From 29c36d72535deb3d8961b3fb4b6a565190a6c63b Mon Sep 17 00:00:00 2001 From: Anand Jain Date: Fri, 14 Aug 2015 18:32:58 +0800 Subject: [PATCH] Btrfs: add btrfs_read_dev_one_super() to read one specific SB This uses a chunk of code from btrfs_read_dev_super() and creates a function called btrfs_read_dev_one_super() so that next patch can use it for scratch superblock. Signed-off-by: Anand Jain [renamed bufhead to bh] Signed-off-by: David Sterba --- fs/btrfs/disk-io.c | 53 +++++++++++++++++++++++++++++----------------- fs/btrfs/disk-io.h | 2 ++ 2 files changed, 35 insertions(+), 20 deletions(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 0f8e33f2bcea..c7c739f420b5 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3188,6 +3188,37 @@ static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate) put_bh(bh); } +int btrfs_read_dev_one_super(struct block_device *bdev, int copy_num, + struct buffer_head **bh_ret) +{ + struct buffer_head *bh; + struct btrfs_super_block *super; + u64 bytenr; + + bytenr = btrfs_sb_offset(copy_num); + if (bytenr + BTRFS_SUPER_INFO_SIZE >= i_size_read(bdev->bd_inode)) + return -EINVAL; + + bh = __bread(bdev, bytenr / 4096, BTRFS_SUPER_INFO_SIZE); + /* + * If we fail to read from the underlying devices, as of now + * the best option we have is to mark it EIO. + */ + if (!bh) + return -EIO; + + super = (struct btrfs_super_block *)bh->b_data; + if (btrfs_super_bytenr(super) != bytenr || + btrfs_super_magic(super) != BTRFS_MAGIC) { + brelse(bh); + return -EINVAL; + } + + *bh_ret = bh; + return 0; +} + + struct buffer_head *btrfs_read_dev_super(struct block_device *bdev) { struct buffer_head *bh; @@ -3195,7 +3226,6 @@ struct buffer_head *btrfs_read_dev_super(struct block_device *bdev) struct btrfs_super_block *super; int i; u64 transid = 0; - u64 bytenr; int ret = -EINVAL; /* we would like to check all the supers, but that would make @@ -3204,28 +3234,11 @@ struct buffer_head *btrfs_read_dev_super(struct block_device *bdev) * later supers, using BTRFS_SUPER_MIRROR_MAX instead */ for (i = 0; i < 1; i++) { - bytenr = btrfs_sb_offset(i); - if (bytenr + BTRFS_SUPER_INFO_SIZE >= - i_size_read(bdev->bd_inode)) - break; - bh = __bread(bdev, bytenr / 4096, - BTRFS_SUPER_INFO_SIZE); - /* - * If we fail to read from the underlying devices, as of now - * the best option we have is to mark it EIO. - */ - if (!bh) { - ret = -EIO; + ret = btrfs_read_dev_one_super(bdev, i, &bh); + if (ret) continue; - } super = (struct btrfs_super_block *)bh->b_data; - if (btrfs_super_bytenr(super) != bytenr || - btrfs_super_magic(super) != BTRFS_MAGIC) { - brelse(bh); - ret = -EINVAL; - continue; - } if (!latest || btrfs_super_generation(super) > transid) { brelse(latest); diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h index bdfb479ea859..adeb31830b9c 100644 --- a/fs/btrfs/disk-io.h +++ b/fs/btrfs/disk-io.h @@ -60,6 +60,8 @@ void close_ctree(struct btrfs_root *root); int write_ctree_super(struct btrfs_trans_handle *trans, struct btrfs_root *root, int max_mirrors); struct buffer_head *btrfs_read_dev_super(struct block_device *bdev); +int btrfs_read_dev_one_super(struct block_device *bdev, int copy_num, + struct buffer_head **bh_ret); int btrfs_commit_super(struct btrfs_root *root); struct extent_buffer *btrfs_find_tree_block(struct btrfs_fs_info *fs_info, u64 bytenr); -- 2.20.1