raid5: Retry R5_ReadNoMerge flag when hit a read error.

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Because of block layer merge, one bio fails will cause other bios
which belongs to the same request fails, so raid5_end_read_request
will record all these bios as badblocks.
If retry request with R5_ReadNoMerge flag to avoid bios merge,
badblocks can only record sector which is bad exactly.

test:
hdparm --yes-i-know-what-i-am-doing --make-bad-sector 300000 /dev/sdb
mdadm -C /dev/md0 -l5 -n3 /dev/sd[bcd] --assume-clean
mdadm /dev/md0 -f /dev/sdd
mdadm /dev/md0 -r /dev/sdd
mdadm --zero-superblock /dev/sdd
mdadm /dev/md0 -a /dev/sdd

1. Without this patch:
cat /sys/block/md0/md/rd*/bad_blocks
299776 256
299776 256

2. With this patch:
cat /sys/block/md0/md/rd*/bad_blocks
300000 8
300000 8

Signed-off-by: Bian Yu <bianyu@kedacom.com>
Signed-off-by: NeilBrown <neilb@suse.de>

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This commit is contained in:

Bian Yu 2013-11-14 15:16:17 +11:00 • committed by NeilBrown

parent 4bda556aea

commit edfa1f651e

1 changed files with 3 additions and 0 deletions

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drivers/md/raid5.c

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