[PATCH 28/28] xfs: repair metadata directory file path connectivity

Darrick J. Wong
2024-10-11T00:55:41Z

Fix disconnected or incorrect metadata directory paths.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
fs/xfs/scrub/metapath.c | 351 +++++++++++++++++++++++++++++++++++++++++++++++
fs/xfs/scrub/repair.h | 3
fs/xfs/scrub/scrub.c | 2
fs/xfs/scrub/trace.h | 5 +
4 files changed, 358 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/scrub/metapath.c b/fs/xfs/scrub/metapath.c
index b7bd86df9877cd..edc1a395c4015a 100644
--- a/fs/xfs/scrub/metapath.c
+++ b/fs/xfs/scrub/metapath.c
@@ -16,10 +16,15 @@
#include "xfs_quota.h"
#include "xfs_qm.h"
#include "xfs_dir2.h"
+#include "xfs_parent.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_trans_space.h"
+#include "xfs_attr.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/trace.h"
#include "scrub/readdir.h"
+#include "scrub/repair.h"

/*
* Metadata Directory Tree Paths
@@ -38,15 +43,28 @@ struct xchk_metapath {
/* Name for lookup */
struct xfs_name xname;

- /* Path for this metadata file and the parent directory */
+ /* Directory update for repairs */
+ struct xfs_dir_update du;
+
+ /* Path down to this metadata file from the parent directory */
const char *path;
- const char *parent_path;

/* Directory parent of the metadata file. */
struct xfs_inode *dp;

/* Locks held on dp */
unsigned int dp_ilock_flags;
+
+ /* Transaction block reservations */
+ unsigned int link_resblks;
+ unsigned int unlink_resblks;
+
+ /* Parent pointer updates */
+ struct xfs_parent_args link_ppargs;
+ struct xfs_parent_args unlink_ppargs;
+
+ /* Scratchpads for removing links */
+ struct xfs_da_args pptr_args;
};

