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_linux.h> 24 #include <linux/coda_psdev.h> 25 #include <linux/coda_fs_i.h> 26 #include <linux/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(&cii->c_lock); 36 cii->c_cached_epoch = atomic_read(&permission_epoch); 37 if (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 */ 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 */ 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 */ 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 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 */ 91 static void coda_flag_children(struct dentry *parent, int flag) 92 { 93 struct list_head *child; 94 struct dentry *de; 95 96 spin_lock(&dcache_lock); 97 list_for_each(child, &parent->d_subdirs) 98 { 99 de = list_entry(child, struct dentry, d_u.d_child); 100 /* don't know what to do with negative dentries */ 101 if ( ! de->d_inode ) 102 continue; 103 coda_flag_inode(de->d_inode, flag); 104 } 105 spin_unlock(&dcache_lock); 106 return; 107 } 108 109 void coda_flag_inode_children(struct inode *inode, int flag) 110 { 111 struct dentry *alias_de; 112 113 if ( !inode || !S_ISDIR(inode->i_mode)) 114 return; 115 116 alias_de = d_find_alias(inode); 117 if (!alias_de) 118 return; 119 coda_flag_children(alias_de, flag); 120 shrink_dcache_parent(alias_de); 121 dput(alias_de); 122 } 123 124