Commit 22aaf714 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFSv4.1: Ensure that the layout sequence id stays 'close' to the current 



Clamp the layout barrier sequence id to the current sequence id
minus the maximum number of outstanding layoutget requests.

Also ensure that we correctly initialise lo->plh_barrier if there are
no layout segments associated to this layout header.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 0f35ad6f

fs/nfs/pnfs.c

+8 −13
Original line number Diff line number Diff line
@@ -563,28 +563,23 @@ void 
pnfs_set_layout_stateid(struct pnfs_layout_hdr *lo, const nfs4_stateid *new,

			bool update_barrier)

{

	u32 oldseq, newseq;

	u32 oldseq, newseq, new_barrier;

	int empty = list_empty(&lo->plh_segs);



	oldseq = be32_to_cpu(lo->plh_stateid.seqid);

	newseq = be32_to_cpu(new->seqid);

	if (list_empty(&lo->plh_segs) || pnfs_seqid_is_newer(newseq, oldseq)) {

	if (empty || pnfs_seqid_is_newer(newseq, oldseq)) {

		nfs4_stateid_copy(&lo->plh_stateid, new);

		if (update_barrier) {

			u32 new_barrier = be32_to_cpu(new->seqid);



			if (pnfs_seqid_is_newer(new_barrier, lo->plh_barrier))

				lo->plh_barrier = new_barrier;

			new_barrier = be32_to_cpu(new->seqid);

		} else {

			/* Because of wraparound, we want to keep the barrier

			 * "close" to the current seqids.  It needs to be

			 * within 2**31 to count as "behind", so if it

			 * gets too near that limit, give us a litle leeway

			 * and bring it to within 2**30.

			 * NOTE - and yes, this is all unsigned arithmetic.

			 * "close" to the current seqids.

			 */

			if (unlikely((newseq - lo->plh_barrier) > (3 << 29)))

				lo->plh_barrier = newseq - (1 << 30);

			new_barrier = newseq - atomic_read(&lo->plh_outstanding);

		}

		if (empty || pnfs_seqid_is_newer(new_barrier, lo->plh_barrier))

			lo->plh_barrier = new_barrier;

	}

}