[PATCH 18/25] xfs: scrub directory/attribute btrees

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

Provide a way to check the shape and scrub the hashes and records
in a directory or extended attribute btree.  These are helper functions
for the directory & attribute scrubbers in subsequent patches.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
[fengguang: remove unneeded variable to store return value]
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
---
 fs/xfs/Makefile        |    1 
 fs/xfs/scrub/dabtree.c |  556 ++++++++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/scrub/dabtree.h |   51 ++++
 3 files changed, 608 insertions(+)
 create mode 100644 fs/xfs/scrub/dabtree.c
 create mode 100644 fs/xfs/scrub/dabtree.h


diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index 5a77489..b48437f 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -151,6 +151,7 @@ xfs-y				+= $(addprefix scrub/, \
 				   bmap.o \
 				   btree.o \
 				   common.o \
+				   dabtree.o \
 				   ialloc.o \
 				   inode.o \
 				   refcount.o \
diff --git a/fs/xfs/scrub/dabtree.c b/fs/xfs/scrub/dabtree.c
new file mode 100644
index 0000000..392a76c
--- /dev/null
+++ b/fs/xfs/scrub/dabtree.c
@@ -0,0 +1,556 @@
+/*
+ * 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_inode_fork.h"
+#include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_dir2.h"
+#include "xfs_dir2_priv.h"
+#include "xfs_attr_leaf.h"
+#include "scrub/xfs_scrub.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/trace.h"
+#include "scrub/dabtree.h"
+
+/* Directory/Attribute Btree */
+
+/*
+ * Check for da btree operation errors.  See the section about handling
+ * operational errors in common.c.
+ */
+bool
+xfs_scrub_da_op_ok(
+	struct xfs_scrub_da_btree	*ds,
+	int				level,
+	int				*error)
+{
+	struct xfs_scrub_context	*sc = ds->sc;
+
+	if (*error == 0)
+		return true;
+
+	switch (*error) {
+	case -EDEADLOCK:
+		/* Used to restart an op with deadlock avoidance. */
+		trace_xfs_scrub_deadlock_retry(sc->ip, sc->sm, *error);
+		break;
+	case -EFSBADCRC:
+	case -EFSCORRUPTED:
+		/* Note the badness but don't abort. */
+		sc->sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT;
+		*error = 0;
+		/* fall through */
+	default:
+		trace_xfs_scrub_file_op_error(sc, ds->dargs.whichfork,
+				xfs_dir2_da_to_db(ds->dargs.geo,
+					ds->state->path.blk[level].blkno),
+				*error, __return_address);
+		break;
+	}
+	return false;
+}
+
+/*
+ * Check for da btree corruption.  See the section about handling
+ * operational errors in common.c.
+ */
+void
+xfs_scrub_da_set_corrupt(
+	struct xfs_scrub_da_btree	*ds,
+	int				level)
+{
+	struct xfs_scrub_context	*sc = ds->sc;
+
+	sc->sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT;
+
+	trace_xfs_scrub_fblock_error(sc, ds->dargs.whichfork,
+			xfs_dir2_da_to_db(ds->dargs.geo,
+				ds->state->path.blk[level].blkno),
+			__return_address);
+}
+
+/* Find an entry at a certain level in a da btree. */
+STATIC void *
+xfs_scrub_da_btree_entry(
+	struct xfs_scrub_da_btree	*ds,
+	int				level,
+	int				rec)
+{
+	char				*ents;
+	void				*(*fn)(void *);
+	size_t				sz;
+	struct xfs_da_state_blk		*blk;
+
+	/* Dispatch the entry finding function. */
+	blk = &ds->state->path.blk[level];
+	switch (blk->magic) {
+	case XFS_ATTR_LEAF_MAGIC:
+	case XFS_ATTR3_LEAF_MAGIC:
+		fn = (xfs_da_leaf_ents_fn)xfs_attr3_leaf_entryp;
+		sz = sizeof(struct xfs_attr_leaf_entry);
+		break;
+	case XFS_DIR2_LEAFN_MAGIC:
+	case XFS_DIR3_LEAFN_MAGIC:
+		fn = (xfs_da_leaf_ents_fn)ds->dargs.dp->d_ops->leaf_ents_p;
+		sz = sizeof(struct xfs_dir2_leaf_entry);
+		break;
+	case XFS_DIR2_LEAF1_MAGIC:
+	case XFS_DIR3_LEAF1_MAGIC:
+		fn = (xfs_da_leaf_ents_fn)ds->dargs.dp->d_ops->leaf_ents_p;
+		sz = sizeof(struct xfs_dir2_leaf_entry);
+		break;
+	case XFS_DA_NODE_MAGIC:
+	case XFS_DA3_NODE_MAGIC:
