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/dirent.h>
  17 #include <linux/smb_fs.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/net.h>
  20
  21 #include <asm/page.h>
  22
  23 #include "smb_debug.h"
  24 #include "proto.h"
  25
  26 /*
  27  * Force the next attempt to use the cache to be a timeout.
  28  * If we can't find the page that's fine, it will cause a refresh.
  29  */
  30 void
  31 smb_invalid_dir_cache(struct inode * dir)
  32 {
  33         struct smb_sb_info *server = server_from_inode(dir);
  34         union  smb_dir_cache *cache = NULL;
  35         struct page *page = NULL;
  36
  37         page = grab_cache_page(&dir->i_data, 0);
  38         if (!page)
  39                 goto out;
  40
  41         if (!PageUptodate(page))
  42                 goto out_unlock;
  43
  44         cache = kmap(page);
  45         cache->head.time = jiffies - SMB_MAX_AGE(server);
  46
  47         kunmap(page);
  48         SetPageUptodate(page);
  49 out_unlock:
  50         unlock_page(page);
  51         page_cache_release(page);
  52 out:
  53         return;
  54 }
  55
  56 /*
  57  * Mark all dentries for 'parent' as invalid, forcing them to be re-read
  58  */
  59 void
  60 smb_invalidate_dircache_entries(struct dentry *parent)
  61 {
  62         struct smb_sb_info *server = server_from_dentry(parent);
  63         struct list_head *next;
  64         struct dentry *dentry;
  65
  66         spin_lock(&dcache_lock);
  67         next = parent->d_subdirs.next;
  68         while (next != &parent->d_subdirs) {
  69                 dentry = list_entry(next, struct dentry, d_u.d_child);
  70                 dentry->d_fsdata = NULL;
  71                 smb_age_dentry(server, dentry);
  72                 next = next->next;
  73         }
  74         spin_unlock(&dcache_lock);
  75 }
  76
  77 /*
  78  * dget, but require that fpos and parent matches what the dentry contains.
  79  * dentry is not known to be a valid pointer at entry.
  80  */
  81 struct dentry *
  82 smb_dget_fpos(struct dentry *dentry, struct dentry *parent, unsigned long fpos)
  83 {
  84         struct dentry *dent = dentry;
  85         struct list_head *next;
  86
  87         if (d_validate(dent, parent)) {
  88                 if (dent->d_name.len <= SMB_MAXNAMELEN &&
  89                     (unsigned long)dent->d_fsdata == fpos) {
  90                         if (!dent->d_inode) {
  91                                 dput(dent);
  92                                 dent = NULL;
  93                         }
  94                         return dent;
  95                 }
  96                 dput(dent);
  97         }
  98
  99         /* If a pointer is invalid, we search the dentry. */
 100         spin_lock(&dcache_lock);
 101         next = parent->d_subdirs.next;
 102         while (next != &parent->d_subdirs) {
 103                 dent = list_entry(next, struct dentry, d_u.d_child);
 104                 if ((unsigned long)dent->d_fsdata == fpos) {
 105                         if (dent->d_inode)
 106                                 dget_locked(dent);
 107                         else
 108                                 dent = NULL;
 109                         goto out_unlock;
 110                 }
 111                 next = next->next;
 112         }
 113         dent = NULL;
 114 out_unlock:
 115         spin_unlock(&dcache_lock);
 116         return dent;
 117 }
 118
 119
 120 /*
 121  * Create dentry/inode for this file and add it to the dircache.
 122  */
 123 int
 124 smb_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
 125                struct smb_cache_control *ctrl, struct qstr *qname,
 126                struct smb_fattr *entry)
 127 {
 128         struct dentry *newdent, *dentry = filp->f_path.dentry;
 129         struct inode *newino, *inode = dentry->d_inode;
 130         struct smb_cache_control ctl = *ctrl;
 131         int valid = 0;
 132         int hashed = 0;
 133         ino_t ino = 0;
 134
 135         qname->hash = full_name_hash(qname->name, qname->len);
 136
 137         if (dentry->d_op && dentry->d_op->d_hash)
 138                 if (dentry->d_op->d_hash(dentry, qname) != 0)
 139                         goto end_advance;
 140
 141         newdent = d_lookup(dentry, qname);
 142
 143         if (!newdent) {
 144                 newdent = d_alloc(dentry, qname);
 145                 if (!newdent)
 146                         goto end_advance;
 147         } else {
 148                 hashed = 1;
 149                 memcpy((char *) newdent->d_name.name, qname->name,
 150                        newdent->d_name.len);
 151         }
 152
 153         if (!newdent->d_inode) {
 154                 smb_renew_times(newdent);
 155                 entry->f_ino = iunique(inode->i_sb, 2);
 156                 newino = smb_iget(inode->i_sb, entry);
 157                 if (newino) {
 158                         smb_new_dentry(newdent);
 159                         d_instantiate(newdent, newino);
 160                         if (!hashed)
 161                                 d_rehash(newdent);
 162                 }
 163         } else
 164                 smb_set_inode_attr(newdent->d_inode, entry);
 165
 166         if (newdent->d_inode) {
 167                 ino = newdent->d_inode->i_ino;
 168                 newdent->d_fsdata = (void *) ctl.fpos;
 169                 smb_new_dentry(newdent);
 170         }
 171
 172         if (ctl.idx >= SMB_DIRCACHE_SIZE) {
 173                 if (ctl.page) {
 174                         kunmap(ctl.page);
 175                         SetPageUptodate(ctl.page);
 176                         unlock_page(ctl.page);
 177                         page_cache_release(ctl.page);
 178                 }
 179                 ctl.cache = NULL;
 180                 ctl.idx  -= SMB_DIRCACHE_SIZE;
 181                 ctl.ofs  += 1;
 182                 ctl.page  = grab_cache_page(&inode->i_data, ctl.ofs);
 183                 if (ctl.page)
 184                         ctl.cache = kmap(ctl.page);
 185         }
 186         if (ctl.cache) {
 187                 ctl.cache->dentry[ctl.idx] = newdent;
 188                 valid = 1;
 189         }
 190         dput(newdent);
 191
 192 end_advance:
 193         if (!valid)
 194                 ctl.valid = 0;
 195         if (!ctl.filled && (ctl.fpos == filp->f_pos)) {
 196                 if (!ino)
 197                         ino = find_inode_number(dentry, qname);
 198                 if (!ino)
 199                         ino = iunique(inode->i_sb, 2);
 200                 ctl.filled = filldir(dirent, qname->name, qname->len,
 201                                      filp->f_pos, ino, DT_UNKNOWN);
 202                 if (!ctl.filled)
 203                         filp->f_pos += 1;
 204         }
 205         ctl.fpos += 1;
 206         ctl.idx  += 1;
 207         *ctrl = ctl;
 208         return (ctl.valid || !ctl.filled);
 209 }