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dm: implement REQ_FLUSH/FUA support for bio-based dm 

This patch converts bio-based dm to support REQ_FLUSH/FUA instead of
now deprecated REQ_HARDBARRIER.

* -EOPNOTSUPP handling logic dropped.

* Preflush is handled as before but postflush is dropped and replaced
  with passing down REQ_FUA to member request_queues.  This replaces
  one array wide cache flush w/ member specific FUA writes.

* __split_and_process_bio() now calls __clone_and_map_flush() directly
  for flushes and guarantees all FLUSH bio's going to targets are zero
`  length.

* It's now guaranteed that all FLUSH bio's which are passed onto dm
  targets are zero length.  bio_empty_barrier() tests are replaced
  with REQ_FLUSH tests.

* Empty WRITE_BARRIERs are replaced with WRITE_FLUSHes.

* Dropped unlikely() around REQ_FLUSH tests.  Flushes are not unlikely
  enough to be marked with unlikely().

* Block layer now filters out REQ_FLUSH/FUA bio's if the request_queue
  doesn't support cache flushing.  Advertise REQ_FLUSH | REQ_FUA
  capability.

* Request based dm isn't converted yet.  dm_init_request_based_queue()
  resets flush support to 0 for now.  To avoid disturbing request
  based dm code, dm->flush_error is added for bio based dm while
  requested based dm continues to use dm->barrier_error.

Lightly tested linear, stripe, raid1, snap and crypt targets.  Please
proceed with caution as I'm not familiar with the code base.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: dm-devel@redhat.com
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Tejun Heo 2010-09-03 11:56:19 +02:00 committed by Jens Axboe
parent 3a2edd0d6d
commit d87f4c14f2
9 changed files with 80 additions and 97 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/md/dm-crypt.c
View File

@ -1278,7 +1278,7 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
struct dm_crypt_io *io;
struct crypt_config *cc;
if (unlikely(bio_empty_barrier(bio))) {
if (bio->bi_rw & REQ_FLUSH) {
cc = ti->private;
bio->bi_bdev = cc->dev->bdev;
return DM_MAPIO_REMAPPED;

20
drivers/md/dm-io.c
View File

@ -31,7 +31,6 @@ struct dm_io_client {
*/
struct io {
unsigned long error_bits;
unsigned long eopnotsupp_bits;
atomic_t count;
struct task_struct *sleeper;
struct dm_io_client *client;
@ -130,11 +129,8 @@ static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io,
*---------------------------------------------------------------*/
static void dec_count(struct io *io, unsigned int region, int error)
{
if (error) {
if (error)
set_bit(region, &io->error_bits);
if (error == -EOPNOTSUPP)
set_bit(region, &io->eopnotsupp_bits);
}
if (atomic_dec_and_test(&io->count)) {
if (io->sleeper)
@ -310,8 +306,8 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
sector_t remaining = where->count;
/*
* where->count may be zero if rw holds a write barrier and we
* need to send a zero-sized barrier.
* where->count may be zero if rw holds a flush and we need to
* send a zero-sized flush.
*/
do {
/*
@ -364,7 +360,7 @@ static void dispatch_io(int rw, unsigned int num_regions,
*/
for (i = 0; i < num_regions; i++) {
*dp = old_pages;
if (where[i].count || (rw & REQ_HARDBARRIER))
if (where[i].count || (rw & REQ_FLUSH))
do_region(rw, i, where + i, dp, io);
}
@ -393,9 +389,7 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions,
return -EIO;
}
retry:
io->error_bits = 0;
io->eopnotsupp_bits = 0;
atomic_set(&io->count, 1); /* see dispatch_io() */
io->sleeper = current;
io->client = client;
@ -412,11 +406,6 @@ retry:
}
set_current_state(TASK_RUNNING);
if (io->eopnotsupp_bits && (rw & REQ_HARDBARRIER)) {
rw &= ~REQ_HARDBARRIER;
goto retry;
}
if (error_bits)
*error_bits = io->error_bits;
@ -437,7 +426,6 @@ static int async_io(struct dm_io_client *client, unsigned int num_regions,
io = mempool_alloc(client->pool, GFP_NOIO);
io->error_bits = 0;
io->eopnotsupp_bits = 0;
atomic_set(&io->count, 1); /* see dispatch_io() */
io->sleeper = NULL;
io->client = client;

