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authorNeil Brown <neilb@suse.de>2007-02-08 14:20:29 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-02-09 09:25:46 -0800
commit387bb17374c5fa057462d00d4ba941d49f45de4d (patch)
tree85c68bbd2f077724563cfb26a3357d6679f12104
parent6649a3863232eb2e2f15ea6c622bd8ceacf96d76 (diff)
downloadlinux-2.6.34-ux500-387bb17374c5fa057462d00d4ba941d49f45de4d.tar.gz
[PATCH] md: fix various bugs with aligned reads in RAID5
It is possible for raid5 to be sent a bio that is too big for an underlying device. So if it is a READ that we pass stright down to a device, it will fail and confuse RAID5. So in 'chunk_aligned_read' we check that the bio fits within the parameters for the target device and if it doesn't fit, fall back on reading through the stripe cache and making lots of one-page requests. Note that this is the earliest time we can check against the device because earlier we don't have a lock on the device, so it could change underneath us. Also, the code for handling a retry through the cache when a read fails has not been tested and was badly broken. This patch fixes that code. Signed-off-by: Neil Brown <neilb@suse.de> Cc: "Kai" <epimetreus@fastmail.fm> Cc: <stable@suse.de> Cc: <org@suse.de> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--block/ll_rw_blk.c2
-rw-r--r--drivers/md/raid5.c42
2 files changed, 40 insertions, 4 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index fb6789725e1..38c293b987b 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1264,7 +1264,7 @@ new_hw_segment:
bio->bi_hw_segments = nr_hw_segs;
bio->bi_flags |= (1 << BIO_SEG_VALID);
}
-
+EXPORT_SYMBOL(blk_recount_segments);
static int blk_phys_contig_segment(request_queue_t *q, struct bio *bio,
struct bio *nxt)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 467c16982d0..11c3d7bfa79 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2620,7 +2620,7 @@ static struct bio *remove_bio_from_retry(raid5_conf_t *conf)
}
bi = conf->retry_read_aligned_list;
if(bi) {
- conf->retry_read_aligned = bi->bi_next;
+ conf->retry_read_aligned_list = bi->bi_next;
bi->bi_next = NULL;
bi->bi_phys_segments = 1; /* biased count of active stripes */
bi->bi_hw_segments = 0; /* count of processed stripes */
@@ -2669,6 +2669,27 @@ static int raid5_align_endio(struct bio *bi, unsigned int bytes, int error)
return 0;
}
+static int bio_fits_rdev(struct bio *bi)
+{
+ request_queue_t *q = bdev_get_queue(bi->bi_bdev);
+
+ if ((bi->bi_size>>9) > q->max_sectors)
+ return 0;
+ blk_recount_segments(q, bi);
+ if (bi->bi_phys_segments > q->max_phys_segments ||
+ bi->bi_hw_segments > q->max_hw_segments)
+ return 0;
+
+ if (q->merge_bvec_fn)
+ /* it's too hard to apply the merge_bvec_fn at this stage,
+ * just just give up
+ */
+ return 0;
+
+ return 1;
+}
+
+
static int chunk_aligned_read(request_queue_t *q, struct bio * raid_bio)
{
mddev_t *mddev = q->queuedata;
@@ -2715,6 +2736,13 @@ static int chunk_aligned_read(request_queue_t *q, struct bio * raid_bio)
align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
align_bi->bi_sector += rdev->data_offset;
+ if (!bio_fits_rdev(align_bi)) {
+ /* too big in some way */
+ bio_put(align_bi);
+ rdev_dec_pending(rdev, mddev);
+ return 0;
+ }
+
spin_lock_irq(&conf->device_lock);
wait_event_lock_irq(conf->wait_for_stripe,
conf->quiesce == 0,
@@ -3107,7 +3135,9 @@ static int retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
for (; logical_sector < last_sector;
- logical_sector += STRIPE_SECTORS, scnt++) {
+ logical_sector += STRIPE_SECTORS,
+ sector += STRIPE_SECTORS,
+ scnt++) {
if (scnt < raid_bio->bi_hw_segments)
/* already done this stripe */
@@ -3123,7 +3153,13 @@ static int retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
}
set_bit(R5_ReadError, &sh->dev[dd_idx].flags);
- add_stripe_bio(sh, raid_bio, dd_idx, 0);
+ if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
+ release_stripe(sh);
+ raid_bio->bi_hw_segments = scnt;
+ conf->retry_read_aligned = raid_bio;
+ return handled;
+ }
+
handle_stripe(sh, NULL);
release_stripe(sh);
handled++;