diff options
Diffstat (limited to 'fs/xfs/scrub/nlinks.c')
| -rw-r--r-- | fs/xfs/scrub/nlinks.c | 930 |
1 files changed, 930 insertions, 0 deletions
diff --git a/fs/xfs/scrub/nlinks.c b/fs/xfs/scrub/nlinks.c new file mode 100644 index 000000000000..8a7d9557897c --- /dev/null +++ b/fs/xfs/scrub/nlinks.c @@ -0,0 +1,930 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) 2021-2024 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_mount.h" +#include "xfs_log_format.h" +#include "xfs_trans.h" +#include "xfs_inode.h" +#include "xfs_icache.h" +#include "xfs_iwalk.h" +#include "xfs_ialloc.h" +#include "xfs_dir2.h" +#include "xfs_dir2_priv.h" +#include "xfs_ag.h" +#include "scrub/scrub.h" +#include "scrub/common.h" +#include "scrub/repair.h" +#include "scrub/xfile.h" +#include "scrub/xfarray.h" +#include "scrub/iscan.h" +#include "scrub/nlinks.h" +#include "scrub/trace.h" +#include "scrub/readdir.h" + +/* + * Live Inode Link Count Checking + * ============================== + * + * Inode link counts are "summary" metadata, in the sense that they are + * computed as the number of directory entries referencing each file on the + * filesystem. Therefore, we compute the correct link counts by creating a + * shadow link count structure and walking every inode. + */ + +/* Set us up to scrub inode link counts. */ +int +xchk_setup_nlinks( + struct xfs_scrub *sc) +{ + xchk_fsgates_enable(sc, XCHK_FSGATES_DIRENTS); + + sc->buf = kzalloc(sizeof(struct xchk_nlink_ctrs), XCHK_GFP_FLAGS); + if (!sc->buf) + return -ENOMEM; + + return xchk_setup_fs(sc); +} + +/* + * Part 1: Collecting file link counts. For each file, we create a shadow link + * counting structure, then walk the entire directory tree, incrementing parent + * and child link counts for each directory entry seen. + * + * To avoid false corruption reports in part 2, any failure in this part must + * set the INCOMPLETE flag even when a negative errno is returned. This care + * must be taken with certain errno values (i.e. EFSBADCRC, EFSCORRUPTED, + * ECANCELED) that are absorbed into a scrub state flag update by + * xchk_*_process_error. Scrub and repair share the same incore data + * structures, so the INCOMPLETE flag is critical to prevent a repair based on + * insufficient information. + * + * Because we are scanning a live filesystem, it's possible that another thread + * will try to update the link counts for an inode that we've already scanned. + * This will cause our counts to be incorrect. Therefore, we hook all + * directory entry updates because that is when link count updates occur. By + * shadowing transaction updates in this manner, live nlink check can ensure by + * locking the inode and the shadow structure that its own copies are not out + * of date. Because the hook code runs in a different process context from the + * scrub code and the scrub state flags are not accessed atomically, failures + * in the hook code must abort the iscan and the scrubber must notice the + * aborted scan and set the incomplete flag. + * + * Note that we use jump labels and srcu notifier hooks to minimize the + * overhead when live nlinks is /not/ running. Locking order for nlink + * observations is inode ILOCK -> iscan_lock/xchk_nlink_ctrs lock. + */ + +/* + * Add a delta to an nlink counter, clamping the value to U32_MAX. Because + * XFS_MAXLINK < U32_MAX, the checking code will produce the correct results + * even if we lose some precision. + */ +static inline void +careful_add( + xfs_nlink_t *nlinkp, + int delta) +{ + uint64_t new_value = (uint64_t)(*nlinkp) + delta; + + BUILD_BUG_ON(XFS_MAXLINK > U32_MAX); + *nlinkp = min_t(uint64_t, new_value, U32_MAX); +} + +/* Update incore link count information. Caller must hold the nlinks lock. */ +STATIC int +xchk_nlinks_update_incore( + struct xchk_nlink_ctrs *xnc, + xfs_ino_t ino, + int parents_delta, + int backrefs_delta, + int children_delta) +{ + struct xchk_nlink nl; + int error; + + if (!xnc->nlinks) + return 0; + + error = xfarray_load_sparse(xnc->nlinks, ino, &nl); + if (error) + return error; + + trace_xchk_nlinks_update_incore(xnc->sc->mp, ino, &nl, parents_delta, + backrefs_delta, children_delta); + + careful_add(&nl.parents, parents_delta); + careful_add(&nl.backrefs, backrefs_delta); + careful_add(&nl.children, children_delta); + + nl.flags |= XCHK_NLINK_WRITTEN; + error = xfarray_store(xnc->nlinks, ino, &nl); + if (error == -EFBIG) { + /* + * EFBIG means we tried to store data at too high a byte offset + * in the sparse array. IOWs, we cannot complete the check and + * must notify userspace that the check was incomplete. + */ + error = -ECANCELED; + } + return error; +} + +/* + * Apply a link count change from the regular filesystem into our shadow link + * count structure based on a directory update in progress. + */ +STATIC int +xchk_nlinks_live_update( + struct notifier_block *nb, + unsigned long action, + void *data) +{ + struct xfs_dir_update_params *p = data; + struct xchk_nlink_ctrs *xnc; + int error; + + xnc = container_of(nb, struct xchk_nlink_ctrs, dhook.dirent_hook.nb); + + trace_xchk_nlinks_live_update(xnc->sc->mp, p->dp, action, p->ip->i_ino, + p->delta, p->name->name, p->name->len); + + /* + * If we've already scanned @dp, update the number of parents that link + * to @ip. If @ip is a subdirectory, update the number of child links + * going out of @dp. + */ + if (xchk_iscan_want_live_update(&xnc->collect_iscan, p->dp->i_ino)) { + mutex_lock(&xnc->lock); + error = xchk_nlinks_update_incore(xnc, p->ip->i_ino, p->delta, + 0, 0); + if (!error && S_ISDIR(VFS_IC(p->ip)->i_mode)) + error = xchk_nlinks_update_incore(xnc, p->dp->i_ino, 0, + 0, p->delta); + mutex_unlock(&xnc->lock); + if (error) + goto out_abort; + } + + /* + * If @ip is a subdirectory and we've already scanned it, update the + * number of backrefs pointing to @dp. + */ + if (S_ISDIR(VFS_IC(p->ip)->i_mode) && + xchk_iscan_want_live_update(&xnc->collect_iscan, p->ip->i_ino)) { + mutex_lock(&xnc->lock); + error = xchk_nlinks_update_incore(xnc, p->dp->i_ino, 0, + p->delta, 0); + mutex_unlock(&xnc->lock); + if (error) + goto out_abort; + } + + return NOTIFY_DONE; + +out_abort: + xchk_iscan_abort(&xnc->collect_iscan); + return NOTIFY_DONE; +} + +/* Bump the observed link count for the inode referenced by this entry. */ +STATIC int +xchk_nlinks_collect_dirent( + 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_nlink_ctrs *xnc = priv; + bool dot = false, dotdot = false; + int error; + + /* Does this name make sense? */ + if (name->len == 0 || !xfs_dir2_namecheck(name->name, name->len)) { + error = -ECANCELED; + goto out_abort; + } + + if (name->len == 1 && name->name[0] == '.') + dot = true; + else if (name->len == 2 && name->name[0] == '.' && + name->name[1] == '.') + dotdot = true; + + /* Don't accept a '.' entry that points somewhere else. */ + if (dot && ino != dp->i_ino) { + error = -ECANCELED; + goto out_abort; + } + + /* Don't accept an invalid inode number. */ + if (!xfs_verify_dir_ino(sc->mp, ino)) { + error = -ECANCELED; + goto out_abort; + } + + /* Update the shadow link counts if we haven't already failed. */ + + if (xchk_iscan_aborted(&xnc->collect_iscan)) { + error = -ECANCELED; + goto