Commit df481968 authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: scrub directory freespace 



Check the free space information in a directory.

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
parent a5c46e5e

fs/xfs/scrub/dir.c

+495 −0
Original line number Diff line number Diff line
@@ -259,6 +259,493 @@ xfs_scrub_dir_rec( 
	return error;

}



/*

 * Is this unused entry either in the bestfree or smaller than all of

 * them?  We've already checked that the bestfrees are sorted longest to

 * shortest, and that there aren't any bogus entries.

 */

STATIC void

xfs_scrub_directory_check_free_entry(

	struct xfs_scrub_context	*sc,

	xfs_dablk_t			lblk,

	struct xfs_dir2_data_free	*bf,

	struct xfs_dir2_data_unused	*dup)

{

	struct xfs_dir2_data_free	*dfp;

	unsigned int			dup_length;



	dup_length = be16_to_cpu(dup->length);



	/* Unused entry is shorter than any of the bestfrees */

	if (dup_length < be16_to_cpu(bf[XFS_DIR2_DATA_FD_COUNT - 1].length))

		return;



	for (dfp = &bf[XFS_DIR2_DATA_FD_COUNT - 1]; dfp >= bf; dfp--)

		if (dup_length == be16_to_cpu(dfp->length))

			return;



	/* Unused entry should be in the bestfrees but wasn't found. */

	xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

}



/* Check free space info in a directory data block. */

STATIC int

xfs_scrub_directory_data_bestfree(

	struct xfs_scrub_context	*sc,

	xfs_dablk_t			lblk,

	bool				is_block)

{

	struct xfs_dir2_data_unused	*dup;

	struct xfs_dir2_data_free	*dfp;

	struct xfs_buf			*bp;

	struct xfs_dir2_data_free	*bf;

	struct xfs_mount		*mp = sc->mp;

	const struct xfs_dir_ops	*d_ops;

	char				*ptr;

	char				*endptr;

	u16				tag;

	unsigned int			nr_bestfrees = 0;

	unsigned int			nr_frees = 0;

	unsigned int			smallest_bestfree;

	int				newlen;

	int				offset;

	int				error;



	d_ops = sc->ip->d_ops;



	if (is_block) {

		/* dir block format */

		if (lblk != XFS_B_TO_FSBT(mp, XFS_DIR2_DATA_OFFSET))

			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

		error = xfs_dir3_block_read(sc->tp, sc->ip, &bp);

	} else {

		/* dir data format */

		error = xfs_dir3_data_read(sc->tp, sc->ip, lblk, -1, &bp);

	}

	if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, lblk, &error))

		goto out;



	/* XXX: Check xfs_dir3_data_hdr.pad is zero once we start setting it. */



	/* Do the bestfrees correspond to actual free space? */

	bf = d_ops->data_bestfree_p(bp->b_addr);

	smallest_bestfree = UINT_MAX;

	for (dfp = &bf[0]; dfp < &bf[XFS_DIR2_DATA_FD_COUNT]; dfp++) {

		offset = be16_to_cpu(dfp->offset);

		if (offset == 0)

			continue;

		if (offset >= mp->m_dir_geo->blksize) {

			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

			goto out_buf;

		}

		dup = (struct xfs_dir2_data_unused *)(bp->b_addr + offset);

		tag = be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup));



		/* bestfree doesn't match the entry it points at? */

		if (dup->freetag != cpu_to_be16(XFS_DIR2_DATA_FREE_TAG) ||

		    be16_to_cpu(dup->length) != be16_to_cpu(dfp->length) ||

		    tag != ((char *)dup - (char *)bp->b_addr)) {

			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

			goto out_buf;

		}



		/* bestfree records should be ordered largest to smallest */

		if (smallest_bestfree < be16_to_cpu(dfp->length)) {

			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

			goto out_buf;

		}



		smallest_bestfree = be16_to_cpu(dfp->length);

		nr_bestfrees++;

	}



	/* Make sure the bestfrees are actually the best free spaces. */

	ptr = (char *)d_ops->data_entry_p(bp->b_addr);

	if (is_block) {

		struct xfs_dir2_block_tail	*btp;



		btp = xfs_dir2_block_tail_p(mp->m_dir_geo, bp->b_addr);

		endptr = (char *)xfs_dir2_block_leaf_p(btp);

