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yaml
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r: 58515
b: refs/heads/master
c: c0613c1
h: refs/heads/master
i:
  58513: 57eb6a2
  58511: b5fee78
v: v3
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Geert Uytterhoeven authored and Jens Axboe committed Jul 10, 2007
1 parent fea691d commit b897f31
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2 changes: 1 addition & 1 deletion [refs]
Original file line number Diff line number Diff line change
@@ -1,2 +1,2 @@
---
refs/heads/master: 70cee26e020c1d74ff559c991b96c7b19fa4173b
refs/heads/master: c0613c1c940dac991b9e54db75dc9976491d9f0a
16 changes: 3 additions & 13 deletions trunk/Documentation/block/barrier.txt
Original file line number Diff line number Diff line change
Expand Up @@ -82,33 +82,23 @@ including draining and flushing.
typedef void (prepare_flush_fn)(request_queue_t *q, struct request *rq);

int blk_queue_ordered(request_queue_t *q, unsigned ordered,
prepare_flush_fn *prepare_flush_fn,
unsigned gfp_mask);

int blk_queue_ordered_locked(request_queue_t *q, unsigned ordered,
prepare_flush_fn *prepare_flush_fn,
unsigned gfp_mask);

The only difference between the two functions is whether or not the
caller is holding q->queue_lock on entry. The latter expects the
caller is holding the lock.
prepare_flush_fn *prepare_flush_fn);

@q : the queue in question
@ordered : the ordered mode the driver/device supports
@prepare_flush_fn : this function should prepare @rq such that it
flushes cache to physical medium when executed
@gfp_mask : gfp_mask used when allocating data structures
for ordered processing

For example, SCSI disk driver's prepare_flush_fn looks like the
following.

static void sd_prepare_flush(request_queue_t *q, struct request *rq)
{
memset(rq->cmd, 0, sizeof(rq->cmd));
rq->flags |= REQ_BLOCK_PC;
rq->cmd_type = REQ_TYPE_BLOCK_PC;
rq->timeout = SD_TIMEOUT;
rq->cmd[0] = SYNCHRONIZE_CACHE;
rq->cmd_len = 10;
}

The following seven ordered modes are supported. The following table
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