[PATCH 4/4] xfs: fix corruptions in the directory tree

Darrick J. Wong
2024-04-16T01:41:25Z

Repair corruptions in the directory tree itself. Cycles are broken by
removing an incoming parent->child link. Multiply-owned directories are
fixed by pruning the extra parent -> child links Disconnected subtrees
are reconnected to the lost and found.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
fs/xfs/Makefile | 1
fs/xfs/scrub/dirtree.c | 38 ++
fs/xfs/scrub/dirtree.h | 29 +
fs/xfs/scrub/dirtree_repair.c | 821 +++++++++++++++++++++++++++++++++++++++++
fs/xfs/scrub/orphanage.c | 6
fs/xfs/scrub/orphanage.h | 8
fs/xfs/scrub/repair.h | 4
fs/xfs/scrub/scrub.c | 2
fs/xfs/scrub/trace.h | 23 +
fs/xfs/xfs_inode.c | 2
fs/xfs/xfs_inode.h | 1
11 files changed, 927 insertions(+), 8 deletions(-)
create mode 100644 fs/xfs/scrub/dirtree_repair.c

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index 8ec0dd257a984..d1ce1213797be 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -204,6 +204,7 @@ xfs-y += $(addprefix scrub/, \
bmap_repair.o \
cow_repair.o \
dir_repair.o \
+ dirtree_repair.o \
findparent.o \
fscounters_repair.o \
ialloc_repair.o \
diff --git a/fs/xfs/scrub/dirtree.c b/fs/xfs/scrub/dirtree.c
index ecc56eb5ed270..bde58fb561ea1 100644
--- a/fs/xfs/scrub/dirtree.c
+++ b/fs/xfs/scrub/dirtree.c
@@ -26,6 +26,8 @@
#include "scrub/xfblob.h"
#include "scrub/listxattr.h"
#include "scrub/trace.h"
+#include "scrub/repair.h"
+#include "scrub/orphanage.h"
#include "scrub/dirtree.h"

/*
@@ -95,6 +97,12 @@ xchk_setup_dirtree(

xchk_fsgates_enable(sc, XCHK_FSGATES_DIRENTS);

+ if (xchk_could_repair(sc)) {
+ error = xrep_setup_dirtree(sc);
+ if (error)
+ return error;
+ }
+
dl = kvzalloc(sizeof(struct xchk_dirtree), XCHK_GFP_FLAGS);
if (!dl)
return -ENOMEM;
@@ -104,6 +112,7 @@ xchk_setup_dirtree(
INIT_LIST_HEAD(&dl->path_list);
dl->root_ino = NULLFSINO;
dl->scan_ino = NULLFSINO;
+ dl->parent_ino = NULLFSINO;

mutex_init(&dl->lock);

@@ -142,7 +151,7 @@ xchk_setup_dirtree(
* Add the parent pointer described by @dl->pptr to the given path as a new
* step. Returns -ELNRNG if the path is too deep.
*/
-STATIC int
+int
xchk_dirpath_append(
struct xchk_dirtree *dl,
struct xfs_inode *ip,
@@ -609,6 +618,22 @@ xchk_dirpath_step_is_stale(
if (memcmp(dl->hook_xname.name, p->name->name, p->name->len) != 0)
return 0;

+ /*
+ * If the update comes from the repair code itself, walk the state
+ * machine forward.
+ */
+ if (p->ip->i_ino == dl->scan_ino &&
+ path->outcome == XREP_DIRPATH_ADOPTING) {
+ xchk_dirpath_set_outcome(dl, path, XREP_DIRPATH_ADOPTED);
+ return 0;
+ }
+
+ if (p->ip->i_ino == dl->scan_ino &&
+ path->outcome == XREP_DIRPATH_DELETING) {
+ xchk_dirpath_set_outcome(dl, path, XREP_DIRPATH_DELETED);
+ return 0;
+ }
+
/* Exact match, scan data is out of date. */
trace_xchk_dirpath_changed(dl->sc, path->path_nr, step_nr, p->dp,
p->ip, p->name);
@@ -747,7 +772,7 @@ xchk_dirtree_load_path(
* path was too deep; -ENOSR if there were too many parent pointers; or
* a negative errno.
*/
-STATIC int
+int
xchk_dirtree_find_paths_to_root(
struct xchk_dirtree *dl)
{
@@ -819,7 +844,7 @@ xchk_dirtree_find_paths_to_root(
* Figure out what to do with the paths we tried to find. Do not call this
* if the scan results are stale.
*/
-STATIC void
+void
xchk_dirtree_evaluate(
struct xchk_dirtree *dl,
struct xchk_dirtree_outcomes *oc)
@@ -856,6 +881,13 @@ xchk_dirtree_evaluate(
/* This path got all the way to the root. */
oc->good++;
break;
+ case XREP_DIRPATH_DELETING:
+ case XREP_DIRPATH_DELETED:
+ case XREP_DIRPATH_ADOPTING:
+ case XREP_DIRPATH_ADOPTED:
+ /* These should not be in progress! */
+ ASSERT(0);
+ break;
}
}

diff --git a/fs/xfs/scrub/dirtree.h b/fs/xfs/scrub/dirtree.h
index 2ddbcf43c2915..1e1686365c61c 100644
--- a/fs/xfs/scrub/dirtree.h
+++ b/fs/xfs/scrub/dirtree.h
@@ -26,6 +26,11 @@ enum xchk_dirpath_outcome {
XCHK_DIRPATH_LOOP, /* cycle detected further up */
XCHK_DIRPATH_STALE, /* path is stale */
XCHK_DIRPATH_OK, /* path reaches the root */
+
+ XREP_DIRPATH_DELETING, /* path is being deleted */
+ XREP_DIRPATH_DELETED, /* path has been deleted */
+ XREP_DIRPATH_ADOPTING, /* path is being adopted */
+ XREP_DIRPATH_ADOPTED, /* path has been adopted */
};

