From 8530c37a70df71ea8a04fbafabba0b92f4475c6c Mon Sep 17 00:00:00 2001 From: David Sterba Date: Fri, 30 Aug 2019 15:42:07 +0200 Subject: [PATCH] btrfs: get bdev from latest_dev for dio bh_result To remove use of extent_map::bdev we need to find a replacement, and the latest_bdev is the only one we can use here, because inode::i_bdev and superblock::s_bdev are NULL. The DIO code uses bdev in two places: * to read blocksize to perform alignment checks in do_blockdev_direct_IO, but we do them in btrfs code before any call to DIO * in the following call chain: do_direct_IO get_more_blocks sdio->get_block() <-- this is btrfs_get_blocks_direct subsequently the map_bh->b_dev member is used in clean_bdev_aliases and dio_new_bio to set the bio's bdev to that of the buffer_head. However, because we have provided a submit function dio_bio_submit calls our submission function and ignores the bdev. So it's safe to pass any valid bdev that's used within the filesystem. Reviewed-by: Nikolay Borisov Signed-off-by: David Sterba --- fs/btrfs/inode.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index b943c9770533..5edc6a27ea4a 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -7662,6 +7662,8 @@ static int btrfs_get_blocks_direct_read(struct extent_map *em, struct inode *inode, u64 start, u64 len) { + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); + if (em->block_start == EXTENT_MAP_HOLE || test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) return -ENOENT; @@ -7671,7 +7673,7 @@ static int btrfs_get_blocks_direct_read(struct extent_map *em, bh_result->b_blocknr = (em->block_start + (start - em->start)) >> inode->i_blkbits; bh_result->b_size = len; - bh_result->b_bdev = em->bdev; + bh_result->b_bdev = fs_info->fs_devices->latest_bdev; set_buffer_mapped(bh_result); return 0; @@ -7754,7 +7756,7 @@ skip_cow: bh_result->b_blocknr = (em->block_start + (start - em->start)) >> inode->i_blkbits; bh_result->b_size = len; - bh_result->b_bdev = em->bdev; + bh_result->b_bdev = fs_info->fs_devices->latest_bdev; set_buffer_mapped(bh_result); if (!test_bit(EXTENT_FLAG_PREALLOC, &em->flags))