From: Sage Weil <sage@newdream.net>
Date: Tue, 26 Jul 2011 18:26:31 +0000 (-0700)
Subject: ceph: fix snap writeback when racing with writes
X-Git-Tag: v3.1-rc1~220^2~19
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=af0ed569d7019f1b49e9e51e77b47092e656b00e;p=pandora-kernel.git

ceph: fix snap writeback when racing with writes

There are two problems that come up when we try to queue a capsnap while a
write is in progress:

 - The FILE_WR cap is held, but not yet dirty, so we may queue a capsnap
   with dirty == 0.  That will crash later in __ceph_flush_snaps().  Or
   on the FILE_WR cap if a write is in progress.
 - We may not have i_head_snapc set, which causes problems pretty quickly.
   Look to the snaprealm in this case.

Reviewed-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
---

Reading git-diff-tree failed