+		fn = (xfs_da_leaf_ents_fn)ds->dargs.dp->d_ops->node_tree_p;
+		sz = sizeof(struct xfs_da_node_entry);
+		break;
+	default:
+		return NULL;
+	}
+
+	ents = fn(blk->bp->b_addr);
+	return ents + (sz * rec);
+}
+
+/* Scrub a da btree hash (key). */
+int
+xfs_scrub_da_btree_hash(
+	struct xfs_scrub_da_btree	*ds,
+	int				level,
+	__be32				*hashp)
+{
+	struct xfs_da_state_blk		*blks;
+	struct xfs_da_node_entry	*btree;
+	xfs_dahash_t			hash;
+	xfs_dahash_t			parent_hash;
+
+	/* Is this hash in order? */
+	hash = be32_to_cpu(*hashp);
+	if (hash < ds->hashes[level])
+		xfs_scrub_da_set_corrupt(ds, level);
+	ds->hashes[level] = hash;
+
+	if (level == 0)
+		return 0;
+
+	/* Is this hash no larger than the parent hash? */
+	blks = ds->state->path.blk;
+	btree = xfs_scrub_da_btree_entry(ds, level - 1, blks[level - 1].index);
+	parent_hash = be32_to_cpu(btree->hashval);
+	if (parent_hash < hash)
+		xfs_scrub_da_set_corrupt(ds, level);
+
+	return 0;
+}
+
+/*
+ * Check a da btree pointer.  Returns true if it's ok to use this
+ * pointer.
+ */
+STATIC bool
+xfs_scrub_da_btree_ptr_ok(
+	struct xfs_scrub_da_btree	*ds,
+	int				level,
+	xfs_dablk_t			blkno)
+{
+	if (blkno < ds->lowest || (ds->highest != 0 && blkno >= ds->highest)) {
+		xfs_scrub_da_set_corrupt(ds, level);
+		return false;
+	}
+
+	return true;
+}
+
+/*
+ * The da btree scrubber can handle leaf1 blocks as a degenerate
+ * form of da btree.  Since the regular da code doesn't handle
+ * leaf1, we must multiplex the verifiers.
+ */
+static void
+xfs_scrub_da_btree_read_verify(
+	struct xfs_buf		*bp)
+{
+	struct xfs_da_blkinfo	*info = bp->b_addr;
+
+	switch (be16_to_cpu(info->magic)) {
+	case XFS_DIR2_LEAF1_MAGIC:
+	case XFS_DIR3_LEAF1_MAGIC:
+		bp->b_ops = &xfs_dir3_leaf1_buf_ops;
+		bp->b_ops->verify_read(bp);
+		return;
+	default:
+		bp->b_ops = &xfs_da3_node_buf_ops;
+		bp->b_ops->verify_read(bp);
+		return;
+	}
+}
+static void
+xfs_scrub_da_btree_write_verify(
+	struct xfs_buf	*bp)
+{
+	struct xfs_da_blkinfo	*info = bp->b_addr;
+
+	switch (be16_to_cpu(info->magic)) {
+	case XFS_DIR2_LEAF1_MAGIC:
+	case XFS_DIR3_LEAF1_MAGIC:
+		bp->b_ops = &xfs_dir3_leaf1_buf_ops;
+		bp->b_ops->verify_write(bp);
+		return;
+	default:
+		bp->b_ops = &xfs_da3_node_buf_ops;
+		bp->b_ops->verify_write(bp);
+		return;
+	}
+}
+
+static const struct xfs_buf_ops xfs_scrub_da_btree_buf_ops = {
+	.name = "xfs_scrub_da_btree",
+	.verify_read = xfs_scrub_da_btree_read_verify,
+	.verify_write = xfs_scrub_da_btree_write_verify,
+};
+
+/* Check a block's sibling. */
+STATIC int
+xfs_scrub_da_btree_block_check_sibling(
+	struct xfs_scrub_da_btree	*ds,
+	int				level,
+	int				direction,
+	xfs_dablk_t			sibling)
+{
+	int				retval;
+	int				error;
+
+	if (!sibling)
+		return 0;
+
+	/* Move the alternate cursor back one block. */
+	memcpy(&ds->state->altpath, &ds->state->path,
+			sizeof(ds->state->altpath));
+	error = xfs_da3_path_shift(ds->state, &ds->state->altpath,
+			direction, false, &retval);
+	if (!xfs_scrub_da_op_ok(ds, level, &error))
+		return error;
+	if (retval) {
+		xfs_scrub_da_set_corrupt(ds, level);
+		return error;
+	}
+
+	if (ds->state->altpath.blk[level].blkno != sibling)
+		xfs_scrub_da_set_corrupt(ds, level);
+	xfs_trans_brelse(ds->dargs.trans, ds->state->altpath.blk[level].bp);
+	return error;
+}
+
+/* Check a block's sibling pointers. */
+STATIC int
+xfs_scrub_da_btree_block_check_siblings(
+	struct xfs_scrub_da_btree	*ds,
+	int				level,
+	struct xfs_da_blkinfo		*hdr)
+{
+	xfs_dablk_t			forw;
+	xfs_dablk_t			back;
+	int				error = 0;
+
+	forw = be32_to_cpu(hdr->forw);
+	back = be32_to_cpu(hdr->back);
+
+	/* Top level blocks should not have sibling pointers. */
+	if (level == 0) {
+		if (forw != 0 || back != 0)
+			xfs_scrub_da_set_corrupt(ds, level);
+		return error;
+	}
+
+	/*
+	 * Check back (left) and forw (right) pointers.  These functions
+	 * absorb error codes for us.
