__blkdev_issue_discard

Name:__blkdev_issue_discard

Proto:int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, sector_t nr_sects, gfp_t gfp_mask, int flags, struct bio **biop)

Type:int

Parameter:

Type	Parameter	Name
struct block_device *	bdev
sector_t	sector
sector_t	nr_sects
gfp_t	gfp_mask
int	flags
struct bio **	biop

29

q = bdev_get_queue(bdev)

30

bio = biop

34

If Not q Then Return -ENXIO

37

If bdev_read_only(bdev) Then Return -EPERM

40

If flags & ssue a secure erase Then

41

If Not blk_queue_secure_erase(q) Then Return -EOPNOTSUPP

43

op = REQ_OP_SECURE_ERASE

44

Else

45

If Not blk_queue_discard(q) Then Return -EOPNOTSUPP

47

op = REQ_OP_DISCARD

50

bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1

51

If (sector | nr_sects) & bs_mask Then Return -EINVAL

54

If Not nr_sects Then Return -EINVAL

57

When nr_sects cycle

58

req_sects = min_t - return minimum of two values, using the specified type*@type: data type to use*@x: first value*@y: second value(sector_t, nr_sects, The max size one bio can handle is UINT_MAX becasue bvec_iter.bi_size* is defined as 'unsigned int', meantime it has to aligned to with logical* block size which is the minimum accepted unit by hardware.)

61

WARN_ON_ONCE((req_sects << 9) > UINT_MAX)

63

bio = blk_next_bio(bio, 0, gfp_mask)

64

device address in 512 byte sectors = sector

65

bio_set_dev(bio, bdev)

66

bsolete, don't use in new code

68

residual I/O count = req_sects << 9

69

sector += req_sects

70

nr_sects -= req_sects

78

81

biop = bio

82

Return 0

**Caller**
Name	Describe
blkdev_issue_discard	lkdev_issue_discard - queue a discard@bdev: blockdev to issue discard for@sector: start sector@nr_sects: number of sectors to discard@gfp_mask: memory allocation flags (for bio_alloc)@flags: BLKDEV_DISCARD_ flags to control behaviour* Description:

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