From 8ad345306d1eba337a3b88f9acbe762f9e770f76 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Mon, 22 Apr 2024 09:48:04 -0700 Subject: xfs: deferred scrub of parent pointers If the trylock-based dirent check fails, retain those parent pointers and check them at the end. This may involve dropping the locks on the file being scanned, so yay. Signed-off-by: Darrick J. Wong Reviewed-by: Christoph Hellwig --- fs/xfs/Makefile | 2 +- fs/xfs/scrub/parent.c | 267 ++++++++++++++++++++++++++++++++++++++++++++++++-- fs/xfs/scrub/trace.h | 3 + 3 files changed, 264 insertions(+), 8 deletions(-) diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile index c969b11ce0f4..af99a455ce4d 100644 --- a/fs/xfs/Makefile +++ b/fs/xfs/Makefile @@ -177,6 +177,7 @@ xfs-y += $(addprefix scrub/, \ scrub.o \ symlink.o \ xfarray.o \ + xfblob.o \ xfile.o \ ) @@ -218,7 +219,6 @@ xfs-y += $(addprefix scrub/, \ rmap_repair.o \ symlink_repair.o \ tempfile.o \ - xfblob.o \ ) xfs-$(CONFIG_XFS_RT) += $(addprefix scrub/, \ diff --git a/fs/xfs/scrub/parent.c b/fs/xfs/scrub/parent.c index 6ebbb7104126..f14e6f643fb6 100644 --- a/fs/xfs/scrub/parent.c +++ b/fs/xfs/scrub/parent.c @@ -23,6 +23,9 @@ #include "scrub/tempfile.h" #include "scrub/repair.h" #include "scrub/listxattr.h" +#include "scrub/xfile.h" +#include "scrub/xfarray.h" +#include "scrub/xfblob.h" #include "scrub/trace.h" /* Set us up to scrub parents. */ @@ -211,6 +214,18 @@ out_rele: * forward to the child file. */ +/* Deferred parent pointer entry that we saved for later. */ +struct xchk_pptr { + /* Cookie for retrieval of the pptr name. */ + xfblob_cookie name_cookie; + + /* Parent pointer record. */ + struct xfs_parent_rec pptr_rec; + + /* Length of the pptr name. */ + uint8_t namelen; +}; + struct xchk_pptrs { struct xfs_scrub *sc; @@ -219,6 +234,22 @@ struct xchk_pptrs { /* Parent of this directory. */ xfs_ino_t parent_ino; + + /* Fixed-size array of xchk_pptr structures. */ + struct xfarray *pptr_entries; + + /* Blobs containing parent pointer names. */ + struct xfblob *pptr_names; + + /* Scratch buffer for scanning pptr xattrs */ + struct xfs_da_args pptr_args; + + /* If we've cycled the ILOCK, we must revalidate all deferred pptrs. */ + bool need_revalidate; + + /* Name buffer */ + struct xfs_name xname; + char namebuf[MAXNAMELEN]; }; /* Does this parent pointer match the dotdot entry? */ @@ -461,8 +492,25 @@ xchk_parent_scan_attr( /* Try to lock the inode. */ lockmode = xchk_parent_lock_dir(sc, dp); if (!lockmode) { - xchk_set_incomplete(sc); - error = -ECANCELED; + struct xchk_pptr save_pp = { + .pptr_rec = *pptr_rec, /* struct copy */ + .namelen = namelen, + }; + + /* Couldn't lock the inode, so save the pptr for later. */ + trace_xchk_parent_defer(sc->ip, &xname, dp->i_ino); + + error = xfblob_storename(pp->pptr_names, &save_pp.name_cookie, + &xname); + if (!xchk_fblock_xref_process_error(sc, XFS_ATTR_FORK, 0, + &error)) + goto out_rele; + + error = xfarray_append(pp->pptr_entries, &save_pp); + if (!xchk_fblock_xref_process_error(sc, XFS_ATTR_FORK, 0, + &error)) + goto out_rele; + goto out_rele; } @@ -477,6 +525,162 @@ out_rele: return error; } +/* + * Revalidate a parent pointer that we collected in the past but couldn't check + * because of lock contention. Returns 0 if the parent pointer is still valid, + * -ENOENT