Commit 7efb3673 authored Aug 30, 2016 by Mikulas Patocka Committed by Mike Snitzer Aug 30, 2016

dm log writes: fix bug with too large bios



bio_alloc() can allocate a bio with at most BIO_MAX_PAGES (256) vector
entries.  However, the incoming bio may have more vector entries if it
was allocated by other means.  For example, bcache submits bios with
more than BIO_MAX_PAGES entries.  This results in bio_alloc() failure.

To avoid the failure, change the code so that it allocates bio with at
most BIO_MAX_PAGES entries.  If the incoming bio has more entries,
bio_add_page() will fail and a new bio will be allocated - the code that
handles bio_add_page() failure already exists in the dm-log-writes
target.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Josef Bacik <jbacik@fb,com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # v4.1+

parent a5d60783

drivers/md/dm-log-writes.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -260,7 +260,7 @@ static int log_one_block(struct log_writes_c *lc,
		sector++;

		atomic_inc(&lc->io_blocks);
		bio = bio_alloc(GFP_KERNEL, block->vec_cnt);
		bio = bio_alloc(GFP_KERNEL, min(block->vec_cnt, BIO_MAX_PAGES));
		if (!bio) {
		DMERR("Couldn't alloc log bio");
		goto error;
		@@ -282,7 +282,7 @@ static int log_one_block(struct log_writes_c *lc,
		if (ret != block->vecs[i].bv_len) {
		atomic_inc(&lc->io_blocks);
		submit_bio(bio);
		bio = bio_alloc(GFP_KERNEL, block->vec_cnt - i);
		bio = bio_alloc(GFP_KERNEL, min(block->vec_cnt - i, BIO_MAX_PAGES));
		if (!bio) {
		DMERR("Couldn't alloc log bio");
		goto error;