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, 4 insertions, 2 deletions

diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
index 58cfbd450a55..cd1268fd843f 100644
--- a/fs/smb/client/cifsproto.h
+++ b/fs/smb/client/cifsproto.h
@@ -404,7 +404,8 @@ extern int CIFSSMBSetFileDisposition(const unsigned int xid,
 				     __u32 pid_of_opener);
 extern int CIFSSMBSetEOF(const unsigned int xid, struct cifs_tcon *tcon,
 			 const char *file_name, __u64 size,
-			 struct cifs_sb_info *cifs_sb, bool set_allocation);
+			 struct cifs_sb_info *cifs_sb, bool set_allocation,
+			 struct dentry *dentry);
 extern int CIFSSMBSetFileSize(const unsigned int xid, struct cifs_tcon *tcon,
 			      struct cifsFileInfo *cfile, __u64 size,
 			      bool set_allocation);
@@ -440,7 +441,8 @@ extern int CIFSPOSIXDelFile(const unsigned int xid, struct cifs_tcon *tcon,
 			const struct nls_table *nls_codepage,
 			int remap_special_chars);
 extern int CIFSSMBDelFile(const unsigned int xid, struct cifs_tcon *tcon,
-			  const char *name, struct cifs_sb_info *cifs_sb);
+			  const char *name, struct cifs_sb_info *cifs_sb,
+			  struct dentry *dentry);
 int CIFSSMBRename(const unsigned int xid, struct cifs_tcon *tcon,
 		  struct dentry *source_dentry,
 		  const char *from_name, const char *to_name,