/*
@@ -64,6 +69,9 @@ struct xchk_dirtree_outcomes {

/* Number of XCHK_DIRPATH_OK */
unsigned int good;
+
+ /* Directory needs to be added to lost+found */
+ bool needs_adoption;
};

struct xchk_dirtree {
@@ -79,6 +87,14 @@ struct xchk_dirtree {
*/
xfs_ino_t scan_ino;

+ /*
+ * If we start deleting redundant paths to this subdirectory, this is
+ * the inode number of the surviving parent and the dotdot entry will
+ * be set to this value. If the value is NULLFSINO, then use @root_ino
+ * as a stand-in until the orphanage can adopt the subdirectory.
+ */
+ xfs_ino_t parent_ino;
+
/* Scratch buffer for scanning pptr xattrs */
struct xfs_parent_rec pptr_rec;
struct xfs_da_args pptr_args;
@@ -87,12 +103,18 @@ struct xchk_dirtree {
struct xfs_name xname;
char namebuf[MAXNAMELEN];

+ /* Information for reparenting this directory. */
+ struct xrep_adoption adoption;
+
/*
* Hook into directory updates so that we can receive live updates
* from other writer threads.
*/
struct xfs_dir_hook dhook;

+ /* Parent pointer update arguments. */
+ struct xfs_parent_args ppargs;
+
/* lock for everything below here */
struct mutex lock;

@@ -146,4 +168,11 @@ xchk_dirtree_parentless(const struct xchk_dirtree *dl)
return false;
}

