Merge tag 'scrub-dir-iget-fixes-6.4_2023-04-12' of...

Merge tag 'scrub-dir-iget-fixes-6.4_2023-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into guilt/xfs-for-next

xfs: fix iget usage in directory scrub [v24.5]

In this series, we fix some problems with how the directory scrubber
grabs child inodes.  First, we want to reduce EDEADLOCK returns by
replacing fixed-iteration loops with interruptible trylock loops.
Second, we add UNTRUSTED to the child iget call so that we can detect a
dirent that points to an unallocated inode.  Third, we fix a bug where
we weren't checking the inode pointed to by dotdot entries at all.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/Makefile

@@ -158,6 +158,7 @@ xfs-y				+= $(addprefix scrub/, \
 				   ialloc.o \
 				   inode.o \
 				   parent.o \
+				   readdir.o \
 				   refcount.o \
 				   rmap.o \
 				   scrub.o \

fs/xfs/scrub/parent.c

@@ -16,6 +16,7 @@
 #include "xfs_dir2_priv.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
+#include "scrub/readdir.h"
 
 /* Set us up to scrub parents. */
 int
@@ -30,39 +31,36 @@ xchk_setup_parent(
 /* Look for an entry in a parent pointing to this inode. */
 
 struct xchk_parent_ctx {
-	struct dir_context	dc;
 	struct xfs_scrub	*sc;
-	xfs_ino_t		ino;
 	xfs_nlink_t		nlink;
-	bool			cancelled;
 };
 
 /* Look for a single entry in a directory pointing to an inode. */
-STATIC bool
+STATIC int
 xchk_parent_actor(
-	struct dir_context	*dc,
-	const char		*name,
-	int			namelen,
-	loff_t			pos,
-	u64			ino,
-	unsigned		type)
+	struct xfs_scrub	*sc,
+	struct xfs_inode	*dp,
+	xfs_dir2_dataptr_t	dapos,
+	const struct xfs_name	*name,
+	xfs_ino_t		ino,
+	void			*priv)
 {
-	struct xchk_parent_ctx	*spc;
+	struct xchk_parent_ctx	*spc = priv;
 	int			error = 0;
 
-	spc = container_of(dc, struct xchk_parent_ctx, dc);
-	if (spc->ino == ino)
+	/* Does this name make sense? */
+	if (!xfs_dir2_namecheck(name->name, name->len))
+		error = -EFSCORRUPTED;
+	if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, 0, &error))
+		return error;
+
+	if (sc->ip->i_ino == ino)
 		spc->nlink++;
 
-	/*
-	 * If we're facing a fatal signal, bail out.  Store the cancellation
-	 * status separately because the VFS readdir code squashes error codes
-	 * into short directory reads.
-	 */
 	if (xchk_should_terminate(spc->sc, &error))
-		spc->cancelled = true;
+		return error;
 
-	return !error;
+	return 0;
 }
 
 /* Count the number of dentries in the parent dir that point to this inode. */
@@ -73,50 +71,19 @@ xchk_parent_count_parent_dentries(
 	xfs_nlink_t		*nlink)
 {
 	struct xchk_parent_ctx	spc = {
-		.dc.actor	= xchk_parent_actor,
-		.ino		= sc->ip->i_ino,
 		.sc		= sc,
+		.nlink		= 0,
 	};
-	size_t			bufsize;
-	loff_t			oldpos;
 	uint			lock_mode;
 	int			error = 0;
 
-	/*
-	 * If there are any blocks, read-ahead block 0 as we're almost
-	 * certain to have the next operation be a read there.  This is
-	 * how we guarantee that the parent's extent map has been loaded,
-	 * if there is one.
-	 */
 	lock_mode = xfs_ilock_data_map_shared(parent);
-	if (parent->i_df.if_nextents > 0)
-		error = xfs_dir3_data_readahead(parent, 0, 0);
+	error = xchk_dir_walk(sc, parent, xchk_parent_actor, &spc);
 	xfs_iunlock(parent, lock_mode);
 	if (error)
 		return error;
 