/* Release resources tracked in the buffer. */
@@ -172,3 +190,332 @@ xchk_metapath(
xchk_trans_cancel(sc);
return error;
}
+
+#ifdef CONFIG_XFS_ONLINE_REPAIR
+/* Create the dirent represented by the final component of the path. */
+STATIC int
+xrep_metapath_link(
+ struct xchk_metapath *mpath)
+{
+ struct xfs_scrub *sc = mpath->sc;
+
+ mpath->du.dp = mpath->dp;
+ mpath->du.name = &mpath->xname;
+ mpath->du.ip = sc->ip;
+
+ if (xfs_has_parent(sc->mp))
+ mpath->du.ppargs = &mpath->link_ppargs;
+ else
+ mpath->du.ppargs = NULL;
+
+ trace_xrep_metapath_link(sc, mpath->path, mpath->dp, sc->ip->i_ino);
+
+ return xfs_dir_add_child(sc->tp, mpath->link_resblks, &mpath->du);
+}
+
+/* Remove the dirent at the final component of the path. */
+STATIC int
+xrep_metapath_unlink(
+ struct xchk_metapath *mpath,
+ xfs_ino_t ino,
+ struct xfs_inode *ip)
+{
+ struct xfs_parent_rec rec;
+ struct xfs_scrub *sc = mpath->sc;
+ struct xfs_mount *mp = sc->mp;
+ int error;
+
+ trace_xrep_metapath_unlink(sc, mpath->path, mpath->dp, ino);
+
+ if (!ip) {
+ /* The child inode isn't allocated. Junk the dirent. */
+ xfs_trans_log_inode(sc->tp, mpath->dp, XFS_ILOG_CORE);
+ return xfs_dir_removename(sc->tp, mpath->dp, &mpath->xname,
+ ino, mpath->unlink_resblks);
+ }
+
+ mpath->du.dp = mpath->dp;
+ mpath->du.name = &mpath->xname;
+ mpath->du.ip = ip;
+ mpath->du.ppargs = NULL;
+
+ /* Figure out if we're removing a parent pointer too. */
+ if (xfs_has_parent(mp)) {
+ xfs_inode_to_parent_rec(&rec, ip);
+ error = xfs_parent_lookup(sc->tp, ip, &mpath->xname, &rec,
+ &mpath->pptr_args);
+ switch (error) {
+ case -ENOATTR:
+ break;
+ case 0:
+ mpath->du.ppargs = &mpath->unlink_ppargs;
+ break;
+ default:
+ return error;
+ }
+ }
+
+ return xfs_dir_remove_child(sc->tp, mpath->unlink_resblks, &mpath->du);
+}
+
+/*
+ * Try to create a dirent in @mpath->dp with the name @mpath->xname that points
+ * to @sc->ip. Returns:
+ *
+ * -EEXIST and an @alleged_child if the dirent that points to the wrong inode;
+ * 0 if there is now a dirent pointing to @sc->ip; or
+ * A negative errno on error.
+ */
+STATIC int
+xrep_metapath_try_link(
+ struct xchk_metapath *mpath,
+ xfs_ino_t *alleged_child)
+{
+ struct xfs_scrub *sc = mpath->sc;
+ xfs_ino_t ino;
+ int error;
+
+ /* Allocate transaction, lock inodes, join to transaction. */
+ error = xchk_trans_alloc(sc, mpath->link_resblks);
+ if (error)
+ return error;
+
+ error = xchk_metapath_ilock_both(mpath);
+ if (error) {
+ xchk_trans_cancel(sc);
+ return error;
+ }
+ xfs_trans_ijoin(sc->tp, mpath->dp, 0);
+ xfs_trans_ijoin(sc->tp, sc->ip, 0);
+
+ error = xchk_dir_lookup(sc, mpath->dp, &mpath->xname, &ino);
+ trace_xrep_metapath_lookup(sc, mpath->path, mpath->dp, ino);
+ if (error == -ENOENT) {
+ /*
+ * There is no dirent in the directory. Create an entry
+ * pointing to @sc->ip.
+ */
+ error = xrep_metapath_link(mpath);
+ if (error)
+ goto out_cancel;
+
+ error = xrep_trans_commit(sc);
+ xchk_metapath_iunlock(mpath);
+ return error;
+ }
+ if (error)
+ goto out_cancel;
+
+ if (ino == sc->ip->i_ino) {
+ /* The dirent already points to @sc->ip; we're done. */
+ error = 0;
+ goto out_cancel;
+ }
+
+ /*
+ * The dirent points elsewhere; pass that back so that the caller
+ * can try to remove the dirent.
+ */
+ *alleged_child = ino;
+ error = -EEXIST;
+
+out_cancel:
+ xchk_trans_cancel(sc);
+ xchk_metapath_iunlock(mpath);
+ return error;
+}
+
+/*
+ * Take the ILOCK on the metadata directory parent and a bad child, if one is
+ * supplied. We do not know that the metadata directory is not corrupt, so we
+ * lock the parent and try to lock the child. Returns 0 if successful, or
+ * -EINTR to abort the repair. The lock state of @dp is not recorded in @mpath.
+ */
+STATIC int
+xchk_metapath_ilock_parent_and_child(
+ struct xchk_metapath *mpath,
+ struct xfs_inode *ip)
+{
+ struct xfs_scrub *sc = mpath->sc;
+ int error = 0;
+
+ while (true) {
+ xfs_ilock(mpath->dp, XFS_ILOCK_EXCL);
+ if (!ip || xfs_ilock_nowait(ip, XFS_ILOCK_EXCL))
+ return 0;
+ xfs_iunlock(mpath->dp, XFS_ILOCK_EXCL);
+
+ if (xchk_should_terminate(sc, &error))
+ return error;
+
+ delay(1);
+ }
+
+ ASSERT(0);
+ return -EINTR;
+}
+
+/*
+ * Try to remove a dirent in @mpath->dp with the name @mpath->xname that points
+ * to @alleged_child. Returns:
+ *
+ * 0 if there is no longer a dirent;
+ * -EEXIST if the dirent points to @sc->ip;
+ * -EAGAIN and an updated @alleged_child if the dirent points elsewhere; or
+ * A negative errno for any other error.
+ */
+STATIC int
+xrep_metapath_try_unlink(
+ struct xchk_metapath *mpath,
+ xfs_ino_t *alleged_child)
+{
+ struct xfs_scrub *sc = mpath->sc;
+ struct xfs_inode *ip = NULL;
+ xfs_ino_t ino;
+ int error;
+
+ ASSERT(*alleged_child != sc->ip->i_ino);
+
+ trace_xrep_metapath_try_unlink(sc, mpath->path, mpath->dp,
+ *alleged_child);
+
+ /*
+ * Allocate transaction, grab the alleged child inode, lock inodes,
+ * join to transaction.
+ */
+ error = xchk_trans_alloc(sc, mpath->unlink_resblks);
+ if (error)
+ return error;
+
+ error = xchk_iget(sc, *alleged_child, &ip);
+ if (error == -EINVAL || error == -ENOENT) {
+ /* inode number is bogus, junk the dirent */
+ error = 0;
+ }
+ if (error) {
+ xchk_trans_cancel(sc);
+ return error;
+ }
+
+ error = xchk_metapath_ilock_parent_and_child(mpath, ip);
+ if (error) {
+ xchk_trans_cancel(sc);
+ return error;
+ }
+ xfs_trans_ijoin(sc->tp, mpath->dp, 0);
+ if (ip)
+ xfs_trans_ijoin(sc->tp, ip, 0);
+
+ error = xchk_dir_lookup(sc, mpath->dp, &mpath->xname, &ino);
+ trace_xrep_metapath_lookup(sc, mpath->path, mpath->dp, ino);
+ if (error == -ENOENT) {
+ /*
+ * There is no dirent in the directory anymore. We're ready to
+ * try the link operation again.
+ */
+ error = 0;
+ goto out_cancel;
+ }
+ if (error)
+ goto out_cancel;
+
+ if (ino == sc->ip->i_ino) {
+ /* The dirent already points to @sc->ip; we're done. */
+ error = -EEXIST;
+ goto out_cancel;
+ }
+
+ /*
+ * The dirent does not point to the alleged child. Update the caller
+ * and signal that we want to be called again.
+ */
+ if (ino != *alleged_child) {
+ *alleged_child = ino;
+ error = -EAGAIN;
+ goto out_cancel;
+ }
+
+ /* Remove the link to the child. */
+ error = xrep_metapath_unlink(mpath, ino, ip);
+ if (error)
+ goto out_cancel;
+
+ error = xrep_trans_commit(sc);
+ goto out_unlock;
+
+out_cancel:
+ xchk_trans_cancel(sc);
+out_unlock:
+ xfs_iunlock(mpath->dp, XFS_ILOCK_EXCL);
+ if (ip) {
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ xchk_irele(sc, ip);
+ }
+ return error;
+}
+
+/*
+ * Make sure the metadata directory path points to the child being examined.
+ *
+ * Repair needs to be able to create a directory structure, create its own
+ * transactions, and take ILOCKs. This function /must/ be called after all
+ * other repairs have completed.
+ */
+int
+xrep_metapath(
+ struct xfs_scrub *sc)
+{
+ struct xchk_metapath *mpath = sc->buf;
+ struct xfs_mount *mp = sc->mp;
+ int error = 0;
+
+ /* Just probing, nothing to repair. */
+ if (sc->sm->sm_ino == XFS_SCRUB_METAPATH_PROBE)
+ return 0;
+
+ /* Parent required to do anything else. */
+ if (mpath->dp == NULL)
+ return -EFSCORRUPTED;
+
+ /*
+ * Make sure the child file actually has an attr fork to receive a new
+ * parent pointer if the fs has parent pointers.
+ */
+ if (xfs_has_parent(mp)) {
+ error = xfs_attr_add_fork(sc->ip,
+ sizeof(struct xfs_attr_sf_hdr), 1);
+ if (error)
+ return error;
+ }
+
+ /* Compute block reservation required to unlink and link a file. */
+ mpath->unlink_resblks = xfs_remove_space_res(mp, MAXNAMELEN);
+ mpath->link_resblks = xfs_link_space_res(mp, MAXNAMELEN);
+
+ do {
+ xfs_ino_t alleged_child;
+
+ /* Re-establish the link, or tell us which inode to remove. */
+ error = xrep_metapath_try_link(mpath, &alleged_child);
+ if (!error)
+ return 0;
+ if (error != -EEXIST)
+ return error;
+
+ /*
+ * Remove an incorrect link to an alleged child, or tell us
+ * which inode to remove.
+ */
+ do {
+ error = xrep_metapath_try_unlink(mpath, &alleged_child);
+ } while (error == -EAGAIN);
+ if (error == -EEXIST) {
+ /* Link established; we're done. */
+ error = 0;
+ break;
+ }
+ } while (!error);
+
+ return error;
+}
+#endif /* CONFIG_XFS_ONLINE_REPAIR */
diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
index 0e0dc2bf985c21..90f9cb3b5ad8ba 100644
--- a/fs/xfs/scrub/repair.h
+++ b/fs/xfs/scrub/repair.h
@@ -134,6 +134,7 @@ 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);
+int xrep_metapath(struct xfs_scrub *sc);

