From 5a65503f3dbdb4aa1cd6cb58c479c015d093292b Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Tue, 2 Oct 2012 16:47:14 -0700 Subject: NFSv4.1: Deal with wraparound issues when updating the layout stateid ...and add a helper function. Signed-off-by: Trond Myklebust --- fs/nfs/pnfs.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c index c8c1d0cc197a..f1387e87513f 100644 --- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -549,6 +549,15 @@ pnfs_destroy_all_layouts(struct nfs_client *clp) } } +/* + * Compare 2 layout stateid sequence ids, to see which is newer, + * taking into account wraparound issues. + */ +static bool pnfs_seqid_is_newer(u32 s1, u32 s2) +{ + return (s32)s1 - (s32)s2 > 0; +} + /* update lo->plh_stateid with new if is more recent */ void pnfs_set_layout_stateid(struct pnfs_layout_hdr *lo, const nfs4_stateid *new, @@ -558,7 +567,7 @@ pnfs_set_layout_stateid(struct pnfs_layout_hdr *lo, const nfs4_stateid *new, oldseq = be32_to_cpu(lo->plh_stateid.seqid); newseq = be32_to_cpu(new->seqid); - if (list_empty(&lo->plh_segs) || (int)(newseq - oldseq) > 0) { + if (list_empty(&lo->plh_segs) || pnfs_seqid_is_newer(newseq, oldseq)) { nfs4_stateid_copy(&lo->plh_stateid, new); if (update_barrier) { u32 new_barrier = be32_to_cpu(new->seqid); -- cgit v1.2.3-59-g8ed1b