[PATCH] cifs: Do not leak EDEADLK to dgetents64 for STATUS_USER_SESSION_DELETED

[Ronnie Sahlberg <lsahlber@redhat.com>]

RHBZ: 1994393

If we hit a STATUS_USER_SESSION_DELETED for the Create part in the
Create/QueryDirectory compound that starts a directory scan
we will leak EDEADLK back to userspace and surprise glibc and the application.

Pick this up cifs_readdir() and retry a small number of tries before we
return an error to userspace.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
---
 fs/cifs/readdir.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index bfee176b901d..56e5d456366d 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -930,6 +930,7 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 	unsigned int max_len;
 	const char *full_path;
 	void *page = alloc_dentry_path();
+	int retry_count = 0;
 
 	xid = get_xid();
 
@@ -944,8 +945,15 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 	 * '..'. Otherwise we won't be able to notify VFS in case of failure.
 	 */
 	if (file->private_data == NULL) {
+		again:
 		rc = initiate_cifs_search(xid, file, full_path);
-		cifs_dbg(FYI, "initiate cifs search rc %d\n", rc);
+		if (rc == -EDEADLK && retry_count++ < 5) {
+			/*
+			 * We don't have enough credits to start reading the
+			 * directory so just try again.
+			 */
+			goto again;
+		}
 		if (rc)
 			goto rddir2_exit;
 	}
-- 
2.30.2