dm: consolidate spinlocks in dm_io struct

No reason to have separate startio_lock and endio_lock given endio_lock
could be used during submission anyway.

This change leaves the dm_io struct weighing in at 256 bytes (down
from 272 bytes, so saves a cacheline).

Signed-off-by: Mike Snitzer <snitzer@kernel.org>

diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index f186d7a..2c49aa6 100644 (file)
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -250,12 +250,11 @@ struct dm_io {
        struct mapped_device *md;
        struct bio *orig_bio;
        blk_status_t status;
+       spinlock_t lock;
        unsigned long start_time;
        void *data;
        struct hlist_node node;
        struct task_struct *map_task;
-       spinlock_t startio_lock;
-       spinlock_t endio_lock;
        struct dm_stats_aux stats_aux;
        /* last member of dm_target_io is 'struct bio' */
        struct dm_target_io tio;

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index cca11cf..b762a48 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -550,9 +550,9 @@ static void dm_start_io_acct(struct dm_io *io, struct bio *clone)
                if (dm_io_flagged(io, DM_IO_ACCOUNTED))
                        return;
                /* Can afford locking given DM_TIO_IS_DUPLICATE_BIO */
-               spin_lock_irqsave(&io->startio_lock, flags);
+               spin_lock_irqsave(&io->lock, flags);
                dm_io_set_flag(io, DM_IO_ACCOUNTED);
-               spin_unlock_irqrestore(&io->startio_lock, flags);
+               spin_unlock_irqrestore(&io->lock, flags);
        }
 
        __dm_start_io_acct(io, bio);
@@ -584,8 +584,7 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
        io->orig_bio = NULL;
        io->md = md;
        io->map_task = current;
-       spin_lock_init(&io->startio_lock);
-       spin_lock_init(&io->endio_lock);
+       spin_lock_init(&io->lock);
        io->start_time = jiffies;
        io->flags = 0;
 
@@ -933,11 +932,11 @@ void dm_io_dec_pending(struct dm_io *io, blk_status_t error)
        /* Push-back supersedes any I/O errors */
        if (unlikely(error)) {
                unsigned long flags;
-               spin_lock_irqsave(&io->endio_lock, flags);
+               spin_lock_irqsave(&io->lock, flags);
                if (!(io->status == BLK_STS_DM_REQUEUE &&
                      __noflush_suspending(io->md)))
                        io->status = error;
-               spin_unlock_irqrestore(&io->endio_lock, flags);
+               spin_unlock_irqrestore(&io->lock, flags);
        }
 
        if (atomic_dec_and_test(&io->io_count))