1/*
2 * Cache operations for Coda.
3 * For Linux 2.1: (C) 1997 Carnegie Mellon University
4 * For Linux 2.3: (C) 2000 Carnegie Mellon University
5 *
6 * Carnegie Mellon encourages users of this code to contribute improvements
7 * to the Coda project http://www.coda.cs.cmu.edu/ <coda@cs.cmu.edu>.
8 */
9
10#include <linux/types.h>
11#include <linux/kernel.h>
12#include <linux/time.h>
13#include <linux/fs.h>
14#include <linux/stat.h>
15#include <linux/errno.h>
16#include <asm/uaccess.h>
17#include <linux/string.h>
18#include <linux/list.h>
19#include <linux/sched.h>
20
21#include <linux/coda.h>
22#include <linux/coda_linux.h>
23#include <linux/coda_psdev.h>
24#include <linux/coda_fs_i.h>
25#include <linux/coda_cache.h>
26
27static atomic_t permission_epoch = ATOMIC_INIT(0);
28
29/* replace or extend an acl cache hit */
30void coda_cache_enter(struct inode *inode, int mask)
31{
32	struct coda_inode_info *cii = ITOC(inode);
33
34	cii->c_cached_epoch = atomic_read(&permission_epoch);
35	if (cii->c_uid != current->fsuid) {
36                cii->c_uid = current->fsuid;
37                cii->c_cached_perm = mask;
38        } else
39                cii->c_cached_perm |= mask;
40}
41
42/* remove cached acl from an inode */
43void coda_cache_clear_inode(struct inode *inode)
44{
45	struct coda_inode_info *cii = ITOC(inode);
46        cii->c_cached_perm = 0;
47}
48
49/* remove all acl caches */
50void coda_cache_clear_all(struct super_block *sb)
51{
52        struct coda_sb_info *sbi;
53
54        sbi = coda_sbp(sb);
55	BUG_ON(!sbi);
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        hit = (mask & cii->c_cached_perm) == mask &&
68		cii->c_uid == current->fsuid &&
69		cii->c_cached_epoch == atomic_read(&permission_epoch);
70
71        return hit;
72}
73
74
75/* Purging dentries and children */
76/* The following routines drop dentries which are not
77   in use and flag dentries which are in use to be
78   zapped later.
79
80   The flags are detected by:
81   - coda_dentry_revalidate (for lookups) if the flag is C_PURGE
82   - coda_dentry_delete: to remove dentry from the cache when d_count
83     falls to zero
84   - an inode method coda_revalidate (for attributes) if the
85     flag is C_VATTR
86*/
87
88/* this won't do any harm: just flag all children */
89static void coda_flag_children(struct dentry *parent, int flag)
90{
91	struct list_head *child;
92	struct dentry *de;
93
94	spin_lock(&dcache_lock);
95	list_for_each(child, &parent->d_subdirs)
96	{
97		de = list_entry(child, struct dentry, d_u.d_child);
98		/* don't know what to do with negative dentries */
99		if ( ! de->d_inode )
100			continue;
101		coda_flag_inode(de->d_inode, flag);
102	}
103	spin_unlock(&dcache_lock);
104	return;
105}
106
107void coda_flag_inode_children(struct inode *inode, int flag)
108{
109	struct dentry *alias_de;
110
111	if ( !inode || !S_ISDIR(inode->i_mode))
112		return;
113
114	alias_de = d_find_alias(inode);
115	if (!alias_de)
116		return;
117	coda_flag_children(alias_de, flag);
118	shrink_dcache_parent(alias_de);
119	dput(alias_de);
120}
121