linux/fs/gfs2/dentry.c
Abhi Das dd00aaeb34 gfs2: Use GL_NOBLOCK flag for non-blocking lookups
Add the GL_NOBLOCK flag to the locking requests in gfs2_permission() and
gfs2_drevalidate() when called with the MAY_NOT_BLOCK flag and
LOOKUP_RCU flag, respectively.  This will cause the locking requests to
be handled without sleeping if possible.  We bail out with -ECHILD if we
can't grant the glock immediately.

Make sure not to dget() + dput() the parent dentry in gfs2_drevalidate()
in LOOKUP_RCU mode; dput() is a sleeping operation.

Signed-off-by: Abhi Das <adas@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2023-12-18 14:24:33 +01:00

114 lines
2.4 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
*/
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/gfs2_ondisk.h>
#include <linux/namei.h>
#include <linux/crc32.h>
#include "gfs2.h"
#include "incore.h"
#include "dir.h"
#include "glock.h"
#include "super.h"
#include "util.h"
#include "inode.h"
/**
* gfs2_drevalidate - Check directory lookup consistency
* @dentry: the mapping to check
* @flags: lookup flags
*
* Check to make sure the lookup necessary to arrive at this inode from its
* parent is still good.
*
* Returns: 1 if the dentry is ok, 0 if it isn't
*/
static int gfs2_drevalidate(struct dentry *dentry, unsigned int flags)
{
struct dentry *parent = NULL;
struct gfs2_sbd *sdp;
struct gfs2_inode *dip;
struct inode *dinode, *inode;
struct gfs2_holder d_gh;
struct gfs2_inode *ip = NULL;
int error, valid = 0;
int had_lock = 0;
if (flags & LOOKUP_RCU) {
dinode = d_inode_rcu(READ_ONCE(dentry->d_parent));
if (!dinode)
return -ECHILD;
} else {
parent = dget_parent(dentry);
dinode = d_inode(parent);
}
sdp = GFS2_SB(dinode);
dip = GFS2_I(dinode);
inode = d_inode(dentry);
if (inode) {
if (is_bad_inode(inode))
goto out;
ip = GFS2_I(inode);
}
if (sdp->sd_lockstruct.ls_ops->lm_mount == NULL) {
valid = 1;
goto out;
}
had_lock = (gfs2_glock_is_locked_by_me(dip->i_gl) != NULL);
if (!had_lock) {
error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED,
flags & LOOKUP_RCU ? GL_NOBLOCK : 0, &d_gh);
if (error)
goto out;
}
error = gfs2_dir_check(d_inode(parent), &dentry->d_name, ip);
valid = inode ? !error : (error == -ENOENT);
if (!had_lock)
gfs2_glock_dq_uninit(&d_gh);
out:
dput(parent);
return valid;
}
static int gfs2_dhash(const struct dentry *dentry, struct qstr *str)
{
str->hash = gfs2_disk_hash(str->name, str->len);
return 0;
}
static int gfs2_dentry_delete(const struct dentry *dentry)
{
struct gfs2_inode *ginode;
if (d_really_is_negative(dentry))
return 0;
ginode = GFS2_I(d_inode(dentry));
if (!gfs2_holder_initialized(&ginode->i_iopen_gh))
return 0;
if (test_bit(GLF_DEMOTE, &ginode->i_iopen_gh.gh_gl->gl_flags))
return 1;
return 0;
}
const struct dentry_operations gfs2_dops = {
.d_revalidate = gfs2_drevalidate,
.d_hash = gfs2_dhash,
.d_delete = gfs2_dentry_delete,
};