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md/raid5: Remove use of sh->lock in sync_request

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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>
This commit is contained in:
NeilBrown 2011-07-26 11:19:49 +10:00
parent ffd96e35c1
commit 83206d66b6
2 changed files with 27 additions and 19 deletions
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13
drivers/md/raid5.c
View File

@ -3022,6 +3022,10 @@ static void handle_stripe5(struct stripe_head *sh)
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 @@ static void handle_stripe6(struct stripe_head *sh)
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 @@ static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *ski
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);

33
drivers/md/raid5.h
View File

@ -289,21 +289,24 @@ struct r6_state {
/*
* Stripe state
*/
#define STRIPE_HANDLE 2
#define STRIPE_SYNCING 3
#define STRIPE_INSYNC 4
#define STRIPE_PREREAD_ACTIVE 5
#define STRIPE_DELAYED 6
#define STRIPE_DEGRADED 7
#define STRIPE_BIT_DELAY 8
#define STRIPE_EXPANDING 9
#define STRIPE_EXPAND_SOURCE 10
#define STRIPE_EXPAND_READY 11
#define STRIPE_IO_STARTED 12 /* do not count towards 'bypass_count' */
#define STRIPE_FULL_WRITE 13 /* all blocks are set to be overwritten */
#define STRIPE_BIOFILL_RUN 14
#define STRIPE_COMPUTE_RUN 15
#define STRIPE_OPS_REQ_PENDING 16
enum {
STRIPE_HANDLE,
STRIPE_SYNC_REQUESTED,
STRIPE_SYNCING,
STRIPE_INSYNC,
STRIPE_PREREAD_ACTIVE,
STRIPE_DELAYED,
STRIPE_DEGRADED,
STRIPE_BIT_DELAY,
STRIPE_EXPANDING,
STRIPE_EXPAND_SOURCE,
STRIPE_EXPAND_READY,
STRIPE_IO_STARTED, /* do not count towards 'bypass_count' */
STRIPE_FULL_WRITE, /* all blocks are set to be overwritten */
STRIPE_BIOFILL_RUN,
STRIPE_COMPUTE_RUN,
STRIPE_OPS_REQ_PENDING,
};
/*
* Operation request flags