Commit 3e198f78 authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: tidyup some issues with raid1 resync and prepare for catching read errors 



We are dereferencing ->rdev without an rcu lock!

Signed-off-by: default avatarNeil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent ddaf22ab

drivers/md/raid1.c

+56 −54
Original line number Diff line number Diff line
@@ -177,6 +177,13 @@ static inline void free_r1bio(r1bio_t *r1_bio) 
static inline void put_buf(r1bio_t *r1_bio)

{

	conf_t *conf = mddev_to_conf(r1_bio->mddev);

	int i;



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

		struct bio *bio = r1_bio->bios[i];

		if (bio->bi_end_io)

			rdev_dec_pending(conf->mirrors[i].rdev, r1_bio->mddev);

	}



	mempool_free(r1_bio, conf->r1buf_pool);
@@ -1085,7 +1092,6 @@ static int end_sync_read(struct bio *bio, unsigned int bytes_done, int error) 
			 conf->mirrors[r1_bio->read_disk].rdev);

	} else

		set_bit(R1BIO_Uptodate, &r1_bio->state);

	rdev_dec_pending(conf->mirrors[r1_bio->read_disk].rdev, conf->mddev);

	reschedule_retry(r1_bio);

	return 0;

}
@@ -1116,7 +1122,6 @@ static int end_sync_write(struct bio *bio, unsigned int bytes_done, int error) 
		md_done_sync(mddev, r1_bio->sectors, uptodate);

		put_buf(r1_bio);

	}

	rdev_dec_pending(conf->mirrors[mirror].rdev, mddev);

	return 0;

}
@@ -1153,10 +1158,14 @@ static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio) 
	atomic_set(&r1_bio->remaining, 1);

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

		wbio = r1_bio->bios[i];

		if (wbio->bi_end_io != end_sync_write)

		if (wbio->bi_end_io == NULL ||

		    (wbio->bi_end_io == end_sync_read &&

		     (i == r1_bio->read_disk ||

		      !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))

			continue;



		atomic_inc(&conf->mirrors[i].rdev->nr_pending);

		wbio->bi_rw = WRITE;

		wbio->bi_end_io = end_sync_write;

		atomic_inc(&r1_bio->remaining);

		md_sync_acct(conf->mirrors[i].rdev->bdev, wbio->bi_size >> 9);
@@ -1388,14 +1397,13 @@ static int init_resync(conf_t *conf) 
static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)

{

	conf_t *conf = mddev_to_conf(mddev);

	mirror_info_t *mirror;

	r1bio_t *r1_bio;

	struct bio *bio;

	sector_t max_sector, nr_sectors;

	int disk;

	int disk = -1;

	int i;

	int wonly;

	int write_targets = 0;

	int wonly = -1;

	int write_targets = 0, read_targets = 0;

	int sync_blocks;

	int still_degraded = 0;
@@ -1447,44 +1455,24 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i 


	conf->next_resync = sector_nr;



	r1_bio = mempool_alloc(conf->r1buf_pool, GFP_NOIO);

	rcu_read_lock();

	/*

	 * If reconstructing, and >1 working disc,

	 * could dedicate one to rebuild and others to

	 * service read requests ..

	 * If we get a correctably read error during resync or recovery,

	 * we might want to read from a different device.  So we

	 * flag all drives that could conceivably be read from for READ,

	 * and any others (which will be non-In_sync devices) for WRITE.

	 * If a read fails, we try reading from something else for which READ

	 * is OK.

	 */

	disk = conf->last_used;

	/* make sure disk is operational */

	wonly = disk;

	while (conf->mirrors[disk].rdev == NULL ||

	       !test_bit(In_sync, &conf->mirrors[disk].rdev->flags) ||

	       test_bit(WriteMostly, &conf->mirrors[disk].rdev->flags)

		) {

		if (conf->mirrors[disk].rdev  &&

		    test_bit(In_sync, &conf->mirrors[disk].rdev->flags))

			wonly = disk;

		if (disk <= 0)

			disk = conf->raid_disks;

		disk--;

		if (disk == conf->last_used) {

			disk = wonly;

			break;

		}

	}

	conf->last_used = disk;

	atomic_inc(&conf->mirrors[disk].rdev->nr_pending);





	mirror = conf->mirrors + disk;



	r1_bio = mempool_alloc(conf->r1buf_pool, GFP_NOIO);



	r1_bio->mddev = mddev;

	r1_bio->sector = sector_nr;

	r1_bio->state = 0;

	set_bit(R1BIO_IsSync, &r1_bio->state);

	r1_bio->read_disk = disk;



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

		mdk_rdev_t *rdev;

		bio = r1_bio->bios[i];



		/* take from bio_init */
@@ -1499,35 +1487,49 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i 
		bio->bi_end_io = NULL;

		bio->bi_private = NULL;



		if (i == disk) {

			bio->bi_rw = READ;

			bio->bi_end_io = end_sync_read;

		} else if (conf->mirrors[i].rdev == NULL ||

			   test_bit(Faulty, &conf->mirrors[i].rdev->flags)) {

		rdev = rcu_dereference(conf->mirrors[i].rdev);

		if (rdev == NULL ||

			   test_bit(Faulty, &rdev->flags)) {

			still_degraded = 1;

			continue;

		} else if (!test_bit(In_sync, &conf->mirrors[i].rdev->flags) ||

			   sector_nr + RESYNC_SECTORS > mddev->recovery_cp   ||

			   test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {

		} else if (!test_bit(In_sync, &rdev->flags)) {

			bio->bi_rw = WRITE;

			bio->bi_end_io = end_sync_write;

			write_targets ++;

		} else

			/* no need to read or write here */

			continue;

		bio->bi_sector = sector_nr + conf->mirrors[i].rdev->data_offset;

		bio->bi_bdev = conf->mirrors[i].rdev->bdev;

		} else {

			/* may need to read from here */

			bio->bi_rw = READ;

			bio->bi_end_io = end_sync_read;

			if (test_bit(WriteMostly, &rdev->flags)) {

				if (wonly < 0)

					wonly = i;

			} else {

				if (disk < 0)

					disk = i;

			}

			read_targets++;

		}

		atomic_inc(&rdev->nr_pending);

		bio->bi_sector = sector_nr + rdev->data_offset;

		bio->bi_bdev = rdev->bdev;

		bio->bi_private = r1_bio;

	}

	rcu_read_unlock();

	if (disk < 0)

		disk = wonly;

	r1_bio->read_disk = disk;



	if (write_targets == 0) {

	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && read_targets > 0)

		/* extra read targets are also write targets */

		write_targets += read_targets-1;



	if (write_targets == 0 || read_targets == 0) {

		/* There is nowhere to write, so all non-sync

		 * drives must be failed - so we are finished

		 */

		sector_t rv = max_sector - sector_nr;

		*skipped = 1;

		put_buf(r1_bio);

		rdev_dec_pending(conf->mirrors[disk].rdev, mddev);

		return rv;

	}
@@ -1578,10 +1580,10 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i 
		sync_blocks -= (len>>9);

	} while (r1_bio->bios[disk]->bi_vcnt < RESYNC_PAGES);

 bio_full:

	bio = r1_bio->bios[disk];

	bio = r1_bio->bios[r1_bio->read_disk];

	r1_bio->sectors = nr_sectors;



	md_sync_acct(mirror->rdev->bdev, nr_sectors);

	md_sync_acct(conf->mirrors[r1_bio->read_disk].rdev->bdev, nr_sectors);



	generic_make_request(bio);

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