2
drivers/md/dm-log.c
View File

@ -300,7 +300,7 @@ static int flush_header(struct log_c *lc)
.count = 0,
};
lc->io_req.bi_rw = WRITE_BARRIER;
lc->io_req.bi_rw = WRITE_FLUSH;
return dm_io(&lc->io_req, 1, &null_location, NULL);
}

8
drivers/md/dm-raid1.c
View File

@ -259,7 +259,7 @@ static int mirror_flush(struct dm_target *ti)
struct dm_io_region io[ms->nr_mirrors];
struct mirror *m;
struct dm_io_request io_req = {
.bi_rw = WRITE_BARRIER,
.bi_rw = WRITE_FLUSH,
.mem.type = DM_IO_KMEM,
.mem.ptr.bvec = NULL,
.client = ms->io_client,
@ -629,7 +629,7 @@ static void do_write(struct mirror_set *ms, struct bio *bio)
struct dm_io_region io[ms->nr_mirrors], *dest = io;
struct mirror *m;
struct dm_io_request io_req = {
.bi_rw = WRITE | (bio->bi_rw & WRITE_BARRIER),
.bi_rw = WRITE | (bio->bi_rw & WRITE_FLUSH_FUA),
.mem.type = DM_IO_BVEC,
.mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
.notify.fn = write_callback,
@ -670,7 +670,7 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
bio_list_init(&requeue);
while ((bio = bio_list_pop(writes))) {
if (unlikely(bio_empty_barrier(bio))) {
if (bio->bi_rw & REQ_FLUSH) {
bio_list_add(&sync, bio);
continue;
}
@ -1203,7 +1203,7 @@ static int mirror_end_io(struct dm_target *ti, struct bio *bio,
* We need to dec pending if this was a write.
*/
if (rw == WRITE) {
if (likely(!bio_empty_barrier(bio)))
if (!(bio->bi_rw & REQ_FLUSH))
dm_rh_dec(ms->rh, map_context->ll);
return error;
}

16
drivers/md/dm-region-hash.c
View File

@ -81,9 +81,9 @@ struct dm_region_hash {
struct list_head failed_recovered_regions;
/*
* If there was a barrier failure no regions can be marked clean.
* If there was a flush failure no regions can be marked clean.
*/
int barrier_failure;
int flush_failure;
void *context;
sector_t target_begin;
@ -217,7 +217,7 @@ struct dm_region_hash *dm_region_hash_create(
INIT_LIST_HEAD(&rh->quiesced_regions);
INIT_LIST_HEAD(&rh->recovered_regions);
INIT_LIST_HEAD(&rh->failed_recovered_regions);
rh->barrier_failure = 0;
rh->flush_failure = 0;
rh->region_pool = mempool_create_kmalloc_pool(MIN_REGIONS,
sizeof(struct dm_region));
@ -399,8 +399,8 @@ void dm_rh_mark_nosync(struct dm_region_hash *rh, struct bio *bio)
region_t region = dm_rh_bio_to_region(rh, bio);
int recovering = 0;
if (bio_empty_barrier(bio)) {
rh->barrier_failure = 1;
if (bio->bi_rw & REQ_FLUSH) {
rh->flush_failure = 1;
return;
}
@ -524,7 +524,7 @@ void dm_rh_inc_pending(struct dm_region_hash *rh, struct bio_list *bios)
struct bio *bio;
for (bio = bios->head; bio; bio = bio->bi_next) {
if (bio_empty_barrier(bio))
if (bio->bi_rw & REQ_FLUSH)
continue;
rh_inc(rh, dm_rh_bio_to_region(rh, bio));
}
@ -555,9 +555,9 @@ void dm_rh_dec(struct dm_region_hash *rh, region_t region)
*/
/* do nothing for DM_RH_NOSYNC */
if (unlikely(rh->barrier_failure)) {
if (unlikely(rh->flush_failure)) {
/*
* If a write barrier failed some time ago, we
* If a write flush failed some time ago, we
* don't know whether or not this write made it
* to the disk, so we must resync the device.
*/