-	/*
-	 * Iterate the parent dir to confirm that there is
-	 * exactly one entry pointing back to the inode being
-	 * scanned.
-	 */
-	bufsize = (size_t)min_t(loff_t, XFS_READDIR_BUFSIZE,
-			parent->i_disk_size);
-	oldpos = 0;
-	while (true) {
-		error = xfs_readdir(sc->tp, parent, &spc.dc, bufsize);
-		if (error)
-			goto out;
-		if (spc.cancelled) {
-			error = -EAGAIN;
-			goto out;
-		}
-		if (oldpos == spc.dc.pos)
-			break;
-		oldpos = spc.dc.pos;
-	}
 	*nlink = spc.nlink;
-out:
 	return error;
 }
 

fs/xfs/scrub/readdir.c

+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2022-2023 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_inode.h"
+#include "xfs_dir2.h"
+#include "xfs_dir2_priv.h"
+#include "xfs_trace.h"
+#include "xfs_bmap.h"
+#include "xfs_trans.h"
+#include "xfs_error.h"
+#include "scrub/scrub.h"
+#include "scrub/readdir.h"
+
+/* Call a function for every entry in a shortform directory. */
+STATIC int
+xchk_dir_walk_sf(
+	struct xfs_scrub	*sc,
+	struct xfs_inode	*dp,
+	xchk_dirent_fn		dirent_fn,
+	void			*priv)
+{
+	struct xfs_name		name = {
+		.name		= ".",
+		.len		= 1,
+		.type		= XFS_DIR3_FT_DIR,
+	};
+	struct xfs_mount	*mp = dp->i_mount;
+	struct xfs_da_geometry	*geo = mp->m_dir_geo;
+	struct xfs_dir2_sf_entry *sfep;
+	struct xfs_dir2_sf_hdr	*sfp;
+	xfs_ino_t		ino;
+	xfs_dir2_dataptr_t	dapos;
+	unsigned int		i;
+	int			error;
+
+	ASSERT(dp->i_df.if_bytes == dp->i_disk_size);
+	ASSERT(dp->i_df.if_u1.if_data != NULL);
+
+	sfp = (struct xfs_dir2_sf_hdr *)dp->i_df.if_u1.if_data;
+
+	/* dot entry */
+	dapos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
+			geo->data_entry_offset);
+
+	error = dirent_fn(sc, dp, dapos, &name, dp->i_ino, priv);
+	if (error)
+		return error;
+
+	/* dotdot entry */
+	dapos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
+			geo->data_entry_offset +
+			xfs_dir2_data_entsize(mp, sizeof(".") - 1));
+	ino = xfs_dir2_sf_get_parent_ino(sfp);
+	name.name = "..";
+	name.len = 2;
+
+	error = dirent_fn(sc, dp, dapos, &name, ino, priv);
+	if (error)
+		return error;
+
+	/* iterate everything else */
+	sfep = xfs_dir2_sf_firstentry(sfp);
+	for (i = 0; i < sfp->count; i++) {
+		dapos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
+				xfs_dir2_sf_get_offset(sfep));
+		ino = xfs_dir2_sf_get_ino(mp, sfp, sfep);
+		name.name = sfep->name;
+		name.len = sfep->namelen;
+		name.type = xfs_dir2_sf_get_ftype(mp, sfep);
+
+		error = dirent_fn(sc, dp, dapos, &name, ino, priv);
+		if (error)
+			return error;
+
+		sfep = xfs_dir2_sf_nextentry(mp, sfp, sfep);
+	}
+
+	return 0;
+}
+
+/* Call a function for every entry in a block directory. */
+STATIC int
+xchk_dir_walk_block(
+	struct xfs_scrub	*sc,
+	struct xfs_inode	*dp,
+	xchk_dirent_fn		dirent_fn,
+	void			*priv)
+{
+	struct xfs_mount	*mp = dp->i_mount;
+	struct xfs_da_geometry	*geo = mp->m_dir_geo;
+	struct xfs_buf		*bp;
+	unsigned int		off, next_off, end;
+	int			error;
+
+	error = xfs_dir3_block_read(sc->tp, dp, &bp);
+	if (error)
+		return error;
+
+	/* Walk each directory entry. */
+	end = xfs_dir3_data_end_offset(geo, bp->b_addr);
+	for (off = geo->data_entry_offset; off < end; off = next_off) {
+		struct xfs_name			name = { };
+		struct xfs_dir2_data_unused	*dup = bp->b_addr + off;
+		struct xfs_dir2_data_entry	*dep = bp->b_addr + off;
+		xfs_ino_t			ino;
+		xfs_dir2_dataptr_t		dapos;
+
+		/* Skip an empty entry. */
+		if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
