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authorBenny Halevy <bhalevy@panasas.com>2009-04-01 09:22:14 -0400
committerBenny Halevy <bhalevy@panasas.com>2009-06-17 10:46:37 -0700
commit510b81756f18922a4c5b555e8145f4fed5beb569 (patch)
tree9253ad2063b37292b3cf8c7425cbf6882807882a
parentce5039c1be1fd04c2d9b1af80d41a6d003f2e20c (diff)
nfs41: find slot
Find a free slot using bitmap-based allocation. Use the optimized ffz function to find a zero bit in the bitmap that indicates a free slot, starting the search from the 'lowest_free_slotid' position. If found, mark the slot as used in the bitmap, get the slot's slotid and seqid, and update max_slotid to be used by the SEQUENCE operation. Also, update lowest_free_slotid for next search. If no free slot was found the caller has to wait for a free slot (outside the scope of this function) Signed-off-by: Benny Halevy <bhalevy@panasas.com> [nfs41: find slot return slotid] Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> [use find_first_zero_bit for nfs4_find_slot as per review comment 21/85.] [use NFS4_MAX_SLOT_TABLE rather than NFS4_NO_SLOT] [nfs41: rpc_sleep_on slot_tbl_waitq must be called under slot_tbl_lock] Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
-rw-r--r--fs/nfs/nfs4proc.c33
1 files changed, 33 insertions, 0 deletions
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 90aed76e593..a0946a0d116 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -273,6 +273,39 @@ static void renew_lease(const struct nfs_server *server, unsigned long timestamp
#if defined(CONFIG_NFS_V4_1)
+/*
+ * nfs4_find_slot - efficiently look for a free slot
+ *
+ * nfs4_find_slot looks for an unset bit in the used_slots bitmap.
+ * If found, we mark the slot as used, update the highest_used_slotid,
+ * and respectively set up the sequence operation args.
+ * The slot number is returned if found, or NFS4_MAX_SLOT_TABLE otherwise.
+ */
+static u8
+nfs4_find_slot(struct nfs4_slot_table *tbl, struct rpc_task *task)
+{
+ int slotid;
+ u8 ret_id = NFS4_MAX_SLOT_TABLE;
+ BUILD_BUG_ON((u8)NFS4_MAX_SLOT_TABLE != (int)NFS4_MAX_SLOT_TABLE);
+
+ spin_lock(&tbl->slot_tbl_lock);
+ dprintk("--> %s used_slots=%04lx highest_used=%d max_slots=%d\n",
+ __func__, tbl->used_slots[0], tbl->highest_used_slotid,
+ tbl->max_slots);
+ slotid = find_first_zero_bit(tbl->used_slots, tbl->max_slots);
+ if (slotid >= tbl->max_slots)
+ goto out;
+ __set_bit(slotid, tbl->used_slots);
+ if (slotid > tbl->highest_used_slotid)
+ tbl->highest_used_slotid = slotid;
+ ret_id = slotid;
+out:
+ dprintk("<-- %s used_slots=%04lx highest_used=%d slotid=%d \n",
+ __func__, tbl->used_slots[0], tbl->highest_used_slotid, ret_id);
+ spin_unlock(&tbl->slot_tbl_lock);
+ return ret_id;
+}
+
static int nfs41_setup_sequence(struct nfs4_session *session,
struct nfs4_sequence_args *args,
struct nfs4_sequence_res *res,