Commit 8473fee3 authored by Brian Foster's avatar Brian Foster Committed by Darrick J. Wong
Browse files

xfs: distinguish between inobt and finobt magic values 



The inode btree verifier code is shared between the inode btree and
free inode btree because the underlying metadata formats are
essentially equivalent. A side effect of this is that the verifier
cannot determine whether a particular btree block should have an
inobt or finobt magic value.

This logic allows an unfortunate xfs_repair bug to escape detection
where certain level > 0 nodes of the finobt are stamped with inobt
magic by xfs_repair finobt reconstruction. This is fortunately not a
severe problem since the inode btree magic values do not contribute
to any changes in kernel behavior, but we do need a means to detect
and prevent this problem in the future.

Add a field to xfs_buf_ops to store the v4 and v5 superblock magic
values expected by a particular verifier. Add a helper to check an
on-disk magic value against the value expected by the verifier. Call
the helper from the shared [f]inobt verifier code for magic value
verification. This ensures that the inode btree blocks each have the
appropriate magic value based on specific tree type and superblock
version.

Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent 01e68f40

fs/xfs/libxfs/xfs_ialloc_btree.c

+7 −9
Original line number Diff line number Diff line
@@ -260,6 +260,9 @@ xfs_inobt_verify( 
	xfs_failaddr_t		fa;

	unsigned int		level;



	if (!xfs_verify_magic(bp, block->bb_magic))

		return __this_address;



	/*

	 * During growfs operations, we can't verify the exact owner as the

	 * perag is not fully initialised and hence not attached to the buffer.
@@ -270,18 +273,10 @@ xfs_inobt_verify( 
	 * but beware of the landmine (i.e. need to check pag->pagi_init) if we

	 * ever do.

	 */

	switch (block->bb_magic) {

	case cpu_to_be32(XFS_IBT_CRC_MAGIC):

	case cpu_to_be32(XFS_FIBT_CRC_MAGIC):

	if (xfs_sb_version_hascrc(&mp->m_sb)) {

		fa = xfs_btree_sblock_v5hdr_verify(bp);

		if (fa)

			return fa;

		/* fall through */

	case cpu_to_be32(XFS_IBT_MAGIC):

	case cpu_to_be32(XFS_FIBT_MAGIC):

		break;

	default:

		return __this_address;

	}



	/* level verification */
@@ -328,6 +323,7 @@ xfs_inobt_write_verify( 


const struct xfs_buf_ops xfs_inobt_buf_ops = {

	.name = "xfs_inobt",

	.magic = { cpu_to_be32(XFS_IBT_MAGIC), cpu_to_be32(XFS_IBT_CRC_MAGIC) },

	.verify_read = xfs_inobt_read_verify,

	.verify_write = xfs_inobt_write_verify,

	.verify_struct = xfs_inobt_verify,
@@ -335,6 +331,8 @@ const struct xfs_buf_ops xfs_inobt_buf_ops = { 


const struct xfs_buf_ops xfs_finobt_buf_ops = {

	.name = "xfs_finobt",

	.magic = { cpu_to_be32(XFS_FIBT_MAGIC),

		   cpu_to_be32(XFS_FIBT_CRC_MAGIC) },

	.verify_read = xfs_inobt_read_verify,

	.verify_write = xfs_inobt_write_verify,

	.verify_struct = xfs_inobt_verify,

fs/xfs/xfs_buf.c

+19 −0
Original line number Diff line number Diff line
@@ -2204,3 +2204,22 @@ void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref) 


	atomic_set(&bp->b_lru_ref, lru_ref);

}



/*

 * Verify an on-disk magic value against the magic value specified in the

 * verifier structure. The verifier magic is in disk byte order so the caller is

 * expected to pass the value directly from disk.

 */

bool

xfs_verify_magic(

	struct xfs_buf		*bp,

	uint32_t		dmagic)

{

	struct xfs_mount	*mp = bp->b_target->bt_mount;

	int			idx;



	idx = xfs_sb_version_hascrc(&mp->m_sb);

	if (unlikely(WARN_ON(!bp->b_ops || !bp->b_ops->magic[idx])))

		return false;

	return dmagic == bp->b_ops->magic[idx];

}

fs/xfs/xfs_buf.h

+2 −0
Original line number Diff line number Diff line
@@ -125,6 +125,7 @@ struct xfs_buf_map { 


struct xfs_buf_ops {

	char *name;

	uint32_t magic[2];		/* v4 and v5 on disk magic values */

	void (*verify_read)(struct xfs_buf *);

	void (*verify_write)(struct xfs_buf *);

	xfs_failaddr_t (*verify_struct)(struct xfs_buf *bp);
@@ -386,5 +387,6 @@ extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int); 
#define xfs_readonly_buftarg(buftarg)	bdev_read_only((buftarg)->bt_bdev)



int xfs_buf_reverify(struct xfs_buf *bp, const struct xfs_buf_ops *ops);

bool xfs_verify_magic(struct xfs_buf *bp, uint32_t dmagic);



#endif	/* __XFS_BUF_H__ */

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