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authorTrond Myklebust <Trond.Myklebust@netapp.com>2012-10-04 16:32:22 -0700
committerTrond Myklebust <Trond.Myklebust@netapp.com>2012-10-04 16:57:48 -0700
commit22aaf71495570b31350c37fd0aa736551bbaa3c9 (patch)
tree513b8cb36005322aa2c418e3e0519aefe597cda5 /fs/nfs
parent0f35ad6f688e9b7bcaa918a42130695822906f11 (diff)
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: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'fs/nfs')
-rw-r--r--fs/nfs/pnfs.c21
1 files changed, 8 insertions, 13 deletions
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 42613bd19f8e..861dd97b569e 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -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;
}
}