diff options
| author | Benny Halevy <bhalevy@panasas.com> | 2009-04-01 09:22:14 -0400 |
|---|---|---|
| committer | Benny Halevy <bhalevy@panasas.com> | 2009-06-17 10:46:37 -0700 |
| commit | 510b81756f18922a4c5b555e8145f4fed5beb569 (patch) | |
| tree | 9253ad2063b37292b3cf8c7425cbf6882807882a /fs/nfs | |
| parent | ce5039c1be1fd04c2d9b1af80d41a6d003f2e20c (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>
Diffstat (limited to 'fs/nfs')
| -rw-r--r-- | fs/nfs/nfs4proc.c | 33 |
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, |