req_attempt_discard_merge

Name:req_attempt_discard_merge

Proto:static bool req_attempt_discard_merge(struct request_queue *q, struct request *req, struct request *next)

Type:bool

Parameter:

Type	Parameter	Name
struct request_queue *	q
struct request *	req
struct request *	next

627

segments = Number of discard segments (or ranges) the driver needs to fill in.* Each discard bio merged into a request is counted as one segment.

629

If segments >= queue_max_discard_segments(q) Then Go to no_merge

631

If blk_rq_sectors(req) + bio_sectors(bio) > blk_rq_get_max_sectors(req, lk_rq_pos() : the current sector* blk_rq_bytes() : bytes left in the entire request* blk_rq_cur_bytes() : bytes left in the current segment* blk_rq_err_bytes() : bytes left till the next error boundary* blk_rq_sectors() : sectors left in the entire ) Then Go to no_merge

635

* Number of scatter-gather DMA addr+len pairs after * physical address coalescing is performed. = segments + Number of discard segments (or ranges) the driver needs to fill in.* Each discard bio merged into a request is counted as one segment.

636

Return true

637

638

req_set_nomerge(q, req)

639

Return false

**Caller**
Name	Describe
attempt_merge	For non-mq, this has to be called with the request spinlock acquired.* For mq with scheduling, the appropriate queue wide lock should be held.

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