2
drivers/md/dm-snap-persistent.c
View File

@ -687,7 +687,7 @@ static void persistent_commit_exception(struct dm_exception_store *store,
/*
* Commit exceptions to disk.
*/
if (ps->valid && area_io(ps, WRITE_BARRIER))
if (ps->valid && area_io(ps, WRITE_FLUSH_FUA))
ps->valid = 0;
/*

6
drivers/md/dm-snap.c
View File

@ -1587,7 +1587,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
chunk_t chunk;
struct dm_snap_pending_exception *pe = NULL;
if (unlikely(bio_empty_barrier(bio))) {
if (bio->bi_rw & REQ_FLUSH) {
bio->bi_bdev = s->cow->bdev;
return DM_MAPIO_REMAPPED;
}
@ -1691,7 +1691,7 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio,
int r = DM_MAPIO_REMAPPED;
chunk_t chunk;
if (unlikely(bio_empty_barrier(bio))) {
if (bio->bi_rw & REQ_FLUSH) {
if (!map_context->target_request_nr)
bio->bi_bdev = s->origin->bdev;
else
@ -2135,7 +2135,7 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
struct dm_dev *dev = ti->private;
bio->bi_bdev = dev->bdev;
if (unlikely(bio_empty_barrier(bio)))
if (bio->bi_rw & REQ_FLUSH)
return DM_MAPIO_REMAPPED;
/* Only tell snapshots if this is a write */

2
drivers/md/dm-stripe.c
View File

@ -271,7 +271,7 @@ static int stripe_map(struct dm_target *ti, struct bio *bio,
uint32_t stripe;
unsigned target_request_nr;
if (unlikely(bio_empty_barrier(bio))) {
if (bio->bi_rw & REQ_FLUSH) {
target_request_nr = map_context->target_request_nr;
BUG_ON(target_request_nr >= sc->stripes);
bio->bi_bdev = sc->stripe[target_request_nr].dev->bdev;

