Commit d7bd398e authored by Song Liu's avatar Song Liu Committed by Shaohua Li
Browse files

md/r5cache: handle alloc_page failure 



RMW of r5c write back cache uses an extra page to store old data for
prexor. handle_stripe_dirtying() allocates this page by calling
alloc_page(). However, alloc_page() may fail.

To handle alloc_page() failures, this patch adds an extra page to
disk_info. When alloc_page fails, handle_stripe() trys to use these
pages. When these pages are used by other stripe (R5C_EXTRA_PAGE_IN_USE),
the stripe is added to delayed_list.

Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
Reviewed-by: default avatarNeilBrown <neilb@suse.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent 034e33f5

drivers/md/raid5-cache.c

+26 −1
Original line number Diff line number Diff line
@@ -2326,15 +2326,40 @@ int r5c_try_caching_write(struct r5conf *conf, 
 */

void r5c_release_extra_page(struct stripe_head *sh)

{

	struct r5conf *conf = sh->raid_conf;

	int i;

	bool using_disk_info_extra_page;



	using_disk_info_extra_page =

		sh->dev[0].orig_page == conf->disks[0].extra_page;



	for (i = sh->disks; i--; )

		if (sh->dev[i].page != sh->dev[i].orig_page) {

			struct page *p = sh->dev[i].orig_page;



			sh->dev[i].orig_page = sh->dev[i].page;

			if (!using_disk_info_extra_page)

				put_page(p);

		}



	if (using_disk_info_extra_page) {

		clear_bit(R5C_EXTRA_PAGE_IN_USE, &conf->cache_state);

		md_wakeup_thread(conf->mddev->thread);

	}

}



void r5c_use_extra_page(struct stripe_head *sh)

{

	struct r5conf *conf = sh->raid_conf;

	int i;

	struct r5dev *dev;



	for (i = sh->disks; i--; ) {

		dev = &sh->dev[i];

		if (dev->orig_page != dev->page)

			put_page(dev->orig_page);

		dev->orig_page = conf->disks[i].extra_page;

	}

}



/*

drivers/md/raid5.c

+66 −12
Original line number Diff line number Diff line
@@ -876,6 +876,8 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s) 


	if (!test_bit(STRIPE_R5C_CACHING, &sh->state)) {

		/* writing out phase */

		if (s->waiting_extra_page)

			return;

		if (r5l_write_stripe(conf->log, sh) == 0)

			return;

	} else {  /* caching phase */
@@ -2007,6 +2009,7 @@ static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp, 
		INIT_LIST_HEAD(&sh->batch_list);

		INIT_LIST_HEAD(&sh->lru);

		INIT_LIST_HEAD(&sh->r5c);

		INIT_LIST_HEAD(&sh->log_list);

		atomic_set(&sh->count, 1);

		sh->log_start = MaxSector;

		for (i = 0; i < disks; i++) {
@@ -2253,10 +2256,24 @@ static int resize_stripes(struct r5conf *conf, int newsize) 
	 */

	ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);

	if (ndisks) {

		for (i=0; i<conf->raid_disks; i++)

		for (i = 0; i < conf->pool_size; i++)

			ndisks[i] = conf->disks[i];



		for (i = conf->pool_size; i < newsize; i++) {

			ndisks[i].extra_page = alloc_page(GFP_NOIO);

			if (!ndisks[i].extra_page)

				err = -ENOMEM;

		}



		if (err) {

			for (i = conf->pool_size; i < newsize; i++)

				if (ndisks[i].extra_page)

					put_page(ndisks[i].extra_page);

			kfree(ndisks);

		} else {

			kfree(conf->disks);

			conf->disks = ndisks;

		}

	} else

		err = -ENOMEM;
@@ -3580,7 +3597,7 @@ unhash: 
		break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);

}



static void handle_stripe_dirtying(struct r5conf *conf,

static int handle_stripe_dirtying(struct r5conf *conf,

				  struct stripe_head *sh,

				  struct stripe_head_state *s,

				  int disks)
@@ -3649,12 +3666,32 @@ static void handle_stripe_dirtying(struct r5conf *conf, 
			    dev->page == dev->orig_page &&

			    !test_bit(R5_LOCKED, &sh->dev[sh->pd_idx].flags)) {

				/* alloc page for prexor */

				dev->orig_page = alloc_page(GFP_NOIO);

				struct page *p = alloc_page(GFP_NOIO);



