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
  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