xfs: scrub directory metadata

Scrub the hash tree and all the entries in a directory.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

1 files changed, 331 insertions, 0 deletions

diff --git a/fs/xfs/scrub/dir.c b/fs/xfs/scrub/dir.c
new file mode 100644
index 000000000000..da0f4b1308b0
--- /dev/null
+++ b/fs/xfs/scrub/dir.c
@@ -0,0 +1,331 @@
+/*
+ * Copyright (C) 2017 Oracle.  All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_defer.h"
+#include "xfs_btree.h"
+#include "xfs_bit.h"
+#include "xfs_log_format.h"
+#include "xfs_trans.h"
+#include "xfs_sb.h"
+#include "xfs_inode.h"
+#include "xfs_icache.h"
+#include "xfs_itable.h"
+#include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_dir2.h"
+#include "xfs_dir2_priv.h"
+#include "xfs_ialloc.h"
+#include "scrub/xfs_scrub.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/trace.h"
+#include "scrub/dabtree.h"
+
+/* Set us up to scrub directories. */
+int
+xfs_scrub_setup_directory(
+	struct xfs_scrub_context	*sc,
+	struct xfs_inode		*ip)
+{
+	return xfs_scrub_setup_inode_contents(sc, ip, 0);
+}
+
+/* Directories */
+
+/* Scrub a directory entry. */
+
+struct xfs_scrub_dir_ctx {
+	/* VFS fill-directory iterator */
+	struct dir_context		dir_iter;
+
+	struct xfs_scrub_context	*sc;
+};
+
+/* Check that an inode's mode matches a given DT_ type. */
+STATIC int
+xfs_scrub_dir_check_ftype(
+	struct xfs_scrub_dir_ctx	*sdc,
+	xfs_fileoff_t			offset,
+	xfs_ino_t			inum,
+	int				dtype)
+{
+	struct xfs_mount		*mp = sdc->sc->mp;
+	struct xfs_inode		*ip;
+	int				ino_dtype;
+	int				error = 0;
+
+	if (!xfs_sb_version_hasftype(&mp->m_sb)) {
+		if (dtype != DT_UNKNOWN && dtype != DT_DIR)
+			xfs_scrub_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
+					offset);
+		goto out;
+	}
+
+	/*
+	 * Grab the inode pointed to by the dirent.  We release the
+	 * inode before we cancel the scrub transaction.  Since we're
+	 * don't know a priori that releasing the inode won't trigger
+	 * eofblocks cleanup (which allocates what would be a nested
+	 * transaction), we can't use DONTCACHE here because DONTCACHE
+	 * inodes can trigger immediate inactive cleanup of the inode.
+	 */
+	error = xfs_iget(mp, sdc->sc->tp, inum, 0, 0, &ip);
+	if (!xfs_scrub_fblock_process_error(sdc->sc, XFS_DATA_FORK, offset,
+			&error))
+		goto out;
+
+	/* Convert mode to the DT_* values that dir_emit uses. */
+	ino_dtype = xfs_dir3_get_dtype(mp,
+			xfs_mode_to_ftype(VFS_I(ip)->i_mode));
+	if (ino_dtype != dtype)
+		xfs_scrub_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK, offset);
+	iput(VFS_I(ip));
+out:
+	return error;
+}
+
+/*
+ * Scrub a single directory entry.
+ *
+ * We use the VFS directory iterator (i.e. readdir) to call this
+ * function for every directory entry in a directory.  Once we're here,
+ * we check the inode number to make sure it's sane, then we check that
+ * we can look up this filename.  Finally, we check the ftype.
