From: Neil Brown Date: Thu, 8 Feb 2007 22:20:29 +0000 (-0800) Subject: [PATCH] md: fix various bugs with aligned reads in RAID5 X-Git-Tag: v2.6.21-rc1~83^2~21 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=387bb17374c5fa057462d00d4ba941d49f45de4d;p=linux-2.6 [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 Cc: "Kai" Cc: Cc: Cc: Jens Axboe Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index fb6789725e..38c293b987 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 467c16982d..11c3d7bfa7 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++;