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raid5: Add R5_ReadNoMerge flag which prevent bio from merging at block layer 

Because bios will merge at block-layer,so bios-error may caused by other
bio which be merged into to the same request.
Using this flag,it will find exactly error-sector and not do redundant
operation like re-write and re-read.

V0->V1:Using REQ_FLUSH instead REQ_NOMERGE avoid bio merging at block
layer.

Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
majianpeng 2012-07-31 10:04:21 +10:00 committed by NeilBrown
parent 12cee5a8a2
commit 3f9e7c140e
2 changed files with 13 additions and 2 deletions
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14
drivers/md/raid5.c
View File

@ -653,6 +653,9 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
else
bi->bi_sector = (sh->sector
+ rdev->data_offset);
if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
bi->bi_rw |= REQ_FLUSH;
bi->bi_flags = 1 << BIO_UPTODATE;
bi->bi_idx = 0;
bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
@ -1750,7 +1753,9 @@ static void raid5_end_read_request(struct bio * bi, int error)
atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
clear_bit(R5_ReadError, &sh->dev[i].flags);
clear_bit(R5_ReWrite, &sh->dev[i].flags);
}
} else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
if (atomic_read(&rdev->read_errors))
atomic_set(&rdev->read_errors, 0);
} else {
@ -1795,7 +1800,11 @@ static void raid5_end_read_request(struct bio * bi, int error)
else
retry = 1;
if (retry)
set_bit(R5_ReadError, &sh->dev[i].flags);
if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
set_bit(R5_ReadError, &sh->dev[i].flags);
clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
} else
set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
else {
clear_bit(R5_ReadError, &sh->dev[i].flags);
clear_bit(R5_ReWrite, &sh->dev[i].flags);
@ -4515,6 +4524,7 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
return handled;
}
set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
handle_stripe(sh);
release_stripe(sh);
handled++;

1
drivers/md/raid5.h
View File

@ -274,6 +274,7 @@ enum r5dev_flags {
R5_Wantwrite,
R5_Overlap, /* There is a pending overlapping request
* on this block */
R5_ReadNoMerge, /* prevent bio from merging in block-layer */
R5_ReadError, /* seen a read error here recently */
R5_ReWrite, /* have tried to over-write the readerror */