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dm cache: fix use after freeing migrations

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Both free_io_migration() and issue_discard() dereference a migration
that was just freed.  Fix those by saving off the migrations's cache
object before freeing the migration.  Also cleanup needless mg->cache
dereferences now that the cache object is available directly.

Fixes: e44b6a5a3c ("dm cache: move wake_waker() from free_migrations() to where it is needed")
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber 2015-09-01 11:38:19 +01:00 • committed by Mike Snitzer
parent dc9cee5db5
commit cc7da0ba9c
1 changed files with 9 additions and 6 deletions
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15
drivers/md/dm-cache-target.c
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@ -1113,9 +1113,11 @@ static void cell_requeue(struct cache *cache, struct dm_bio_prison_cell *cell)
static void free_io_migration(struct dm_cache_migration *mg) static void free_io_migration(struct dm_cache_migration *mg)
{ {
dec_io_migrations(mg->cache); struct cache *cache = mg->cache;
dec_io_migrations(cache);
free_migration(mg); free_migration(mg);
wake_worker(mg->cache); wake_worker(cache);
} }
static void migration_failure(struct dm_cache_migration *mg) static void migration_failure(struct dm_cache_migration *mg)
@ -1342,17 +1344,18 @@ static void issue_discard(struct dm_cache_migration *mg)
{ {
dm_dblock_t b, e; dm_dblock_t b, e;
struct bio *bio = mg->new_ocell->holder; struct bio *bio = mg->new_ocell->holder;
struct cache *cache = mg->cache;
calc_discard_block_range(mg->cache, bio, &b, &e); calc_discard_block_range(cache, bio, &b, &e);
while (b != e) { while (b != e) {
set_discard(mg->cache, b); set_discard(cache, b);
b = to_dblock(from_dblock(b) + 1); b = to_dblock(from_dblock(b) + 1);
} }
bio_endio(bio, 0); bio_endio(bio, 0);
cell_defer(mg->cache, mg->new_ocell, false); cell_defer(cache, mg->new_ocell, false);
free_migration(mg); free_migration(mg);
wake_worker(mg->cache); wake_worker(cache);
} }
static void issue_copy_or_discard(struct dm_cache_migration *mg) static void issue_copy_or_discard(struct dm_cache_migration *mg)