On 10/2/19 1:14 PM, Mikulas Patocka wrote:
> This is simple refactoring that moves code for modifying the semaphore
> cow_count into separate functions. It is needed by the following patch.
>
> Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # v5.0+
> Fixes: 721b1d98fb51 ("dm snapshot: Fix excessive memory usage and workqueue stalls")
>
Reviewed-by: Nikos Tsironis <ntsironis@xxxxxxxxxxx>
> ---
> drivers/md/dm-snap.c | 20 +++++++++++++++-----
> 1 file changed, 15 insertions(+), 5 deletions(-)
>
> Index: linux-2.6/drivers/md/dm-snap.c
> ===================================================================
> --- linux-2.6.orig/drivers/md/dm-snap.c 2019-10-01 15:19:20.000000000 +0200
> +++ linux-2.6/drivers/md/dm-snap.c 2019-10-01 15:23:10.000000000 +0200
> @@ -1512,6 +1512,16 @@ static void snapshot_dtr(struct dm_targe
> kfree(s);
> }
>
> +static void account_start_copy(struct dm_snapshot *s)
> +{
> + down(&s->cow_count);
> +}
> +
> +static void account_end_copy(struct dm_snapshot *s)
> +{
> + up(&s->cow_count);
> +}
> +
> /*
> * Flush a list of buffers.
> */
> @@ -1732,7 +1742,7 @@ static void copy_callback(int read_err,
> rb_link_node(&pe->out_of_order_node, parent, p);
> rb_insert_color(&pe->out_of_order_node, &s->out_of_order_tree);
> }
> - up(&s->cow_count);
> + account_end_copy(s);
> }
>
> /*
> @@ -1756,7 +1766,7 @@ static void start_copy(struct dm_snap_pe
> dest.count = src.count;
>
> /* Hand over to kcopyd */
> - down(&s->cow_count);
> + account_start_copy(s);
> dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, copy_callback, pe);
> }
>
> @@ -1776,7 +1786,7 @@ static void start_full_bio(struct dm_sna
> pe->full_bio = bio;
> pe->full_bio_end_io = bio->bi_end_io;
>
> - down(&s->cow_count);
> + account_start_copy(s);
> callback_data = dm_kcopyd_prepare_callback(s->kcopyd_client,
> copy_callback, pe);
>
> @@ -1866,7 +1876,7 @@ static void zero_callback(int read_err,
> struct bio *bio = context;
> struct dm_snapshot *s = bio->bi_private;
>
> - up(&s->cow_count);
> + account_end_copy(s);
> bio->bi_status = write_err ? BLK_STS_IOERR : 0;
> bio_endio(bio);
> }
> @@ -1880,7 +1890,7 @@ static void zero_exception(struct dm_sna
> dest.sector = bio->bi_iter.bi_sector;
> dest.count = s->store->chunk_size;
>
> - down(&s->cow_count);
> + account_start_copy(s);
> WARN_ON_ONCE(bio->bi_private);
> bio->bi_private = s;
> dm_kcopyd_zero(s->kcopyd_client, 1, &dest, 0, zero_callback, bio);
>
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
