From 54d9a1b4513b96cbd835ca6866c6a604d194b2ae Mon Sep 17 00:00:00 2001
From: Alasdair G Kergon <agk@redhat.com>
Date: Thu, 9 Apr 2009 00:27:14 +0100
Subject: [PATCH] dm: simplify dm_request loop
Refactor the code in dm_request().
Require the new DMF_BLOCK_FOR_SUSPEND flag on readahead bios we will
discard so we don't drop such bios while processing a barrier.
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
---
drivers/md/dm.c | 18 +++++++-----------
1 file changed, 7 insertions(+), 11 deletions(-)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 7cac7220937f7..bb97ec8d66448 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -929,7 +929,6 @@ static int dm_merge_bvec(struct request_queue *q,
*/
static int dm_request(struct request_queue *q, struct bio *bio)
{
- int r = -EIO;
int rw = bio_data_dir(bio);
struct mapped_device *md = q->queuedata;
int cpu;
@@ -957,11 +956,14 @@ static int dm_request(struct request_queue *q, struct bio *bio)
while (test_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags)) {
up_read(&md->io_lock);
- if (bio_rw(bio) != READA)
- r = queue_io(md, bio);
+ if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) &&
+ bio_rw(bio) == READA) {
+ bio_io_error(bio);
+ return 0;
+ }
- if (r <= 0)
- goto out_req;
+ if (!queue_io(md, bio))
+ return 0;
/*
* We're in a while loop, because someone could suspend
@@ -973,12 +975,6 @@ static int dm_request(struct request_queue *q, struct bio *bio)
__split_and_process_bio(md, bio);
up_read(&md->io_lock);
return 0;
-
-out_req:
- if (r < 0)
- bio_io_error(bio);
-
- return 0;
}
static void dm_unplug_all(struct request_queue *q)
--
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