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.
Signed-off-by: majianpeng <majianpeng@xxxxxxxxx>
---
block/blk-core.c | 8 ++++++++
drivers/md/raid5.c | 16 +++++++++++++---
drivers/md/raid5.h | 1 +
3 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 3c923a7..ee04bfc 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1401,6 +1401,9 @@ void init_request_from_bio(struct request *req, struct bio *bio)
if (bio->bi_rw & REQ_RAHEAD)
req->cmd_flags |= REQ_FAILFAST_MASK;
+ if (unlikely(bio->bi_rw & REQ_NOMERGE))
+ req->cmd_flags |= REQ_NOMERGE;
+
req->errors = 0;
req->__sector = bio->bi_sector;
req->ioprio = bio_prio(bio);
@@ -1428,6 +1431,11 @@ void blk_queue_bio(struct request_queue *q, struct bio *bio)
goto get_rq;
}
+ if (unlikely(bio->bi_rw & REQ_NOMERGE)) {
+ spin_lock_irq(q->queue_lock);
+ where = ELEVATOR_INSERT_BACK;
+ goto get_rq;
+ }
/*
* Check if we can merge with the plugged list before grabbing
* any locks.
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index d267672..04f78d2 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -632,6 +632,9 @@ 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_NOMERGE;
+
bi->bi_flags = 1 << BIO_UPTODATE;
bi->bi_idx = 0;
bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
@@ -1731,7 +1734,9 @@ 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 {
@@ -1773,7 +1778,11 @@ 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);
@@ -4481,7 +4490,8 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
conf->retry_read_aligned = raid_bio;
return handled;
}
-
+ if (likely(raid_bio->bi_size >> 9) > STRIPE_SECTORS)
+ set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
handle_stripe(sh);
release_stripe(sh);
handled++;
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 2164021..6767d07 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -273,6 +273,7 @@ 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 */
--
1.7.5.4
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