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 | |
28 | static atomic_t permission_epoch = ATOMIC_INIT(0); |
29 | |
30 | /* replace or extend an acl cache hit */ |
31 | void coda_cache_enter(struct inode *inode, int mask) |
32 | { |
33 | struct coda_inode_info *cii = ITOC(inode); |
34 | |
35 | spin_lock(lock: &cii->c_lock); |
36 | cii->c_cached_epoch = atomic_read(v: &permission_epoch); |
37 | if (!uid_eq(left: 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(lock: &cii->c_lock); |
43 | } |
44 | |
45 | /* remove cached acl from an inode */ |
46 | void coda_cache_clear_inode(struct inode *inode) |
47 | { |
48 | struct coda_inode_info *cii = ITOC(inode); |
49 | spin_lock(lock: &cii->c_lock); |
50 | cii->c_cached_epoch = atomic_read(v: &permission_epoch) - 1; |
51 | spin_unlock(lock: &cii->c_lock); |
52 | } |
53 | |
54 | /* remove all acl caches */ |
55 | void coda_cache_clear_all(struct super_block *sb) |
56 | { |
57 | atomic_inc(v: &permission_epoch); |
58 | } |
59 | |
60 | |
61 | /* check if the mask has been matched against the acl already */ |
62 | int coda_cache_check(struct inode *inode, int mask) |
63 | { |
64 | struct coda_inode_info *cii = ITOC(inode); |
65 | int hit; |
66 | |
67 | spin_lock(lock: &cii->c_lock); |
68 | hit = (mask & cii->c_cached_perm) == mask && |
69 | uid_eq(left: cii->c_uid, current_fsuid()) && |
70 | cii->c_cached_epoch == atomic_read(v: &permission_epoch); |
71 | spin_unlock(lock: &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 */ |
91 | static void coda_flag_children(struct dentry *parent, int flag) |
92 | { |
93 | struct dentry *de; |
94 | |
95 | spin_lock(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(dentry: de) ) |
99 | coda_flag_inode(inode: d_inode(dentry: de), flag); |
100 | } |
101 | spin_unlock(lock: &parent->d_lock); |
102 | return; |
103 | } |
104 | |
105 | void 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(parent: alias_de, flag); |
116 | shrink_dcache_parent(alias_de); |
117 | dput(alias_de); |
118 | } |
119 | |
120 | |