On Fri, Jun 23, 2017 at 05:34:05AM -0500, Bill O'Donnell wrote:
> xfs_db doesn't take sector size into account when setting type.
> This can result in an errant crc. For example, with a sector size
> of 4096:
>
> xfs_db> agi 0
> xfs_db> p crc
> crc = 0xab85043e (correct)
> xfs_db> daddr
> current daddr is 16
> xfs_db> daddr 42
> xfs_db> daddr 16
> xfs_db> type agi
> Metadata CRC error detected at xfs_agi block 0x10/0x200
> xfs_db> p crc
> crc = 0xab85043e (bad)
>
> When xfs_db sets the new daddr in daddr_f, it does so with one
> BBSIZE sector (512). Changing the type doesn't change the size
> of the current buffer in iocur_top, so the checksum is calculated
> on the wrong length for the type (when the actual sector size > BBSIZE (512).
>
> For types with fields, reread the buffer to pick up the correct size for
> the new type when it gets set. Facilitate the reread by setting the cursor
> with set_cur().
>
> Signed-off-by: Bill O'Donnell <billodo@xxxxxxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
--D
> ---
>
> v2: correction to argument 3 in call to set_cur: compute and pass basic block count;
> add comment regarding conditional call to set_cur.
> v3: include bit.h for byteize function
>
> db/io.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/db/io.c b/db/io.c
> index 9918a51..b97b710 100644
> --- a/db/io.c
> +++ b/db/io.c
> @@ -28,6 +28,7 @@
> #include "init.h"
> #include "malloc.h"
> #include "crc.h"
> +#include "bit.h"
>
> static int pop_f(int argc, char **argv);
> static void pop_help(void);
> @@ -615,7 +616,13 @@ set_iocur_type(
> const typ_t *t)
> {
> struct xfs_buf *bp = iocur_top->bp;
> + int bb_count;
>
> + /* adjust cursor for types that contain fields */
> + if (t->fields) {
> + bb_count = BTOBB(byteize(fsize(t->fields, iocur_top->data, 0, 0)));
> + set_cur(t, iocur_top->bb, bb_count, DB_RING_IGN, NULL);
> + }
> iocur_top->typ = t;
>
> /* verify the buffer if the type has one. */
> --
> 2.9.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