+int xchk_dirtree_find_paths_to_root(struct xchk_dirtree *dl);
+int xchk_dirpath_append(struct xchk_dirtree *dl, struct xfs_inode *ip,
+ struct xchk_dirpath *path, const struct xfs_name *name,
+ const struct xfs_parent_rec *pptr);
+void xchk_dirtree_evaluate(struct xchk_dirtree *dl,
+ struct xchk_dirtree_outcomes *oc);
+
#endif /* __XFS_SCRUB_DIRTREE_H__ */
diff --git a/fs/xfs/scrub/dirtree_repair.c b/fs/xfs/scrub/dirtree_repair.c
new file mode 100644
index 0000000000000..5c04e70ba9518
--- /dev/null
+++ b/fs/xfs/scrub/dirtree_repair.c
@@ -0,0 +1,821 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2023-2024 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_trans_resv.h"
+#include "xfs_trans_space.h"
+#include "xfs_mount.h"
+#include "xfs_log_format.h"
+#include "xfs_trans.h"
+#include "xfs_inode.h"
+#include "xfs_icache.h"
+#include "xfs_dir2.h"
+#include "xfs_dir2_priv.h"
+#include "xfs_attr.h"
+#include "xfs_parent.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/bitmap.h"
+#include "scrub/ino_bitmap.h"
+#include "scrub/xfile.h"
+#include "scrub/xfarray.h"
+#include "scrub/xfblob.h"
+#include "scrub/listxattr.h"
+#include "scrub/trace.h"
+#include "scrub/repair.h"
+#include "scrub/orphanage.h"
+#include "scrub/dirtree.h"
+#include "scrub/readdir.h"
+
+/*
+ * Directory Tree Structure Repairs
+ * ================================
+ *
+ * If we decide that the directory being scanned is participating in a
+ * directory loop, the only change we can make is to remove directory entries
+ * pointing down to @sc->ip. If that leaves it with no parents, the directory
+ * should be adopted by the orphanage.
+ */
+
+/* Set up to repair directory loops. */
+int
+xrep_setup_dirtree(
+ struct xfs_scrub *sc)
+{
+ return xrep_orphanage_try_create(sc);
+}
+
+/* Change the outcome of this path. */
+static inline void
+xrep_dirpath_set_outcome(
+ struct xchk_dirtree *dl,
+ struct xchk_dirpath *path,
+ enum xchk_dirpath_outcome outcome)
+{
+ trace_xrep_dirpath_set_outcome(dl->sc, path->path_nr, path->nr_steps,
+ outcome);
+
+ path->outcome = outcome;
+}
+
+/* Delete all paths. */
+STATIC void
+xrep_dirtree_delete_all_paths(
+ struct xchk_dirtree *dl,
+ struct xchk_dirtree_outcomes *oc)
+{
+ struct xchk_dirpath *path;
+
+ xchk_dirtree_for_each_path(dl, path) {
+ switch (path->outcome) {
+ case XCHK_DIRPATH_CORRUPT:
+ case XCHK_DIRPATH_LOOP:
+ oc->suspect--;
+ oc->bad++;
+ xrep_dirpath_set_outcome(dl, path, XCHK_DIRPATH_DELETE);
+ break;
+ case XCHK_DIRPATH_OK:
+ oc->good--;
+ oc->bad++;
+ xrep_dirpath_set_outcome(dl, path, XCHK_DIRPATH_DELETE);
+ break;
+ default:
+ break;
+ }
+ }
+
+ ASSERT(oc->suspect == 0);
+ ASSERT(oc->good == 0);
+}
+
+/* Since this is the surviving path, set the dotdot entry to this value. */
+STATIC void
+xrep_dirpath_retain_parent(
+ struct xchk_dirtree *dl,
+ struct xchk_dirpath *path)
+{
+ struct xchk_dirpath_step step;
+ int error;
+
+ error = xfarray_load(dl->path_steps, path->first_step, &step);
+ if (error)
+ return;
+
+ dl->parent_ino = be64_to_cpu(step.pptr_rec.p_ino);
+}
+
+/* Find the one surviving path so we know how to set dotdot. */
+STATIC void
+xrep_dirtree_find_surviving_path(
+ struct xchk_dirtree *dl,
+ struct xchk_dirtree_outcomes *oc)
+{
+ struct xchk_dirpath *path;
+ bool foundit = false;
+
+ xchk_dirtree_for_each_path(dl, path) {
+ switch (path->outcome) {
+ case XCHK_DIRPATH_CORRUPT:
+ case XCHK_DIRPATH_LOOP:
+ case XCHK_DIRPATH_OK:
+ if (!foundit) {
+ xrep_dirpath_retain_parent(dl, path);
+ foundit = true;
+ continue;
+ }
+ ASSERT(foundit == false);
+ break;
+ default:
+ break;
+ }
+ }
+
+ ASSERT(oc->suspect + oc->good == 1);
+}
+
+/* Delete all paths except for the one good one. */
+STATIC void
+xrep_dirtree_keep_one_good_path(
+ struct xchk_dirtree *dl,
+ struct xchk_dirtree_outcomes *oc)
+{
+ struct xchk_dirpath *path;
+ bool foundit = false;
+
+ xchk_dirtree_for_each_path(dl, path) {
+ switch (path->outcome) {
+ case XCHK_DIRPATH_CORRUPT:
+ case XCHK_DIRPATH_LOOP:
+ oc->suspect--;
+ oc->bad++;
+ xrep_dirpath_set_outcome(dl, path, XCHK_DIRPATH_DELETE);
+ break;
+ case XCHK_DIRPATH_OK:
+ if (!foundit) {
+ xrep_dirpath_retain_parent(dl, path);
+ foundit = true;
+ continue;
+ }
+ oc->good--;
+ oc->bad++;
+ xrep_dirpath_set_outcome(dl, path, XCHK_DIRPATH_DELETE);
+ break;
+ default:
+ break;
+ }
+ }
+
+ ASSERT(oc->suspect == 0);
+ ASSERT(oc->good < 2);
+}
+
+/* Delete all paths except for one suspect one. */
+STATIC void
+xrep_dirtree_keep_one_suspect_path(
+ struct xchk_dirtree *dl,
+ struct xchk_dirtree_outcomes *oc)
+{
+ struct xchk_dirpath *path;
+ bool foundit = false;
+
+ xchk_dirtree_for_each_path(dl, path) {
+ switch (path->outcome) {
+ case XCHK_DIRPATH_CORRUPT:
+ case XCHK_DIRPATH_LOOP:
+ if (!foundit) {
+ xrep_dirpath_retain_parent(dl, path);
+ foundit = true;
+ continue;
+ }
+ oc->suspect--;
+ oc->bad++;
+ xrep_dirpath_set_outcome(dl, path, XCHK_DIRPATH_DELETE);
+ break;
+ case XCHK_DIRPATH_OK:
+ ASSERT(0);
+ break;
+ default:
+ break;
+ }
+ }
+
+ ASSERT(oc->suspect == 1);
+ ASSERT(oc->good == 0);
+}
+
+/*
+ * Figure out what to do with the paths we tried to find. Returns -EDEADLOCK
+ * if the scan results have become stale.
+ */
+STATIC void
+xrep_dirtree_decide_fate(
+ struct xchk_dirtree *dl,
+ struct xchk_dirtree_outcomes *oc)
+{
+ xchk_dirtree_evaluate(dl, oc);
+
+ /* Parentless directories should not have any paths at all. */
+ if (xchk_dirtree_parentless(dl)) {
+ xrep_dirtree_delete_all_paths(dl, oc);
+ return;
+ }
+
+ /* One path is exactly the number of paths we want. */
+ if (oc->good + oc->suspect == 1) {
+ xrep_dirtree_find_surviving_path(dl, oc);
+ return;
+ }
+
+ /* Zero paths means we should reattach the subdir to the orphanage. */
+ if (oc->good + oc->suspect == 0) {
+ if (dl->sc->orphanage)
+ oc->needs_adoption = true;
+ return;
+ }
+
+ /*
+ * Otherwise, this subdirectory has too many parents. If there's at
+ * least one good path, keep it and delete the others.
+ */
+ if (oc->good > 0) {
+ xrep_dirtree_keep_one_good_path(dl, oc);
+ return;
+ }
+
+ /*
+ * There are no good paths and there are too many suspect paths.
+ * Keep the first suspect path and delete the rest.
+ */
+ xrep_dirtree_keep_one_suspect_path(dl, oc);
+}
+
+/*
+ * Load the first step of this path into @step and @dl->xname/pptr
+ * for later repair work.
+ */
+STATIC int
+xrep_dirtree_prep_path(
+ struct xchk_dirtree *dl,
+ struct xchk_dirpath *path,
+ struct xchk_dirpath_step *step)
+{
+ int error;
+
+ error = xfarray_load(dl->path_steps, path->first_step, step);
+ if (error)
+ return error;
+
+ error = xfblob_loadname(dl->path_names, step->name_cookie, &dl->xname,
+ step->name_len);
+ if (error)
+ return error;
+
+ dl->pptr_rec = step->pptr_rec; /* struct copy */
+ return 0;
+}
+
+/* Delete the VFS dentry for a removed child. */
+STATIC int
