For sync and flush io, it may take long time to complete. So it's better to use wait_for_completion_io_timeout() in a while loop to avoid prevent hung check and crash(when set /proc/sys/kernel/hung_task_panic).
This is similar to prevent hung task check in submit_bio_wait(), blk_execute_rq(). Signed-off-by: Xianting Tian <[email protected]> --- fs/btrfs/disk-io.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 9ae25f632..1eb560de0 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -17,6 +17,7 @@ #include <linux/error-injection.h> #include <linux/crc32c.h> #include <linux/sched/mm.h> +#include <linux/sched/sysctl.h> #include <asm/unaligned.h> #include <crypto/hash.h> #include "ctree.h" @@ -3699,12 +3700,21 @@ static void write_dev_flush(struct btrfs_device *device) static blk_status_t wait_dev_flush(struct btrfs_device *device) { struct bio *bio = device->flush_bio; + unsigned long hang_check; if (!test_bit(BTRFS_DEV_STATE_FLUSH_SENT, &device->dev_state)) return BLK_STS_OK; clear_bit(BTRFS_DEV_STATE_FLUSH_SENT, &device->dev_state); - wait_for_completion_io(&device->flush_wait); + + /* Prevent hang_check timer from firing at us during very long I/O */ + hang_check = sysctl_hung_task_timeout_secs; + if (hang_check) + while (!wait_for_completion_io_timeout(&device->flush_wait, + hang_check * (HZ/2))) + ; + else + wait_for_completion_io(&device->flush_wait); return bio->bi_status; } -- 2.17.1