				/* will handle failure in a later patch*/

				BUG_ON(!dev->orig_page);

				if (p) {

					dev->orig_page = p;

					continue;

				}



				/*

				 * alloc_page() failed, try use

				 * disk_info->extra_page

				 */

				if (!test_and_set_bit(R5C_EXTRA_PAGE_IN_USE,

						      &conf->cache_state)) {

					r5c_use_extra_page(sh);

					break;

				}



				/* extra_page in use, add to delayed_list */

				set_bit(STRIPE_DELAYED, &sh->state);

				s->waiting_extra_page = 1;

				return -EAGAIN;

			}

		}



		for (i = disks; i--; ) {

			struct r5dev *dev = &sh->dev[i];

			if ((dev->towrite ||

			     i == sh->pd_idx || i == sh->qd_idx ||

			     test_bit(R5_InJournal, &dev->flags)) &&
@@ -3730,6 +3767,7 @@ static void handle_stripe_dirtying(struct r5conf *conf, 
	    (s->locked == 0 && (rcw == 0 || rmw == 0) &&

	     !test_bit(STRIPE_BIT_DELAY, &sh->state)))

		schedule_reconstruction(sh, s, rcw == 0, 0);

	return 0;

}



static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
@@ -4545,8 +4583,12 @@ static void handle_stripe(struct stripe_head *sh) 
			if (ret == -EAGAIN ||

			    /* stripe under reclaim: !caching && injournal */

			    (!test_bit(STRIPE_R5C_CACHING, &sh->state) &&

			     s.injournal > 0))

				handle_stripe_dirtying(conf, sh, &s, disks);

			     s.injournal > 0)) {

				ret = handle_stripe_dirtying(conf, sh, &s,

							     disks);

				if (ret == -EAGAIN)

					goto finish;

			}

		}

	}
@@ -6458,6 +6500,8 @@ static void raid5_free_percpu(struct r5conf *conf) 


static void free_conf(struct r5conf *conf)

{

	int i;



	if (conf->log)

		r5l_exit_log(conf->log);

	if (conf->shrinker.nr_deferred)
@@ -6466,6 +6510,9 @@ static void free_conf(struct r5conf *conf) 
	free_thread_groups(conf);

	shrink_stripes(conf);

	raid5_free_percpu(conf);

	for (i = 0; i < conf->pool_size; i++)

		if (conf->disks[i].extra_page)

			put_page(conf->disks[i].extra_page);

	kfree(conf->disks);

	kfree(conf->stripe_hashtbl);

	kfree(conf);
@@ -6612,9 +6659,16 @@ static struct r5conf *setup_conf(struct mddev *mddev) 


	conf->disks = kzalloc(max_disks * sizeof(struct disk_info),

			      GFP_KERNEL);



	if (!conf->disks)

		goto abort;



	for (i = 0; i < max_disks; i++) {

		conf->disks[i].extra_page = alloc_page(GFP_KERNEL);

		if (!conf->disks[i].extra_page)

			goto abort;

	}



	conf->mddev = mddev;



	if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)

drivers/md/raid5.h

+6 −0
Original line number Diff line number Diff line
@@ -276,6 +276,7 @@ struct stripe_head_state { 
	struct md_rdev *blocked_rdev;

	int handle_bad_blocks;

	int log_failed;

	int waiting_extra_page;

};



/* Flags for struct r5dev.flags */
@@ -439,6 +440,7 @@ enum { 


struct disk_info {

	struct md_rdev	*rdev, *replacement;

	struct page	*extra_page; /* extra page to use in prexor */

};



/*
@@ -559,6 +561,9 @@ enum r5_cache_state { 
				 * only process stripes that are already

				 * occupying the log

				 */

	R5C_EXTRA_PAGE_IN_USE,	/* a stripe is using disk_info.extra_page

				 * for prexor

				 */

};



struct r5conf {
@@ -765,6 +770,7 @@ extern void 
r5c_finish_stripe_write_out(struct r5conf *conf, struct stripe_head *sh,

			    struct stripe_head_state *s);

extern void r5c_release_extra_page(struct stripe_head *sh);

extern void r5c_use_extra_page(struct stripe_head *sh);

extern void r5l_wake_reclaim(struct r5l_log *log, sector_t space);

extern void r5c_handle_cached_data_endio(struct r5conf *conf,

	struct stripe_head *sh, int disks, struct bio_list *return_bi);

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