+xrep_dirtree_purge_dentry(
+ struct xchk_dirtree *dl,
+ struct xfs_inode *dp,
+ const struct xfs_name *name)
+{
+ struct qstr qname = QSTR_INIT(name->name, name->len);
+ struct dentry *parent_dentry, *child_dentry;
+ int error = 0;
+
+ /*
+ * Find the dentry for the parent directory. If there isn't one, we're
+ * done. Caller already holds i_rwsem for parent and child.
+ */
+ parent_dentry = d_find_alias(VFS_I(dp));
+ if (!parent_dentry)
+ return 0;
+
+ /* The VFS thinks the parent is a directory, right? */
+ if (!d_is_dir(parent_dentry)) {
+ ASSERT(d_is_dir(parent_dentry));
+ error = -EFSCORRUPTED;
+ goto out_dput_parent;
+ }
+
+ /*
+ * Try to find the dirent pointing to the child. If there isn't one,
+ * we're done.
+ */
+ qname.hash = full_name_hash(parent_dentry, name->name, name->len);
+ child_dentry = d_lookup(parent_dentry, &qname);
+ if (!child_dentry) {
+ error = 0;
+ goto out_dput_parent;
+ }
+
+ trace_xrep_dirtree_delete_child(dp->i_mount, child_dentry);
+
+ /* Child is not a directory? We're screwed. */
+ if (!d_is_dir(child_dentry)) {
+ ASSERT(d_is_dir(child_dentry));
+ error = -EFSCORRUPTED;
+ goto out_dput_child;
+ }
+
+ /* Replace the child dentry with a negative one. */
+ d_delete(child_dentry);
+
+out_dput_child:
+ dput(child_dentry);
+out_dput_parent:
+ dput(parent_dentry);
+ return error;
+}
+
+/*
+ * Prepare to delete a link by taking the IOLOCK of the parent and the child
+ * (scrub target). Caller must hold IOLOCK_EXCL on @sc->ip. Returns 0 if we
+ * took both locks, or a negative errno if we couldn't lock the parent in time.
+ */
+static inline int
+xrep_dirtree_unlink_iolock(
+ struct xfs_scrub *sc,
+ struct xfs_inode *dp)
+{
+ int error;
+
+ ASSERT(sc->ilock_flags & XFS_IOLOCK_EXCL);
+
+ if (xfs_ilock_nowait(dp, XFS_IOLOCK_EXCL))
+ return 0;
+
+ xchk_iunlock(sc, XFS_IOLOCK_EXCL);
+ do {
+ xfs_ilock(dp, XFS_IOLOCK_EXCL);
+ if (xchk_ilock_nowait(sc, XFS_IOLOCK_EXCL))
+ break;
+ xfs_iunlock(dp, XFS_IOLOCK_EXCL);
+
+ if (xchk_should_terminate(sc, &error)) {
+ xchk_ilock(sc, XFS_IOLOCK_EXCL);
+ return error;
+ }
+
+ delay(1);
+ } while (1);
+
+ return 0;
+}
+
+/*
+ * Remove a link from the directory tree and update the dcache. Returns
+ * -ESTALE if the scan data are now out of date.
+ */
+STATIC int
+xrep_dirtree_unlink(
+ struct xchk_dirtree *dl,
+ struct xfs_inode *dp,
+ struct xchk_dirpath *path,
+ struct xchk_dirpath_step *step)
+{
+ struct xfs_scrub *sc = dl->sc;
+ struct xfs_mount *mp = sc->mp;
+ xfs_ino_t dotdot_ino;
+ xfs_ino_t parent_ino = dl->parent_ino;
+ unsigned int resblks;
+ int dontcare;
+ int error;
+
+ /* Take IOLOCK_EXCL of the parent and child. */
+ error = xrep_dirtree_unlink_iolock(sc, dp);
+ if (error)
+ return error;
+
+ /*
+ * Create the transaction that we need to sever the path. Ignore
+ * EDQUOT and ENOSPC being returned via nospace_error because the
+ * directory code can handle a reservationless update.
+ */
+ resblks = xfs_remove_space_res(mp, step->name_len);
+ error = xfs_trans_alloc_dir(dp, &M_RES(mp)->tr_remove, sc->ip,
+ &resblks, &sc->tp, &dontcare);
+ if (error)
+ goto out_iolock;
+
+ /*
+ * Cancel if someone invalidate the paths while we were trying to get
+ * the ILOCK.
+ */
+ mutex_lock(&dl->lock);
+ if (dl->stale) {
+ mutex_unlock(&dl->lock);
+ error = -ESTALE;
+ goto out_trans_cancel;
+ }
+ xrep_dirpath_set_outcome(dl, path, XREP_DIRPATH_DELETING);
+ mutex_unlock(&dl->lock);
+
+ trace_xrep_dirtree_delete_path(dl->sc, sc->ip, path->path_nr,
+ &dl->xname, &dl->pptr_rec);
+
+ /*
+ * Decide if we need to reset the dotdot entry. Rules:
+ *
+ * - If there's a surviving parent, we want dotdot to point there.
+ * - If we don't have any surviving parents, then point dotdot at the
+ * root dir.
+ * - If dotdot is already set to the value we want, pass in NULLFSINO
+ * for no change necessary.
+ *
+ * Do this /before/ we dirty anything, in case the dotdot lookup
+ * fails.
+ */
+ error = xchk_dir_lookup(sc, sc->ip, &xfs_name_dotdot, &dotdot_ino);
+ if (error)
+ goto out_trans_cancel;
+ if (parent_ino == NULLFSINO)
+ parent_ino = dl->root_ino;
+ if (dotdot_ino == parent_ino)
+ parent_ino = NULLFSINO;
+
+ /* Drop the link from sc->ip's dotdot entry. */
+ error = xfs_droplink(sc->tp, dp);
+ if (error)
+ goto out_trans_cancel;
+
+ /* Reset the dotdot entry to a surviving parent. */
+ if (parent_ino != NULLFSINO) {
+ error = xfs_dir_replace(sc->tp, sc->ip, &xfs_name_dotdot,
+ parent_ino, 0);
+ if (error)
+ goto out_trans_cancel;
+ }
+
+ /* Drop the link from dp to sc->ip. */
+ error = xfs_droplink(sc->tp, sc->ip);
+ if (error)
+ goto out_trans_cancel;
+
+ error = xfs_dir_removename(sc->tp, dp, &dl->xname, sc->ip->i_ino,
+ resblks);
+ if (error) {
+ ASSERT(error != -ENOENT);
+ goto out_trans_cancel;
+ }
+
+ if (xfs_has_parent(sc->mp)) {
+ error = xfs_parent_removename(sc->tp, &dl->ppargs, dp,
+ &dl->xname, sc->ip);
+ if (error)
+ goto out_trans_cancel;
+ }
+
+ /*
+ * Notify dirent hooks that we removed the bad link, invalidate the
+ * dcache, and commit the repair.
+ */
+ xfs_dir_update_hook(dp, sc->ip, -1, &dl->xname);
+ error = xrep_dirtree_purge_dentry(dl, dp, &dl->xname);
+ if (error)
+ goto out_trans_cancel;
+
+ error = xrep_trans_commit(sc);
+ goto out_ilock;
+
+out_trans_cancel:
+ xchk_trans_cancel(sc);
+out_ilock:
+ xfs_iunlock(sc->ip, XFS_ILOCK_EXCL);
+ xfs_iunlock(dp, XFS_ILOCK_EXCL);
+out_iolock:
+ xfs_iunlock(dp, XFS_IOLOCK_EXCL);
+ return error;
+}
+
+/*
+ * Delete a directory entry that points to this directory. Returns -ESTALE
+ * if the scan data are now out of date.
+ */
+STATIC int
+xrep_dirtree_delete_path(
+ struct xchk_dirtree *dl,
+ struct xchk_dirpath *path)
+{
+ struct xchk_dirpath_step step;
+ struct xfs_scrub *sc = dl->sc;
+ struct xfs_inode *dp;
+ int error;
+
+ /*
+ * Load the parent pointer and directory inode for this path, then
+ * drop the scan lock, the ILOCK, and the transaction so that
+ * _delete_path can reserve the proper transaction. This sets up
+ * @dl->xname for the deletion.
+ */
+ error = xrep_dirtree_prep_path(dl, path, &step);
+ if (error)
+ return error;
+
+ error = xchk_iget(sc, be64_to_cpu(step.pptr_rec.p_ino), &dp);
+ if (error)
+ return error;
+
+ mutex_unlock(&dl->lock);
+ xchk_trans_cancel(sc);
+ xchk_iunlock(sc, XFS_ILOCK_EXCL);
+
+ /* Delete the directory link and release the parent. */
+ error = xrep_dirtree_unlink(dl, dp, path, &step);
+ xchk_irele(sc, dp);
+
+ /*
+ * Retake all the resources we had at the beginning even if the repair
+ * failed or the scan data are now stale. This keeps things simple for
+ * the caller.
+ */
+ xchk_trans_alloc_empty(sc);
+ xchk_ilock(sc, XFS_ILOCK_EXCL);
+ mutex_lock(&dl->lock);
+
+ if (!error && dl->stale)
+ error = -ESTALE;
+ return error;
+}
+
+/* Add a new path to represent our in-progress adoption. */
+STATIC int
+xrep_dirtree_create_adoption_path(