+ */
+STATIC int
+xfs_scrub_dir_actor(
+	struct dir_context		*dir_iter,
+	const char			*name,
+	int				namelen,
+	loff_t				pos,
+	u64				ino,
+	unsigned			type)
+{
+	struct xfs_mount		*mp;
+	struct xfs_inode		*ip;
+	struct xfs_scrub_dir_ctx	*sdc;
+	struct xfs_name			xname;
+	xfs_ino_t			lookup_ino;
+	xfs_dablk_t			offset;
+	int				error = 0;
+
+	sdc = container_of(dir_iter, struct xfs_scrub_dir_ctx, dir_iter);
+	ip = sdc->sc->ip;
+	mp = ip->i_mount;
+	offset = xfs_dir2_db_to_da(mp->m_dir_geo,
+			xfs_dir2_dataptr_to_db(mp->m_dir_geo, pos));
+
+	/* Does this inode number make sense? */
+	if (!xfs_verify_dir_ino(mp, ino)) {
+		xfs_scrub_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK, offset);
+		goto out;
+	}
+
+	if (!strncmp(".", name, namelen)) {
+		/* If this is "." then check that the inum matches the dir. */
+		if (xfs_sb_version_hasftype(&mp->m_sb) && type != DT_DIR)
+			xfs_scrub_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
+					offset);
+		if (ino != ip->i_ino)
+			xfs_scrub_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
+					offset);
+	} else if (!strncmp("..", name, namelen)) {
+		/*
+		 * If this is ".." in the root inode, check that the inum
+		 * matches this dir.
+		 */
+		if (xfs_sb_version_hasftype(&mp->m_sb) && type != DT_DIR)
+			xfs_scrub_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
+					offset);
+		if (ip->i_ino == mp->m_sb.sb_rootino && ino != ip->i_ino)
+			xfs_scrub_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
+					offset);
+	}
+
+	/* Verify that we can look up this name by hash. */
+	xname.name = name;
+	xname.len = namelen;
+	xname.type = XFS_DIR3_FT_UNKNOWN;
+
+	error = xfs_dir_lookup(sdc->sc->tp, ip, &xname, &lookup_ino, NULL);
+	if (!xfs_scrub_fblock_process_error(sdc->sc, XFS_DATA_FORK, offset,
+			&error))
+		goto fail_xref;
+	if (lookup_ino != ino) {
+		xfs_scrub_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK, offset);
+		goto out;
+	}
+
+	/* Verify the file type.  This function absorbs error codes. */
+	error = xfs_scrub_dir_check_ftype(sdc, offset, lookup_ino, type);
+	if (error)
+		goto out;
+out:
+	return error;
+fail_xref:
+	return error;
+}
+
+/* Scrub a directory btree record. */
+STATIC int
+xfs_scrub_dir_rec(
+	struct xfs_scrub_da_btree	*ds,
+	int				level,
+	void				*rec)
+{
+	struct xfs_mount		*mp = ds->state->mp;
+	struct xfs_dir2_leaf_entry	*ent = rec;
+	struct xfs_inode		*dp = ds->dargs.dp;
+	struct xfs_dir2_data_entry	*dent;
+	struct xfs_buf			*bp;
+	xfs_ino_t			ino;
+	xfs_dablk_t			rec_bno;
+	xfs_dir2_db_t			db;
+	xfs_dir2_data_aoff_t		off;
+	xfs_dir2_dataptr_t		ptr;
+	xfs_dahash_t			calc_hash;
+	xfs_dahash_t			hash;
+	unsigned int			tag;
+	int				error;
+
+	/* Check the hash of the entry. */
+	error = xfs_scrub_da_btree_hash(ds, level, &ent->hashval);
+	if (error)
+		goto out;
+
+	/* Valid hash pointer? */
+	ptr = be32_to_cpu(ent->address);
+	if (ptr == 0)
+		return 0;
+
+	/* Find the directory entry's location. */
+	db = xfs_dir2_dataptr_to_db(mp->m_dir_geo, ptr);
