fs/pipe.c: skip file_update_time on frozen fs

Pipe has no data associated with fs so it is not good idea to block
pipe_write() if FS is frozen, but we can not update file's time on such
filesystem.  Let's use same idea as we use in touch_time().

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=65701

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/pipe.c b/fs/pipe.c
index 0e0752ef2715..78fd0d0788db 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -663,10 +663,11 @@ out:
                 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
         }
-        if (ret > 0) {
+        if (ret > 0 && sb_start_write_trylock(file_inode(filp)->i_sb)) {
                 int err = file_update_time(filp);
                 if (err)
                         ret = err;
+                sb_end_write(file_inode(filp)->i_sb);
         }
         return ret;
 }