On Wed, Apr 26, 2017 at 01:47:47PM -0500, Eric Sandeen wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> The function block_to_bt plays an integral role in determining the btree
> geometry of a block that we want to manipulate with the debugger.
> Normally we use the block magic to find the geometry profile, but if the
> magic is bad we'll never find it and return NULL. The callers of this
> function do not check for NULL and crash.
>
> Therefore, if we can't find a geometry profile matching the magic
> number, use the iocursor type to guess the profile and scowl about that
> to stdout. This makes it so that even with a corrupt magic we can try
> to print the fields instead of crashing the debugger.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> v2: be less macro-happy and only evaluate hascrc once
> v3: braces around the for loop body
> v4: proposed maintainer changes from eric:
> fix comments, add magic assert, keep other asserts which
> were removed for unknown reasons...
Needs a S-o-b: Eric Sandeen for the changes you made, but otherwise,
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
--D
> ---
>
> diff --git a/db/btblock.c b/db/btblock.c
> index 835a5f0..b7eacb5 100644
> --- a/db/btblock.c
> +++ b/db/btblock.c
> @@ -25,6 +25,8 @@
> #include "print.h"
> #include "bit.h"
> #include "init.h"
> +#include "io.h"
> +#include "output.h"
>
> /*
> * Definition of the possible btree block layouts.
> @@ -113,22 +115,60 @@ struct xfs_db_btree {
> };
>
> /*
> - * Find the right block defintion for a given ondisk block.
> - *
> - * We use the least significant bit of the magic number as index into
> - * the array of block defintions.
> + * Find the right block definition for a given ondisk block.
> */
> static struct xfs_db_btree *
> block_to_bt(
> struct xfs_btree_block *bb)
> {
> - struct xfs_db_btree *btp = &btrees[0];
> + struct xfs_db_btree *btp;
> + uint32_t magic;
> + bool crc;
>
> - do {
> - if (be32_to_cpu((bb)->bb_magic) == btp->magic)
> + magic = be32_to_cpu((bb)->bb_magic);
> + for (btp = &btrees[0]; btp->magic != 0; btp++) {
> + if (magic == btp->magic)
> + return btp;
> + }
> +
> + /* Magic is invalid/unknown. Guess based on iocur type */
> + crc = xfs_sb_version_hascrc(&mp->m_sb);
> + switch (iocur_top->typ->typnm) {
> + case TYP_BMAPBTA:
> + case TYP_BMAPBTD:
> + magic = crc ? XFS_BMAP_CRC_MAGIC : XFS_BMAP_MAGIC;
> + break;
> + case TYP_BNOBT:
> + magic = crc ? XFS_ABTB_CRC_MAGIC : XFS_ABTB_MAGIC;
> + break;
> + case TYP_CNTBT:
> + magic = crc ? XFS_ABTC_CRC_MAGIC : XFS_ABTC_MAGIC;
> + break;
> + case TYP_INOBT:
> + magic = crc ? XFS_IBT_CRC_MAGIC : XFS_IBT_MAGIC;
> + break;
> + case TYP_FINOBT:
> + magic = crc ? XFS_FIBT_CRC_MAGIC : XFS_FIBT_MAGIC;
> + break;
> + case TYP_RMAPBT:
> + magic = crc ? XFS_RMAP_CRC_MAGIC : 0;
> + break;
> + case TYP_REFCBT:
> + magic = crc ? XFS_REFC_CRC_MAGIC : 0;
> + break;
> + default:
> + ASSERT(0);
> + }
> +
> + ASSERT(magic);
> + dbprintf(_("Bad btree magic 0x%x; coercing to %s.\n"),
> + be32_to_cpu((bb)->bb_magic),
> + iocur_top->typ->name);
> +
> + for (btp = &btrees[0]; btp->magic != 0; btp++) {
> + if (magic == btp->magic)
> return btp;
> - btp++;
> - } while (btp->magic != 0);
> + }
>
> return NULL;
> }
>
> --
> 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
