Dmitry Monakhov | f31e7e4 | 2010-04-28 17:55:08 +0400 | [diff] [blame^] | 1 | /* |
| 2 | * Functions related to generic helpers functions |
| 3 | */ |
| 4 | #include <linux/kernel.h> |
| 5 | #include <linux/module.h> |
| 6 | #include <linux/bio.h> |
| 7 | #include <linux/blkdev.h> |
| 8 | #include <linux/scatterlist.h> |
| 9 | |
| 10 | #include "blk.h" |
| 11 | |
| 12 | static void blkdev_discard_end_io(struct bio *bio, int err) |
| 13 | { |
| 14 | if (err) { |
| 15 | if (err == -EOPNOTSUPP) |
| 16 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); |
| 17 | clear_bit(BIO_UPTODATE, &bio->bi_flags); |
| 18 | } |
| 19 | |
| 20 | if (bio->bi_private) |
| 21 | complete(bio->bi_private); |
| 22 | __free_page(bio_page(bio)); |
| 23 | |
| 24 | bio_put(bio); |
| 25 | } |
| 26 | |
| 27 | /** |
| 28 | * blkdev_issue_discard - queue a discard |
| 29 | * @bdev: blockdev to issue discard for |
| 30 | * @sector: start sector |
| 31 | * @nr_sects: number of sectors to discard |
| 32 | * @gfp_mask: memory allocation flags (for bio_alloc) |
| 33 | * @flags: BLKDEV_IFL_* flags to control behaviour |
| 34 | * |
| 35 | * Description: |
| 36 | * Issue a discard request for the sectors in question. |
| 37 | */ |
| 38 | int blkdev_issue_discard(struct block_device *bdev, sector_t sector, |
| 39 | sector_t nr_sects, gfp_t gfp_mask, unsigned long flags) |
| 40 | { |
| 41 | DECLARE_COMPLETION_ONSTACK(wait); |
| 42 | struct request_queue *q = bdev_get_queue(bdev); |
| 43 | int type = flags & BLKDEV_IFL_BARRIER ? |
| 44 | DISCARD_BARRIER : DISCARD_NOBARRIER; |
| 45 | struct bio *bio; |
| 46 | struct page *page; |
| 47 | int ret = 0; |
| 48 | |
| 49 | if (!q) |
| 50 | return -ENXIO; |
| 51 | |
| 52 | if (!blk_queue_discard(q)) |
| 53 | return -EOPNOTSUPP; |
| 54 | |
| 55 | while (nr_sects && !ret) { |
| 56 | unsigned int sector_size = q->limits.logical_block_size; |
| 57 | unsigned int max_discard_sectors = |
| 58 | min(q->limits.max_discard_sectors, UINT_MAX >> 9); |
| 59 | |
| 60 | bio = bio_alloc(gfp_mask, 1); |
| 61 | if (!bio) |
| 62 | goto out; |
| 63 | bio->bi_sector = sector; |
| 64 | bio->bi_end_io = blkdev_discard_end_io; |
| 65 | bio->bi_bdev = bdev; |
| 66 | if (flags & BLKDEV_IFL_WAIT) |
| 67 | bio->bi_private = &wait; |
| 68 | |
| 69 | /* |
| 70 | * Add a zeroed one-sector payload as that's what |
| 71 | * our current implementations need. If we'll ever need |
| 72 | * more the interface will need revisiting. |
| 73 | */ |
| 74 | page = alloc_page(gfp_mask | __GFP_ZERO); |
| 75 | if (!page) |
| 76 | goto out_free_bio; |
| 77 | if (bio_add_pc_page(q, bio, page, sector_size, 0) < sector_size) |
| 78 | goto out_free_page; |
| 79 | |
| 80 | /* |
| 81 | * And override the bio size - the way discard works we |
| 82 | * touch many more blocks on disk than the actual payload |
| 83 | * length. |
| 84 | */ |
| 85 | if (nr_sects > max_discard_sectors) { |
| 86 | bio->bi_size = max_discard_sectors << 9; |
| 87 | nr_sects -= max_discard_sectors; |
| 88 | sector += max_discard_sectors; |
| 89 | } else { |
| 90 | bio->bi_size = nr_sects << 9; |
| 91 | nr_sects = 0; |
| 92 | } |
| 93 | |
| 94 | bio_get(bio); |
| 95 | submit_bio(type, bio); |
| 96 | |
| 97 | if (flags & BLKDEV_IFL_WAIT) |
| 98 | wait_for_completion(&wait); |
| 99 | |
| 100 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) |
| 101 | ret = -EOPNOTSUPP; |
| 102 | else if (!bio_flagged(bio, BIO_UPTODATE)) |
| 103 | ret = -EIO; |
| 104 | bio_put(bio); |
| 105 | } |
| 106 | return ret; |
| 107 | out_free_page: |
| 108 | __free_page(page); |
| 109 | out_free_bio: |
| 110 | bio_put(bio); |
| 111 | out: |
| 112 | return -ENOMEM; |
| 113 | } |
| 114 | EXPORT_SYMBOL(blkdev_issue_discard); |