+	 */
+	error = xfs_scrub_da_btree_block_check_sibling(ds, level, 0, back);
+	if (error)
+		goto out;
+	error = xfs_scrub_da_btree_block_check_sibling(ds, level, 1, forw);
+
+out:
+	memset(&ds->state->altpath, 0, sizeof(ds->state->altpath));
+	return error;
+}
+
+/* Load a dir/attribute block from a btree. */
+STATIC int
+xfs_scrub_da_btree_block(
+	struct xfs_scrub_da_btree	*ds,
+	int				level,
+	xfs_dablk_t			blkno)
+{
+	struct xfs_da_state_blk		*blk;
+	struct xfs_da_intnode		*node;
+	struct xfs_da_node_entry	*btree;
+	struct xfs_da3_blkinfo		*hdr3;
+	struct xfs_da_args		*dargs = &ds->dargs;
+	struct xfs_inode		*ip = ds->dargs.dp;
+	xfs_ino_t			owner;
+	int				*pmaxrecs;
+	struct xfs_da3_icnode_hdr	nodehdr;
+	int				error;
+
+	blk = &ds->state->path.blk[level];
+	ds->state->path.active = level + 1;
+
+	/* Release old block. */
+	if (blk->bp) {
+		xfs_trans_brelse(dargs->trans, blk->bp);
+		blk->bp = NULL;
+	}
+
+	/* Check the pointer. */
+	blk->blkno = blkno;
+	if (!xfs_scrub_da_btree_ptr_ok(ds, level, blkno))
+		goto out_nobuf;
+
+	/* Read the buffer. */
+	error = xfs_da_read_buf(dargs->trans, dargs->dp, blk->blkno, -2,
+			&blk->bp, dargs->whichfork,
+			&xfs_scrub_da_btree_buf_ops);
+	if (!xfs_scrub_da_op_ok(ds, level, &error))
+		goto out_nobuf;
+
+	/* It's ok for a directory not to have a da btree in it. */
+	if (ds->dargs.whichfork == XFS_DATA_FORK && level == 0 &&
+			blk->bp == NULL)
+		goto out_nobuf;
+
+	/* It's /not/ ok for attr trees not to have a da btree. */
+	if (blk->bp == NULL) {
+		xfs_scrub_da_set_corrupt(ds, level);
+		goto out_nobuf;
+	}
+
+	hdr3 = blk->bp->b_addr;
+	blk->magic = be16_to_cpu(hdr3->hdr.magic);
+	pmaxrecs = &ds->maxrecs[level];
+
+	/* Check the owner. */
+	if (xfs_sb_version_hascrc(&ip->i_mount->m_sb)) {
+		owner = be64_to_cpu(hdr3->owner);
+		if (owner != ip->i_ino)
+			xfs_scrub_da_set_corrupt(ds, level);
+	}
+
+	/* Check the siblings. */
+	error = xfs_scrub_da_btree_block_check_siblings(ds, level, &hdr3->hdr);
+	if (error)
+		goto out;
+
+	/* Interpret the buffer. */
+	switch (blk->magic) {
+	case XFS_ATTR_LEAF_MAGIC:
+	case XFS_ATTR3_LEAF_MAGIC:
+		xfs_trans_buf_set_type(dargs->trans, blk->bp,
+				XFS_BLFT_ATTR_LEAF_BUF);
+		blk->magic = XFS_ATTR_LEAF_MAGIC;
+		blk->hashval = xfs_attr_leaf_lasthash(blk->bp, pmaxrecs);
+		if (ds->tree_level != 0)
+			xfs_scrub_da_set_corrupt(ds, level);
+		break;
+	case XFS_DIR2_LEAFN_MAGIC:
+	case XFS_DIR3_LEAFN_MAGIC:
+		xfs_trans_buf_set_type(dargs->trans, blk->bp,
+				XFS_BLFT_DIR_LEAFN_BUF);
+		blk->magic = XFS_DIR2_LEAFN_MAGIC;
+		blk->hashval = xfs_dir2_leaf_lasthash(ip, blk->bp, pmaxrecs);
+		if (ds->tree_level != 0)
+			xfs_scrub_da_set_corrupt(ds, level);
+		break;
+	case XFS_DIR2_LEAF1_MAGIC:
