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Commit 097426f6 authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: fix possible problem in raid1/raid10 error overwriting 



The code to overwrite/reread for addressing read errors in raid1/raid10
currently assumes that the read will not alter the buffer which could be used
to write to the next device.  This is not a safe assumption to make.

So we split the loops into a overwrite loop and a separate re-read loop, so
that the writing is complete before reading is attempted.

Cc: Paul Clements <paul.clements@steeleye.com>
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 2604b703

drivers/md/raid1.c

+30 −8
Original line number Diff line number Diff line
@@ -1253,6 +1253,7 @@ static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio) 
			} while (!success && d != r1_bio->read_disk);



			if (success) {

				int start = d;

				/* write it back and re-read */

				set_bit(R1BIO_Uptodate, &r1_bio->state);

				while (d != r1_bio->read_disk) {
@@ -1266,15 +1267,24 @@ static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio) 
							 sect + rdev->data_offset,

							 s<<9,

							 bio->bi_io_vec[idx].bv_page,

							 WRITE) == 0 ||

					    sync_page_io(rdev->bdev,

							 WRITE) == 0)

						md_error(mddev, rdev);

				}

				d = start;

				while (d != r1_bio->read_disk) {

					if (d == 0)

						d = conf->raid_disks;

					d--;

					if (r1_bio->bios[d]->bi_end_io != end_sync_read)

						continue;

					rdev = conf->mirrors[d].rdev;

					if (sync_page_io(rdev->bdev,

							 sect + rdev->data_offset,

							 s<<9,

							 bio->bi_io_vec[idx].bv_page,

							 READ) == 0) {

							 READ) == 0)

						md_error(mddev, rdev);

				}

				}

			} else {

				char b[BDEVNAME_SIZE];

				/* Cannot read from anywhere, array is toast */
@@ -1445,6 +1455,7 @@ static void raid1d(mddev_t *mddev) 


				if (success) {

					/* write it back and re-read */

					int start = d;

					while (d != r1_bio->read_disk) {

						if (d==0)

							d = conf->raid_disks;
@@ -1454,14 +1465,25 @@ static void raid1d(mddev_t *mddev) 
						    test_bit(In_sync, &rdev->flags)) {

							if (sync_page_io(rdev->bdev,

									 sect + rdev->data_offset,

									 s<<9, conf->tmppage, WRITE) == 0 ||

							    sync_page_io(rdev->bdev,

									 sect + rdev->data_offset,

									 s<<9, conf->tmppage, READ) == 0) {

									 s<<9, conf->tmppage, WRITE) == 0)

								/* Well, this device is dead */

								md_error(mddev, rdev);

						}

					}

					d = start;

					while (d != r1_bio->read_disk) {

						if (d==0)

							d = conf->raid_disks;

						d--;

						rdev = conf->mirrors[d].rdev;

						if (rdev &&

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

							if (sync_page_io(rdev->bdev,

									 sect + rdev->data_offset,

									 s<<9, conf->tmppage, READ) == 0)

								/* Well, this device is dead */

								md_error(mddev, rdev);

						}

					}

				} else {

					/* Cannot read from anywhere -- bye bye array */

drivers/md/raid10.c

+18 −4
Original line number Diff line number Diff line
@@ -1421,6 +1421,7 @@ static void raid10d(mddev_t *mddev) 
				} while (!success && sl != r10_bio->read_slot);



				if (success) {

					int start = sl;

					/* write it back and re-read */

					while (sl != r10_bio->read_slot) {

						int d;
@@ -1434,16 +1435,29 @@ static void raid10d(mddev_t *mddev) 
							if (sync_page_io(rdev->bdev,

									 r10_bio->devs[sl].addr +

									 sect + rdev->data_offset,

									 s<<9, conf->tmppage, WRITE) == 0 ||

							    sync_page_io(rdev->bdev,

									 s<<9, conf->tmppage, WRITE) == 0)

								/* Well, this device is dead */

								md_error(mddev, rdev);

						}

					}

					sl = start;

					while (sl != r10_bio->read_slot) {

						int d;

						if (sl==0)

							sl = conf->copies;

						sl--;

						d = r10_bio->devs[sl].devnum;

						rdev = conf->mirrors[d].rdev;

						if (rdev &&

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

							if (sync_page_io(rdev->bdev,

									 r10_bio->devs[sl].addr +

									 sect + rdev->data_offset,

									 s<<9, conf->tmppage, READ) == 0) {

									 s<<9, conf->tmppage, READ) == 0)

								/* Well, this device is dead */

								md_error(mddev, rdev);

						}

					}

					}

				} else {

					/* Cannot read from anywhere -- bye bye array */

					md_error(mddev, conf->mirrors[r10_bio->devs[r10_bio->read_slot].devnum].rdev);