#ifdef CONFIG_XFS_RT
int xrep_rtbitmap(struct xfs_scrub *sc);
@@ -208,6 +209,7 @@ 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_metapath xrep_setup_nothing

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

@@ -243,6 +245,7 @@ static inline int xrep_setup_symlink(struct xfs_scrub *sc, unsigned int *x)
#define xrep_parent xrep_notsupported
#define xrep_symlink xrep_notsupported
#define xrep_dirtree xrep_notsupported
+#define xrep_metapath xrep_notsupported

#endif /* CONFIG_XFS_ONLINE_REPAIR */

diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index f1b2714e2894af..04a7a5944837d7 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -447,7 +447,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
.setup = xchk_setup_metapath,
.scrub = xchk_metapath,
.has = xfs_has_metadir,
- .repair = xrep_notsupported,
+ .repair = xrep_metapath,
},
};

diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index bb52baaa2fa726..b6c8d0944fa453 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -3598,6 +3598,11 @@ 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);

+DEFINE_XCHK_METAPATH_EVENT(xrep_metapath_lookup);
+DEFINE_XCHK_METAPATH_EVENT(xrep_metapath_try_unlink);
+DEFINE_XCHK_METAPATH_EVENT(xrep_metapath_unlink);
+DEFINE_XCHK_METAPATH_EVENT(xrep_metapath_link);
+
#endif /* IS_ENABLED(CONFIG_XFS_ONLINE_REPAIR) */

#endif /* _TRACE_XFS_SCRUB_TRACE_H */