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Commit 3f9e7c14 authored by majianpeng's avatar majianpeng Committed by NeilBrown
Browse files

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: default avatarJianpeng Ma <majianpeng@gmail.com>
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 12cee5a8

drivers/md/raid5.c

+12 −2
Original line number Diff line number Diff line
@@ -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)

			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++;

drivers/md/raid5.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */