Re: [PATCH v3.1 1/3] btrfs-progs: factor out super_block reading from load_and_dump_sb

[Johannes Thumshirn <jthumshirn@suse.de>]

On Tue, May 14, 2019 at 03:58:04PM +0200, Johannes Thumshirn wrote:
> inspect-internal dump-superblock's load_and_dump_sb() already reads a
> super block from a file descriptor and places it into a 'struct
> btrfs_super_block'.
> 
> For inspect-internal dump-csum we need this super block as well but don't
> care about printing it.
> 
> Separate the read from the dump phase so we can re-use it elsewhere.
> 
> Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
> ---
> - Fix double sizeof() @!$#$ (Nikolay)
> 
>  cmds-inspect-dump-super.c | 15 ++++++---------
>  utils.c                   | 15 +++++++++++++++
>  utils.h                   |  2 ++
>  3 files changed, 23 insertions(+), 9 deletions(-)
> 
> diff --git a/cmds-inspect-dump-super.c b/cmds-inspect-dump-super.c
> index 7815c863f2ed..879f979f526a 100644
> --- a/cmds-inspect-dump-super.c
> +++ b/cmds-inspect-dump-super.c
> @@ -477,16 +477,13 @@ static void dump_superblock(struct btrfs_super_block *sb, int full)
>  static int load_and_dump_sb(char *filename, int fd, u64 sb_bytenr, int full,
>  		int force)
>  {
> -	u8 super_block_data[BTRFS_SUPER_INFO_SIZE];
> -	struct btrfs_super_block *sb;
> +	struct btrfs_super_block sb;
>  	u64 ret;
>  
> -	sb = (struct btrfs_super_block *)super_block_data;
> -
> -	ret = pread64(fd, super_block_data, BTRFS_SUPER_INFO_SIZE, sb_bytenr);
> -	if (ret != BTRFS_SUPER_INFO_SIZE) {
> +	ret = load_sb(fd, sb_bytenr, &sb);
> +	if (ret) {

This is buggy. We need to copy the whole BTRFS_SUPER_INFO_SIZE and calculate
the checksums over this area.

Sorry,
	Johannes
-- 
Johannes Thumshirn                            SUSE Labs Filesystems
jthumshirn@suse.de                                +49 911 74053 689
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