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Commit 858333dc authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: check btree block ownership with bnobt/rmapbt when scrubbing btree 



When scanning a metadata btree block, cross-reference the block location
with the free space btree and the reverse mapping btree to ensure that
the rmapbt knows about the block and the bnobt does not.  Add a
mechanism to defer checks when we happen to be scanning the bnobt/rmapbt
itself because it's less efficient to repeatedly clone and destroy the
cursor.

This patch provides the framework to make btree block owner checks
happen; the actual meat will be added in subsequent patches.

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
parent 9a7e2695

fs/xfs/scrub/btree.c

+93 −0
Original line number Diff line number Diff line
@@ -361,6 +361,80 @@ xfs_scrub_btree_block_check_siblings( 
	return error;

}



struct check_owner {

	struct list_head	list;

	xfs_daddr_t		daddr;

	int			level;

};



/*

 * Make sure this btree block isn't in the free list and that there's

 * an rmap record for it.

 */

STATIC int

xfs_scrub_btree_check_block_owner(

	struct xfs_scrub_btree		*bs,

	int				level,

	xfs_daddr_t			daddr)

{

	xfs_agnumber_t			agno;

	bool				init_sa;

	int				error = 0;



	if (!bs->cur)

		return 0;



	agno = xfs_daddr_to_agno(bs->cur->bc_mp, daddr);



	init_sa = bs->cur->bc_flags & XFS_BTREE_LONG_PTRS;

	if (init_sa) {

		error = xfs_scrub_ag_init(bs->sc, agno, &bs->sc->sa);

		if (!xfs_scrub_btree_xref_process_error(bs->sc, bs->cur,

				level, &error))

			return error;

	}



	if (init_sa)

		xfs_scrub_ag_free(bs->sc, &bs->sc->sa);



	return error;

}



/* Check the owner of a btree block. */

STATIC int

xfs_scrub_btree_check_owner(

	struct xfs_scrub_btree		*bs,

	int				level,

	struct xfs_buf			*bp)

{

	struct xfs_btree_cur		*cur = bs->cur;

	struct check_owner		*co;



	if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) && bp == NULL)

		return 0;



	/*

	 * We want to cross-reference each btree block with the bnobt

	 * and the rmapbt.  We cannot cross-reference the bnobt or

	 * rmapbt while scanning the bnobt or rmapbt, respectively,

	 * because we cannot alter the cursor and we'd prefer not to

	 * duplicate cursors.  Therefore, save the buffer daddr for

	 * later scanning.

	 */

	if (cur->bc_btnum == XFS_BTNUM_BNO || cur->bc_btnum == XFS_BTNUM_RMAP) {

		co = kmem_alloc(sizeof(struct check_owner),

				KM_MAYFAIL | KM_NOFS);

		if (!co)

			return -ENOMEM;

		co->level = level;

		co->daddr = XFS_BUF_ADDR(bp);

		list_add_tail(&co->list, &bs->to_check);

		return 0;

	}



	return xfs_scrub_btree_check_block_owner(bs, level, XFS_BUF_ADDR(bp));

}



/*

 * Grab and scrub a btree block given a btree pointer.  Returns block

 * and buffer pointers (if applicable) if they're ok to use.
@@ -396,6 +470,14 @@ xfs_scrub_btree_get_block( 
		return 0;

	}



	/*

	 * Check the block's owner; this function absorbs error codes

	 * for us.

	 */

	error = xfs_scrub_btree_check_owner(bs, level, *pbp);

	if (error)

		return error;



	/*

	 * Check the block's siblings; this function absorbs error codes

	 * for us.
@@ -467,6 +549,8 @@ xfs_scrub_btree( 
	struct xfs_btree_block		*block;

	int				level;

	struct xfs_buf			*bp;

	struct check_owner		*co;

	struct check_owner		*n;

	int				i;

	int				error = 0;
@@ -558,5 +642,14 @@ xfs_scrub_btree( 
	}



out:

	/* Process deferred owner checks on btree blocks. */

	list_for_each_entry_safe(co, n, &bs.to_check, list) {

		if (!error && bs.cur)

			error = xfs_scrub_btree_check_block_owner(&bs,

					co->level, co->daddr);

		list_del(&co->list);

		kmem_free(co);

	}



	return error;

}