blk_bio_segment

函数名称：lk_bio_segment_split - split a bio in two bios*@q: [in] request queue pointer*@bio: [in] bio to be split*@bs: [in] bio set to allocate the clone from*@segs: [out] number of segments in the bio with the first half of the sectors* Clone @bio, update the

函数原型：static struct bio *blk_bio_segment_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, unsigned *segs)

返回类型：struct bio

参数：

类型	参数	名称
struct request_queue *	q
struct bio *	bio
struct bio_set *	bs
unsigned *	segs

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struct bio_vec bv, bvprv, * bvprvp = NULL

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nsegs等于0, sectors等于0

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max_sectors等于Return the maximum number of sectors from the start of a bio that may be* submitted as a single request to a block device. If enough sectors remain,* align the end to the physical block size. Otherwise align the end to the* logical block size

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max_segs等于queue_max_segments(q)

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rate over multi-page bvec (bv, bio, iter)

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如果bvprvp且Check if adding a bio_vec after bprv with offset would create a gap in* the SG list. Most drivers don't care about this, but some do.则转到:split

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如果nsegs小于max_segs且sectors加bv_len右移9位的值小于等于max_sectors且bv_offset加bv_len小于等于PAGE_SIZE则

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nsegs自加

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sectors加等于bv_len右移9位

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否则如果vec_split_segs - verify whether or not a bvec should be split in the middle*@q: [in] request queue associated with the bio associated with @bv*@bv: [in] bvec to examine*@nsegs: [in,out] Number of segments in the bio being built则

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转到:split

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bvprv等于bv

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bvprvp等于bvprv

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segs等于nsegs

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返回:NULL

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split :

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segs等于nsegs

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返回:_split - split a bio*@bio: bio to split*@sectors: number of sectors to split from the front of @bio*@gfp: gfp mask*@bs: bio set to allocate from* Allocates and returns a new bio which represents @sectors from the start of

**调用者**
名称	描述
__blk_queue_split	__blk_queue_split - split a bio and submit the second half@q: [in] request queue pointer@bio: [in, out] bio to be split@nr_segs: [out] number of segments in the first bio Split a bio into two bios, chain the two bios, submit the second half and

源代码转换工具开放的插件接口	X
支持：c/c++/esqlc/java Oracle/Informix/Mysql 插件可实现：逻辑报告代码生成和批量转换代码

函数逻辑报告