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dm: simplify bio-based IO accounting further 

Now that io splitting is recorded prior to, or during, ->map IO
accounting can happen immediately rather than defer until after
bio splitting in dm_split_and_process_bio().

Remove the DM_IO_START_ACCT flag and also remove dm_io's map_task
member because there is no longer any need to wait for splitting to
occur before accounting.

Also move dm_io struct's 'flags' member to consolidate struct holes.

Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Mike Snitzer 2022-04-15 20:08:23 -04:00
parent ec211631ae
commit 9d20653fe8
2 changed files with 6 additions and 34 deletions
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6
drivers/md/dm-core.h
View File

@ -255,15 +255,12 @@ static inline bool dm_tio_is_normal(struct dm_target_io *tio)
#define DM_IO_MAGIC 19577
struct dm_io {
unsigned short magic;
blk_short_t flags;
spinlock_t lock;
unsigned long start_time;
void *data;
struct dm_io *next;
struct task_struct *map_task;
struct dm_stats_aux stats_aux;
blk_short_t flags;
blk_status_t status;
atomic_t io_count;
struct mapped_device *md;
@ -281,7 +278,6 @@ struct dm_io {
* dm_io flags
*/
enum {
DM_IO_START_ACCT,
DM_IO_ACCOUNTED,
DM_IO_WAS_SPLIT
};

34
drivers/md/dm.c
View File

@ -596,7 +596,6 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
this_cpu_inc(*md->pending_io);
io->orig_bio = bio;
io->md = md;
io->map_task = current;
spin_lock_init(&io->lock);
io->start_time = jiffies;
io->flags = 0;
@ -1241,13 +1240,6 @@ void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors)
}
EXPORT_SYMBOL_GPL(dm_accept_partial_bio);
static inline void __dm_submit_bio_remap(struct bio *clone,
dev_t dev, sector_t old_sector)
{
trace_block_bio_remap(clone, dev, old_sector);
submit_bio_noacct(clone);
}
/*
* @clone: clone bio that DM core passed to target's .map function
* @tgt_clone: clone of @clone bio that target needs submitted
@ -1262,8 +1254,6 @@ void dm_submit_bio_remap(struct bio *clone, struct bio *tgt_clone)
struct dm_target_io *tio = clone_to_tio(clone);
struct dm_io *io = tio->io;
WARN_ON_ONCE(!tio->ti->accounts_remapped_io);
/* establish bio that will get submitted */
if (!tgt_clone)
tgt_clone = clone;
@ -1272,15 +1262,11 @@ void dm_submit_bio_remap(struct bio *clone, struct bio *tgt_clone)
* Account io->origin_bio to DM dev on behalf of target
* that took ownership of IO with DM_MAPIO_SUBMITTED.
*/
if (io->map_task == current) {
/* Still in target's map function */
dm_io_set_flag(io, DM_IO_START_ACCT);
} else {
dm_start_io_acct(io, clone);
}
dm_start_io_acct(io, clone);
__dm_submit_bio_remap(tgt_clone, disk_devt(io->md->disk),
trace_block_bio_remap(tgt_clone, disk_devt(io->md->disk),
tio->old_sector);
submit_bio_noacct(tgt_clone);
}
EXPORT_SYMBOL_GPL(dm_submit_bio_remap);
@ -1340,16 +1326,10 @@ static void __map_bio(struct bio *clone)
case DM_MAPIO_SUBMITTED:
/* target has assumed ownership of this io */
if (!ti->accounts_remapped_io)
dm_io_set_flag(io, DM_IO_START_ACCT);
dm_start_io_acct(io, clone);
break;
case DM_MAPIO_REMAPPED:
/*
* the bio has been remapped so dispatch it, but defer
* dm_start_io_acct() until after possible bio_split().
*/
__dm_submit_bio_remap(clone, disk_devt(md->disk),
tio->old_sector);
dm_io_set_flag(io, DM_IO_START_ACCT);
dm_submit_bio_remap(clone, NULL);
break;
case DM_MAPIO_KILL:
case DM_MAPIO_REQUEUE:
@ -1667,7 +1647,6 @@ static void dm_split_and_process_bio(struct mapped_device *md,
}
error = __split_and_process_bio(&ci);
io->map_task = NULL;
if (error || !ci.sector_count)
goto out;
/*
@ -1679,9 +1658,6 @@ static void dm_split_and_process_bio(struct mapped_device *md,
bio_inc_remaining(bio);
submit_bio_noacct(bio);
out:
if (dm_io_flagged(io, DM_IO_START_ACCT))
dm_start_io_acct(io, NULL);
/*
* Drop the extra reference count for non-POLLED bio, and hold one
* reference for POLLED bio, which will be released in dm_poll_bio