diff options
| -rw-r--r-- | fs/xfs/Makefile | 1 | ||||
| -rw-r--r-- | fs/xfs/libxfs/xfs_fs.h | 3 | ||||
| -rw-r--r-- | fs/xfs/scrub/common.h | 2 | ||||
| -rw-r--r-- | fs/xfs/scrub/parent.c | 317 | ||||
| -rw-r--r-- | fs/xfs/scrub/scrub.c | 4 | ||||
| -rw-r--r-- | fs/xfs/scrub/scrub.h | 1 |
6 files changed, 327 insertions, 1 deletions
diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile index 9ffcc81b3b7f..174c05d36db5 100644 --- a/fs/xfs/Makefile +++ b/fs/xfs/Makefile @@ -153,6 +153,7 @@ xfs-y += $(addprefix scrub/, \ dir.o \ ialloc.o \ inode.o \ + parent.o \ refcount.o \ rmap.o \ scrub.o \ diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h index bb8bcd0c32de..7444094072d5 100644 --- a/fs/xfs/libxfs/xfs_fs.h +++ b/fs/xfs/libxfs/xfs_fs.h @@ -501,9 +501,10 @@ struct xfs_scrub_metadata { #define XFS_SCRUB_TYPE_DIR 15 /* directory */ #define XFS_SCRUB_TYPE_XATTR 16 /* extended attribute */ #define XFS_SCRUB_TYPE_SYMLINK 17 /* symbolic link */ +#define XFS_SCRUB_TYPE_PARENT 18 /* parent pointers */ /* Number of scrub subcommands. */ -#define XFS_SCRUB_TYPE_NR 18 +#define XFS_SCRUB_TYPE_NR 19 /* i: Repair this metadata. */ #define XFS_SCRUB_IFLAG_REPAIR (1 << 0) diff --git a/fs/xfs/scrub/common.h b/fs/xfs/scrub/common.h index b71c1a8d328b..0542e7d4356a 100644 --- a/fs/xfs/scrub/common.h +++ b/fs/xfs/scrub/common.h @@ -99,6 +99,8 @@ int xfs_scrub_setup_xattr(struct xfs_scrub_context *sc, struct xfs_inode *ip); int xfs_scrub_setup_symlink(struct xfs_scrub_context *sc, struct xfs_inode *ip); +int xfs_scrub_setup_parent(struct xfs_scrub_context *sc, + struct xfs_inode *ip); void xfs_scrub_ag_free(struct xfs_scrub_context *sc, struct xfs_scrub_ag *sa); int xfs_scrub_ag_init(struct xfs_scrub_context *sc, xfs_agnumber_t agno, diff --git a/fs/xfs/scrub/parent.c b/fs/xfs/scrub/parent.c new file mode 100644 index 000000000000..cc2b8f665416 --- /dev/null +++ b/fs/xfs/scrub/parent.c @@ -0,0 +1,317 @@ +/* + * Copyright (C) 2017 Oracle. All Rights Reserved. + * + * Author: Darrick J. Wong <darrick.wong@oracle.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it would be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. + */ +#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_defer.h" +#include "xfs_btree.h" +#include "xfs_bit.h" +#include "xfs_log_format.h" +#include "xfs_trans.h" +#include "xfs_sb.h" +#include "xfs_inode.h" +#include "xfs_icache.h" +#include "xfs_dir2.h" +#include "xfs_dir2_priv.h" +#include "xfs_ialloc.h" +#include "scrub/xfs_scrub.h" +#include "scrub/scrub.h" +#include "scrub/common.h" +#include "scrub/trace.h" + +/* Set us up to scrub parents. */ +int +xfs_scrub_setup_parent( + struct xfs_scrub_context *sc, + struct xfs_inode *ip) +{ + return xfs_scrub_setup_inode_contents(sc, ip, 0); +} + +/* Parent pointers */ + +/* Look for an entry in a parent pointing to this inode. */ + +struct xfs_scrub_parent_ctx { + struct dir_context dc; + xfs_ino_t ino; + xfs_nlink_t nlink; +}; + +/* Look for a single entry in a directory pointing to an inode. */ +STATIC int +xfs_scrub_parent_actor( + struct dir_context *dc, + const char *name, + int namelen, + loff_t pos, + u64 ino, + unsigned type) +{ + struct xfs_scrub_parent_ctx *spc; + + spc = container_of(dc, struct xfs_scrub_parent_ctx, dc); + if (spc->ino == ino) + spc->nlink++; + return 0; +} + +/* Count the number of dentries in the parent dir that point to this inode. */ +STATIC int +xfs_scrub_parent_count_parent_dentries( + struct xfs_scrub_context *sc, + struct xfs_inode *parent, + xfs_nlink_t *nlink) +{ + struct xfs_scrub_parent_ctx spc = { + .dc.actor = xfs_scrub_parent_actor, + .dc.pos = 0, + .ino = sc->ip->i_ino, + .