smb: client: reuse file lease key in compound operations

Currently, when a rename, unlink or set path size compound operation
is requested on a file that has a lot of dirty pages to be written
to the server, we do not send the lease key for these requests. As a
result, the server can assume that this request is from a new client, and
send a lease break notification to the same client, on the same
connection. As a response to the lease break, the client can consume
several credits to write the dirty pages to the server. Depending on the
server's credit grant implementation, the server can stop granting more
credits to this connection, and this can cause a deadlock (which can only
be resolved when the lease timer on the server expires).
One of the problems here is that the client is sending no lease key,
even if it has a lease for the file. This patch fixes the problem by
reusing the existing lease key on the file for rename, unlink and set path
size compound operations so that the client does not break its own lease.

A very trivial example could be a set of commands by a client that
maintains open handle (for write) to a file and then tries to copy the
contents of that file to another one, eg.,

tail -f /dev/null > myfile &
mv myfile myfile2

Presently, the network capture on the client shows that the move (or
rename) would trigger a lease break on the same client, for the same file.
With the lease key reused, the lease break request-response overhead is
eliminated, thereby reducing the roundtrips performed for this set of
operations.

The patch fixes the bug described above and also provides perf benefit.

Signed-off-by: Meetakshi Setiya <msetiya@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index ec9a26bd05a1..0ad08642b7cf 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -371,7 +371,8 @@ struct smb_version_operations {
 			    struct cifs_open_info_data *data);
 	/* set size by path */
 	int (*set_path_size)(const unsigned int, struct cifs_tcon *,
-			     const char *, __u64, struct cifs_sb_info *, bool);
+			     const char *, __u64, struct cifs_sb_info *, bool,
+				 struct dentry *);
 	/* set size by file handle */
 	int (*set_file_size)(const unsigned int, struct cifs_tcon *,
 			     struct cifsFileInfo *, __u64, bool);
@@ -401,7 +402,7 @@ struct smb_version_operations {
 		     struct cifs_sb_info *);
 	/* unlink file */
 	int (*unlink)(const unsigned int, struct cifs_tcon *, const char *,
-		      struct cifs_sb_info *);
+		      struct cifs_sb_info *, struct dentry *);
 	/* open, rename and delete file */
 	int (*rename_pending_delete)(const char *, struct dentry *,
 				     const unsigned int);