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@xxxxxxxxxxx>
[nfs41: find slot return slotid]
Signed-off-by: Andy Adamson <andros@xxxxxxxxxx>
Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
[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@xxxxxxxxxxx>
---
fs/nfs/nfs4proc.c | 37 +++++++++++++++++++++++++++++++++++++
1 files changed, 37 insertions(+), 0 deletions(-)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index c12cf91..9bc6bb7 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -279,6 +279,43 @@ static void renew_lease(const struct nfs_server *server, unsigned long timestamp
spin_unlock(&clp->cl_lock);
}
+#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;
+}
+
+#endif /* CONFIG_NFS_V4_1 */
+
static void update_changeattr(struct inode *dir, struct nfs4_change_info *cinfo)
{
struct nfs_inode *nfsi = NFS_I(dir);
--
1.6.1.3
--
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