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_d.di_nextents > 0) + error = xfs_dir3_data_readahead(parent, 0, -1); + 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_d.di_size); + oldpos = 0; + while (true) { + error = xfs_readdir(sc->tp, parent, &spc.dc, bufsize); + if (error) + goto out; + if (oldpos == spc.dc.pos) + break; + oldpos = spc.dc.pos; + } + *nlink = spc.nlink; +out: + return error; +} + +/* + * Given the inode number of the alleged parent of the inode being + * scrubbed, try to validate that the parent has exactly one directory + * entry pointing back to the inode being scrubbed. + */ +STATIC int +xfs_scrub_parent_validate( + struct xfs_scrub_context *sc, + xfs_ino_t dnum, + bool *try_again) +{ + struct xfs_mount *mp = sc->mp; + struct xfs_inode *dp = NULL; + xfs_nlink_t expected_nlink; + xfs_nlink_t nlink; + int error; + + *try_again = false; + + /* '..' must not point to ourselves. */ + if (sc->ip->i_ino == dnum) { + xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, 0); + goto out; + } + + /* + * If we're an unlinked directory, the parent /won't/ have a link + * to us. Otherwise, it should have one link. + */ + expected_nlink = VFS_I(sc->ip)->i_nlink == 0 ? 0 : 1; + + /* + * Grab this parent inode. We release the inode before we + * cancel the scrub transaction. Since we're don't know a + * priori that releasing the inode won't trigger eofblocks + * cleanup (which allocates what would be a nested transaction) + * if the parent pointer erroneously points to a file, we + * can't use DONTCACHE here because DONTCACHE inodes can trigger + * immediate inactive cleanup of the inode. + */ + error = xfs_iget(mp, sc->tp, dnum, 0, 0, &dp); + if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, 0, &error)) + goto out; + if (dp == sc->ip) { + xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, 0); + goto out_rele; + } + + /* + * We prefer to keep the inode locked while we lock and search + * its alleged parent for a forward reference. If we can grab + * the iolock, validate the pointers and we're done. We must + * use nowait here to avoid an ABBA deadlock on the parent and + * the child inodes. + */ + if (xfs_ilock_nowait(dp, XFS_IOLOCK_SHARED)) { + error = xfs_scrub_parent_count_parent_dentries(sc, dp, &nlink); + if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, 0, + &error)) + goto out_unlock; + if (nlink != expected_nlink) + xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, 0); + goto out_unlock; + } + + /* + * The game changes if we get here. We failed to lock the parent, + * so we're going to try to verify both pointers while only holding + * one lock so as to avoid deadlocking with something that's actually + * trying to traverse down the directory tree. + */ + xfs_iunlock(sc->ip, sc->ilock_flags); + sc->ilock_flags = 0; + xfs_ilock(dp, XFS_IOLOCK_SHARED); + + /* Go looking for our dentry. */ + error = xfs_scrub_parent_count_parent_dentries(sc, dp, &nlink); + if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, 0, &error)) + goto out_unlock; + + /* Drop the parent lock, relock this inode. */ + xfs_iunlock(dp, XFS_IOLOCK_SHARED); + sc->ilock_flags = XFS_IOLOCK_EXCL; + xfs_ilock(sc->ip, sc->ilock_flags); + + /* + * If we're an unlinked directory, the parent /won't/ have a link + * to us. Otherwise, it should have one link. We have to re-set + * it here because we dropped the lock on sc->ip. + */ + expected_nlink = VFS_I(sc->ip)->i_nlink == 0 ? 