+	case XFS_DIR3_LEAF1_MAGIC:
+		xfs_trans_buf_set_type(dargs->trans, blk->bp,
+				XFS_BLFT_DIR_LEAF1_BUF);
+		blk->magic = XFS_DIR2_LEAF1_MAGIC;
+		blk->hashval = xfs_dir2_leaf_lasthash(ip, blk->bp, pmaxrecs);
+		if (ds->tree_level != 0)
+			xfs_scrub_da_set_corrupt(ds, level);
+		break;
+	case XFS_DA_NODE_MAGIC:
+	case XFS_DA3_NODE_MAGIC:
+		xfs_trans_buf_set_type(dargs->trans, blk->bp,
+				XFS_BLFT_DA_NODE_BUF);
+		blk->magic = XFS_DA_NODE_MAGIC;
+		node = blk->bp->b_addr;
+		ip->d_ops->node_hdr_from_disk(&nodehdr, node);
+		btree = ip->d_ops->node_tree_p(node);
+		*pmaxrecs = nodehdr.count;
+		blk->hashval = be32_to_cpu(btree[*pmaxrecs - 1].hashval);
+		if (level == 0) {
+			if (nodehdr.level >= XFS_DA_NODE_MAXDEPTH) {
+				xfs_scrub_da_set_corrupt(ds, level);
+				goto out_freebp;
+			}
+			ds->tree_level = nodehdr.level;
+		} else {
+			if (ds->tree_level != nodehdr.level) {
+				xfs_scrub_da_set_corrupt(ds, level);
+				goto out_freebp;
+			}
+		}
+		break;
+	default:
+		xfs_scrub_da_set_corrupt(ds, level);
+		goto out_freebp;
+	}
+
+out:
+	return error;
+out_freebp:
+	xfs_trans_brelse(dargs->trans, blk->bp);
+	blk->bp = NULL;
+out_nobuf:
+	blk->blkno = 0;
+	return error;
+}
+
+/* Visit all nodes and leaves of a da btree. */
+int
+xfs_scrub_da_btree(
+	struct xfs_scrub_context	*sc,
+	int				whichfork,
+	xfs_scrub_da_btree_rec_fn	scrub_fn)
+{
+	struct xfs_scrub_da_btree	ds;
+	struct xfs_mount		*mp = sc->mp;
+	struct xfs_da_state_blk		*blks;
+	struct xfs_da_node_entry	*key;
+	void				*rec;
+	xfs_dablk_t			blkno;
+	bool				is_attr;
+	int				level;
+	int				error;
+
+	memset(&ds, 0, sizeof(ds));
+	/* Skip short format data structures; no btree to scan. */
+	if (XFS_IFORK_FORMAT(sc->ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
+	    XFS_IFORK_FORMAT(sc->ip, whichfork) != XFS_DINODE_FMT_BTREE)
+		return 0;
+
+	/* Set up initial da state. */
+	is_attr = whichfork == XFS_ATTR_FORK;
+	ds.dargs.geo = is_attr ? mp->m_attr_geo : mp->m_dir_geo;
+	ds.dargs.dp = sc->ip;
+	ds.dargs.whichfork = whichfork;
+	ds.dargs.trans = sc->tp;
+	ds.dargs.op_flags = XFS_DA_OP_OKNOENT;
+	ds.state = xfs_da_state_alloc();
+	ds.state->args = &ds.dargs;
+	ds.state->mp = mp;
+	ds.sc = sc;
+	blkno = ds.lowest = is_attr ? 0 : ds.dargs.geo->leafblk;
+	ds.highest = is_attr ? 0 : ds.dargs.geo->freeblk;
+	level = 0;
+
+	/* Find the root of the da tree, if present. */
+	blks = ds.state->path.blk;
+	error = xfs_scrub_da_btree_block(&ds, level, blkno);
+	if (error)
+		goto out_state;
+	if (blks[level].bp == NULL)
+		goto out_state;
+
+	blks[level].index = 0;
+	while (level >= 0 && level < XFS_DA_NODE_MAXDEPTH) {
+		/* Handle leaf block. */
+		if (blks[level].magic != XFS_DA_NODE_MAGIC) {
+			/* End of leaf, pop back towards the root. */
