diff options
| author | Omar Sandoval <osandov@fb.com> | 2019-09-16 21:30:55 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2019-11-18 14:46:48 +0300 |
| commit | e732fe95e4cad35fc1df278c23a32903341b08b3 (patch) | |
| tree | ce00fb9dc70673edb62aca1e5aabe0c90ae7fea7 /fs/btrfs/reada.c | |
| parent | 9be490f1e15c34193b1aae17da58e14dd9f55a95 (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.c | 10 |
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) |