Commit ef963341 authored by Eric Wheeler's avatar Eric Wheeler Committed by Ben Hutchings

bcache: register_bcache(): call blkdev_put() when cache_alloc() fails

commit d9dc1702 upstream.

register_cache() is supposed to return an error string on error so that
register_bcache() will will blkdev_put and cleanup other user counters,
but it does not set 'char *err' when cache_alloc() fails (eg, due to
memory pressure) and thus register_bcache() performs no cleanup.

register_bcache() <----------\  <- no jump to err_close, no blkdev_put()
   |                         |
   +->register_cache()       |  <- fails to set char *err
         |                   |
         +->cache_alloc() ---/  <- returns error

This patch sets `char *err` for this failure case so that register_cache()
will cause register_bcache() to correctly jump to err_close and do
cleanup.  This was tested under OOM conditions that triggered the bug.
Signed-off-by: default avatarEric Wheeler <bcache@linux.ewheeler.net>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent c01214f7
......@@ -1854,7 +1854,7 @@ static int register_cache(struct cache_sb *sb, struct page *sb_page,
struct block_device *bdev, struct cache *ca)
{
char name[BDEVNAME_SIZE];
const char *err = NULL;
const char *err = NULL; /* must be set for any error case */
int ret = 0;
memcpy(&ca->sb, sb, sizeof(struct cache_sb));
......@@ -1871,8 +1871,13 @@ static int register_cache(struct cache_sb *sb, struct page *sb_page,
ca->discard = CACHE_DISCARD(&ca->sb);
ret = cache_alloc(sb, ca);
if (ret != 0)
if (ret != 0) {
if (ret == -ENOMEM)
err = "cache_alloc(): -ENOMEM";
else
err = "cache_alloc(): unknown error";
goto err;
}
if (kobject_add(&ca->kobj, &part_to_dev(bdev->bd_part)->kobj, "bcache")) {
err = "error calling kobject_add";
......
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