	} else

		endptr = (char *)bp->b_addr + BBTOB(bp->b_length);



	/* Iterate the entries, stopping when we hit or go past the end. */

	while (ptr < endptr) {

		dup = (struct xfs_dir2_data_unused *)ptr;

		/* Skip real entries */

		if (dup->freetag != cpu_to_be16(XFS_DIR2_DATA_FREE_TAG)) {

			struct xfs_dir2_data_entry	*dep;



			dep = (struct xfs_dir2_data_entry *)ptr;

			newlen = d_ops->data_entsize(dep->namelen);

			if (newlen <= 0) {

				xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK,

						lblk);

				goto out_buf;

			}

			ptr += newlen;

			continue;

		}



		/* Spot check this free entry */

		tag = be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup));

		if (tag != ((char *)dup - (char *)bp->b_addr))

			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);



		/*

		 * Either this entry is a bestfree or it's smaller than

		 * any of the bestfrees.

		 */

		xfs_scrub_directory_check_free_entry(sc, lblk, bf, dup);



		/* Move on. */

		newlen = be16_to_cpu(dup->length);

		if (newlen <= 0) {

			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

			goto out_buf;

		}

		ptr += newlen;

		if (ptr <= endptr)

			nr_frees++;

	}



	/* We're required to fill all the space. */

	if (ptr != endptr)

		xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);



	/* Did we see at least as many free slots as there are bestfrees? */

	if (nr_frees < nr_bestfrees)

		xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

out_buf:

	xfs_trans_brelse(sc->tp, bp);

out:

	return error;

}



/*

 * Does the free space length in the free space index block ($len) match

 * the longest length in the directory data block's bestfree array?

 * Assume that we've already checked that the data block's bestfree

 * array is in order.

 */

STATIC void

xfs_scrub_directory_check_freesp(

	struct xfs_scrub_context	*sc,

	xfs_dablk_t			lblk,

	struct xfs_buf			*dbp,

	unsigned int			len)

{

	struct xfs_dir2_data_free	*bf;

	struct xfs_dir2_data_free	*dfp;

	int				offset;



	if (len == 0)

		return;



	bf = sc->ip->d_ops->data_bestfree_p(dbp->b_addr);

	for (dfp = &bf[0]; dfp < &bf[XFS_DIR2_DATA_FD_COUNT]; dfp++) {

		offset = be16_to_cpu(dfp->offset);

		if (offset == 0)

			break;

		if (len == be16_to_cpu(dfp->length))

			return;

		/* Didn't find the best length in the bestfree data */

		break;

	}



	xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

}



/* Check free space info in a directory leaf1 block. */

STATIC int

xfs_scrub_directory_leaf1_bestfree(

	struct xfs_scrub_context	*sc,

	struct xfs_da_args		*args,

	xfs_dablk_t			lblk)

{

	struct xfs_dir3_icleaf_hdr	leafhdr;

	struct xfs_dir2_leaf_entry	*ents;

	struct xfs_dir2_leaf_tail	*ltp;

	struct xfs_dir2_leaf		*leaf;

	struct xfs_buf			*dbp;

	struct xfs_buf			*bp;

	const struct xfs_dir_ops	*d_ops = sc->ip->d_ops;

	struct xfs_da_geometry		*geo = sc->mp->m_dir_geo;

	__be16				*bestp;

	__u16				best;

	__u32				hash;

	__u32				lasthash = 0;

	__u32				bestcount;

	unsigned int			stale = 0;

	int				i;

	int				error;



	/* Read the free space block. */

	error = xfs_dir3_leaf_read(sc->tp, sc->ip, lblk, -1, &bp);

	if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, lblk, &error))

		goto out;



	leaf = bp->b_addr;

	d_ops->leaf_hdr_from_disk(&leafhdr, leaf);

	ents = d_ops->leaf_ents_p(leaf);

	ltp = xfs_dir2_leaf_tail_p(geo, leaf);

	bestcount = be32_to_cpu(ltp->bestcount);

	bestp = xfs_dir2_leaf_bests_p(ltp);



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

		struct xfs_dir3_leaf_hdr	*hdr3 = bp->b_addr;



		if (hdr3->pad != cpu_to_be32(0))

			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

	}



	/*

	 * There should be as many bestfree slots as there are dir data

	 * blocks that can fit under i_size.

