[CIFS] Add writepages support to shrink memory usage on writes,

eliminate the double copy, and improve cifs write performance and
help the server by upping the typical write size from 4K to 16K
(or even larger if wsize set explicitly)  for servers which support this.
Part 1 of 2

Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Steve French  <sfrench@us.ibm.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index e27e5ad8b591..f05d9e2016d5 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1891,6 +1891,10 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
                                 }
                         }
                 }
+                if (!(tcon->ses->capabilities & CAP_LARGE_WRITE_X))
+                        cifs_sb->wsize = min(cifs_sb->wsize,
+                                             (tcon->ses->server->maxBuf -
+                                              MAX_CIFS_HDR_SIZE));
         }
 
         /* volume_info.password is freed above when existing session found