From: Milan Broz <mbroz@redhat.com>
Date: Fri, 8 Feb 2008 02:10:27 +0000 (+0000)
Subject: dm: split dm_suspend io_lock hold into two
X-Git-Tag: v2.6.25-rc1~280^2~28
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=94d6351e147231b2c5a9512d69693ee8ac0c204d;p=linux-2.6-omap-h63xx.git

dm: split dm_suspend io_lock hold into two

Change io_locking to allow processing flush in separate thread.

Because we have DMF_BLOCK_IO already set, any possible
new ios are queued in dm_requests now.

In the case of interrupting previous wait there can be more
ios queued (we unlocked io_lock for a while) but this is safe.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
---

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 5191954a18b..11f422ecfda 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1434,9 +1434,11 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
 
 	if (noflush)
 		__merge_pushback_list(md);
+	up_write(&md->io_lock);
 
 	/* were we interrupted ? */
 	if (pending) {
+		down_write(&md->io_lock);
 		__flush_deferred_io(md);
 		up_write(&md->io_lock);
 
@@ -1444,7 +1446,6 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
 		r = -EINTR;
 		goto out; /* pushback list is already flushed, so skip flush */
 	}
-	up_write(&md->io_lock);
 
 	dm_table_postsuspend_targets(map);