Right now, when we set the stateid, we blindly overwrite the current
one, allowing the seqid to incorrectly roll backward.
Signed-off-by: Fred Isaman <iisaman@xxxxxxxxxx>
---
fs/nfs/pnfs.c | 38 ++++++++++++++++++++++++++++++++------
1 files changed, 32 insertions(+), 6 deletions(-)
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 39bce9b..555955b 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -459,16 +459,42 @@ pnfs_destroy_all_layouts(struct nfs_client *clp)
}
}
+/* update lo->stateid with new if is more recent
+ *
+ * lo->stateid could be the open stateid, in which case we just use what given.
+ */
static void
pnfs_set_layout_stateid(struct pnfs_layout_hdr *lo,
- const nfs4_stateid *stateid)
+ const nfs4_stateid *new)
{
- /* TODO - should enforce that embedded seqid, in the case
- * that the two stateid.others are equal, only increases.
- * Complicated by wrap-around.
- */
+ nfs4_stateid *old = &lo->stateid;
+ bool overwrite = false;
+
write_seqlock(&lo->seqlock);
- memcpy(lo->stateid.data, stateid->data, sizeof(lo->stateid.data));
+ if (!test_bit(NFS_LAYOUT_STATEID_SET, &lo->state) ||
+ memcmp(old->stateid.other, new->stateid.other, sizeof(new->stateid.other)))
+ overwrite = true;
+ else {
+ u32 oldseq, newseq, limit;
+
+ oldseq = be32_to_cpu(old->stateid.seqid);
+ newseq = be32_to_cpu(new->stateid.seqid);
+ /* There are no good bounds on window size, so just
+ * use a ridiculously large window of 2^31.
+ */
+ limit = oldseq + (1 << 31);
+ if (oldseq < limit) {
+ /* The easy, non-wraparound case */
+ if (oldseq < newseq && newseq < limit)
+ overwrite = true;
+ } else {
+ /* Near wraparound edge */
+ if (oldseq < newseq || newseq < limit)
+ overwrite = true;
+ }
+ }
+ if (overwrite)
+ memcpy(&old->stateid, &new->stateid, sizeof(new->stateid));
write_sequnlock(&lo->seqlock);
}
--
1.7.2.1
--
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