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 20 #include <linux/coda.h> 21 #include <linux/coda_linux.h> 22 #include <linux/coda_psdev.h> 23 #include <linux/coda_fs_i.h> 24 #include <linux/coda_cache.h> 25 26 static atomic_t permission_epoch = ATOMIC_INIT(0); 27 28 /* replace or extend an acl cache hit */ 29 void coda_cache_enter(struct inode *inode, int mask) 30 { 31 struct coda_inode_info *cii = ITOC(inode); 32 33 cii->c_cached_epoch = atomic_read(&permission_epoch); 34 if (cii->c_uid != current->fsuid) { 35 cii->c_uid = current->fsuid; 36 cii->c_cached_perm = mask; 37 } else 38 cii->c_cached_perm |= mask; 39 } 40 41 /* remove cached acl from an inode */ 42 void coda_cache_clear_inode(struct inode *inode) 43 { 44 struct coda_inode_info *cii = ITOC(inode); 45 cii->c_cached_perm = 0; 46 } 47 48 /* remove all acl caches */ 49 void coda_cache_clear_all(struct super_block *sb) 50 { 51 struct coda_sb_info *sbi; 52 53 sbi = coda_sbp(sb); 54 BUG_ON(!sbi); 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 hit = (mask & cii->c_cached_perm) == mask && 67 cii->c_uid == current->fsuid && 68 cii->c_cached_epoch == atomic_read(&permission_epoch); 69 70 return hit; 71 } 72 73 74 /* Purging dentries and children */ 75 /* The following routines drop dentries which are not 76 in use and flag dentries which are in use to be 77 zapped later. 78 79 The flags are detected by: 80 - coda_dentry_revalidate (for lookups) if the flag is C_PURGE 81 - coda_dentry_delete: to remove dentry from the cache when d_count 82 falls to zero 83 - an inode method coda_revalidate (for attributes) if the 84 flag is C_VATTR 85 */ 86 87 /* this won't do any harm: just flag all children */ 88 static void coda_flag_children(struct dentry *parent, int flag) 89 { 90 struct list_head *child; 91 struct dentry *de; 92 93 spin_lock(&dcache_lock); 94 list_for_each(child, &parent->d_subdirs) 95 { 96 de = list_entry(child, struct dentry, d_u.d_child); 97 /* don't know what to do with negative dentries */ 98 if ( ! de->d_inode ) 99 continue; 100 coda_flag_inode(de->d_inode, flag); 101 } 102 spin_unlock(&dcache_lock); 103 return; 104 } 105 106 void coda_flag_inode_children(struct inode *inode, int flag) 107 { 108 struct dentry *alias_de; 109 110 if ( !inode || !S_ISDIR(inode->i_mode)) 111 return; 112 113 alias_de = d_find_alias(inode); 114 if (!alias_de) 115 return; 116 coda_flag_children(alias_de, flag); 117 shrink_dcache_parent(alias_de); 118 dput(alias_de); 119 } 120 121