+ struct xchk_dirtree *dl)
+{
+ struct xfs_scrub *sc = dl->sc;
+ struct xchk_dirpath *path;
+ int error;
+
+ /*
+ * We should have capped the number of paths at XFS_MAXLINK-1 in the
+ * scanner.
+ */
+ if (dl->nr_paths > XFS_MAXLINK) {
+ ASSERT(dl->nr_paths <= XFS_MAXLINK);
+ return -EFSCORRUPTED;
+ }
+
+ /*
+ * Create a new xchk_path structure to remember this parent pointer
+ * and record the first name step.
+ */
+ path = kmalloc(sizeof(struct xchk_dirpath), XCHK_GFP_FLAGS);
+ if (!path)
+ return -ENOMEM;
+
+ INIT_LIST_HEAD(&path->list);
+ xino_bitmap_init(&path->seen_inodes);
+ path->nr_steps = 0;
+ path->outcome = XREP_DIRPATH_ADOPTING;
+
+ /*
+ * Record the new link that we just created in the orphanage. Because
+ * adoption is the last repair that we perform, we don't bother filling
+ * in the path all the way back to the root.
+ */
+ xfs_inode_to_parent_rec(&dl->pptr_rec, sc->orphanage);
+
+ error = xino_bitmap_set(&path->seen_inodes, sc->orphanage->i_ino);
+ if (error)
+ goto out_path;
+
+ trace_xrep_dirtree_create_adoption(sc, sc->ip, dl->nr_paths,
+ &dl->xname, &dl->pptr_rec);
+
+ error = xchk_dirpath_append(dl, sc->ip, path, &dl->xname,
+ &dl->pptr_rec);
+ if (error)
+ goto out_path;
+
+ path->first_step = xfarray_length(dl->path_steps) - 1;
+ path->second_step = XFARRAY_NULLIDX;
+ path->path_nr = dl->nr_paths;
+
+ list_add_tail(&path->list, &dl->path_list);
+ dl->nr_paths++;
+ return 0;
+
+out_path:
+ kfree(path);
+ return error;
+}
+
+/*
+ * Prepare to move a file to the orphanage by taking the IOLOCK of the
+ * orphanage and the child (scrub target). Caller must hold IOLOCK_EXCL on
+ * @sc->ip. Returns 0 if we took both locks, or a negative errno if we
+ * couldn't lock the orphanage in time.
+ */
+static inline int
+xrep_dirtree_adopt_iolock(
+ struct xfs_scrub *sc)
+{
+ int error;
+
+ ASSERT(sc->ilock_flags & XFS_IOLOCK_EXCL);
+
+ if (xrep_orphanage_ilock_nowait(sc, XFS_IOLOCK_EXCL))
+ return 0;
+
+ xchk_iunlock(sc, XFS_IOLOCK_EXCL);
+ do {
+ xrep_orphanage_ilock(sc, XFS_IOLOCK_EXCL);
+ if (xchk_ilock_nowait(sc, XFS_IOLOCK_EXCL))
+ break;
+ xrep_orphanage_iunlock(sc, XFS_IOLOCK_EXCL);
+
+ if (xchk_should_terminate(sc, &error)) {
+ xchk_ilock(sc, XFS_IOLOCK_EXCL);
+ return error;
+ }
+
+ delay(1);
+ } while (1);
+
+ return 0;
+}
+
+/*
+ * Reattach this orphaned directory to the orphanage. Do not call this with
+ * any resources held. Returns -ESTALE if the scan data have become out of
+ * date.
+ */
+STATIC int
+xrep_dirtree_adopt(
+ struct xchk_dirtree *dl)
+{
+ struct xfs_scrub *sc = dl->sc;
+ int error;
+
+ /* Take the IOLOCK of the orphanage and the scrub target. */
+ error = xrep_dirtree_adopt_iolock(sc);
+ if (error)
+ return error;
+
+ /*
+ * Set up for an adoption. The directory tree fixer runs after the
+ * link counts have been corrected. Therefore, we must bump the
+ * child's link count since there will be no further opportunity to fix
+ * errors.
+ */
+ error = xrep_adoption_trans_alloc(sc, &dl->adoption);
+ if (error)
+ goto out_iolock;
+ dl->adoption.bump_child_nlink = true;
+
+ /* Figure out what name we're going to use here. */
+ error = xrep_adoption_compute_name(&dl->adoption, &dl->xname);
+ if (error)
+ goto out_trans;
+
+ /*
+ * Now that we have a proposed name for the orphanage entry, create
+ * a faux path so that the live update hook will see it.
+ */
+ mutex_lock(&dl->lock);
+ if (dl->stale) {
+ mutex_unlock(&dl->lock);
+ error = -ESTALE;
+ goto out_trans;
+ }
+ error = xrep_dirtree_create_adoption_path(dl);
+ mutex_unlock(&dl->lock);
+ if (error)
+ goto out_trans;
+
+ /* Reparent the directory. */
+ error = xrep_adoption_move(&dl->adoption);
+ if (error)
+ goto out_trans;
+
+ /*
+ * Commit the name and release all inode locks except for the scrub
+ * target's IOLOCK.
+ */
+ error = xrep_trans_commit(sc);
+ goto out_ilock;
+
+out_trans:
+ xchk_trans_cancel(sc);
+out_ilock:
+ xchk_iunlock(sc, XFS_ILOCK_EXCL);
+ xrep_orphanage_iunlock(sc, XFS_ILOCK_EXCL);
+out_iolock:
+ xrep_orphanage_iunlock(sc, XFS_IOLOCK_EXCL);
+ return error;
+}
+
+/*
+ * This newly orphaned directory needs to be adopted by the orphanage.
+ * Make this happen.
+ */
+STATIC int
+xrep_dirtree_move_to_orphanage(
+ struct xchk_dirtree *dl)
+{
+ struct xfs_scrub *sc = dl->sc;
+ int error;
+
+ /*
+ * Start by dropping all the resources that we hold so that we can grab
+ * all the resources that we need for the adoption.
+ */
+ mutex_unlock(&dl->lock);
+ xchk_trans_cancel(sc);
+ xchk_iunlock(sc, XFS_ILOCK_EXCL);
+
+ /* Perform the adoption. */
+ error = xrep_dirtree_adopt(dl);
+
+ /*
+ * Retake all the resources we had at the beginning even if the repair
+ * failed or the scan data are now stale. This keeps things simple for
+ * the caller.
+ */
+ xchk_trans_alloc_empty(sc);
+ xchk_ilock(sc, XFS_ILOCK_EXCL);
+ mutex_lock(&dl->lock);
+
+ if (!error && dl->stale)
+ error = -ESTALE;
+ return error;
+}
+
+/*
+ * Try to fix all the problems. Returns -ESTALE if the scan data have become
+ * out of date.
+ */
+STATIC int
+xrep_dirtree_fix_problems(
+ struct xchk_dirtree *dl,
+ struct xchk_dirtree_outcomes *oc)
+{
+ struct xchk_dirpath *path;
+ int error;
+
+ /* Delete all the paths we don't want. */
+ xchk_dirtree_for_each_path(dl, path) {
+ if (path->outcome != XCHK_DIRPATH_DELETE)
+ continue;
+
+ error = xrep_dirtree_delete_path(dl, path);
+ if (error)
+ return error;
+ }
+
+ /* Reparent this directory to the orphanage. */
+ if (oc->needs_adoption) {
+ if (xrep_orphanage_can_adopt(dl->sc))
+ return xrep_dirtree_move_to_orphanage(dl);
+ return -EFSCORRUPTED;
+ }
+
+ return 0;
+}
+
+/* Fix directory loops involving this directory. */
+int
+xrep_dirtree(
+ struct xfs_scrub *sc)
+{
+ struct xchk_dirtree *dl = sc->buf;
+ struct xchk_dirtree_outcomes oc;
+ int error;
+
+ /*
+ * Prepare to fix the directory tree by retaking the scan lock. The
+ * order of resource acquisition is still IOLOCK -> transaction ->
+ * ILOCK -> scan lock.
+ */
+ mutex_lock(&dl->lock);
+ do {
+ /*
+ * Decide what we're going to do, then do it. An -ESTALE
+ * return here means the scan results are invalid and we have
+ * to walk again.
+ */
+ if (!dl->stale) {
+ xrep_dirtree_decide_fate(dl, &oc);
+
+ trace_xrep_dirtree_decided_fate(dl, &oc);
+
+ error = xrep_dirtree_fix_problems(dl, &oc);
+ if (!error || error != -ESTALE)
+ break;
+ }
+ error = xchk_dirtree_find_paths_to_root(dl);
+ if (error == -ELNRNG || error == -ENOSR)
+ error = -EFSCORRUPTED;
+ } while (!error);
+ mutex_unlock(&dl->lock);
+
+ return error;
+}
diff --git a/fs/xfs/scrub/orphanage.c b/fs/xfs/scrub/orphanage.c
index b2f905924d0d8..b1c6c60ee1da6 100644
--- a/fs/xfs/scrub/orphanage.c
+++ b/fs/xfs/scrub/orphanage.c
@@ -570,6 +570,12 @@ xrep_adoption_move(
xfs_bumplink(sc->tp, sc->orphanage);
xfs_trans_log_inode(sc->tp, sc->orphanage, XFS_ILOG_CORE);