119
drivers/md/dm.c
View File

@ -144,15 +144,16 @@ struct mapped_device {
spinlock_t deferred_lock;
/*
* An error from the barrier request currently being processed.
* An error from the flush request currently being processed.
*/
int barrier_error;
int flush_error;
/*
* Protect barrier_error from concurrent endio processing
* in request-based dm.
*/
spinlock_t barrier_error_lock;
int barrier_error;
/*
* Processing queue (flush/barriers)
@ -200,8 +201,8 @@ struct mapped_device {
/* sysfs handle */
struct kobject kobj;
/* zero-length barrier that will be cloned and submitted to targets */
struct bio barrier_bio;
/* zero-length flush that will be cloned and submitted to targets */
struct bio flush_bio;
};
/*
@ -512,7 +513,7 @@ static void end_io_acct(struct dm_io *io)
/*
* After this is decremented the bio must not be touched if it is
* a barrier.
* a flush.
*/
dm_disk(md)->part0.in_flight[rw] = pending =
atomic_dec_return(&md->pending[rw]);
@ -626,7 +627,7 @@ static void dec_pending(struct dm_io *io, int error)
*/
spin_lock_irqsave(&md->deferred_lock, flags);
if (__noflush_suspending(md)) {
if (!(io->bio->bi_rw & REQ_HARDBARRIER))
if (!(io->bio->bi_rw & REQ_FLUSH))
bio_list_add_head(&md->deferred,
io->bio);
} else
@ -638,20 +639,14 @@ static void dec_pending(struct dm_io *io, int error)
io_error = io->error;
bio = io->bio;
if (bio->bi_rw & REQ_HARDBARRIER) {
if (bio->bi_rw & REQ_FLUSH) {
/*
* There can be just one barrier request so we use
* There can be just one flush request so we use
* a per-device variable for error reporting.
* Note that you can't touch the bio after end_io_acct
*
* We ignore -EOPNOTSUPP for empty flush reported by
* underlying devices. We assume that if the device
* doesn't support empty barriers, it doesn't need
* cache flushing commands.
*/
if (!md->barrier_error &&
!(bio_empty_barrier(bio) && io_error == -EOPNOTSUPP))
md->barrier_error = io_error;
if (!md->flush_error)
md->flush_error = io_error;
end_io_acct(io);
free_io(md, io);
} else {
@ -1119,7 +1114,7 @@ static void dm_bio_destructor(struct bio *bio)
}
/*
* Creates a little bio that is just does part of a bvec.
* Creates a little bio that just does part of a bvec.
*/
static struct bio *split_bvec(struct bio *bio, sector_t sector,
unsigned short idx, unsigned int offset,
@ -1134,7 +1129,7 @@ static struct bio *split_bvec(struct bio *bio, sector_t sector,
clone->bi_sector = sector;
clone->bi_bdev = bio->bi_bdev;
clone->bi_rw = bio->bi_rw & ~REQ_HARDBARRIER;
clone->bi_rw = bio->bi_rw;
clone->bi_vcnt = 1;
clone->bi_size = to_bytes(len);
clone->bi_io_vec->bv_offset = offset;
@ -1161,7 +1156,6 @@ static struct bio *clone_bio(struct bio *bio, sector_t sector,
clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
__bio_clone(clone, bio);
clone->bi_rw &= ~REQ_HARDBARRIER;
clone->bi_destructor = dm_bio_destructor;
clone->bi_sector = sector;
clone->bi_idx = idx;
@ -1225,7 +1219,7 @@ static void __issue_target_requests(struct clone_info *ci, struct dm_target *ti,
__issue_target_request(ci, ti, request_nr, len);
}
static int __clone_and_map_empty_barrier(struct clone_info *ci)
static int __clone_and_map_flush(struct clone_info *ci)
{
unsigned target_nr = 0;
struct dm_target *ti;
@ -1289,9 +1283,6 @@ static int __clone_and_map(struct clone_info *ci)
sector_t len = 0, max;
struct dm_target_io *tio;
if (unlikely(bio_empty_barrier(bio)))
return __clone_and_map_empty_barrier(ci);
if (unlikely(bio->bi_rw & REQ_DISCARD))
return __clone_and_map_discard(ci);
@ -1383,11 +1374,11 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
ci.map = dm_get_live_table(md);
if (unlikely(!ci.map)) {
if (!(bio->bi_rw & REQ_HARDBARRIER))
if (!(bio->bi_rw & REQ_FLUSH))
bio_io_error(bio);
else
if (!md->barrier_error)
md->barrier_error = -EIO;
