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 27static atomic_t permission_epoch = ATOMIC_INIT(0); 28 29/* replace or extend an acl cache hit */ 30void 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 */ 43void 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 */ 50void 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 */ 57int 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 */ 84static 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 102void 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