The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c6d6e9b0f6b4201c77f2cea3964dd122697e3543 Mon Sep 17 00:00:00 2001

From: Jaegeuk Kim jaegeuk@kernel.org Date: Tue, 18 Dec 2018 09:25:37 -0800 Subject: [PATCH] dm: do not allow readahead to limit IO size

Update DM to set the bdi's io_pages. This fixes reads to be capped at the device's max request size (even if user's read IO exceeds the established readahead setting).

Fixes: 9491ae4a ("mm: don't cap request size based on read-ahead setting") Cc: stable@vger.kernel.org Reviewed-by: Jens Axboe axboe@kernel.dk Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Mike Snitzer snitzer@redhat.com

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 844f7d0f2ef8..4b1be754cc41 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -1927,6 +1927,9 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, */ if (blk_queue_is_zoned(q)) blk_revalidate_disk_zones(t->md->disk); + + /* Allow reads to exceed readahead limits */ + q->backing_dev_info->io_pages = limits->max_sectors >> (PAGE_SHIFT - 9); }

unsigned int dm_table_get_num_targets(struct dm_table *t)