xref: /openbmc/linux/fs/coda/cache.c (revision 8fc8b9df)
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 */
coda_cache_enter(struct inode * inode,int mask)31 void 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 */
coda_cache_clear_inode(struct inode * inode)46 void 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 */
coda_cache_clear_all(struct super_block * sb)55 void 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 */
coda_cache_check(struct inode * inode,int mask)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(&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 */
coda_flag_children(struct dentry * parent,int flag)91 static 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 
coda_flag_inode_children(struct inode * inode,int flag)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(alias_de, flag);
116 	shrink_dcache_parent(alias_de);
117 	dput(alias_de);
118 }
119 
120