LXR linux/fs/coda/cache.c

   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
 117