[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>
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index fb67897..38c293b 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1264,7 +1264,7 @@
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)