md/raid5: Remove use of sh->lock in sync_request
This is the start of a series of patches to remove sh->lock.
sync_request takes sh->lock before setting STRIPE_SYNCING to ensure
there is no race with testing it in handle_stripe[56].
Instead, use a new flag STRIPE_SYNC_REQUESTED and test it early
in handle_stripe[56] (after getting the same lock) and perform the
same set/clear operations if it was set.
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Namhyung Kim <namhyung@gmail.com>
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 7148064..f2f2ab32 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3022,6 +3022,10 @@
sh->reconstruct_state);
spin_lock(&sh->lock);
+ if (test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
+ set_bit(STRIPE_SYNCING, &sh->state);
+ clear_bit(STRIPE_INSYNC, &sh->state);
+ }
clear_bit(STRIPE_HANDLE, &sh->state);
clear_bit(STRIPE_DELAYED, &sh->state);
@@ -3313,6 +3317,10 @@
memset(&s, 0, sizeof(s));
spin_lock(&sh->lock);
+ if (test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
+ set_bit(STRIPE_SYNCING, &sh->state);
+ clear_bit(STRIPE_INSYNC, &sh->state);
+ }
clear_bit(STRIPE_HANDLE, &sh->state);
clear_bit(STRIPE_DELAYED, &sh->state);
@@ -4373,10 +4381,7 @@
bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
- spin_lock(&sh->lock);
- set_bit(STRIPE_SYNCING, &sh->state);
- clear_bit(STRIPE_INSYNC, &sh->state);
- spin_unlock(&sh->lock);
+ set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
handle_stripe(sh);
release_stripe(sh);