Re: [PATCH] xfs_db: take BB cluster offset into account when using 'type' cmd

["Darrick J. Wong" <djwong@kernel.org>]

On Tue, Apr 19, 2022 at 02:19:51PM +0200, Andrey Albershteyn wrote:
> Changing the interpretation type of data under the cursor moves the
> cursor to the beginning of BB cluster. When cursor is set to an
> inode the cursor is offset in BB buffer. However, this offset is not
> considered when type of the data is changed - the cursor points to
> the beginning of BB buffer. For example:
> 
> $ xfs_db -c "inode 131" -c "daddr" -c "type text" \
> 	-c "daddr" /dev/sdb1
> current daddr is 131
> current daddr is 128
> 
> Signed-off-by: Andrey Albershteyn <aalbersh@redhat.com>
> ---
>  db/io.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/db/io.c b/db/io.c
> index df97ed91..107f2e11 100644
> --- a/db/io.c
> +++ b/db/io.c
> @@ -589,6 +589,7 @@ set_iocur_type(
>  	const typ_t	*type)
>  {
>  	int		bb_count = 1;	/* type's size in basic blocks */
> +	int boff = iocur_top->boff;

Nit: Please line up the variable names.

>  
>  	/*
>  	 * Inodes are special; verifier checks all inodes in the chunk, the
> @@ -613,6 +614,9 @@ set_iocur_type(
>  		bb_count = BTOBB(byteize(fsize(type->fields,
>  				       iocur_top->data, 0, 0)));
>  	set_cur(type, iocur_top->bb, bb_count, DB_RING_IGN, NULL);
> +	iocur_top->boff = boff;
> +	iocur_top->off = ((xfs_off_t)iocur_top->bb << BBSHIFT) + boff;
> +	iocur_top->data = (void *)((char *)iocur_top->buf + boff);

It seems reasonable to me to preserve the io cursor's boff when we're
setting /only/ the buffer type, but this function and off_cur() could
share these three lines of code that (re)set boff/off/data.

Alternately, I guess you could just call off_cur(boff, BBTOB(bb_count))
here.

--D

>  }
>  
>  static void
> -- 
> 2.27.0
>