+ /* Bump the link count of the child. */
+ if (adopt->bump_child_nlink) {
+ xfs_bumplink(sc->tp, sc->ip);
+ xfs_trans_log_inode(sc->tp, sc->ip, XFS_ILOG_CORE);
+ }
+
/* Replace the dotdot entry if the child is a subdirectory. */
if (isdir) {
error = xfs_dir_replace(sc->tp, sc->ip, &xfs_name_dotdot,
diff --git a/fs/xfs/scrub/orphanage.h b/fs/xfs/scrub/orphanage.h
index beb6b686784e6..7c7a2e7d81dbd 100644
--- a/fs/xfs/scrub/orphanage.h
+++ b/fs/xfs/scrub/orphanage.h
@@ -60,6 +60,14 @@ struct xrep_adoption {
/* Block reservations for orphanage and child (if directory). */
unsigned int orphanage_blkres;
unsigned int child_blkres;
+
+ /*
+ * Does the caller want us to bump the child link count? This is not
+ * needed when reattaching files that have become disconnected but have
+ * nlink > 1. It is necessary when changing the directory tree
+ * structure.
+ */
+ bool bump_child_nlink:1;
};

bool xrep_orphanage_can_adopt(struct xfs_scrub *sc);
diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
index 622eb486a16fb..0e0dc2bf985c2 100644
--- a/fs/xfs/scrub/repair.h
+++ b/fs/xfs/scrub/repair.h
@@ -95,6 +95,7 @@ int xrep_setup_directory(struct xfs_scrub *sc);
int xrep_setup_parent(struct xfs_scrub *sc);
int xrep_setup_nlinks(struct xfs_scrub *sc);
int xrep_setup_symlink(struct xfs_scrub *sc, unsigned int *resblks);
+int xrep_setup_dirtree(struct xfs_scrub *sc);