	 */

	if (bestcount != xfs_dir2_byte_to_db(geo, sc->ip->i_d.di_size)) {

		xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

		goto out;

	}



	/* Is the leaf count even remotely sane? */

	if (leafhdr.count > d_ops->leaf_max_ents(geo)) {

		xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

		goto out;

	}



	/* Leaves and bests don't overlap in leaf format. */

	if ((char *)&ents[leafhdr.count] > (char *)bestp) {

		xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

		goto out;

	}



	/* Check hash value order, count stale entries.  */

	for (i = 0; i < leafhdr.count; i++) {

		hash = be32_to_cpu(ents[i].hashval);

		if (i > 0 && lasthash > hash)

			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

		lasthash = hash;

		if (ents[i].address == cpu_to_be32(XFS_DIR2_NULL_DATAPTR))

			stale++;

	}

	if (leafhdr.stale != stale)

		xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);



	/* Check all the bestfree entries. */

	for (i = 0; i < bestcount; i++, bestp++) {

		best = be16_to_cpu(*bestp);

		if (best == NULLDATAOFF)

			continue;

		error = xfs_dir3_data_read(sc->tp, sc->ip,

				i * args->geo->fsbcount, -1, &dbp);

		if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, lblk,

				&error))

			continue;

		xfs_scrub_directory_check_freesp(sc, lblk, dbp, best);

		xfs_trans_brelse(sc->tp, dbp);

	}

out:

	return error;

}



/* Check free space info in a directory freespace block. */

STATIC int

xfs_scrub_directory_free_bestfree(

	struct xfs_scrub_context	*sc,

	struct xfs_da_args		*args,

	xfs_dablk_t			lblk)

{

	struct xfs_dir3_icfree_hdr	freehdr;

	struct xfs_buf			*dbp;

	struct xfs_buf			*bp;

	__be16				*bestp;

	__be16				best;

	unsigned int			stale = 0;

	int				i;

	int				error;



	/* Read the free space block */

	error = xfs_dir2_free_read(sc->tp, sc->ip, lblk, &bp);

	if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, lblk, &error))

		goto out;



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

		struct xfs_dir3_free_hdr	*hdr3 = bp->b_addr;



		if (hdr3->pad != cpu_to_be32(0))

			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

	}



	/* Check all the entries. */

	sc->ip->d_ops->free_hdr_from_disk(&freehdr, bp->b_addr);

	bestp = sc->ip->d_ops->free_bests_p(bp->b_addr);

	for (i = 0; i < freehdr.nvalid; i++, bestp++) {

		best = be16_to_cpu(*bestp);

		if (best == NULLDATAOFF) {

			stale++;

			continue;

		}

		error = xfs_dir3_data_read(sc->tp, sc->ip,

				(freehdr.firstdb + i) * args->geo->fsbcount,

				-1, &dbp);

		if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, lblk,

				&error))

			continue;

		xfs_scrub_directory_check_freesp(sc, lblk, dbp, best);

		xfs_trans_brelse(sc->tp, dbp);

	}



	if (freehdr.nused + stale != freehdr.nvalid)

		xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

out:

	return error;

}



/* Check free space information in directories. */

STATIC int

xfs_scrub_directory_blocks(

	struct xfs_scrub_context	*sc)

{

	struct xfs_bmbt_irec		got;

	struct xfs_da_args		args;

	struct xfs_ifork		*ifp;

	struct xfs_mount		*mp = sc->mp;

	xfs_fileoff_t			leaf_lblk;

	xfs_fileoff_t			free_lblk;

	xfs_fileoff_t			lblk;

	xfs_extnum_t			idx;

	xfs_dablk_t			dabno;

	bool				found;

	int				is_block = 0;

	int				error;



