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 #include <linux/spinlock.h>
21
22 #include <linux/coda.h>
23 #include <linux/coda_psdev.h>
24 #include "coda_linux.h"
25 #include "coda_cache.h"
26
27 static atomic_t permission_epoch = ATOMIC_INIT(0);
28
29 /* replace or extend an acl cache hit */
coda_cache_enter(struct inode * inode,int mask)30 void coda_cache_enter(struct inode *inode, int mask)
31 {
32 struct coda_inode_info *cii = ITOC(inode);
33
34 spin_lock(&cii->c_lock);
35 cii->c_cached_epoch = atomic_read(&permission_epoch);
36 if (cii->c_uid != current_fsuid()) {
37 cii->c_uid = current_fsuid();
38 cii->c_cached_perm = mask;
39 } else
40 cii->c_cached_perm |= mask;
41 spin_unlock(&cii->c_lock);
42 }
43
44 /* remove cached acl from an inode */
coda_cache_clear_inode(struct inode * inode)45 void coda_cache_clear_inode(struct inode *inode)
46 {
47 struct coda_inode_info *cii = ITOC(inode);
48 spin_lock(&cii->c_lock);
49 cii->c_cached_epoch = atomic_read(&permission_epoch) - 1;
50 spin_unlock(&cii->c_lock);
51 }
52
53 /* remove all acl caches */
coda_cache_clear_all(struct super_block * sb)54 void coda_cache_clear_all(struct super_block *sb)
55 {
56 atomic_inc(&permission_epoch);
57 }
58
59
60 /* check if the mask has been matched against the acl already */
coda_cache_check(struct inode * inode,int mask)61 int coda_cache_check(struct inode *inode, int mask)
62 {
63 struct coda_inode_info *cii = ITOC(inode);
64 int hit;
65
66 spin_lock(&cii->c_lock);
67 hit = (mask & cii->c_cached_perm) == mask &&
68 cii->c_uid == current_fsuid() &&
69 cii->c_cached_epoch == atomic_read(&permission_epoch);
70 spin_unlock(&cii->c_lock);
71
72 return hit;
73 }
74
75
76 /* Purging dentries and children */
77 /* The following routines drop dentries which are not
78 in use and flag dentries which are in use to be
79 zapped later.
80
81 The flags are detected by:
82 - coda_dentry_revalidate (for lookups) if the flag is C_PURGE
83 - coda_dentry_delete: to remove dentry from the cache when d_count
84 falls to zero
85 - an inode method coda_revalidate (for attributes) if the
86 flag is C_VATTR
87 */
88
89 /* this won't do any harm: just flag all children */
coda_flag_children(struct dentry * parent,int flag)90 static void coda_flag_children(struct dentry *parent, int flag)
91 {
92 struct list_head *child;
93 struct dentry *de;
94
95 spin_lock(&parent->d_lock);
96 list_for_each(child, &parent->d_subdirs)
97 {
98 de = list_entry(child, struct dentry, d_u.d_child);
99 /* don't know what to do with negative dentries */
100 if ( ! de->d_inode )
101 continue;
102 coda_flag_inode(de->d_inode, flag);
103 }
104 spin_unlock(&parent->d_lock);
105 return;
106 }
107
coda_flag_inode_children(struct inode * inode,int flag)108 void coda_flag_inode_children(struct inode *inode, int flag)
109 {
110 struct dentry *alias_de;
111
112 if ( !inode || !S_ISDIR(inode->i_mode))
113 return;
114
115 alias_de = d_find_alias(inode);
116 if (!alias_de)
117 return;
118 coda_flag_children(alias_de, flag);
119 shrink_dcache_parent(alias_de);
120 dput(alias_de);
121 }
122
123