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xfs: btree scrub should check minrecs

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Strengthen the btree block header checks to detect the number of records
being less than the btree type's minimum record count.  Certain blocks
are allowed to violate this constraint -- specifically any btree block
at the top of the tree can have fewer than minrecs records.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
This commit is contained in:
Darrick J. Wong 2018-05-09 10:02:00 -07:00
parent 631fc955bd
commit 08a3a692ef
1 changed files with 40 additions and 0 deletions
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40
fs/xfs/scrub/btree.c
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@ -454,6 +454,44 @@ xfs_scrub_btree_check_owner(
return xfs_scrub_btree_check_block_owner(bs, level, XFS_BUF_ADDR(bp));
}
/*
* Check that this btree block has at least minrecs records or is one of the
* special blocks that don't require that.
*/
STATIC void
xfs_scrub_btree_check_minrecs(
struct xfs_scrub_btree *bs,
int level,
struct xfs_btree_block *block)
{
unsigned int numrecs;
int ok_level;
numrecs = be16_to_cpu(block->bb_numrecs);
/* More records than minrecs means the block is ok. */
if (numrecs >= bs->cur->bc_ops->get_minrecs(bs->cur, level))
return;
/*
* Certain btree blocks /can/ have fewer than minrecs records. Any
* level greater than or equal to the level of the highest dedicated
* btree block are allowed to violate this constraint.
*
* For a btree rooted in a block, the btree root can have fewer than
* minrecs records. If the btree is rooted in an inode and does not
* store records in the root, the direct children of the root and the
* root itself can have fewer than minrecs records.
*/
ok_level = bs->cur->bc_nlevels - 1;
if (bs->cur->bc_flags & XFS_BTREE_ROOT_IN_INODE)
ok_level--;
if (level >= ok_level)
return;
xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, level);
}
/*
* Grab and scrub a btree block given a btree pointer. Returns block
* and buffer pointers (if applicable) if they're ok to use.
@ -491,6 +529,8 @@ xfs_scrub_btree_get_block(
if (*pbp)
xfs_scrub_buffer_recheck(bs->sc, *pbp);
xfs_scrub_btree_check_minrecs(bs, level, *pblock);
/*
* Check the block's owner; this function absorbs error codes
* for us.