+			next_off = off + be16_to_cpu(dup->length);
+			continue;
+		}
+
+		/* Otherwise, find the next entry and report it. */
+		next_off = off + xfs_dir2_data_entsize(mp, dep->namelen);
+		if (next_off > end)
+			break;
+
+		dapos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk, off);
+		ino = be64_to_cpu(dep->inumber);
+		name.name = dep->name;
+		name.len = dep->namelen;
+		name.type = xfs_dir2_data_get_ftype(mp, dep);
+
+		error = dirent_fn(sc, dp, dapos, &name, ino, priv);
+		if (error)
+			break;
+	}
+
+	xfs_trans_brelse(sc->tp, bp);
+	return error;
+}
+
+/* Read a leaf-format directory buffer. */
+STATIC int
+xchk_read_leaf_dir_buf(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*dp,
+	struct xfs_da_geometry	*geo,
+	xfs_dir2_off_t		*curoff,
+	struct xfs_buf		**bpp)
+{
+	struct xfs_iext_cursor	icur;
+	struct xfs_bmbt_irec	map;
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(dp, XFS_DATA_FORK);
+	xfs_dablk_t		last_da;
+	xfs_dablk_t		map_off;
+	xfs_dir2_off_t		new_off;
+
+	*bpp = NULL;
+
+	/*
+	 * Look for mapped directory blocks at or above the current offset.
+	 * Truncate down to the nearest directory block to start the scanning
+	 * operation.
+	 */
+	last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
+	map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *curoff));
+
+	if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map))
+		return 0;
+	if (map.br_startoff >= last_da)
+		return 0;
+	xfs_trim_extent(&map, map_off, last_da - map_off);
+
+	/* Read the directory block of that first mapping. */
+	new_off = xfs_dir2_da_to_byte(geo, map.br_startoff);
+	if (new_off > *curoff)
+		*curoff = new_off;
+
+	return xfs_dir3_data_read(tp, dp, map.br_startoff, 0, bpp);
+}
+
+/* Call a function for every entry in a leaf directory. */
+STATIC int
+xchk_dir_walk_leaf(
+	struct xfs_scrub	*sc,
+	struct xfs_inode	*dp,
+	xchk_dirent_fn		dirent_fn,
+	void			*priv)
+{
+	struct xfs_mount	*mp = dp->i_mount;
+	struct xfs_da_geometry	*geo = mp->m_dir_geo;
+	struct xfs_buf		*bp = NULL;
+	xfs_dir2_off_t		curoff = 0;
+	unsigned int		offset = 0;
+	int			error;
+
+	/* Iterate every directory offset in this directory. */
+	while (curoff < XFS_DIR2_LEAF_OFFSET) {
+		struct xfs_name			name = { };
+		struct xfs_dir2_data_unused	*dup;
+		struct xfs_dir2_data_entry	*dep;
+		xfs_ino_t			ino;
+		unsigned int			length;
+		xfs_dir2_dataptr_t		dapos;
+
+		/*
+		 * If we have no buffer, or we're off the end of the
+		 * current buffer, need to get another one.
+		 */
+		if (!bp || offset >= geo->blksize) {
+			if (bp) {
+				xfs_trans_brelse(sc->tp, bp);
+				bp = NULL;
+			}
+
+			error = xchk_read_leaf_dir_buf(sc->tp, dp, geo, &curoff,
+					&bp);
+			if (error || !bp)
+				break;
+
+			/*
+			 * Find our position in the block.
+			 */
+			offset = geo->data_entry_offset;
+			curoff += geo->data_entry_offset;
+		}
+
+		/* Skip an empty entry. */
+		dup = bp->b_addr + offset;
+		if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
+			length = be16_to_cpu(dup->length);
+			offset += length;
+			curoff += length;
+			continue;
+		}
+
+		/* Otherwise, find the next entry and report it. */
+		dep = bp->b_addr + offset;
+		length = xfs_dir2_data_entsize(mp, dep->namelen);
+
+		dapos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
+		ino = be64_to_cpu(dep->inumber);
+		name.name = dep->name;
+		name.len = dep->namelen;
+		name.type = xfs_dir2_data_get_ftype(mp, dep);
+
