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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>
This commit is contained in:
Benny Halevy 2009-04-01 09:22:14 -04:00
parent ce5039c1be
commit 510b81756f
1 changed files with 33 additions and 0 deletions
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33
fs/nfs/nfs4proc.c
View File

@ -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,