out_incomplete; + } + + trace_xchk_nlinks_collect_dirent(sc->mp, dp, ino, name); + + mutex_lock(&xnc->lock); + + /* + * If this is a dotdot entry, it is a back link from dp to ino. How + * we handle this depends on whether or not dp is the root directory. + * + * The root directory is its own parent, so we pretend the dotdot entry + * establishes the "parent" of the root directory. Increment the + * number of parents of the root directory. + * + * Otherwise, increment the number of backrefs pointing back to ino. + */ + if (dotdot) { + if (dp == sc->mp->m_rootip) + error = xchk_nlinks_update_incore(xnc, ino, 1, 0, 0); + else + error = xchk_nlinks_update_incore(xnc, ino, 0, 1, 0); + if (error) + goto out_unlock; + } + + /* + * If this dirent is a forward link from dp to ino, increment the + * number of parents linking into ino. + */ + if (!dot && !dotdot) { + error = xchk_nlinks_update_incore(xnc, ino, 1, 0, 0); + if (error) + goto out_unlock; + } + + /* + * If this dirent is a forward link to a subdirectory, increment the + * number of child links of dp. + */ + if (!dot && !dotdot && name->type == XFS_DIR3_FT_DIR) { + error = xchk_nlinks_update_incore(xnc, dp->i_ino, 0, 0, 1); + if (error) + goto out_unlock; + } + + mutex_unlock(&xnc->lock); + return 0; + +out_unlock: + mutex_unlock(&xnc->lock); +out_abort: + xchk_iscan_abort(&xnc->collect_iscan); +out_incomplete: + xchk_set_incomplete(sc); + return error; +} + +/* Walk a directory to bump the observed link counts of the children. */ +STATIC int +xchk_nlinks_collect_dir( + struct xchk_nlink_ctrs *xnc, + struct xfs_inode *dp) +{ + struct xfs_scrub *sc = xnc->sc; + unsigned int lock_mode; + int error = 0; + + /* Prevent anyone from changing this directory while we walk it. */ + xfs_ilock(dp, XFS_IOLOCK_SHARED); + lock_mode = xfs_ilock_data_map_shared(dp); + + /* + * The dotdot entry of an unlinked directory still points to the last + * parent, but the parent no longer links to this directory. Skip the + * directory to avoid overcounting. + */ + if (VFS_I(dp)->i_nlink == 0) + goto out_unlock; + + /* + * We cannot count file links if the directory looks as though it has + * been zapped by the inode record repair code. + */ + if (xchk_dir_looks_zapped(dp)) { + error = -EBUSY; + goto out_abort; + } + + error = xchk_dir_walk(sc, dp, xchk_nlinks_collect_dirent, xnc); + if (error == -ECANCELED) { + error = 0; + goto out_unlock; + } + if (error) + goto out_abort; + + xchk_iscan_mark_visited(&xnc->collect_iscan, dp); + goto out_unlock; + +out_abort: + xchk_set_incomplete(sc); + xchk_iscan_abort(&xnc->collect_iscan); +out_unlock: + xfs_iunlock(dp, lock_mode); + xfs_iunlock(dp, XFS_IOLOCK_SHARED); + return error; +} + +/* If this looks like a valid pointer, count it. */ +static inline int +xchk_nlinks_collect_metafile( + struct xchk_nlink_ctrs *xnc, + xfs_ino_t ino) +{ + if (!xfs_verify_ino(xnc->sc->mp, ino)) + return 0; + + trace_xchk_nlinks_collect_metafile(xnc->sc->mp, ino); + return xchk_nlinks_update_incore(xnc, ino, 1, 0, 0); +} + +/* Bump the link counts of metadata files rooted in the superblock. */ +STATIC int +xchk_nlinks_collect_metafiles( + struct xchk_nlink_ctrs *xnc) +{ + struct xfs_mount *mp = xnc->sc->mp; + int error = -ECANCELED; + + + if (xchk_iscan_aborted(&xnc->collect_iscan)) + goto out_incomplete; + + mutex_lock(&xnc->lock); + error = xchk_nlinks_collect_metafile(xnc, mp->m_sb.sb_rbmino); + if (error) + goto out_abort; + + error = xchk_nlinks_collect_metafile(xnc, mp->m_sb.sb_rsumino); + if (error) + goto out_abort; + + error = xchk_nlinks_collect_metafile(xnc, mp->m_sb.sb_uquotino); + if (error) + goto out_abort; + + error = xchk_nlinks_collect_metafile(xnc, mp->m_sb.sb_gquotino); + if (error) + goto out_abort; + + error = xchk_nlinks_collect_metafile(xnc, mp->m_sb.sb_pquotino); + if (error) + goto out_abort; + mutex_unlock(&xnc->lock); + + return 0; + +out_abort: + mutex_unlock(&xnc->lock); + xchk_iscan_abort(&xnc->collect_iscan); +out_incomplete: + xchk_set_incomplete(xnc->sc); + return error; +} + +/* Advance the collection scan cursor for this non-directory file. */ +static inline int +xchk_nlinks_collect_file( + struct xchk_nlink_ctrs *xnc, + struct xfs_inode *ip) +{ + xfs_ilock(ip, XFS_IOLOCK_SHARED); + xchk_iscan_mark_visited(&xnc->collect_iscan, ip); + xfs_iunlock(ip, XFS_IOLOCK_SHARED); + return 0; +} + +/* Walk all directories and count inode links. */ +STATIC int +xchk_nlinks_collect( + struct xchk_nlink_ctrs *xnc) +{ + struct xfs_scrub *sc = xnc->sc; + struct xfs_inode *ip; + int error; + + /* Count the rt and quota files that are rooted in the superblock. */ + error = xchk_nlinks_collect_metafiles(xnc); + if (error) + return error; + + /* + * Set up for a potentially lengthy filesystem scan by reducing our + * transaction resource usage for the duration. Specifically: + * + * Cancel the transaction to release the log grant space while we scan + * the filesystem. + * + * Create a new empty transaction to eliminate the possibility of the + * inode scan deadlocking on cyclical metadata. + * + * We pass the empty transaction to the file scanning function to avoid + * repeatedly cycling empty transactions. This can be done even though + * we take the IOLOCK to quiesce the file because empty transactions + * do not take sb_internal. + */ + xchk_trans_cancel(sc); + error = xchk_trans_alloc_empty(sc); + if (error) + return error; + + while ((error = xchk_iscan_iter(&xnc->collect_iscan, &ip)) == 1) { + if (S_ISDIR(VFS_I(ip)->i_mode)) + error = xchk_nlinks_collect_dir(xnc, ip); + else + error = xchk_nlinks_collect_file(xnc, ip); + xchk_irele(sc, ip); + if (error) + break; + + if (xchk_should_terminate(sc, &error)) + break; + } + xchk_iscan_iter_finish(&xnc->collect_iscan); + if (error) { + xchk_set_incomplete(sc); + /* + * If we couldn't grab an inode that was busy with a state + * change, change the error code so that we exit to userspace + * as quickly as possible. + */ + if (error == -EBUSY) + return -ECANCELED; + return error; + } + + /* + * Switch out for a real transaction in preparation for building a new + * tree. + */ + xchk_trans_cancel(sc); + return xchk_setup_fs(sc); +} + +/* + * Part 2: Comparing file link counters. Walk each inode and compare the link + * counts against our shadow information; and then walk each shadow link count + * structure (that wasn't covered in the first part), comparing it against the + * file. + */ + +/* Read the observed link count for comparison with the actual inode. */ +STATIC int +xchk_nlinks_comparison_read( + struct xchk_nlink_ctrs *xnc, + xfs_ino_t ino, + struct xchk_nlink *obs) +{ + struct xchk_nlink nl; + int error; + + error = xfarray_load_sparse(xnc->nlinks, ino, &nl); + if (error) + return error; + + nl.flags |= (XCHK_NLINK_COMPARE_SCANNED | XCHK_NLINK_WRITTEN); + + error = xfarray_store(xnc->nlinks, ino, &nl); + if (error == -EFBIG) { + /* + * EFBIG means we tried to store data at too high a byte offset + * in the sparse array. IOWs, we cannot complete the check and + * must notify userspace that the check was incomplete. This + * shouldn't really happen outside of the collection phase. + */ + xchk_set_incomplete(xnc->sc); + return -ECANCELED; + } + if (error) + return error; + + /* Copy the counters, but do not expose the