+		error = dirent_fn(sc, dp, dapos, &name, ino, priv);
+		if (error)
+			break;
+
+		/* Advance to the next entry. */
+		offset += length;
+		curoff += length;
+	}
+
+	if (bp)
+		xfs_trans_brelse(sc->tp, bp);
+	return error;
+}
+
+/*
+ * Call a function for every entry in a directory.
+ *
+ * Callers must hold the ILOCK.  File types are XFS_DIR3_FT_*.
+ */
+int
+xchk_dir_walk(
+	struct xfs_scrub	*sc,
+	struct xfs_inode	*dp,
+	xchk_dirent_fn		dirent_fn,
+	void			*priv)
+{
+	struct xfs_da_args	args = {
+		.dp		= dp,
+		.geo		= dp->i_mount->m_dir_geo,
+		.trans		= sc->tp,
+	};
+	bool			isblock;
+	int			error;
+
+	if (xfs_is_shutdown(dp->i_mount))
+		return -EIO;
+
+	ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
+	ASSERT(xfs_isilocked(dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
+
+	if (dp->i_df.if_format == XFS_DINODE_FMT_LOCAL)
+		return xchk_dir_walk_sf(sc, dp, dirent_fn, priv);
+
+	/* dir2 functions require that the data fork is loaded */
+	error = xfs_iread_extents(sc->tp, dp, XFS_DATA_FORK);
+	if (error)
+		return error;
+
+	error = xfs_dir2_isblock(&args, &isblock);
+	if (error)
+		return error;
+
+	if (isblock)
+		return xchk_dir_walk_block(sc, dp, dirent_fn, priv);
+
+	return xchk_dir_walk_leaf(sc, dp, dirent_fn, priv);
+}
+
+/*
+ * Look up the inode number for an exact name in a directory.
+ *
+ * Callers must hold the ILOCK.  File types are XFS_DIR3_FT_*.  Names are not
+ * checked for correctness.
+ */
+int
+xchk_dir_lookup(
+	struct xfs_scrub	*sc,
+	struct xfs_inode	*dp,
+	const struct xfs_name	*name,
+	xfs_ino_t		*ino)
+{
+	struct xfs_da_args	args = {
+		.dp		= dp,
+		.geo		= dp->i_mount->m_dir_geo,
+		.trans		= sc->tp,
+		.name		= name->name,
+		.namelen	= name->len,
+		.filetype	= name->type,
+		.hashval	= xfs_dir2_hashname(dp->i_mount, name),
+		.whichfork	= XFS_DATA_FORK,
+		.op_flags	= XFS_DA_OP_OKNOENT,
+	};
+	bool			isblock, isleaf;
+	int			error;
+
+	if (xfs_is_shutdown(dp->i_mount))
+		return -EIO;
+
+	ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
+	ASSERT(xfs_isilocked(dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
+
+	if (dp->i_df.if_format == XFS_DINODE_FMT_LOCAL) {
+		error = xfs_dir2_sf_lookup(&args);
+		goto out_check_rval;
+	}
+
+	/* dir2 functions require that the data fork is loaded */
+	error = xfs_iread_extents(sc->tp, dp, XFS_DATA_FORK);
+	if (error)
+		return error;
+
+	error = xfs_dir2_isblock(&args, &isblock);
+	if (error)
+		return error;
+
+	if (isblock) {
+		error = xfs_dir2_block_lookup(&args);
+		goto out_check_rval;
+	}
+
+	error = xfs_dir2_isleaf(&args, &isleaf);
+	if (error)
+		return error;
+
+	if (isleaf) {
+		error = xfs_dir2_leaf_lookup(&args);
+		goto out_check_rval;
+	}
+
+	error = xfs_dir2_node_lookup(&args);
+
+out_check_rval:
+	if (error == -EEXIST)
+		error = 0;
+	if (!error)
+		*ino = args.inumber;
+	return error;
+}

fs/xfs/scrub/readdir.h

+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2022-2023 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_SCRUB_READDIR_H__
+#define __XFS_SCRUB_READDIR_H__
+
+typedef int (*xchk_dirent_fn)(struct xfs_scrub *sc, struct xfs_inode *dp,
+		xfs_dir2_dataptr_t dapos, const struct xfs_name *name,
+		xfs_ino_t ino, void *priv);
+
+int xchk_dir_walk(struct xfs_scrub *sc, struct xfs_inode *dp,
+		xchk_dirent_fn dirent_fn, void *priv);
+
+int xchk_dir_lookup(struct xfs_scrub *sc, struct xfs_inode *dp,
+		const struct xfs_name *name, xfs_ino_t *ino);
+
+#endif /* __XFS_SCRUB_READDIR_H__ */