cifs: wait for writeback to complete in cifs_flush

The f_op->flush operation is the last chance to return a writeback
related error when closing a file. Ensure that we don't miss reporting
any errors by waiting for writeback to complete in cifs_flush before
proceeding.

There's no reason to do this when the file isn't open for write
however.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Suresh Jayaraman <sjayaraman@suse.de>
Reviewed-by: David Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index baf4b5067ff94bd46ebdea43aed81314cda3d1db..128e07b85d6cb28610ded1f934471b8d64049189 100644 (file)
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1688,20 +1688,13 @@ int cifs_flush(struct file *file, fl_owner_t id)
        struct inode *inode = file->f_path.dentry->d_inode;
        int rc = 0;
 
-       /* Rather than do the steps manually:
-          lock the inode for writing
-          loop through pages looking for write behind data (dirty pages)
-          coalesce into contiguous 16K (or smaller) chunks to write to server
-          send to server (prefer in parallel)
-          deal with writebehind errors
-          unlock inode for writing
-          filemapfdatawrite appears easier for the time being */
-
-       rc = filemap_fdatawrite(inode->i_mapping);
-       /* reset wb rc if we were able to write out dirty pages */
-       if (!rc) {
-               rc = CIFS_I(inode)->write_behind_rc;
-               CIFS_I(inode)->write_behind_rc = 0;
+       if (file->f_mode & FMODE_WRITE) {
+               rc = filemap_write_and_wait(inode->i_mapping);
+               /* reset wb rc if we were able to write out dirty pages */
+               if (!rc) {
+                       rc = CIFS_I(inode)->write_behind_rc;
+                       CIFS_I(inode)->write_behind_rc = 0;
+               }
        }
 
        cFYI(1, "Flush inode %p file %p rc %d", inode, file, rc);