vfs_dentry.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * This file contians vfs dentry ops for the 9P2000 protocol.
  4 *
  5 *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
  6 *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
  7 */
  8
  9#include <linux/module.h>
 10#include <linux/errno.h>
 11#include <linux/fs.h>
 12#include <linux/file.h>
 13#include <linux/pagemap.h>
 14#include <linux/stat.h>
 15#include <linux/string.h>
 16#include <linux/namei.h>
 17#include <linux/sched.h>
 18#include <linux/slab.h>
 19#include <net/9p/9p.h>
 20#include <net/9p/client.h>
 21
 22#include "v9fs.h"
 23#include "v9fs_vfs.h"
 24#include "fid.h"
 25
 26/**
 27 * v9fs_cached_dentry_delete - called when dentry refcount equals 0
 28 * @dentry:  dentry in question
 29 *
 30 */
 31static int v9fs_cached_dentry_delete(const struct dentry *dentry)
 32{
 33	p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p)\n",
 34		 dentry, dentry);
 35
 36	/* Don't cache negative dentries */
 37	if (d_really_is_negative(dentry))
 38		return 1;
 39	return 0;
 40}
 41
 42/**
 43 * v9fs_dentry_release - called when dentry is going to be freed
 44 * @dentry:  dentry that is being release
 45 *
 46 */
 47
 48static void v9fs_dentry_release(struct dentry *dentry)
 49{
 50	struct hlist_node *p, *n;
 51	struct hlist_head head;
 52
 53	p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p)\n",
 54		 dentry, dentry);
 55
 56	spin_lock(&dentry->d_lock);
 57	hlist_move_list((struct hlist_head *)&dentry->d_fsdata, &head);
 58	spin_unlock(&dentry->d_lock);
 59
 60	hlist_for_each_safe(p, n, &head)
 61		p9_fid_put(hlist_entry(p, struct p9_fid, dlist));
 62}
 63
 64static int __v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 65{
 66	struct p9_fid *fid;
 67	struct inode *inode;
 68	struct v9fs_inode *v9inode;
 69
 70	if (flags & LOOKUP_RCU)
 71		return -ECHILD;
 72
 73	inode = d_inode(dentry);
 74	if (!inode)
 75		goto out_valid;
 76
 77	v9inode = V9FS_I(inode);
 78	if (v9inode->cache_validity & V9FS_INO_INVALID_ATTR) {
 79		int retval;
 80		struct v9fs_session_info *v9ses;
 81
 82		fid = v9fs_fid_lookup(dentry);
 83		if (IS_ERR(fid)) {
 84			p9_debug(
 85				P9_DEBUG_VFS,
 86				"v9fs_fid_lookup: dentry = %pd (%p), got error %pe\n",
 87				dentry, dentry, fid);
 88			return PTR_ERR(fid);
 89		}
 90
 91		v9ses = v9fs_inode2v9ses(inode);
 92		if (v9fs_proto_dotl(v9ses))
 93			retval = v9fs_refresh_inode_dotl(fid, inode);
 94		else
 95			retval = v9fs_refresh_inode(fid, inode);
 96		p9_fid_put(fid);
 97
 98		if (retval == -ENOENT) {
 99			p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) invalidated due to ENOENT\n",
100				 dentry, dentry);
101			return 0;
102		}
103		if (v9inode->cache_validity & V9FS_INO_INVALID_ATTR) {
104			p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) invalidated due to type change\n",
105				 dentry, dentry);
106			return 0;
107		}
108		if (retval < 0) {
109			p9_debug(P9_DEBUG_VFS,
110				"refresh inode: dentry = %pd (%p), got error %pe\n",
111				dentry, dentry, ERR_PTR(retval));
112			return retval;
113		}
114	}
115out_valid:
116	p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) is valid\n", dentry, dentry);
117	return 1;
118}
119
120static int v9fs_lookup_revalidate(struct inode *dir, const struct qstr *name,
121				  struct dentry *dentry, unsigned int flags)
122{
123	return __v9fs_lookup_revalidate(dentry, flags);
124}
125
126static bool v9fs_dentry_unalias_trylock(const struct dentry *dentry)
127{
128	struct v9fs_session_info *v9ses = v9fs_dentry2v9ses(dentry);
129	return down_write_trylock(&v9ses->rename_sem);
130}
131
132static void v9fs_dentry_unalias_unlock(const struct dentry *dentry)
133{
134	struct v9fs_session_info *v9ses = v9fs_dentry2v9ses(dentry);
135	up_write(&v9ses->rename_sem);
136}
137
138const struct dentry_operations v9fs_cached_dentry_operations = {
139	.d_revalidate = v9fs_lookup_revalidate,
140	.d_weak_revalidate = __v9fs_lookup_revalidate,
141	.d_delete = v9fs_cached_dentry_delete,
142	.d_release = v9fs_dentry_release,
143	.d_unalias_trylock = v9fs_dentry_unalias_trylock,
144	.d_unalias_unlock = v9fs_dentry_unalias_unlock,
145};
146
147const struct dentry_operations v9fs_dentry_operations = {
148	.d_release = v9fs_dentry_release,
149	.d_unalias_trylock = v9fs_dentry_unalias_trylock,
150	.d_unalias_unlock = v9fs_dentry_unalias_unlock,
151};