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Commit 4f2e9dce authored by Jeff Layton's avatar Jeff Layton Committed by Trond Myklebust
Browse files

nfs4: resend LAYOUTGET when there is a race that changes the seqid 



pnfs_layout_process will check the returned layout stateid against what
the kernel has in-core. If it turns out that the stateid we received is
older, then we should resend the LAYOUTGET instead of falling back to
MDS I/O.

Signed-off-by: default avatarJeff Layton <jeff.layton@primarydata.com>
Cc: stable@vger.kernel.org # 3.18+
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent c812012f

fs/nfs/pnfs.c

+31 −25
Original line number Diff line number Diff line
@@ -872,6 +872,12 @@ send_layoutget(struct pnfs_layout_hdr *lo, 


	dprintk("--> %s\n", __func__);



	/*

	 * Synchronously retrieve layout information from server and

	 * store in lseg. If we race with a concurrent seqid morphing

	 * op, then re-send the LAYOUTGET.

	 */

	do {

		lgp = kzalloc(sizeof(*lgp), gfp_flags);

		if (lgp == NULL)

			return NULL;
@@ -895,10 +901,9 @@ send_layoutget(struct pnfs_layout_hdr *lo, 
		lgp->gfp_flags = gfp_flags;

		lgp->cred = lo->plh_lc_cred;



	/* Synchronously retrieve layout information from server and

	 * store in lseg.

	 */

		lseg = nfs4_proc_layoutget(lgp, gfp_flags);

	} while (lseg == ERR_PTR(-EAGAIN));



	if (IS_ERR(lseg)) {

		switch (PTR_ERR(lseg)) {

		case -ENOMEM:
@@ -1687,6 +1692,7 @@ pnfs_layout_process(struct nfs4_layoutget *lgp) 
		/* existing state ID, make sure the sequence number matches. */

		if (pnfs_layout_stateid_blocked(lo, &res->stateid)) {

			dprintk("%s forget reply due to sequence\n", __func__);

			status = -EAGAIN;

			goto out_forget_reply;

		}

		pnfs_set_layout_stateid(lo, &res->stateid, false);