From: Mikulas Patocka Date: Tue, 30 Aug 2016 20:20:55 +0000 (-0400) Subject: dm log writes: fix bug with too large bios X-Git-Tag: firefly_0821_release~176^2~4^2~26^2~32 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=7eb0153fc42d98d301a5ca946ed31366cd33526f;p=firefly-linux-kernel-4.4.55.git dm log writes: fix bug with too large bios commit 7efb367320f56fc4d549875b6f3a6940018ef2e5 upstream. 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 Reviewed-by: Josef Bacik Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c index d8956b4a7b09..c8b513ee117c 100644 --- a/drivers/md/dm-log-writes.c +++ b/drivers/md/dm-log-writes.c @@ -259,7 +259,7 @@ 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; @@ -280,7 +280,7 @@ static int log_one_block(struct log_writes_c *lc, if (ret != block->vecs[i].bv_len) { atomic_inc(&lc->io_blocks); submit_bio(WRITE, 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;