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
27 static atomic_t permission_epoch = ATOMIC_INIT(0);
28
29 /* replace or extend an acl cache hit */
30 void 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 */
43 void coda_cache_clear_inode(struct inode *inode)
44 {
45 struct coda_inode_info *cii = ITOC(inode);
46 cii->c_cached_epoch = atomic_read(&permission_epoch) - 1;
47 }
48
49 /* remove all acl caches */
50 void coda_cache_clear_all(struct super_block *sb)
51 {
52 atomic_inc(&permission_epoch);
53 }
54
55
56 /* check if the mask has been matched against the acl already */
57 int coda_cache_check(struct inode *inode, int mask)
58 {
59 struct coda_inode_info *cii = ITOC(inode);
60 int hit;
61
62 hit = (mask & cii->c_cached_perm) == mask &&
63 cii->c_uid == current->fsuid &&
64 cii->c_cached_epoch == atomic_read(&permission_epoch);
65
66 return hit;
67 }
68
69
70 /* Purging dentries and children */
71 /* The following routines drop dentries which are not
72 in use and flag dentries which are in use to be
73 zapped later.
74
75 The flags are detected by:
76 - coda_dentry_revalidate (for lookups) if the flag is C_PURGE
77 - coda_dentry_delete: to remove dentry from the cache when d_count
78 falls to zero
79 - an inode method coda_revalidate (for attributes) if the
80 flag is C_VATTR
81 */
82
83 /* this won't do any harm: just flag all children */
84 static void coda_flag_children(struct dentry *parent, int flag)
85 {
86 struct list_head *child;
87 struct dentry *de;
88
89 spin_lock(&dcache_lock);
90 list_for_each(child, &parent->d_subdirs)
91 {
92 de = list_entry(child, struct dentry, d_u.d_child);
93 /* don't know what to do with negative dentries */
94 if ( ! de->d_inode )
95 continue;
96 coda_flag_inode(de->d_inode, flag);
97 }
98 spin_unlock(&dcache_lock);
99 return;
100 }
101
102 void coda_flag_inode_children(struct inode *inode, int flag)
103 {
104 struct dentry *alias_de;
105
106 if ( !inode || !S_ISDIR(inode->i_mode))
107 return;
108
109 alias_de = d_find_alias(inode);
110 if (!alias_de)
111 return;
112 coda_flag_children(alias_de, flag);
113 shrink_dcache_parent(alias_de);
114 dput(alias_de);
115 }
116
117
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