if (!md->flush_error)
md->flush_error = -EIO;
return;
}
@ -1400,14 +1391,22 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
ci.io->md = md;
spin_lock_init(&ci.io->endio_lock);
ci.sector = bio->bi_sector;
ci.sector_count = bio_sectors(bio);
if (unlikely(bio_empty_barrier(bio)))
if (!(bio->bi_rw & REQ_FLUSH))
ci.sector_count = bio_sectors(bio);
else {
/* all FLUSH bio's reaching here should be empty */
WARN_ON_ONCE(bio_has_data(bio));
ci.sector_count = 1;
}
ci.idx = bio->bi_idx;
start_io_acct(ci.io);
while (ci.sector_count && !error)
error = __clone_and_map(&ci);
while (ci.sector_count && !error) {
if (!(bio->bi_rw & REQ_FLUSH))
error = __clone_and_map(&ci);
else
error = __clone_and_map_flush(&ci);
}
/* drop the extra reference count */
dec_pending(ci.io, error);
@ -1492,11 +1491,11 @@ static int _dm_request(struct request_queue *q, struct bio *bio)
part_stat_unlock();
/*
* If we're suspended or the thread is processing barriers
* If we're suspended or the thread is processing flushes
* we have to queue this io for later.
*/
if (unlikely(test_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags)) ||
unlikely(bio->bi_rw & REQ_HARDBARRIER)) {
(bio->bi_rw & REQ_FLUSH)) {
up_read(&md->io_lock);
if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) &&
@ -1940,6 +1939,7 @@ static void dm_init_md_queue(struct mapped_device *md)
blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
md->queue->unplug_fn = dm_unplug_all;
blk_queue_merge_bvec(md->queue, dm_merge_bvec);
blk_queue_flush(md->queue, REQ_FLUSH | REQ_FUA);
}
/*
@ -2245,7 +2245,8 @@ static int dm_init_request_based_queue(struct mapped_device *md)
blk_queue_softirq_done(md->queue, dm_softirq_done);
blk_queue_prep_rq(md->queue, dm_prep_fn);
blk_queue_lld_busy(md->queue, dm_lld_busy);
blk_queue_flush(md->queue, REQ_FLUSH);
/* no flush support for request based dm yet */
blk_queue_flush(md->queue, 0);
elv_register_queue(md->queue);
@ -2406,41 +2407,35 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
return r;
}
static void dm_flush(struct mapped_device *md)
static void process_flush(struct mapped_device *md, struct bio *bio)
{
md->flush_error = 0;
/* handle REQ_FLUSH */
dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
bio_init(&md->barrier_bio);
md->barrier_bio.bi_bdev = md->bdev;
md->barrier_bio.bi_rw = WRITE_BARRIER;
__split_and_process_bio(md, &md->barrier_bio);
bio_init(&md->flush_bio);
md->flush_bio.bi_bdev = md->bdev;
md->flush_bio.bi_rw = WRITE_FLUSH;
__split_and_process_bio(md, &md->flush_bio);
dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
}
static void process_barrier(struct mapped_device *md, struct bio *bio)
{
md->barrier_error = 0;
dm_flush(md);
if (!bio_empty_barrier(bio)) {
__split_and_process_bio(md, bio);
/*
* If the request isn't supported, don't waste time with
* the second flush.
*/
if (md->barrier_error != -EOPNOTSUPP)
dm_flush(md);
/* if it's an empty flush or the preflush failed, we're done */
if (!bio_has_data(bio) || md->flush_error) {
if (md->flush_error != DM_ENDIO_REQUEUE)
bio_endio(bio, md->flush_error);
else {
spin_lock_irq(&md->deferred_lock);
bio_list_add_head(&md->deferred, bio);
spin_unlock_irq(&md->deferred_lock);
}
return;
}
if (md->barrier_error != DM_ENDIO_REQUEUE)
bio_endio(bio, md->barrier_error);
else {
spin_lock_irq(&md->deferred_lock);
bio_list_add_head(&md->deferred, bio);
spin_unlock_irq(&md->deferred_lock);
}
/* issue data + REQ_FUA */
bio->bi_rw &= ~REQ_FLUSH;
__split_and_process_bio(md, bio);
}
/*
@ -2469,8 +2464,8 @@ static void dm_wq_work(struct work_struct *work)
if (dm_request_based(md))
generic_make_request(c);
else {
if (c->bi_rw & REQ_HARDBARRIER)
process_barrier(md, c);
if (c->bi_rw & REQ_FLUSH)
process_flush(md, c);
else
__split_and_process_bio(md, c);
}