On Fri, Feb 14, 2020 at 12:24:33AM +0900, Johannes Thumshirn wrote:
> + bio = bio_alloc(GFP_NOFS, 1);
> + bio_set_dev(bio, device->bdev);
> + bio->bi_iter.bi_sector = bytenr >> SECTOR_SHIFT;
> + bio->bi_private = device;
> + bio->bi_end_io = btrfs_end_super_write;
> + __bio_add_page(bio, page, BTRFS_SUPER_INFO_SIZE,
> + offset_in_page(bytenr));
>
> /*
> - * we fua the first super. The others we allow
> + * We fua the first super. The others we allow
> * to go down lazy.
> */
> - op_flags = REQ_SYNC | REQ_META | REQ_PRIO;
> + bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_META | REQ_PRIO;
> if (i == 0 && !btrfs_test_opt(device->fs_info, NOBARRIER))
> - op_flags |= REQ_FUA;
> - ret = btrfsic_submit_bh(REQ_OP_WRITE, op_flags, bh);
> - if (ret)
> - errors++;
> + bio->bi_opf |= REQ_FUA;
> +
> + btrfsic_submit_bio(bio);
btrfsic_submit_bh forwards the return values, and could increase error
counter, now btrfsic_submit_bio does not forward submit_bio return
value.
I traced it to generic_make_request, the comment says it does not return
error, so not handling it is ok.
> static int wait_dev_supers(struct btrfs_device *device, int max_mirrors)
> for (i = 0; i < max_mirrors; i++) {
> + struct page *page;
> +
> bytenr = btrfs_sb_offset(i);
> if (bytenr + BTRFS_SUPER_INFO_SIZE >=
> device->commit_total_bytes)
> break;
>
> - bh = __find_get_block(device->bdev,
> - bytenr / BTRFS_BDEV_BLOCKSIZE,
> - BTRFS_SUPER_INFO_SIZE);
> - if (!bh) {
> + page = find_get_page(device->bdev->bd_inode->i_mapping,
> + bytenr >> PAGE_SHIFT);
> + if (!page) {
> errors++;
> if (i == 0)
> primary_failed = true;
> continue;
> }
> - wait_on_buffer(bh);
> - if (!buffer_uptodate(bh)) {
> + wait_on_page_locked(page);
And here it's checking the result that could be set by
btrfs_end_super_write (SetPageError). The waiting part is due to the
PG_Locked bit. Please add some comments.
> + if (PageError(page)) {
> errors++;
> if (i == 0)
> primary_failed = true;
> }
>
> /* drop our reference */
> - brelse(bh);
> + put_page(page);
>
> /* drop the reference from the writing run */
> - brelse(bh);
> + put_page(page);
> }
>
> /* log error, force error return */
> --
> 2.24.1
