On Mon, Sep 16, 2019 at 11:30:55AM -0700, Omar Sandoval wrote: > From: Omar Sandoval <osandov@xxxxxx> > > 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. Also remove the local fs_info variable as it got obsolete. Anyways, Reviewed-by: Johannes Thumshirn <jthumshirn@xxxxxxx> -- Johannes Thumshirn SUSE Labs Filesystems jthumshirn@xxxxxxx +49 911 74053 689 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 21284 (AG Nürnberg) Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850