+			if (blks[level].index >= ds.maxrecs[level]) {
+				if (level > 0)
+					blks[level - 1].index++;
+				ds.tree_level++;
+				level--;
+				continue;
+			}
+
+			/* Dispatch record scrubbing. */
+			rec = xfs_scrub_da_btree_entry(&ds, level,
+					blks[level].index);
+			error = scrub_fn(&ds, level, rec);
+			if (error < 0 ||
+			    error == XFS_BTREE_QUERY_RANGE_ABORT)
+				break;
+			if (xfs_scrub_should_terminate(sc, &error))
+				break;
+
+			blks[level].index++;
+			continue;
+		}
+
+
+		/* End of node, pop back towards the root. */
+		if (blks[level].index >= ds.maxrecs[level]) {
+			if (level > 0)
+				blks[level - 1].index++;
+			ds.tree_level++;
+			level--;
+			continue;
+		}
+
+		/* Hashes in order for scrub? */
+		key = xfs_scrub_da_btree_entry(&ds, level, blks[level].index);
+		error = xfs_scrub_da_btree_hash(&ds, level, &key->hashval);
+		if (error)
+			goto out;
+
+		/* Drill another level deeper. */
+		blkno = be32_to_cpu(key->before);
+		level++;
+		ds.tree_level--;
+		error = xfs_scrub_da_btree_block(&ds, level, blkno);
+		if (error)
+			goto out;
+		if (blks[level].bp == NULL)
+			goto out;
+
+		blks[level].index = 0;
+	}
+
+out:
+	/* Release all the buffers we're tracking. */
+	for (level = 0; level < XFS_DA_NODE_MAXDEPTH; level++) {
+		if (blks[level].bp == NULL)
+			continue;
+		xfs_trans_brelse(sc->tp, blks[level].bp);
+		blks[level].bp = NULL;
+	}
+
+out_state:
+	xfs_da_state_free(ds.state);
+	return error;
+}
diff --git a/fs/xfs/scrub/dabtree.h b/fs/xfs/scrub/dabtree.h
new file mode 100644
index 0000000..04e400d
--- /dev/null
+++ b/fs/xfs/scrub/dabtree.h
@@ -0,0 +1,51 @@
+/*
+ * 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.
+ */
+#ifndef __XFS_SCRUB_DABTREE_H__
+#define __XFS_SCRUB_DABTREE_H__
+
+/* dir/attr btree */
+
+struct xfs_scrub_da_btree {
+	struct xfs_da_args		dargs;
+	xfs_dahash_t			hashes[XFS_DA_NODE_MAXDEPTH];
+	int				maxrecs[XFS_DA_NODE_MAXDEPTH];
+	struct xfs_da_state		*state;
+	struct xfs_scrub_context	*sc;
+	xfs_dablk_t			lowest;
+	xfs_dablk_t			highest;
+	int				tree_level;
+};
+
+typedef void *(*xfs_da_leaf_ents_fn)(void *);
+typedef int (*xfs_scrub_da_btree_rec_fn)(struct xfs_scrub_da_btree *ds,
+		int level, void *rec);
+
+/* Check for da btree operation errors. */
+bool xfs_scrub_da_op_ok(struct xfs_scrub_da_btree *ds, int level, int *error);
+
+/* Check for da btree corruption. */
+void xfs_scrub_da_set_corrupt(struct xfs_scrub_da_btree *ds, int level);
+
+int xfs_scrub_da_btree_hash(struct xfs_scrub_da_btree *ds, int level,
+			    __be32 *hashp);
+int xfs_scrub_da_btree(struct xfs_scrub_context *sc, int whichfork,
+		       xfs_scrub_da_btree_rec_fn scrub_fn);
+
+#endif /* __XFS_SCRUB_DABTREE_H__ */