internal state. */ + obs->parents = nl.parents; + obs->backrefs = nl.backrefs; + obs->children = nl.children; + obs->flags = 0; + return 0; +} + +/* Check our link count against an inode. */ +STATIC int +xchk_nlinks_compare_inode( + struct xchk_nlink_ctrs *xnc, + struct xfs_inode *ip) +{ + struct xchk_nlink obs; + struct xfs_scrub *sc = xnc->sc; + uint64_t total_links; + unsigned int actual_nlink; + int error; + + xfs_ilock(ip, XFS_ILOCK_SHARED); + mutex_lock(&xnc->lock); + + if (xchk_iscan_aborted(&xnc->collect_iscan)) { + xchk_set_incomplete(xnc->sc); + error = -ECANCELED; + goto out_scanlock; + } + + error = xchk_nlinks_comparison_read(xnc, ip->i_ino, &obs); + if (error) + goto out_scanlock; + + /* + * If we don't have ftype to get an accurate count of the subdirectory + * entries in this directory, take advantage of the fact that on a + * consistent ftype=0 filesystem, the number of subdirectory + * backreferences (dotdot entries) pointing towards this directory + * should be equal to the number of subdirectory entries in the + * directory. + */ + if (!xfs_has_ftype(sc->mp) && S_ISDIR(VFS_I(ip)->i_mode)) + obs.children = obs.backrefs; + + total_links = xchk_nlink_total(ip, &obs); + actual_nlink = VFS_I(ip)->i_nlink; + + trace_xchk_nlinks_compare_inode(sc->mp, ip, &obs); + + /* + * If we found so many parents that we'd overflow i_nlink, we must flag + * this as a corruption. The VFS won't let users increase the link + * count, but it will let them decrease it. + */ + if (total_links > XFS_MAXLINK) { + xchk_ino_set_corrupt(sc, ip->i_ino); + goto out_corrupt; + } + + /* Link counts should match. */ + if (total_links != actual_nlink) { + xchk_ino_set_corrupt(sc, ip->i_ino); + goto out_corrupt; + } + + if (S_ISDIR(VFS_I(ip)->i_mode) && actual_nlink > 0) { + /* + * The collection phase ignores directories with zero link + * count, so we ignore them here too. + * + * The number of subdirectory backreferences (dotdot entries) + * pointing towards this directory should be equal to the + * number of subdirectory entries in the directory. + */ + if (obs.children != obs.backrefs) + xchk_ino_xref_set_corrupt(sc, ip->i_ino); + } else { + /* + * Non-directories and unlinked directories should not have + * back references. + */ + if (obs.backrefs != 0) { + xchk_ino_set_corrupt(sc, ip->i_ino); + goto out_corrupt; + } + + /* + * Non-directories and unlinked directories should not have + * children. + */ + if (obs.children != 0) { + xchk_ino_set_corrupt(sc, ip->i_ino); + goto out_corrupt; + } + } + + if (ip == sc->mp->m_rootip) { + /* + * For the root of a directory tree, both the '.' and '..' + * entries should point to the root directory. The dotdot + * entry is counted as a parent of the root /and/ a backref of + * the root directory. + */ + if (obs.parents != 1) { + xchk_ino_set_corrupt(sc, ip->i_ino); + goto out_corrupt; + } + } else if (actual_nlink > 0) { + /* + * Linked files that are not the root directory should have at + * least one parent. + */ + if (obs.parents == 0) { + xchk_ino_set_corrupt(sc, ip->i_ino); + goto out_corrupt; + } + } + +out_corrupt: + if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT) + error = -ECANCELED; +out_scanlock: + mutex_unlock(&xnc->lock); + xfs_iunlock(ip, XFS_ILOCK_SHARED); + return error; +} + +/* + * Check our link count against an inode that wasn't checked previously. This + * is intended to catch directories with dangling links, though we could be + * racing with inode allocation in other threads. + */ +STATIC int +xchk_nlinks_compare_inum( + struct xchk_nlink_ctrs *xnc, + xfs_ino_t ino) +{ + struct xchk_nlink obs; + struct