if it has gone away on us, or a negative errno. + */ +STATIC int +xchk_parent_revalidate_pptr( + struct xchk_pptrs *pp, + const struct xfs_name *xname, + struct xfs_parent_rec *pptr) +{ + struct xfs_scrub *sc = pp->sc; + int error; + + error = xfs_parent_lookup(sc->tp, sc->ip, xname, pptr, &pp->pptr_args); + if (error == -ENOATTR) { + /* Parent pointer went away, nothing to revalidate. */ + return -ENOENT; + } + + return error; +} + +/* + * Check a parent pointer the slow way, which means we cycle locks a bunch + * and put up with revalidation until we get it done. + */ +STATIC int +xchk_parent_slow_pptr( + struct xchk_pptrs *pp, + const struct xfs_name *xname, + struct xfs_parent_rec *pptr) +{ + struct xfs_scrub *sc = pp->sc; + struct xfs_inode *dp = NULL; + unsigned int lockmode; + int error; + + /* Check that the deferred parent pointer still exists. */ + if (pp->need_revalidate) { + error = xchk_parent_revalidate_pptr(pp, xname, pptr); + if (error == -ENOENT) + return 0; + if (!xchk_fblock_xref_process_error(sc, XFS_ATTR_FORK, 0, + &error)) + return error; + } + + error = xchk_parent_iget(pp, pptr, &dp); + if (error) + return error; + if (!dp) + return 0; + + /* + * If we can grab both IOLOCK and ILOCK of the alleged parent, we + * can proceed with the validation. + */ + lockmode = xchk_parent_lock_dir(sc, dp); + if (lockmode) { + trace_xchk_parent_slowpath(sc->ip, xname, dp->i_ino); + goto check_dirent; + } + + /* + * We couldn't lock the parent dir. Drop all the locks and try to + * get them again, one at a time. + */ + xchk_iunlock(sc, sc->ilock_flags); + pp->need_revalidate = true; + + trace_xchk_parent_ultraslowpath(sc->ip, xname, dp->i_ino); + + error = xchk_dir_trylock_for_pptrs(sc, dp, &lockmode); + if (error) + goto out_rele; + + /* Revalidate the parent pointer now that we cycled locks. */ + error = xchk_parent_revalidate_pptr(pp, xname, pptr); + if (error == -ENOENT) { + error = 0; + goto out_unlock; + } + if (!xchk_fblock_xref_process_error(sc, XFS_ATTR_FORK, 0, &error)) + goto out_unlock; + +check_dirent: + error = xchk_parent_dirent(pp, xname, dp); +out_unlock: + xfs_iunlock(dp, lockmode); +out_rele: + xchk_irele(sc, dp); + return error; +} + +/* Check all the parent pointers that we deferred the first time around. */ +STATIC int +xchk_parent_finish_slow_pptrs( + struct xchk_pptrs *pp) +{ + xfarray_idx_t array_cur; + int error; + + foreach_xfarray_idx(pp->pptr_entries, array_cur) { + struct xchk_pptr pptr; + + if (pp->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT) + return 0; + + error = xfarray_load(pp->pptr_entries, array_cur, &pptr); + if (error) + return error; + + error = xfblob_loadname(pp->pptr_names, pptr.name_cookie, + &pp->xname, pptr.namelen); + if (error) + return error; + + error = xchk_parent_slow_pptr(pp, &pp->xname, &pptr.pptr_rec); + if (error) + return error; + } + + /* Empty out both xfiles now that we've checked everything. */ + xfarray_truncate(pp->pptr_entries); + xfblob_truncate(pp->pptr_names); + return 0; +} + +/* Count the number of parent pointers. */ +STATIC int +xchk_parent_count_pptr( + struct xfs_scrub *sc, + struct xfs_inode *ip, + unsigned int attr_flags, + const unsigned char *name, + unsigned int namelen, + const void *value, + unsigned int valuelen, + void *priv) +{ + struct xchk_pptrs *pp = priv; + int error; + + if (!