On Thu, Apr 06, 2017 at 11:22:47AM +0800, Anand Jain wrote:
> As of now we do alloc an empty bio and then use the flag REQ_PREFLUSH
> to flush the device cache, instead we can use blkdev_issue_flush()
> for this puspose.
>
> Also now no need to check the return when write_dev_flush() is called
> with wait = 0
>
> Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
> ---
> v2: Title of this patch is changed from
> btrfs: communicate back ENOMEM when it occurs
> And its entirely a new patch, which now use blkdev_issue_flush()
> v3: no change
> v4: no change
>
> fs/btrfs/disk-io.c | 64 +++++++++++++++---------------------------------------
> fs/btrfs/volumes.h | 3 ++-
> 2 files changed, 19 insertions(+), 48 deletions(-)
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 08b74daf35d0..08cbbee228ee 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -3498,70 +3498,42 @@ static int write_dev_supers(struct btrfs_device *device,
> return errors < i ? 0 : -1;
> }
>
> -/*
> - * endio for the write_dev_flush, this will wake anyone waiting
> - * for the barrier when it is done
> - */
> -static void btrfs_end_empty_barrier(struct bio *bio)
> +static void btrfs_dev_issue_flush(struct work_struct *work)
> {
> - if (bio->bi_private)
> - complete(bio->bi_private);
> - bio_put(bio);
> + int ret;
> + struct btrfs_device *device;
> +
> + device = container_of(work, struct btrfs_device, flush_work);
> +
> + /* we are in the commit thread */
What is the above comment trying to explain?
Others look good.
Reviewed-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
Thanks,
-liubo
> + ret = blkdev_issue_flush(device->bdev, GFP_NOFS, NULL);
> + device->last_flush_error = ret;
> + complete(&device->flush_wait);
> }
>
> /*
> * trigger flushes for one the devices. If you pass wait == 0, the flushes are
> * sent down. With wait == 1, it waits for the previous flush.
> - *
> - * any device where the flush fails with eopnotsupp are flagged as not-barrier
> - * capable
> */
> static int write_dev_flush(struct btrfs_device *device, int wait)
> {
> - struct bio *bio;
> - int ret = 0;
> -
> if (device->nobarriers)
> return 0;
>
> if (wait) {
> - bio = device->flush_bio;
> - if (!bio)
> - return 0;
> + int ret;
>
> wait_for_completion(&device->flush_wait);
> -
> - if (bio->bi_error) {
> - ret = bio->bi_error;
> + ret = device->last_flush_error;
> + if (ret)
> btrfs_dev_stat_inc_and_print(device,
> - BTRFS_DEV_STAT_FLUSH_ERRS);
> - }
> -
> - /* drop the reference from the wait == 0 run */
> - bio_put(bio);
> - device->flush_bio = NULL;
> -
> + BTRFS_DEV_STAT_FLUSH_ERRS);
> return ret;
> }
>
> - /*
> - * one reference for us, and we leave it for the
> - * caller
> - */
> - device->flush_bio = NULL;
> - bio = btrfs_io_bio_alloc(GFP_NOFS, 0);
> - if (!bio)
> - return -ENOMEM;
> -
> - bio->bi_end_io = btrfs_end_empty_barrier;
> - bio->bi_bdev = device->bdev;
> - bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
> init_completion(&device->flush_wait);
> - bio->bi_private = &device->flush_wait;
> - device->flush_bio = bio;
> -
> - bio_get(bio);
> - btrfsic_submit_bio(bio);
> + INIT_WORK(&device->flush_work, btrfs_dev_issue_flush);
> + schedule_work(&device->flush_work);
>
> return 0;
> }
> @@ -3590,9 +3562,7 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
> if (!dev->in_fs_metadata || !dev->writeable)
> continue;
>
> - ret = write_dev_flush(dev, 0);
> - if (ret)
> - errors_send++;
> + write_dev_flush(dev, 0);
> }
>
> /* wait for all the barriers */
> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index 59be81206dd7..0df50bc65578 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -124,8 +124,9 @@ struct btrfs_device {
>
> /* for sending down flush barriers */
> int nobarriers;
> - struct bio *flush_bio;
> struct completion flush_wait;
> + struct work_struct flush_work;
> + int last_flush_error;
>
> /* per-device scrub information */
> struct scrub_ctx *scrub_device;
> --
> 2.10.0
>
> --
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