release/src-rt-6.x.4708/linux/linux-2.6.36/fs/smbfs/cache.c

   1 /*
   2  *  cache.c
   3  *
   4  * Copyright (C) 1997 by Bill Hawes
   5  *
   6  * Routines to support directory cacheing using the page cache.
   7  * This cache code is almost directly taken from ncpfs.
   8  *
   9  * Please add a note about your changes to smbfs in the ChangeLog file.
  10  */
  11
  12 #include <linux/time.h>
  13 #include <linux/errno.h>
  14 #include <linux/kernel.h>
  15 #include <linux/mm.h>
  16 #include <linux/smb_fs.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/net.h>
  19
  20 #include <asm/page.h>
  21
  22 #include "smb_debug.h"
  23 #include "proto.h"
  24
  25 /*
  26  * Force the next attempt to use the cache to be a timeout.
  27  * If we can't find the page that's fine, it will cause a refresh.
  28  */
  29 void
  30 smb_invalid_dir_cache(struct inode * dir)
  31 {
  32         struct smb_sb_info *server = server_from_inode(dir);
  33         union  smb_dir_cache *cache = NULL;
  34         struct page *page = NULL;
  35
  36         page = grab_cache_page(&dir->i_data, 0);
  37         if (!page)
  38                 goto out;
  39
  40         if (!PageUptodate(page))
  41                 goto out_unlock;
  42
  43         cache = kmap(page);
  44         cache->head.time = jiffies - SMB_MAX_AGE(server);
  45
  46         kunmap(page);
  47         SetPageUptodate(page);
  48 out_unlock:
  49         unlock_page(page);
  50         page_cache_release(page);
  51 out:
  52         return;
  53 }
  54
  55 /*
  56  * Mark all dentries for 'parent' as invalid, forcing them to be re-read
  57  */
  58 void
  59 smb_invalidate_dircache_entries(struct dentry *parent)
  60 {
  61         struct smb_sb_info *server = server_from_dentry(parent);
  62         struct list_head *next;
  63         struct dentry *dentry;
  64
  65         spin_lock(&dcache_lock);
  66         next = parent->d_subdirs.next;
  67         while (next != &parent->d_subdirs) {
  68                 dentry = list_entry(next, struct dentry, d_u.d_child);
  69                 dentry->d_fsdata = NULL;
  70                 smb_age_dentry(server, dentry);
  71                 next = next->next;
  72         }
  73         spin_unlock(&dcache_lock);
  74 }
  75
  76 /*
  77  * dget, but require that fpos and parent matches what the dentry contains.
  78  * dentry is not known to be a valid pointer at entry.
  79  */
  80 struct dentry *
  81 smb_dget_fpos(struct dentry *dentry, struct dentry *parent, unsigned long fpos)
  82 {
  83         struct dentry *dent = dentry;
  84         struct list_head *next;
  85
  86         if (d_validate(dent, parent)) {
  87                 if (dent->d_name.len <= SMB_MAXNAMELEN &&
  88                     (unsigned long)dent->d_fsdata == fpos) {
  89                         if (!dent->d_inode) {
  90                                 dput(dent);
  91                                 dent = NULL;
  92                         }
  93                         return dent;
  94                 }
  95                 dput(dent);
  96         }
  97
  98         /* If a pointer is invalid, we search the dentry. */
  99         spin_lock(&dcache_lock);
 100         next = parent->d_subdirs.next;
 101         while (next != &parent->d_subdirs) {
 102                 dent = list_entry(next, struct dentry, d_u.d_child);
 103                 if ((unsigned long)dent->d_fsdata == fpos) {
 104                         if (dent->d_inode)
 105                                 dget_locked(dent);
 106                         else
 107                                 dent = NULL;
 108                         goto out_unlock;
 109                 }
 110                 next = next->next;
 111         }
 112         dent = NULL;
 113 out_unlock:
 114         spin_unlock(&dcache_lock);
 115         return dent;
 116 }
 117
 118
 119 /*
 120  * Create dentry/inode for this file and add it to the dircache.
 121  */
 122 int
 123 smb_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
 124                struct smb_cache_control *ctrl, struct qstr *qname,
 125                struct smb_fattr *entry)
 126 {
 127         struct dentry *newdent, *dentry = filp->f_path.dentry;
 128         struct inode *newino, *inode = dentry->d_inode;
 129         struct smb_cache_control ctl = *ctrl;
 130         int valid = 0;
 131         int hashed = 0;
 132         ino_t ino = 0;
 133
 134         qname->hash = full_name_hash(qname->name, qname->len);
 135
 136         if (dentry->d_op && dentry->d_op->d_hash)
 137                 if (dentry->d_op->d_hash(dentry, qname) != 0)
 138                         goto end_advance;
 139
 140         newdent = d_lookup(dentry, qname);
 141
 142         if (!newdent) {
 143                 newdent = d_alloc(dentry, qname);
 144                 if (!newdent)
 145                         goto end_advance;
 146         } else {
 147                 hashed = 1;
 148                 memcpy((char *) newdent->d_name.name, qname->name,
 149                        newdent->d_name.len);
 150         }
 151
 152         if (!newdent->d_inode) {
 153                 smb_renew_times(newdent);
 154                 entry->f_ino = iunique(inode->i_sb, 2);
 155                 newino = smb_iget(inode->i_sb, entry);
 156                 if (newino) {
 157                         smb_new_dentry(newdent);
 158                         d_instantiate(newdent, newino);
 159                         if (!hashed)
 160                                 d_rehash(newdent);
 161                 }
 162         } else
 163                 smb_set_inode_attr(newdent->d_inode, entry);
 164
 165         if (newdent->d_inode) {
 166                 ino = newdent->d_inode->i_ino;
 167                 newdent->d_fsdata = (void *) ctl.fpos;
 168                 smb_new_dentry(newdent);
 169         }
 170
 171         if (ctl.idx >= SMB_DIRCACHE_SIZE) {
 172                 if (ctl.page) {
 173                         kunmap(ctl.page);
 174                         SetPageUptodate(ctl.page);
 175                         unlock_page(ctl.page);
 176                         page_cache_release(ctl.page);
 177                 }
 178                 ctl.cache = NULL;
 179                 ctl.idx  -= SMB_DIRCACHE_SIZE;
 180                 ctl.ofs  += 1;
 181                 ctl.page  = grab_cache_page(&inode->i_data, ctl.ofs);
 182                 if (ctl.page)
 183                         ctl.cache = kmap(ctl.page);
 184         }
 185         if (ctl.cache) {
 186                 ctl.cache->dentry[ctl.idx] = newdent;
 187                 valid = 1;
 188         }
 189         dput(newdent);
 190
 191 end_advance:
 192         if (!valid)
 193                 ctl.valid = 0;
 194         if (!ctl.filled && (ctl.fpos == filp->f_pos)) {
 195                 if (!ino)
 196                         ino = find_inode_number(dentry, qname);
 197                 if (!ino)
 198                         ino = iunique(inode->i_sb, 2);
 199                 ctl.filled = filldir(dirent, qname->name, qname->len,
 200                                      filp->f_pos, ino, DT_UNKNOWN);
 201                 if (!ctl.filled)
 202                         filp->f_pos += 1;
 203         }
 204         ctl.fpos += 1;
 205         ctl.idx  += 1;
 206         *ctrl = ctl;
 207         return (ctl.valid || !ctl.filled);
 208 }