+	off = xfs_dir2_dataptr_to_off(mp->m_dir_geo, ptr);
+	rec_bno = xfs_dir2_db_to_da(mp->m_dir_geo, db);
+
+	if (rec_bno >= mp->m_dir_geo->leafblk) {
+		xfs_scrub_da_set_corrupt(ds, level);
+		goto out;
+	}
+	error = xfs_dir3_data_read(ds->dargs.trans, dp, rec_bno, -2, &bp);
+	if (!xfs_scrub_fblock_process_error(ds->sc, XFS_DATA_FORK, rec_bno,
+			&error))
+		goto out;
+	if (!bp) {
+		xfs_scrub_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno);
+		goto out;
+	}
+
+	/* Retrieve the entry, sanity check it, and compare hashes. */
+	dent = (struct xfs_dir2_data_entry *)(((char *)bp->b_addr) + off);
+	ino = be64_to_cpu(dent->inumber);
+	hash = be32_to_cpu(ent->hashval);
+	tag = be16_to_cpup(dp->d_ops->data_entry_tag_p(dent));
+	if (!xfs_verify_dir_ino(mp, ino) || tag != off)
+		xfs_scrub_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno);
+	if (dent->namelen == 0) {
+		xfs_scrub_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno);
+		goto out_relse;
+	}
+	calc_hash = xfs_da_hashname(dent->name, dent->namelen);
+	if (calc_hash != hash)
+		xfs_scrub_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno);
+
+out_relse:
+	xfs_trans_brelse(ds->dargs.trans, bp);
+out:
+	return error;
+}
+
+/* Scrub a whole directory. */
+int
+xfs_scrub_directory(
+	struct xfs_scrub_context	*sc)
+{
+	struct xfs_scrub_dir_ctx	sdc = {
+		.dir_iter.actor = xfs_scrub_dir_actor,
+		.dir_iter.pos = 0,
+		.sc = sc,
+	};
+	size_t				bufsize;
+	loff_t				oldpos;
+	int				error;
+
+	if (!S_ISDIR(VFS_I(sc->ip)->i_mode))
+		return -ENOENT;
+
+	/* Plausible size? */
+	if (sc->ip->i_d.di_size < xfs_dir2_sf_hdr_size(0)) {
+		xfs_scrub_ino_set_corrupt(sc, sc->ip->i_ino, NULL);
+		goto out;
+	}
+
+	/* Check directory tree structure */
+	error = xfs_scrub_da_btree(sc, XFS_DATA_FORK, xfs_scrub_dir_rec);
+	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.
+	 */
+	bufsize = (size_t)min_t(loff_t, XFS_READDIR_BUFSIZE,
+			sc->ip->i_d.di_size);
+
+	/*
+	 * Look up every name in this directory by hash.
+	 *
+	 * Use the xfs_readdir function to call xfs_scrub_dir_actor on
+	 * every directory entry in this directory.  In _actor, we check
+	 * the name, inode number, and ftype (if applicable) of the
+	 * entry.  xfs_readdir uses the VFS filldir functions to provide
+	 * iteration context.
+	 *
+	 * The VFS grabs a read or write lock via i_rwsem before it reads
+	 * or writes to a directory.  If we've gotten this far we've
+	 * already obtained IOLOCK_EXCL, which (since 4.10) is the same as
+	 * getting a write lock on i_rwsem.  Therefore, it is safe for us
+	 * to drop the ILOCK here in order to reuse the _readdir and
+	 * _dir_lookup routines, which do their own ILOCK locking.
+	 */
+	oldpos = 0;
+	sc->ilock_flags &= ~XFS_ILOCK_EXCL;
+	xfs_iunlock(sc->ip, XFS_ILOCK_EXCL);
+	while (true) {
+		error = xfs_readdir(sc->tp, sc->ip, &sdc.dir_iter, bufsize);
+		if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, 0,
+				&error))
+			goto out;
+		if (oldpos == sdc.dir_iter.pos)
+			break;
+		oldpos = sdc.dir_iter.pos;
+	}
+
+out:
+	return error;
+}