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-rw-r--r--fs/nfs/nfs4proc.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index c9618080317..b6308f6740e 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -274,6 +274,42 @@ static void renew_lease(const struct nfs_server *server, unsigned long timestamp
#if defined(CONFIG_NFS_V4_1)
/*
+ * nfs4_free_slot - free a slot and efficiently update slot table.
+ *
+ * freeing a slot is trivially done by clearing its respective bit
+ * in the bitmap.
+ * If the freed slotid equals highest_used_slotid we want to update it
+ * so that the server would be able to size down the slot table if needed,
+ * otherwise we know that the highest_used_slotid is still in use.
+ * When updating highest_used_slotid there may be "holes" in the bitmap
+ * so we need to scan down from highest_used_slotid to 0 looking for the now
+ * highest slotid in use.
+ * If none found, highest_used_slotid is set to -1.
+ */
+static void
+nfs4_free_slot(struct nfs4_slot_table *tbl, u8 free_slotid)
+{
+ int slotid = free_slotid;
+
+ spin_lock(&tbl->slot_tbl_lock);
+ /* clear used bit in bitmap */
+ __clear_bit(slotid, tbl->used_slots);
+
+ /* update highest_used_slotid when it is freed */
+ if (slotid == tbl->highest_used_slotid) {
+ slotid = find_last_bit(tbl->used_slots, tbl->max_slots);
+ if (slotid >= 0 && slotid < tbl->max_slots)
+ tbl->highest_used_slotid = slotid;
+ else
+ tbl->highest_used_slotid = -1;
+ }
+ rpc_wake_up_next(&tbl->slot_tbl_waitq);
+ spin_unlock(&tbl->slot_tbl_lock);
+ dprintk("%s: free_slotid %u highest_used_slotid %d\n", __func__,
+ free_slotid, tbl->highest_used_slotid);
+}
+
+/*
* nfs4_find_slot - efficiently look for a free slot
*
* nfs4_find_slot looks for an unset bit in the used_slots bitmap.