nfs41: find slot (510b8175) · Commits · 戴 / test

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>

fs/nfs/nfs4proc.c

+33 −0

Original line number	Diff line number	Diff line
		@@ -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,

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