xfs_mount *mp = xnc->sc->mp; + struct xfs_trans *tp = xnc->sc->tp; + struct xfs_buf *agi_bp; + struct xfs_inode *ip; + int error; + + /* + * The first iget failed, so try again with the variant that returns + * either an incore inode or the AGI buffer. If the function returns + * EINVAL/ENOENT, it should have passed us the AGI buffer so that we + * can guarantee that the inode won't be allocated while we check for + * a zero link count in the observed link count data. + */ + error = xchk_iget_agi(xnc->sc, ino, &agi_bp, &ip); + if (!error) { + /* Actually got an inode, so use the inode compare. */ + error = xchk_nlinks_compare_inode(xnc, ip); + xchk_irele(xnc->sc, ip); + return error; + } + if (error == -ENOENT || error == -EINVAL) { + /* No inode was found. Check for zero link count below. */ + error = 0; + } + if (error) + goto out_agi; + + /* Ensure that we have protected against inode allocation/freeing. */ + if (agi_bp == NULL) { + ASSERT(agi_bp != NULL); + xchk_set_incomplete(xnc->sc); + return -ECANCELED; + } + + if (xchk_iscan_aborted(&xnc->collect_iscan)) { + xchk_set_incomplete(xnc->sc); + error = -ECANCELED; + goto out_agi; + } + + mutex_lock(&xnc->lock); + error = xchk_nlinks_comparison_read(xnc, ino, &obs); + if (error) + goto out_scanlock; + + trace_xchk_nlinks_check_zero(mp, ino, &obs); + + /* + * If we can't grab the inode, the link count had better be zero. We + * still hold the AGI to prevent inode allocation/freeing. + */ + if (xchk_nlink_total(NULL, &obs) != 0) { + xchk_ino_set_corrupt(xnc->sc, ino); + error = -ECANCELED; + } + +out_scanlock: + mutex_unlock(&xnc->lock); +out_agi: + if (agi_bp) + xfs_trans_brelse(tp, agi_bp); + return error; +} + +/* + * Try to visit every inode in the filesystem to compare the link count. Move + * on if we can't grab an inode, since we'll revisit unchecked nlink records in + * the second part. + */ +static int +xchk_nlinks_compare_iter( + struct xchk_nlink_ctrs *xnc, + struct xfs_inode **ipp) +{ + int error; + + do { + error = xchk_iscan_iter(&xnc->compare_iscan, ipp); + } while (error == -EBUSY); + + return error; +} + +/* Compare the link counts we observed against the live information. */ +STATIC int +xchk_nlinks_compare( + struct xchk_nlink_ctrs *xnc) +{ + struct xchk_nlink nl; + struct xfs_scrub *sc = xnc->sc; + struct xfs_inode *ip; + xfarray_idx_t cur = XFARRAY_CURSOR_INIT; + int error; + + if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT) + return 0; + + /* + * Create a new empty transaction so that we can advance the iscan + * cursor without deadlocking if the inobt has a cycle and push on the + * inactivation workqueue. + */ + xchk_trans_cancel(sc); + error = xchk_trans_alloc_empty(sc); + if (error) + return error; + + /* + * Use the inobt to walk all allocated inodes to compare the link + * counts. Inodes skipped by _compare_iter will be tried again in the + * next phase of the scan. + */ + xchk_iscan_start(sc, 0, 0, &xnc->compare_iscan); + while ((error = xchk_nlinks_compare_iter(xnc, &ip)) == 1) { + error = xchk_nlinks_compare_inode(xnc, ip); + xchk_iscan_mark_visited(&xnc->compare_iscan, ip); + xchk_irele(sc, ip); + if (error) + break; + + if (xchk_should_terminate(sc, &error)) + break; + } + xchk_iscan_iter_finish(&xnc->compare_iscan); + xchk_iscan_teardown(&xnc->compare_iscan); + if (error) + return error; + + if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT) + return 0; + + /* + * Walk all the non-null nlink observations that weren't checked in the + * previous step. + */ + mutex_lock(&xnc->lock); + while ((error = xfarray_iter(xnc->nlinks, &cur, &nl)) == 1) { + xfs_ino_t