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Commit 83206d66 authored by NeilBrown's avatar NeilBrown
Browse files

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: default avatarNeilBrown <neilb@suse.de>
Reviewed-by: default avatarNamhyung Kim <namhyung@gmail.com>
parent ffd96e35

drivers/md/raid5.c

+9 −4
Original line number Original line Diff line number Diff line
@@ -3022,6 +3022,10 @@ static void handle_stripe5(struct stripe_head *sh) 
		 sh->reconstruct_state);

		 sh->reconstruct_state);





	spin_lock(&sh->lock);

	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_HANDLE, &sh->state);

	clear_bit(STRIPE_DELAYED, &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));

	memset(&s, 0, sizeof(s));





	spin_lock(&sh->lock);

	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_HANDLE, &sh->state);

	clear_bit(STRIPE_DELAYED, &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);

	bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);





	spin_lock(&sh->lock);

	set_bit(STRIPE_SYNC_REQUESTED, &sh->state);

	set_bit(STRIPE_SYNCING, &sh->state);

	clear_bit(STRIPE_INSYNC, &sh->state);

	spin_unlock(&sh->lock);





	handle_stripe(sh);

	handle_stripe(sh);

	release_stripe(sh);

	release_stripe(sh);

drivers/md/raid5.h

+18 −15
Original line number Original line Diff line number Diff line
@@ -289,21 +289,24 @@ struct r6_state { 
/*

/*

 * Stripe state

 * Stripe state

 */

 */

#define STRIPE_HANDLE		2

enum {

#define	STRIPE_SYNCING		3

	STRIPE_HANDLE,

#define	STRIPE_INSYNC		4

	STRIPE_SYNC_REQUESTED,

#define	STRIPE_PREREAD_ACTIVE	5

	STRIPE_SYNCING,

#define	STRIPE_DELAYED		6

	STRIPE_INSYNC,

#define	STRIPE_DEGRADED		7

	STRIPE_PREREAD_ACTIVE,

#define	STRIPE_BIT_DELAY	8

	STRIPE_DELAYED,

#define	STRIPE_EXPANDING	9

	STRIPE_DEGRADED,

#define	STRIPE_EXPAND_SOURCE	10

	STRIPE_BIT_DELAY,

#define	STRIPE_EXPAND_READY	11

	STRIPE_EXPANDING,

#define	STRIPE_IO_STARTED	12 /* do not count towards 'bypass_count' */

	STRIPE_EXPAND_SOURCE,

#define	STRIPE_FULL_WRITE	13 /* all blocks are set to be overwritten */

	STRIPE_EXPAND_READY,

#define	STRIPE_BIOFILL_RUN	14

	STRIPE_IO_STARTED,	/* do not count towards 'bypass_count' */

#define	STRIPE_COMPUTE_RUN	15

	STRIPE_FULL_WRITE,	/* all blocks are set to be overwritten */

#define	STRIPE_OPS_REQ_PENDING	16

	STRIPE_BIOFILL_RUN,

	STRIPE_COMPUTE_RUN,

	STRIPE_OPS_REQ_PENDING,

};





/*

/*

 * Operation request flags

 * Operation request flags