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Commit 12fc0f49 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
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dm io: handle empty barriers 



Accept empty barriers in dm-io.

dm-io will process empty write barrier requests just like the other
read/write requests.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 67a46dad

drivers/md/dm-io.c

+7 −3
Original line number Diff line number Diff line
@@ -309,7 +309,11 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where, 
	unsigned num_bvecs;

	sector_t remaining = where->count;



	while (remaining) {

	/*

	 * where->count may be zero if rw holds a write barrier and we

	 * need to send a zero-sized barrier.

	 */

	do {

		/*

		 * Allocate a suitably sized-bio.

		 */
@@ -339,7 +343,7 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where, 


		atomic_inc(&io->count);

		submit_bio(rw, bio);

	}

	} while (remaining);

}



static void dispatch_io(int rw, unsigned int num_regions,
@@ -360,7 +364,7 @@ static void dispatch_io(int rw, unsigned int num_regions, 
	 */

	for (i = 0; i < num_regions; i++) {

		*dp = old_pages;

		if (where[i].count)

		if (where[i].count || (rw & (1 << BIO_RW_BARRIER)))

			do_region(rw, i, where + i, dp, io);

	}