nfs_atomic_open() call d_drop() on all ->open_context() errors.
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
make-nfs_atomic_open-call-d_drop-on-all-open_context-errors.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d20cb71dbf3487f24549ede1a8e2d67579b4632e Mon Sep 17 00:00:00 2001
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Mon, 20 Jun 2016 13:14:36 -0400
Subject: make nfs_atomic_open() call d_drop() on all ->open_context() errors.
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
commit d20cb71dbf3487f24549ede1a8e2d67579b4632e upstream.
In "NFSv4: Move dentry instantiation into the NFSv4-specific atomic open code"
unconditional d_drop() after the ->open_context() had been removed. It had
been correct for success cases (there ->open_context() itself had been doing
dcache manipulations), but not for error ones. Only one of those (ENOENT)
got a compensatory d_drop() added in that commit, but in fact it should've
been done for all errors. As it is, the case of O_CREAT non-exclusive open
on a hashed negative dentry racing with e.g. symlink creation from another
client ended up with ->open_context() getting an error and proceeding to
call nfs_lookup(). On a hashed dentry, which would've instantly triggered
BUG_ON() in d_materialise_unique() (or, these days, its equivalent in
d_splice_alias()).
Tested-by: Oleg Drokin <green@xxxxxxxxxxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/nfs/dir.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1459,9 +1459,9 @@ int nfs_atomic_open(struct inode *dir, s
err = PTR_ERR(inode);
trace_nfs_atomic_open_exit(dir, ctx, open_flags, err);
put_nfs_open_context(ctx);
+ d_drop(dentry);
switch (err) {
case -ENOENT:
- d_drop(dentry);
d_add(dentry, NULL);
break;
case -EISDIR:
Patches currently in stable-queue which might be from viro@xxxxxxxxxxxxxxxxxx are
queue-3.14/make-nfs_atomic_open-call-d_drop-on-all-open_context-errors.patch
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