On 4/10/17 7:20 PM, Darrick J. Wong 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>
Makes sense generally, minor things below.
> ---
> v2: be less macro-happy and only evaluate hascrc once
> v3: braces around the for loop body
> ---
> db/btblock.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 46 insertions(+), 8 deletions(-)
>
> diff --git a/db/btblock.c b/db/btblock.c
> index 835a5f0..b819fa5 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.
> @@ -122,13 +124,52 @@ static struct xfs_db_btree *
urgh:
/*
* 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.
(nope, we don't, I can remove that on commit...)
*/
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);
maybe -
again:
> + 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);
Bah, wish we could use something like:
magic = xfs_magics[crc][btnum];
but that's static to libxfs/xfs_btree.c and I guess btnum != typnm.
Because of course.
(btnum = xfs_typnm_to_btnum[iocur_top->typ->typnm]; ? :) Ok I'll
drop it...)
> + 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);
we'd better have that by now, yes? Or could we hit the RMAP/REFC
types w/o crc set? I guess then the caller ASSERTs anyway?
> +
> + dbprintf(_("Bad btree magic 0x%x; coercing to %s.\n"),
> + be32_to_cpu((bb)->bb_magic),
> + iocur_top->typ->name);
goto again;
to avoid the cut & paste of the loop below? But maybe that's uglier.
> +
> + for (btp = &btrees[0]; btp->magic != 0; btp++) {
> + if (magic == btp->magic)
> return btp;
> - btp++;
> - } while (btp->magic != 0);
> + }
>
> return NULL;
> }
> @@ -193,7 +234,6 @@ btblock_key_offset(
> int offset;
>
> ASSERT(startoff == 0);
> - ASSERT(block->bb_level != 0);
Help me out, why are these now removed?
-Eric
>
> offset = bt->block_len + (idx - 1) * bt->key_len;
> return bitize(offset);
> @@ -214,7 +254,6 @@ btblock_ptr_offset(
> int maxrecs;
>
> ASSERT(startoff == 0);
> - ASSERT(block->bb_level != 0);
>
> maxrecs = btblock_maxrecs(bt, mp->m_sb.sb_blocksize);
> offset = bt->block_len +
> @@ -238,7 +277,6 @@ btblock_rec_offset(
> int offset;
>
> ASSERT(startoff == 0);
> - ASSERT(block->bb_level == 0);
>
> offset = bt->block_len + (idx - 1) * bt->rec_len;
> return bitize(offset);
> --
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