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_perm = 0; 47 } 48 49 /* remove all acl caches */ 50 void coda_cache_clear_all(struct super_block *sb) 51 { 52 struct coda_sb_info *sbi; 53 54 sbi = coda_sbp(sb); 55 BUG_ON(!sbi); 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 hit = (mask & cii->c_cached_perm) == mask && 68 cii->c_uid == current->fsuid && 69 cii->c_cached_epoch == atomic_read(&permission_epoch); 70 71 return hit; 72 } 73 74 75 /* Purging dentries and children */ 76 /* The following routines drop dentries which are not 77 in use and flag dentries which are in use to be 78 zapped later. 79 80 The flags are detected by: 81 - coda_dentry_revalidate (for lookups) if the flag is C_PURGE 82 - coda_dentry_delete: to remove dentry from the cache when d_count 83 falls to zero 84 - an inode method coda_revalidate (for attributes) if the 85 flag is C_VATTR 86 */ 87 88 /* this won't do any harm: just flag all children */ 89 static void coda_flag_children(struct dentry *parent, int flag) 90 { 91 struct list_head *child; 92 struct dentry *de; 93 94 spin_lock(&dcache_lock); 95 list_for_each(child, &parent->d_subdirs) 96 { 97 de = list_entry(child, struct dentry, d_u.d_child); 98 /* don't know what to do with negative dentries */ 99 if ( ! de->d_inode ) 100 continue; 101 coda_flag_inode(de->d_inode, flag); 102 } 103 spin_unlock(&dcache_lock); 104 return; 105 } 106 107 void coda_flag_inode_children(struct inode *inode, int flag) 108 { 109 struct dentry *alias_de; 110 111 if ( !inode || !S_ISDIR(inode->i_mode)) 112 return; 113 114 alias_de = d_find_alias(inode); 115 if (!alias_de) 116 return; 117 coda_flag_children(alias_de, flag); 118 shrink_dcache_parent(alias_de); 119 dput(alias_de); 120 } 121 122