	/* Ignore local format directories. */

	if (sc->ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS &&

	    sc->ip->i_d.di_format != XFS_DINODE_FMT_BTREE)

		return 0;



	ifp = XFS_IFORK_PTR(sc->ip, XFS_DATA_FORK);

	lblk = XFS_B_TO_FSB(mp, XFS_DIR2_DATA_OFFSET);

	leaf_lblk = XFS_B_TO_FSB(mp, XFS_DIR2_LEAF_OFFSET);

	free_lblk = XFS_B_TO_FSB(mp, XFS_DIR2_FREE_OFFSET);



	/* Is this a block dir? */

	args.dp = sc->ip;

	args.geo = mp->m_dir_geo;

	args.trans = sc->tp;

	error = xfs_dir2_isblock(&args, &is_block);

	if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, lblk, &error))

		goto out;



	/* Iterate all the data extents in the directory... */

	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);

	while (found) {

		/* Block directories only have a single block at offset 0. */

		if (is_block &&

		    (got.br_startoff > 0 ||

		     got.br_blockcount != args.geo->fsbcount)) {

			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK,

					got.br_startoff);

			break;

		}



		/* No more data blocks... */

		if (got.br_startoff >= leaf_lblk)

			break;



		/*

		 * Check each data block's bestfree data.

		 *

		 * Iterate all the fsbcount-aligned block offsets in

		 * this directory.  The directory block reading code is

		 * smart enough to do its own bmap lookups to handle

		 * discontiguous directory blocks.  When we're done

		 * with the extent record, re-query the bmap at the

		 * next fsbcount-aligned offset to avoid redundant

		 * block checks.

		 */

		for (lblk = roundup((xfs_dablk_t)got.br_startoff,

				args.geo->fsbcount);

		     lblk < got.br_startoff + got.br_blockcount;

		     lblk += args.geo->fsbcount) {

			error = xfs_scrub_directory_data_bestfree(sc, lblk,

					is_block);

			if (error)

				goto out;

		}

		dabno = got.br_startoff + got.br_blockcount;

		lblk = roundup(dabno, args.geo->fsbcount);

		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);

	}



	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)

		goto out;



	/* Look for a leaf1 block, which has free info. */

	if (xfs_iext_lookup_extent(sc->ip, ifp, leaf_lblk, &idx, &got) &&

	    got.br_startoff == leaf_lblk &&

	    got.br_blockcount == args.geo->fsbcount &&

	    !xfs_iext_get_extent(ifp, ++idx, &got)) {

		if (is_block) {

			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

			goto out;

		}

		error = xfs_scrub_directory_leaf1_bestfree(sc, &args,

				leaf_lblk);

		if (error)

			goto out;

	}



	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)

		goto out;



	/* Scan for free blocks */

	lblk = free_lblk;

	found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);

	while (found) {

		/*

		 * Dirs can't have blocks mapped above 2^32.

		 * Single-block dirs shouldn't even be here.

		 */

		lblk = got.br_startoff;

		if (lblk & ~0xFFFFFFFFULL) {

			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

			goto out;

		}

		if (is_block) {

			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

			goto out;

		}



		/*

		 * Check each dir free block's bestfree data.

		 *

		 * Iterate all the fsbcount-aligned block offsets in

		 * this directory.  The directory block reading code is

		 * smart enough to do its own bmap lookups to handle

		 * discontiguous directory blocks.  When we're done

		 * with the extent record, re-query the bmap at the

		 * next fsbcount-aligned offset to avoid redundant

		 * block checks.

		 */

		for (lblk = roundup((xfs_dablk_t)got.br_startoff,

				args.geo->fsbcount);

		     lblk < got.br_startoff + got.br_blockcount;

		     lblk += args.geo->fsbcount) {

			error = xfs_scrub_directory_free_bestfree(sc, &args,

					lblk);

			if (error)

				goto out;

		}

		dabno = got.br_startoff + got.br_blockcount;

		lblk = roundup(dabno, args.geo->fsbcount);

		found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &idx, &got);

	}

out:

	return error;

}



/* Scrub a whole directory. */

int

xfs_scrub_directory(
@@ -290,6 +777,14 @@ xfs_scrub_directory( 
	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)

		return error;



	/* Check the freespace. */

	error = xfs_scrub_directory_blocks(sc);

	if (error)

		return error;



	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)

		return error;



	/*

	 * Check that every dirent we see can also be looked up by hash.

	 * Userspace usually asks for a 32k buffer, so we will too.