(attr_flags & XFS_ATTR_PARENT)) + return 0; + + error = xfs_parent_from_attr(sc->mp, attr_flags, name, namelen, value, + valuelen, NULL, NULL); + if (error) + return error; + + pp->pptrs_found++; + return 0; +} + /* * Compare the number of parent pointers to the link count. For * non-directories these should be the same. For unlinked directories the @@ -487,6 +691,23 @@ xchk_parent_count_pptrs( struct xchk_pptrs *pp) { struct xfs_scrub *sc = pp->sc; + int error; + + /* + * If we cycled the ILOCK while cross-checking parent pointers with + * dirents, then we need to recalculate the number of parent pointers. + */ + if (pp->need_revalidate) { + pp->pptrs_found = 0; + error = xchk_xattr_walk(sc, sc->ip, xchk_parent_count_pptr, pp); + if (error == -EFSCORRUPTED) { + /* Found a bad parent pointer */ + xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0); + return 0; + } + if (error) + return error; + } if (S_ISDIR(VFS_I(sc->ip)->i_mode)) { if (sc->ip == sc->mp->m_rootip) @@ -511,23 +732,51 @@ xchk_parent_pptr( struct xfs_scrub *sc) { struct xchk_pptrs *pp; + char *descr; int error; pp = kvzalloc(sizeof(struct xchk_pptrs), XCHK_GFP_FLAGS); if (!pp) return -ENOMEM; pp->sc = sc; + pp->xname.name = pp->namebuf; + + /* + * Set up some staging memory for parent pointers that we can't check + * due to locking contention. + */ + descr = xchk_xfile_ino_descr(sc, "slow parent pointer entries"); + error = xfarray_create(descr, 0, sizeof(struct xchk_pptr), + &pp->pptr_entries); + kfree(descr); + if (error) + goto out_pp; + + descr = xchk_xfile_ino_descr(sc, "slow parent pointer names"); + error = xfblob_create(descr, &pp->pptr_names); + kfree(descr); + if (error) + goto out_entries; error = xchk_xattr_walk(sc, sc->ip, xchk_parent_scan_attr, pp); if (error == -ECANCELED) { error = 0; - goto out_pp; + goto out_names; } if (error) - goto out_pp; + goto out_names; + + error = xchk_parent_finish_slow_pptrs(pp); + if (error == -ETIMEDOUT) { + /* Couldn't grab a lock, scrub was marked incomplete */ + error = 0; + goto out_names; + } + if (error) + goto out_names; if (pp->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT) - goto out_pp; + goto out_names; /* * For subdirectories, make sure the dotdot entry references the same @@ -545,7 +794,7 @@ xchk_parent_pptr( if (S_ISDIR(VFS_I(sc->ip)->i_mode)) { error = xchk_parent_pptr_and_dotdot(pp); if (error) - goto out_pp; + goto out_names; } if (pp->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT) @@ -558,8 +807,12 @@ xchk_parent_pptr( */ error = xchk_parent_count_pptrs(pp); if (error) - goto out_pp; + goto out_names; +out_names: + xfblob_destroy(pp->pptr_names); +out_entries: + xfarray_destroy(pp->pptr_entries); out_pp: kvfree(pp); return error; diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h index 4db762480b8d..97a106519b53 100644 --- a/fs/xfs/scrub/trace.h +++ b/fs/xfs/scrub/trace.h @@ -1544,6 +1544,9 @@ DEFINE_EVENT(xchk_pptr_class, name, \ DEFINE_XCHK_PPTR_EVENT(xchk_dir_defer); DEFINE_XCHK_PPTR_EVENT(xchk_dir_slowpath); DEFINE_XCHK_PPTR_EVENT(xchk_dir_ultraslowpath); +DEFINE_XCHK_PPTR_EVENT(xchk_parent_defer); +DEFINE_XCHK_PPTR_EVENT(xchk_parent_slowpath); +DEFINE_XCHK_PPTR_EVENT(xchk_parent_ultraslowpath); /* repair tracepoints */ #if IS_ENABLED(CONFIG_XFS_ONLINE_REPAIR) -- cgit