Commit 9f0bbd8ca7905fcc0602c038013b095322fec939
1 parent
41b93bc1ee
Exists in
master
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logfs: query block device for number of pages to send with bio
The block device driver puts a limit on maximum number of pages that
can be sent with the bio. Not all block devices can handle
BIO_MAX_PAGES number of pages in bio. Specifically the virtio-blk
diriver limits it to 126. When the LogFS file system was excersized in
KVM, the following bug from do_virtblk_request() was observed
static void do_virtblk_request(struct request_queue *q)
{
....
....
while ((req = blk_peek_request(q)) != NULL) {
BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
....
....
}
....
}
The patch fixes the problem by querring the maximum number of pages in
bio allowed from block device driver and then using those many pages
during submit_bio.
Signed-off-by: Prasad Joshi <prasadjoshi.linux@gmail.com>
Showing 1 changed file with 6 additions and 8 deletions Side-by-side Diff
fs/logfs/dev_bdev.c
| ... | ... | @@ -96,12 +96,11 @@ |
| 96 | 96 | struct address_space *mapping = super->s_mapping_inode->i_mapping; |
| 97 | 97 | struct bio *bio; |
| 98 | 98 | struct page *page; |
| 99 | - struct request_queue *q = bdev_get_queue(sb->s_bdev); | |
| 100 | - unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9); | |
| 99 | + unsigned int max_pages; | |
| 101 | 100 | int i; |
| 102 | 101 | |
| 103 | - if (max_pages > BIO_MAX_PAGES) | |
| 104 | - max_pages = BIO_MAX_PAGES; | |
| 102 | + max_pages = min(nr_pages, (size_t) bio_get_nr_vecs(super->s_bdev)); | |
| 103 | + | |
| 105 | 104 | bio = bio_alloc(GFP_NOFS, max_pages); |
| 106 | 105 | BUG_ON(!bio); |
| 107 | 106 | |
| 108 | 107 | |
| ... | ... | @@ -191,12 +190,11 @@ |
| 191 | 190 | { |
| 192 | 191 | struct logfs_super *super = logfs_super(sb); |
| 193 | 192 | struct bio *bio; |
| 194 | - struct request_queue *q = bdev_get_queue(sb->s_bdev); | |
| 195 | - unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9); | |
| 193 | + unsigned int max_pages; | |
| 196 | 194 | int i; |
| 197 | 195 | |
| 198 | - if (max_pages > BIO_MAX_PAGES) | |
| 199 | - max_pages = BIO_MAX_PAGES; | |
| 196 | + max_pages = min(nr_pages, (size_t) bio_get_nr_vecs(super->s_bdev)); | |
| 197 | + | |
| 200 | 198 | bio = bio_alloc(GFP_NOFS, max_pages); |
| 201 | 199 | BUG_ON(!bio); |
| 202 | 200 |