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authorOmar Sandoval <osandov@fb.com>2019-09-16 11:30:55 -0700
committerDavid Sterba <dsterba@suse.com>2019-11-18 12:46:48 +0100
commite732fe95e4cad35fc1df278c23a32903341b08b3 (patch)
treece00fb9dc70673edb62aca1e5aabe0c90ae7fea7 /fs/btrfs/reada.c
parent9be490f1e15c34193b1aae17da58e14dd9f55a95 (diff)
btrfs: don't prematurely free work in reada_start_machine_worker()
Currently, reada_start_machine_worker() frees the reada_machine_work and then calls __reada_start_machine() to do readahead. This is another potential instance of the bug in "btrfs: don't prematurely free work in run_ordered_work()". There _might_ already be a deadlock here: reada_start_machine_worker() can depend on itself through stacked filesystems (__read_start_machine() -> reada_start_machine_dev() -> reada_tree_block_flagged() -> read_extent_buffer_pages() -> submit_one_bio() -> btree_submit_bio_hook() -> btrfs_map_bio() -> submit_stripe_bio() -> submit_bio() onto a loop device can trigger readahead on the lower filesystem). Either way, let's fix it by freeing the work at the end. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Omar Sandoval <osandov@fb.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/reada.c')
-rw-r--r--fs/btrfs/reada.c10
1 files changed, 4 insertions, 6 deletions
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index ee6f60547a8d..dd4f9c2b7107 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -752,21 +752,19 @@ static int reada_start_machine_dev(struct btrfs_device *dev)
static void reada_start_machine_worker(struct btrfs_work *work)
{
struct reada_machine_work *rmw;
- struct btrfs_fs_info *fs_info;
int old_ioprio;
rmw = container_of(work, struct reada_machine_work, work);
- fs_info = rmw->fs_info;
-
- kfree(rmw);
old_ioprio = IOPRIO_PRIO_VALUE(task_nice_ioclass(current),
task_nice_ioprio(current));
set_task_ioprio(current, BTRFS_IOPRIO_READA);
- __reada_start_machine(fs_info);
+ __reada_start_machine(rmw->fs_info);
set_task_ioprio(current, old_ioprio);
- atomic_dec(&fs_info->reada_works_cnt);
+ atomic_dec(&rmw->fs_info->reada_works_cnt);
+
+ kfree(rmw);
}
static void __reada_start_machine(struct btrfs_fs_info *fs_info)