tree 85c68bbd2f077724563cfb26a3357d6679f12104
parent 6649a3863232eb2e2f15ea6c622bd8ceacf96d76
author Neil Brown <neilb@suse.de> 1170973229 -0800
committer Linus Torvalds <torvalds@woody.linux-foundation.org> 1171041946 -0800

[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>