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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2020 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_defer.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_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_dir2.h"
#include "xfs_dir2_priv.h"
#include "xfs_trans_space.h"
#include "xfs_iwalk.h"
#include "scrub/xfs_scrub.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/trace.h"
#include "scrub/repair.h"
#include "scrub/parent.h"
/*
* Scanning Directory Trees for Parent Pointers
* ============================================
*
* Walk the inode table looking for directories. Scan each directory looking
* for directory entries that point to the target inode. Call a function on
* each match.
*/
struct xrep_parents_scan {
/* Context for scanning all dentries in a directory. */
struct dir_context dc;
void *data;
xrep_parents_iter_fn fn;
/* Potential parent of the directory we're scanning. */
xfs_ino_t *parent_ino;
/* This is the inode for which we want to find the parent. */
xfs_ino_t target_ino;
/* Directory that we're scanning. */
struct xfs_inode *scan_dir;
/* Errors encountered during scanning. */
int scan_error;
};
/*
* If this directory entry points to the directory we're rebuilding, then the
* directory we're scanning is the parent. Call our function.
*
* Note that the vfs readdir functions squash the nonzero codes that we return
* here into a "short" directory read, so the actual error codes are tracked
* and returned separately.
*/
STATIC int
xrep_parents_scan_dentry(
struct dir_context *dc,
const char *name,
int namelen,
loff_t pos,
u64 ino,
unsigned type)
{
struct xrep_parents_scan *rps;
rps = container_of(dc, struct xrep_parents_scan, dc);
if (ino == rps->target_ino) {
struct xfs_name xname = { .name = name, .len = namelen };
rps->scan_error = rps->fn(rps->scan_dir, &xname, type,
rps->data);
if (rps->scan_error)
return 1;
}
return 0;
}
/* Walk this directory's entries looking for any that point to the target. */
STATIC int
xrep_parents_scan_inode(
struct xfs_mount *mp,
struct xfs_trans *tp,
xfs_ino_t ino,
void *data)
{
struct xrep_parents_scan *rps = data;
struct xfs_inode *dp;
loff_t oldpos;
size_t bufsize;
unsigned int lock_mode;
int locked;
int retries = 20;
int error;
if (ino == rps->target_ino)
return 0;
/* Grab inode and lock it so we can scan it. */
error = xfs_iget(mp, tp, ino, XFS_IGET_UNTRUSTED, 0, &dp);
if (error)
return error;
if (!S_ISDIR(VFS_I(dp)->i_mode))
goto out_rele;
/*
* Try a few times to take the directory IOLOCK. We have to use
* trylock here to avoid an ABBA deadlock with another thread that
* might have a parent locked and is asleep trying to lock our target.
* The solution for EDEADLOCK is usually to freeze the fs, so try a
* few times to get the inode to avoid that heavyweight solution.
*/
while (!(locked = xfs_ilock_nowait(dp, XFS_IOLOCK_SHARED)) && --retries)
delay(HZ / 10);
if (!locked) {
error = -EDEADLOCK;
goto out_rele;
}
/*
* 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 directory's extent map has been loaded, if there
* is one.
*/
lock_mode = xfs_ilock_data_map_shared(dp);
if (dp->i_df.if_nextents > 0)
error = xfs_dir3_data_readahead(dp, 0, 0);
xfs_iunlock(dp, lock_mode);
if (error)
goto out_unlock;
/*
* Scan the directory to see if there it contains an entry pointing to
* the directory that we are repairing.
*/
rps->scan_dir = dp;
bufsize = (size_t)min_t(loff_t, XFS_READDIR_BUFSIZE, dp->i_d.di_size);
oldpos = 0;
while (true) {
error = xfs_readdir(tp, dp, &rps->dc, bufsize);
if (error)
break;
if (rps->scan_error) {
error = rps->scan_error;
break;
}
if (oldpos == rps->dc.pos)
break;
oldpos = rps->dc.pos;
}
out_unlock:
xfs_iunlock(dp, XFS_IOLOCK_SHARED);
out_rele:
xfs_irele(dp);
return error;
}
/* Does the dcache have a parent for this directory? */
xfs_ino_t
xrep_parent_check_dcache(
struct xfs_inode *dp)
{
struct inode *pip = NULL;
struct dentry *dentry, *parent;
xfs_ino_t ret = NULLFSINO;
ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
dentry = d_find_alias(VFS_I(dp));
if (!dentry)
goto out;
parent = dget_parent(dentry);
if (!parent)
goto out_dput;
pip = igrab(d_inode(parent));
dput(parent);
ret = pip->i_ino;
xfs_irele(XFS_I(pip));
out_dput:
dput(dentry);
out:
return ret;
}
/* Is this an acceptable parent for the inode we're scrubbing? */
bool
xrep_parent_acceptable(
struct xfs_scrub *sc,
xfs_ino_t ino)
{
return ino != NULLFSINO && ino != 0 && ino != sc->ip->i_ino &&
xfs_verify_dir_ino(sc->mp, ino);
}
/*
* Scan the directory tree to find the directory entries that point to this
* inode.
*/
int
xrep_scan_for_parents(
struct xfs_scrub *sc,
xfs_ino_t target_ino,
xrep_parents_iter_fn fn,
void *data)
{
struct xrep_parents_scan rps = {
.dc.actor = xrep_parents_scan_dentry,
.data = data,
.fn = fn,
.target_ino = target_ino,
};
return xfs_iwalk(sc->mp, sc->tp, 0, 0, xrep_parents_scan_inode, 0,
&rps);
}
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