/* Repair setup functions */
int xrep_setup_ag_allocbt(struct xfs_scrub *sc);
@@ -132,6 +133,7 @@ int xrep_xattr(struct xfs_scrub *sc);
int xrep_directory(struct xfs_scrub *sc);
int xrep_parent(struct xfs_scrub *sc);
int xrep_symlink(struct xfs_scrub *sc);
+int xrep_dirtree(struct xfs_scrub *sc);

#ifdef CONFIG_XFS_RT
int xrep_rtbitmap(struct xfs_scrub *sc);
@@ -205,6 +207,7 @@ xrep_setup_nothing(
#define xrep_setup_directory xrep_setup_nothing
#define xrep_setup_parent xrep_setup_nothing
#define xrep_setup_nlinks xrep_setup_nothing
+#define xrep_setup_dirtree xrep_setup_nothing

#define xrep_setup_inode(sc, imap) ((void)0)

@@ -239,6 +242,7 @@ static inline int xrep_setup_symlink(struct xfs_scrub *sc, unsigned int *x)
#define xrep_directory xrep_notsupported
#define xrep_parent xrep_notsupported
#define xrep_symlink xrep_notsupported
+#define xrep_dirtree xrep_notsupported

#endif /* CONFIG_XFS_ONLINE_REPAIR */

diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index 8f1431db77395..e813b66b603a1 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -441,7 +441,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
.setup = xchk_setup_dirtree,
.scrub = xchk_dirtree,
.has = xfs_has_parent,
- .repair = xrep_notsupported,
+ .repair = xrep_dirtree,
},
};

diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index 509b6f4fd0cd3..b3756722bee1d 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -1685,6 +1685,10 @@ TRACE_DEFINE_ENUM(XCHK_DIRPATH_CORRUPT);
TRACE_DEFINE_ENUM(XCHK_DIRPATH_LOOP);
TRACE_DEFINE_ENUM(XCHK_DIRPATH_STALE);
TRACE_DEFINE_ENUM(XCHK_DIRPATH_OK);
+TRACE_DEFINE_ENUM(XREP_DIRPATH_DELETING);
+TRACE_DEFINE_ENUM(XREP_DIRPATH_DELETED);
+TRACE_DEFINE_ENUM(XREP_DIRPATH_ADOPTING);
+TRACE_DEFINE_ENUM(XREP_DIRPATH_ADOPTED);

