CIFS: Fix write after setting a read lock for read oplock files

If we have a read oplock and set a read lock in it, we can't write to the
locked area - so, filemap_fdatawrite may fail with a no information for a
userspace application even if we request a write to non-locked area. Fix
this by writing directly to the server and then breaking oplock level from
level2 to None.

Also remove CONFIG_CIFS_SMB2 ifdefs because it's suitable for both CIFS
and SMB2 protocols.

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 20 insertions, 28 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 1b322d041f1e..22c37254b64e 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2505,42 +2505,34 @@ cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov,
         struct cifsFileInfo *cfile = (struct cifsFileInfo *)
                                                 iocb->ki_filp->private_data;
         struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
+        ssize_t written;
 
-#ifdef CONFIG_CIFS_SMB2
-        /*
-         * If we have an oplock for read and want to write a data to the file
-         * we need to store it in the page cache and then push it to the server
-         * to be sure the next read will get a valid data.
-         */
-        if (!cinode->clientCanCacheAll && cinode->clientCanCacheRead) {
-                ssize_t written;
-                int rc;
-
-                written = generic_file_aio_write(iocb, iov, nr_segs, pos);
-                rc = filemap_fdatawrite(inode->i_mapping);
-                if (rc)
-                        return (ssize_t)rc;
-
-                return written;
+        if (cinode->clientCanCacheAll) {
+                if (cap_unix(tcon->ses) &&
+                (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability))
+                    && ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
+                        return generic_file_aio_write(iocb, iov, nr_segs, pos);
+                return cifs_writev(iocb, iov, nr_segs, pos);
         }
-#endif
-
         /*
          * For non-oplocked files in strict cache mode we need to write the data
          * to the server exactly from the pos to pos+len-1 rather than flush all
          * affected pages because it may cause a error with mandatory locks on
          * these pages but not on the region from pos to ppos+len-1.
          */
-
-        if (!cinode->clientCanCacheAll)
-                return cifs_user_writev(iocb, iov, nr_segs, pos);
-
-        if (cap_unix(tcon->ses) &&
-            (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
-            ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
-                return generic_file_aio_write(iocb, iov, nr_segs, pos);
-
-        return cifs_writev(iocb, iov, nr_segs, pos);
+        written = cifs_user_writev(iocb, iov, nr_segs, pos);
+        if (written > 0 && cinode->clientCanCacheRead) {
+                /*
+                 * Windows 7 server can delay breaking level2 oplock if a write
+                 * request comes - break it on the client to prevent reading
+                 * an old data.
+                 */
+                cifs_invalidate_mapping(inode);
+                cFYI(1, "Set no oplock for inode=%p after a write operation",
+                     inode);
+                cinode->clientCanCacheRead = false;
+        }
+        return written;
 }
 
 static struct cifs_readdata *