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dm: simplify dm_request loop

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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>
This commit is contained in:
Alasdair G Kergon
2009-04-09 00:27:14 +01:00
parent 1eb787ec18
commit 54d9a1b451
1 changed files with 7 additions and 11 deletions
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18
drivers/md/dm.c
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@@ -929,7 +929,6 @@ out:
*/ */
static int dm_request(struct request_queue *q, struct bio *bio) static int dm_request(struct request_queue *q, struct bio *bio)
{ {
int r = -EIO;
int rw = bio_data_dir(bio); int rw = bio_data_dir(bio);
struct mapped_device *md = q->queuedata; struct mapped_device *md = q->queuedata;
int cpu; 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)) { while (test_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags)) {
up_read(&md->io_lock); up_read(&md->io_lock);
if (bio_rw(bio) != READA) if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) &&
r = queue_io(md, bio); bio_rw(bio) == READA) {
bio_io_error(bio);
return 0;
}
if (r <= 0) if (!queue_io(md, bio))
goto out_req; return 0;
/* /*
* We're in a while loop, because someone could suspend * 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); __split_and_process_bio(md, bio);
up_read(&md->io_lock); up_read(&md->io_lock);
return 0; return 0;
out_req:
if (r < 0)
bio_io_error(bio);
return 0;
} }
static void dm_unplug_all(struct request_queue *q) static void dm_unplug_all(struct request_queue *q)