#define XCHK_DIRPATH_OUTCOME_STRINGS \
{ XCHK_DIRPATH_SCANNING, "scanning" }, \
@@ -1692,7 +1696,11 @@ TRACE_DEFINE_ENUM(XCHK_DIRPATH_OK);
{ XCHK_DIRPATH_CORRUPT, "corrupt" }, \
{ XCHK_DIRPATH_LOOP, "loop" }, \
{ XCHK_DIRPATH_STALE, "stale" }, \
- { XCHK_DIRPATH_OK, "ok" }
+ { XCHK_DIRPATH_OK, "ok" }, \
+ { XREP_DIRPATH_DELETING, "deleting" }, \
+ { XREP_DIRPATH_DELETED, "deleted" }, \
+ { XREP_DIRPATH_ADOPTING, "adopting" }, \
+ { XREP_DIRPATH_ADOPTED, "adopted" }

DECLARE_EVENT_CLASS(xchk_dirpath_outcome_class,
TP_PROTO(struct xfs_scrub *sc, unsigned long long path_nr,
@@ -1738,6 +1746,7 @@ DECLARE_EVENT_CLASS(xchk_dirtree_evaluate_class,
__field(unsigned int, bad)
__field(unsigned int, suspect)
__field(unsigned int, good)
+ __field(bool, needs_adoption)
),
TP_fast_assign(
__entry->dev = dl->sc->mp->m_super->s_dev;
@@ -1747,15 +1756,17 @@ DECLARE_EVENT_CLASS(xchk_dirtree_evaluate_class,
__entry->bad = oc->bad;
__entry->suspect = oc->suspect;
__entry->good = oc->good;
+ __entry->needs_adoption = oc->needs_adoption ? 1 : 0;
),
- TP_printk("dev %d:%d ino 0x%llx rootino 0x%llx nr_paths %u bad %u suspect %u good %u",
+ TP_printk("dev %d:%d ino 0x%llx rootino 0x%llx nr_paths %u bad %u suspect %u good %u adopt? %d",
MAJOR(__entry->dev), MINOR(__entry->dev),
__entry->ino,
__entry->rootino,
__entry->nr_paths,
__entry->bad,
__entry->suspect,
- __entry->good)
+ __entry->good,
+ __entry->needs_adoption)
);
#define DEFINE_XCHK_DIRTREE_EVALUATE_EVENT(name) \
DEFINE_EVENT(xchk_dirtree_evaluate_class, name, \
@@ -3181,6 +3192,7 @@ DEFINE_REPAIR_DENTRY_EVENT(xrep_adoption_check_child);
DEFINE_REPAIR_DENTRY_EVENT(xrep_adoption_check_alias);
DEFINE_REPAIR_DENTRY_EVENT(xrep_adoption_check_dentry);
DEFINE_REPAIR_DENTRY_EVENT(xrep_adoption_invalidate_child);
+DEFINE_REPAIR_DENTRY_EVENT(xrep_dirtree_delete_child);

TRACE_EVENT(xrep_symlink_salvage_target,
TP_PROTO(struct xfs_inode *ip, char *target, unsigned int targetlen),
@@ -3483,6 +3495,11 @@ TRACE_EVENT(xrep_iunlink_commit_bucket,
__entry->agino)
);

+DEFINE_XCHK_DIRPATH_OUTCOME_EVENT(xrep_dirpath_set_outcome);
+DEFINE_XCHK_DIRTREE_EVENT(xrep_dirtree_delete_path);
+DEFINE_XCHK_DIRTREE_EVENT(xrep_dirtree_create_adoption);
+DEFINE_XCHK_DIRTREE_EVALUATE_EVENT(xrep_dirtree_decided_fate);
+
#endif /* IS_ENABLED(CONFIG_XFS_ONLINE_REPAIR) */

#endif /* _TRACE_XFS_SCRUB_TRACE_H */
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 766cbb8b7be51..ad9162b023ba2 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -892,7 +892,7 @@ xfs_init_new_inode(
* link count to go to zero, move the inode to AGI unlinked list so that it can
* be freed when the last active reference goes away via xfs_inactive().
*/
-static int /* error */
+int
xfs_droplink(
struct xfs_trans *tp,
struct xfs_inode *ip)
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 04a91e312993b..9fd4d29a57137 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -626,6 +626,7 @@ void xfs_end_io(struct work_struct *work);
int xfs_ilock2_io_mmap(struct xfs_inode *ip1, struct xfs_inode *ip2);
void xfs_iunlock2_io_mmap(struct xfs_inode *ip1, struct xfs_inode *ip2);
void xfs_iunlock2_remapping(struct xfs_inode *ip1, struct xfs_inode *ip2);
+int xfs_droplink(struct xfs_trans *tp, struct xfs_inode *ip);
void xfs_bumplink(struct xfs_trans *tp, struct xfs_inode *ip);
void xfs_lock_inodes(struct xfs_inode **ips, int inodes, uint lock_mode);
void xfs_sort_inodes(struct xfs_inode **i_tab, unsigned int num_inodes);