Commit db95c876 authored Aug 18, 2017 by David Sterba

btrfs: submit superblock io with REQ_META and REQ_PRIO



The superblock is also metadata of the filesystem so the relevant IO
should be tagged as such. We also tag it as high priority, as it's the
last block committed for metadata from a given transaction. Any delays
would effectively block the whole transaction, also blocking any other
operation holding the device_list_mutex.

Reviewed-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent dc59215d

fs/btrfs/disk-io.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -3433,9 +3433,10 @@ static int write_dev_supers(struct btrfs_device *device,
		*/
		if (i == 0) {
		ret = btrfsic_submit_bh(REQ_OP_WRITE,
		REQ_SYNC \| REQ_FUA, bh);
		REQ_SYNC \| REQ_FUA \| REQ_META \| REQ_PRIO, bh);
		} else {
		ret = btrfsic_submit_bh(REQ_OP_WRITE, REQ_SYNC, bh);
		ret = btrfsic_submit_bh(REQ_OP_WRITE,
		REQ_SYNC \| REQ_META \| REQ_PRIO, bh);
		}
		if (ret)
		errors++;

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