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