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 <linux/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 */ 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 (!uid_eq(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 */ 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 */ 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 */ 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 uid_eq(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 */ 90 static void coda_flag_children(struct dentry *parent, int flag) 91 { 92 struct dentry *de; 93 94 spin_lock(&parent->d_lock); 95 list_for_each_entry(de, &parent->d_subdirs, d_child) { 96 /* don't know what to do with negative dentries */ 97 if (d_inode(de) ) 98 coda_flag_inode(d_inode(de), flag); 99 } 100 spin_unlock(&parent->d_lock); 101 return; 102 } 103 104 void coda_flag_inode_children(struct inode *inode, int flag) 105 { 106 struct dentry *alias_de; 107 108 if ( !inode || !S_ISDIR(inode->i_mode)) 109 return; 110 111 alias_de = d_find_alias(inode); 112 if (!alias_de) 113 return; 114 coda_flag_children(alias_de, flag); 115 shrink_dcache_parent(alias_de); 116 dput(alias_de); 117 } 118 119