linux/fs/xfs/scrub/parent.c
Darrick J. Wong 026f57ebe1 xfs: get rid of the ip parameter to xchk_setup_*
Now that the scrub context stores a pointer to the file that was used to
invoke the scrub call, the struct xfs_inode pointer that we passed to
all the setup functions is no longer necessary.  This is only ever used
if the caller wants us to scrub the metadata of the open file.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2021-04-09 10:27:18 -07:00

335 lines
8.7 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2017 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <darrick.wong@oracle.com>
*/
#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_inode.h"
#include "xfs_icache.h"
#include "xfs_dir2.h"
#include "xfs_dir2_priv.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
/* Set us up to scrub parents. */
int
xchk_setup_parent(
struct xfs_scrub *sc)
{
return xchk_setup_inode_contents(sc, 0);
}
/* Parent pointers */
/* Look for an entry in a parent pointing to this inode. */
struct xchk_parent_ctx {
struct dir_context dc;
struct xfs_scrub *sc;
xfs_ino_t ino;
xfs_nlink_t nlink;
bool cancelled;
};
/* Look for a single entry in a directory pointing to an inode. */
STATIC int
xchk_parent_actor(
struct dir_context *dc,
const char *name,
int namelen,
loff_t pos,
u64 ino,
unsigned type)
{
struct xchk_parent_ctx *spc;
int error = 0;
spc = container_of(dc, struct xchk_parent_ctx, dc);
if (spc->ino == ino)
spc->nlink++;
/*
* If we're facing a fatal signal, bail out. Store the cancellation
* status separately because the VFS readdir code squashes error codes
* into short directory reads.
*/
if (xchk_should_terminate(spc->sc, &error))
spc->cancelled = true;
return error;
}
/* Count the number of dentries in the parent dir that point to this inode. */
STATIC int
xchk_parent_count_parent_dentries(
struct xfs_scrub *sc,
struct xfs_inode *parent,
xfs_nlink_t *nlink)
{
struct xchk_parent_ctx spc = {
.dc.actor = xchk_parent_actor,
.ino = sc->ip->i_ino,
.sc = sc,
};
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_df.if_nextents > 0)
error = xfs_dir3_data_readahead(parent, 0, 0);
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_disk_size);
oldpos = 0;
while (true) {
error = xfs_readdir(sc->tp, parent, &spc.dc, bufsize);
if (error)
goto out;
if (spc.cancelled) {
error = -EAGAIN;
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
xchk_parent_validate(
struct xfs_scrub *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 = 0;
*try_again = false;
if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
goto out;
/* '..' must not point to ourselves. */
if (sc->ip->i_ino == dnum) {
xchk_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.
*
* If _iget returns -EINVAL or -ENOENT then the parent inode number is
* garbage and the directory is corrupt. If the _iget returns
* -EFSCORRUPTED or -EFSBADCRC then the parent is corrupt which is a
* cross referencing error. Any other error is an operational error.
*/
error = xfs_iget(mp, sc->tp, dnum, XFS_IGET_UNTRUSTED, 0, &dp);
if (error == -EINVAL || error == -ENOENT) {
error = -EFSCORRUPTED;
xchk_fblock_process_error(sc, XFS_DATA_FORK, 0, &error);
goto out;
}
if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, 0, &error))
goto out;
if (dp == sc->ip || !S_ISDIR(VFS_I(dp)->i_mode)) {
xchk_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 = xchk_parent_count_parent_dentries(sc, dp, &nlink);
if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, 0,
&error))
goto out_unlock;
if (nlink != expected_nlink)
xchk_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;
error = xchk_ilock_inverted(dp, XFS_IOLOCK_SHARED);
if (error)
goto out_rele;
/* Go looking for our dentry. */
error = xchk_parent_count_parent_dentries(sc, dp, &nlink);
if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, 0, &error))
goto out_unlock;
/* Drop the parent lock, relock this inode. */
xfs_iunlock(dp, XFS_IOLOCK_SHARED);
error = xchk_ilock_inverted(sc->ip, XFS_IOLOCK_EXCL);
if (error)
goto out_rele;
sc->ilock_flags = XFS_IOLOCK_EXCL;
/*
* 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 (!xchk_fblock_process_error(sc, XFS_DATA_FORK, 0, &error))
goto out_rele;
/* Drat, parent changed. Try again! */
if (dnum != dp->i_ino) {
xfs_irele(dp);
*try_again = true;
return 0;
}
xfs_irele(dp);
/*
* '..' didn't change, so check that there was only one entry
* for us in the parent.
*/
if (nlink != expected_nlink)
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
return error;
out_unlock:
xfs_iunlock(dp, XFS_IOLOCK_SHARED);
out_rele:
xfs_irele(dp);
out:
return error;
}
/* Scrub a parent pointer. */
int
xchk_parent(
struct xfs_scrub *sc)
{
struct xfs_mount *mp = sc->mp;
xfs_ino_t dnum;
bool try_again;
int tries = 0;
int error = 0;
/*
* 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)) {
xchk_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 (!xchk_fblock_process_error(sc, XFS_DATA_FORK, 0, &error))
goto out;
if (!xfs_verify_dir_ino(mp, dnum)) {
xchk_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)
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
goto out;
}
do {
error = xchk_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)
xchk_set_incomplete(sc);
out:
/*
* If we failed to lock the parent inode even after a retry, just mark
* this scrub incomplete and return.
*/
if ((sc->flags & XCHK_TRY_HARDER) && error == -EDEADLOCK) {
error = 0;
xchk_set_incomplete(sc);
}
return error;
}