xref: /kernel/linux/linux-5.10/fs/coda/cache.c (revision 8c2ecf20) 
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Cache operations for Coda.
4 * For Linux 2.1: (C) 1997 Carnegie Mellon University
5 * For Linux 2.3: (C) 2000 Carnegie Mellon University
6 *
7 * Carnegie Mellon encourages users of this code to contribute improvements
8 * to the Coda project http://www.coda.cs.cmu.edu/ <coda@cs.cmu.edu>.
9 */
10
11#include <linux/types.h>
12#include <linux/kernel.h>
13#include <linux/time.h>
14#include <linux/fs.h>
15#include <linux/stat.h>
16#include <linux/errno.h>
17#include <linux/uaccess.h>
18#include <linux/string.h>
19#include <linux/list.h>
20#include <linux/sched.h>
21#include <linux/spinlock.h>
22
23#include <linux/coda.h>
24#include "coda_psdev.h"
25#include "coda_linux.h"
26#include "coda_cache.h"
27
28static atomic_t permission_epoch = ATOMIC_INIT(0);
29
30/* replace or extend an acl cache hit */
31void coda_cache_enter(struct inode *inode, int mask)
32{
33	struct coda_inode_info *cii = ITOC(inode);
34
35	spin_lock(&cii->c_lock);
36	cii->c_cached_epoch = atomic_read(&permission_epoch);
37	if (!uid_eq(cii->c_uid, current_fsuid())) {
38		cii->c_uid = current_fsuid();
39                cii->c_cached_perm = mask;
40        } else
41                cii->c_cached_perm |= mask;
42	spin_unlock(&cii->c_lock);
43}
44
45/* remove cached acl from an inode */
46void coda_cache_clear_inode(struct inode *inode)
47{
48	struct coda_inode_info *cii = ITOC(inode);
49	spin_lock(&cii->c_lock);
50	cii->c_cached_epoch = atomic_read(&permission_epoch) - 1;
51	spin_unlock(&cii->c_lock);
52}
53
54/* remove all acl caches */
55void coda_cache_clear_all(struct super_block *sb)
56{
57	atomic_inc(&permission_epoch);
58}
59
60
61/* check if the mask has been matched against the acl already */
62int coda_cache_check(struct inode *inode, int mask)
63{
64	struct coda_inode_info *cii = ITOC(inode);
65	int hit;
66
67	spin_lock(&cii->c_lock);
68	hit = (mask & cii->c_cached_perm) == mask &&
69	    uid_eq(cii->c_uid, current_fsuid()) &&
70	    cii->c_cached_epoch == atomic_read(&permission_epoch);
71	spin_unlock(&cii->c_lock);
72
73	return hit;
74}
75
76
77/* Purging dentries and children */
78/* The following routines drop dentries which are not
79   in use and flag dentries which are in use to be
80   zapped later.
81
82   The flags are detected by:
83   - coda_dentry_revalidate (for lookups) if the flag is C_PURGE
84   - coda_dentry_delete: to remove dentry from the cache when d_count
85     falls to zero
86   - an inode method coda_revalidate (for attributes) if the
87     flag is C_VATTR
88*/
89
90/* this won't do any harm: just flag all children */
91static void coda_flag_children(struct dentry *parent, int flag)
92{
93	struct dentry *de;
94
95	spin_lock(&parent->d_lock);
96	list_for_each_entry(de, &parent->d_subdirs, d_child) {
97		/* don't know what to do with negative dentries */
98		if (d_inode(de) )
99			coda_flag_inode(d_inode(de), flag);
100	}
101	spin_unlock(&parent->d_lock);
102	return;
103}
104
105void coda_flag_inode_children(struct inode *inode, int flag)
106{
107	struct dentry *alias_de;
108
109	if ( !inode || !S_ISDIR(inode->i_mode))
110		return;
111
112	alias_de = d_find_alias(inode);
113	if (!alias_de)
114		return;
115	coda_flag_children(alias_de, flag);
116	shrink_dcache_parent(alias_de);
117	dput(alias_de);
118}
119
120