0 : 1; + + /* Look up '..' to see if the inode changed. */ + error = xfs_dir_lookup(sc->tp, sc->ip, &xfs_name_dotdot, &dnum, NULL); + if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, 0, &error)) + goto out_rele; + + /* Drat, parent changed. Try again! */ + if (dnum != dp->i_ino) { + iput(VFS_I(dp)); + *try_again = true; + return 0; + } + iput(VFS_I(dp)); + + /* + * '..' didn't change, so check that there was only one entry + * for us in the parent. + */ + if (nlink != expected_nlink) + xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, 0); + return error; + +out_unlock: + xfs_iunlock(dp, XFS_IOLOCK_SHARED); +out_rele: + iput(VFS_I(dp)); +out: + return error; +} + +/* Scrub a parent pointer. */ +int +xfs_scrub_parent( + struct xfs_scrub_context *sc) +{ + struct xfs_mount *mp = sc->mp; + xfs_ino_t dnum; + bool try_again; + int tries = 0; + int error; + + /* + * If we're a directory, check that the '..' link points up to + * a directory that has one entry pointing to us. + */ + if (!S_ISDIR(VFS_I(sc->ip)->i_mode)) + return -ENOENT; + + /* We're not a special inode, are we? */ + if (!xfs_verify_dir_ino(mp, sc->ip->i_ino)) { + xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, 0); + goto out; + } + + /* + * The VFS grabs a read or write lock via i_rwsem before it reads + * or writes to a directory. If we've gotten this far we've + * already obtained IOLOCK_EXCL, which (since 4.10) is the same as + * getting a write lock on i_rwsem. Therefore, it is safe for us + * to drop the ILOCK here in order to do directory lookups. + */ + sc->ilock_flags &= ~(XFS_ILOCK_EXCL | XFS_MMAPLOCK_EXCL); + xfs_iunlock(sc->ip, XFS_ILOCK_EXCL | XFS_MMAPLOCK_EXCL); + + /* Look up '..' */ + error = xfs_dir_lookup(sc->tp, sc->ip, &xfs_name_dotdot, &dnum, NULL); + if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, 0, &error)) + goto out; + if (!xfs_verify_dir_ino(mp, dnum)) { + xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, 0); + goto out; + } + + /* Is this the root dir? Then '..' must point to itself. */ + if (sc->ip == mp->m_rootip) { + if (sc->ip->i_ino != mp->m_sb.sb_rootino || + sc->ip->i_ino != dnum) + xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, 0); + goto out; + } + + do { + error = xfs_scrub_parent_validate(sc, dnum, &try_again); + if (error) + goto out; + } while (try_again && ++tries < 20); + + /* + * We gave it our best shot but failed, so mark this scrub + * incomplete. Userspace can decide if it wants to try again. + */ + if (try_again && tries == 20) + xfs_scrub_set_incomplete(sc); +out: + return error; +} diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c index 14487279d460..e9c6635f7d5a 100644 --- a/fs/xfs/scrub/scrub.c +++ b/fs/xfs/scrub/scrub.c @@ -243,6 +243,10 @@ static const struct xfs_scrub_meta_ops meta_scrub_ops[] = { .setup = xfs_scrub_setup_symlink, .scrub = xfs_scrub_symlink, }, + { /* parent pointers */ + .setup = xfs_scrub_setup_parent, + .scrub = xfs_scrub_parent, + }, }; /* This isn't a stable feature, warn once per day. */ diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h index dc4ed8de79d7..a26481070eaf 100644 --- a/fs/xfs/scrub/scrub.h +++ b/fs/xfs/scrub/scrub.h @@ -86,5 +86,6 @@ int xfs_scrub_bmap_cow(struct xfs_scrub_context *sc); int xfs_scrub_directory(struct xfs_scrub_context *sc); int xfs_scrub_xattr(struct xfs_scrub_context *sc); int xfs_scrub_symlink(struct xfs_scrub_context *sc); +int xfs_scrub_parent(struct xfs_scrub_context *sc); #endif /* __XFS_SCRUB_SCRUB_H__ */ |