linux/fs/coda/cache.c
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   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_psdev.h>
  24#include "coda_linux.h"
  25#include "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        spin_lock(&cii->c_lock);
  35        cii->c_cached_epoch = atomic_read(&permission_epoch);
  36        if (cii->c_uid != current_fsuid()) {
  37                cii->c_uid = current_fsuid();
  38                cii->c_cached_perm = mask;
  39        } else
  40                cii->c_cached_perm |= mask;
  41        spin_unlock(&cii->c_lock);
  42}
  43
  44/* remove cached acl from an inode */
  45void coda_cache_clear_inode(struct inode *inode)
  46{
  47        struct coda_inode_info *cii = ITOC(inode);
  48        spin_lock(&cii->c_lock);
  49        cii->c_cached_epoch = atomic_read(&permission_epoch) - 1;
  50        spin_unlock(&cii->c_lock);
  51}
  52
  53/* remove all acl caches */
  54void coda_cache_clear_all(struct super_block *sb)
  55{
  56        atomic_inc(&permission_epoch);
  57}
  58
  59
  60/* check if the mask has been matched against the acl already */
  61int coda_cache_check(struct inode *inode, int mask)
  62{
  63        struct coda_inode_info *cii = ITOC(inode);
  64        int hit;
  65        
  66        spin_lock(&cii->c_lock);
  67        hit = (mask & cii->c_cached_perm) == mask &&
  68            cii->c_uid == current_fsuid() &&
  69            cii->c_cached_epoch == atomic_read(&permission_epoch);
  70        spin_unlock(&cii->c_lock);
  71
  72        return hit;
  73}
  74
  75
  76/* Purging dentries and children */
  77/* The following routines drop dentries which are not
  78   in use and flag dentries which are in use to be 
  79   zapped later.
  80
  81   The flags are detected by:
  82   - coda_dentry_revalidate (for lookups) if the flag is C_PURGE
  83   - coda_dentry_delete: to remove dentry from the cache when d_count
  84     falls to zero
  85   - an inode method coda_revalidate (for attributes) if the 
  86     flag is C_VATTR
  87*/
  88
  89/* this won't do any harm: just flag all children */
  90static void coda_flag_children(struct dentry *parent, int flag)
  91{
  92        struct dentry *de;
  93
  94        spin_lock(&parent->d_lock);
  95        list_for_each_entry(de, &parent->d_subdirs, d_u.d_child) {
  96                /* don't know what to do with negative dentries */
  97                if (de->d_inode ) 
  98                        coda_flag_inode(de->d_inode, flag);
  99        }
 100        spin_unlock(&parent->d_lock);
 101        return; 
 102}
 103
 104void coda_flag_inode_children(struct inode *inode, int flag)
 105{
 106        struct dentry *alias_de;
 107
 108        if ( !inode || !S_ISDIR(inode->i_mode)) 
 109                return; 
 110
 111        alias_de = d_find_alias(inode);
 112        if (!alias_de)
 113                return;
 114        coda_flag_children(alias_de, flag);
 115        shrink_dcache_parent(alias_de);
 116        dput(alias_de);
 117}
 118
 119
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