[PATCH 4.9 20/48] NFSv4: nfs_atomic_open() can race when looking up a non-regular file

Greg Kroah-Hartman
2022-02-07T11:13:59Z

From: Trond Myklebust <trond.myklebust@hammerspace.com>

commit 1751fc1db36f6f411709e143d5393f92d12137a9 upstream.

If the file type changes back to being a regular file on the server
between the failed OPEN and our LOOKUP, then we need to re-run the OPEN.

Fixes: 0dd2b474d0b6 ("nfs: implement i_op->atomic_open()")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/nfs/dir.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1607,12 +1607,17 @@ no_open:
if ((lookup_flags & LOOKUP_DIRECTORY) && inode &&
!S_ISDIR(inode->i_mode))
res = ERR_PTR(-ENOTDIR);
+ else if (inode && S_ISREG(inode->i_mode))
+ res = ERR_PTR(-EOPENSTALE);
} else if (!IS_ERR(res)) {
inode = d_inode(res);
if ((lookup_flags & LOOKUP_DIRECTORY) && inode &&
!S_ISDIR(inode->i_mode)) {
dput(res);
res = ERR_PTR(-ENOTDIR);
+ } else if (inode && S_ISREG(inode->i_mode)) {
+ dput(res);
+ res = ERR_PTR(-EOPENSTALE);
}
}
if (switched) {