ino = cur - 1; + + if (nl.flags & XCHK_NLINK_COMPARE_SCANNED) + continue; + + mutex_unlock(&xnc->lock); + + error = xchk_nlinks_compare_inum(xnc, ino); + if (error) + return error; + + if (xchk_should_terminate(xnc->sc, &error)) + return error; + + mutex_lock(&xnc->lock); + } + mutex_unlock(&xnc->lock); + + return error; +} + +/* Tear down everything associated with a nlinks check. */ +static void +xchk_nlinks_teardown_scan( + void *priv) +{ + struct xchk_nlink_ctrs *xnc = priv; + + /* Discourage any hook functions that might be running. */ + xchk_iscan_abort(&xnc->collect_iscan); + + xfs_dir_hook_del(xnc->sc->mp, &xnc->dhook); + + xfarray_destroy(xnc->nlinks); + xnc->nlinks = NULL; + + xchk_iscan_teardown(&xnc->collect_iscan); + mutex_destroy(&xnc->lock); + xnc->sc = NULL; +} + +/* + * Scan all inodes in the entire filesystem to generate link count data. If + * the scan is successful, the counts will be left alive for a repair. If any + * error occurs, we'll tear everything down. + */ +STATIC int +xchk_nlinks_setup_scan( + struct xfs_scrub *sc, + struct xchk_nlink_ctrs *xnc) +{ + struct xfs_mount *mp = sc->mp; + char *descr; + unsigned long long max_inos; + xfs_agnumber_t last_agno = mp->m_sb.sb_agcount - 1; + xfs_agino_t first_agino, last_agino; + int error; + + ASSERT(xnc->sc == NULL); + xnc->sc = sc; + + mutex_init(&xnc->lock); + + /* Retry iget every tenth of a second for up to 30 seconds. */ + xchk_iscan_start(sc, 30000, 100, &xnc->collect_iscan); + + /* + * Set up enough space to store an nlink record for the highest + * possible inode number in this system. + */ + xfs_agino_range(mp, last_agno, &first_agino, &last_agino); + max_inos = XFS_AGINO_TO_INO(mp, last_agno, last_agino) + 1; + descr = xchk_xfile_descr(sc, "file link counts"); + error = xfarray_create(descr, min(XFS_MAXINUMBER + 1, max_inos), + sizeof(struct xchk_nlink), &xnc->nlinks); + kfree(descr); + if (error) + goto out_teardown; + + /* + * Hook into the directory entry code so that we can capture updates to + * file link counts. The hook only triggers for inodes that were + * already scanned, and the scanner thread takes each inode's ILOCK, + * which means that any in-progress inode updates will finish before we + * can scan the inode. + */ + ASSERT(sc->flags & XCHK_FSGATES_DIRENTS); + xfs_dir_hook_setup(&xnc->dhook, xchk_nlinks_live_update); + error = xfs_dir_hook_add(mp, &xnc->dhook); + if (error) + goto out_teardown; + + /* Use deferred cleanup to pass the inode link count data to repair. */ + sc->buf_cleanup = xchk_nlinks_teardown_scan; + return 0; + +out_teardown: + xchk_nlinks_teardown_scan(xnc); + return error; +} + +/* Scrub the link count of all inodes on the filesystem. */ +int +xchk_nlinks( + struct xfs_scrub *sc) +{ + struct xchk_nlink_ctrs *xnc = sc->buf; + int error = 0; + + /* Set ourselves up to check link counts on the live filesystem. */ + error = xchk_nlinks_setup_scan(sc, xnc); + if (error) + return error; + + /* Walk all inodes, picking up link count information. */ + error = xchk_nlinks_collect(xnc); + if (!xchk_xref_process_error(sc, 0, 0, &error)) + return error; + + /* Fail fast if we're not playing with a full dataset. */ + if (xchk_iscan_aborted(&xnc->collect_iscan)) + xchk_set_incomplete(sc); + if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_INCOMPLETE) + return 0; + + /* Compare link counts. */ + error = xchk_nlinks_compare(xnc); + if (!xchk_xref_process_error(sc, 0, 0, &error)) + return error; + + /* Check one last time for an incomplete dataset. */ + if (xchk_iscan_aborted(&xnc->collect_iscan)) + xchk_set_incomplete(sc); + + return 0; +} |