linux-kernel - [PATCH 1/4] [GFS2] flush the glock completely in inode_go

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Date:	Mon, 18 Jun 2007 15:54:27 +0100
From:	Steven Whitehouse <swhiteho@...hat.com>
To:	cluster-devel@...hat.com, linux-kernel@...r.kernel.org
Cc:	Benjamin Marzinski <bmarzins@...hat.com>,
	Steven Whitehouse <swhiteho@...hat.com>
Subject: [PATCH 1/4] [GFS2] flush the glock completely in inode_go_sync

Fix for bz #231910
When filemap_fdatawrite() is called on the inode mapping in data=ordered mode,
it will add the glock to the log. In inode_go_sync(), if you do the
gfs2_log_flush() before this, after the filemap_fdatawrite() call, the glock
and its associated data buffers will be on the log again. This means you can
demote a lock from exclusive, without having it flushed from the log. The
attached patch simply moves the gfs2_log_flush up to after the
filemap_fdatawrite() call.

Originally, I tried moving the gfs2_log_flush to after gfs2_meta_sync(), but
that caused me to trip the following assert.

GFS2: fsid=cypher-36:test.0: fatal: assertion "!buffer_busy(bh)" failed
GFS2: fsid=cypher-36:test.0:   function = gfs2_ail_empty_gl, file = fs/gfs2/glops.c, line = 61

It appears that gfs2_log_flush() puts some of the glocks buffers in the busy
state and the filemap_fdatawrite() call is necessary to flush them. This makes
me worry slightly that a related problem could happen because of moving the
gfs2_log_flush() after the initial filemap_fdatawrite(), but I assume that
gfs2_ail_empty_gl() would catch that case as well.

Signed-off-by: Benjamin E. Marzinski <bmarzins@...hat.com>
Signed-off-by: Steven Whitehouse <swhiteho@...hat.com>
---
 fs/gfs2/glops.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
View attachment "e92666ae590962682cf23fcae2c3bdcb6e5e2d27.diff" of type "text/x-patch" (474 bytes)