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NFSv4.1: Deal with wraparound issues when updating the layout stateid 

...and add a helper function.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2012-10-02 16:47:14 -07:00
parent 038d649376
commit 5a65503f3d
1 changed files with 10 additions and 1 deletions
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11
fs/nfs/pnfs.c
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@ -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);