2.4.1-pre9

 mm

diff -u --recursive --new-file v2.4.0/linux/mm/shmem.c linux/mm/shmem.c
--- v2.4.0/linux/mm/shmem.c   Fri Dec 29 14:21:48 2000
+++ linux/mm/shmem.c   Wed Jan 17 13:40:03 2001
@@ -117,11 +117,43 @@
    return 0;
 }
 
+/*
+ * shmem_recalc_inode - recalculate the size of an inode
+ *
+ * @inode: inode to recalc
+ *
+ * We have to calculate the free blocks since the mm can drop pages
+ * behind our back
+ *
+ * But we know that normally
+ * inodes->i_blocks == inode->i_mapping->nrpages + info->swapped
+ *
+ * So the mm freed 
+ * inodes->i_blocks - (inode->i_mapping->nrpages + info->swapped)
+ *
+ * It has to be called with the spinlock held.
+ */
+
+static void shmem_recalc_inode(struct inode * inode)
+{
+   unsigned long freed;
+
+   freed = inode->i_blocks -
+      (inode->i_mapping->nrpages + inode->u.shmem_i.swapped);
+   if (freed){
+      struct shmem_sb_info * info = &inode->i_sb->u.shmem_sb;
+      inode->i_blocks -= freed;
+      spin_lock (&info->stat_lock);
+      info->free_blocks += freed;
+      spin_unlock (&info->stat_lock);
+   }
+}
+
 static void shmem_truncate (struct inode * inode)
 {
    int clear_base;
    unsigned long start;
-   unsigned long mmfreed, freed = 0;
+   unsigned long freed = 0;
    swp_entry_t **base, **ptr;
    struct shmem_inode_info * info = &inode->u.shmem_i;
 
@@ -154,26 +186,9 @@
    info->i_indirect = 0;
 
 out:
-
-   /*
-    * We have to calculate the free blocks since we do not know
-    * how many pages the mm discarded
-    *
-    * But we know that normally
-    * inodes->i_blocks == inode->i_mapping->nrpages + info->swapped
-    *
-    * So the mm freed 
-    * inodes->i_blocks - (inode->i_mapping->nrpages + info->swapped)
-    */
-
-   mmfreed = inode->i_blocks - (inode->i_mapping->nrpages + info->swapped);
    info->swapped -= freed;
-   inode->i_blocks -= freed + mmfreed;
+   shmem_recalc_inode(inode);
    spin_unlock (&info->lock);
-
-   spin_lock (&inode->i_sb->u.shmem_sb.stat_lock);
-   inode->i_sb->u.shmem_sb.free_blocks += freed + mmfreed;
-   spin_unlock (&inode->i_sb->u.shmem_sb.stat_lock);
 }
 
 static void shmem_delete_inode(struct inode * inode)
@@ -201,13 +216,12 @@
    swp_entry_t *entry, swap;
 
    info = &page->mapping->host->u.shmem_i;
-   if (info->locked)
-      return 1;
    swap = __get_swap_page(2);
    if (!swap.val)
       return 1;
 
    spin_lock(&info->lock);
+   shmem_recalc_inode(page->mapping->host);
    entry = shmem_swp_entry (info, page->index);
    if (!entry)   /* this had been allocted on page allocation */
       BUG();
@@ -269,6 +283,9 @@
    entry = shmem_swp_entry (info, idx);
    if (!entry)
       goto oom;
+   spin_lock (&info->lock);
+   shmem_recalc_inode(inode);
+   spin_unlock (&info->lock);
    if (entry->val) {
       unsigned long flags;
 
@@ -310,6 +327,8 @@
    }
    /* We have the page */
    SetPageUptodate (page);
+   if (info->locked)
+      page_cache_get(page);
 
 cached_page:
    UnlockPage (page);
@@ -374,8 +393,7 @@
          inode->i_fop = &shmem_dir_operations;
          break;
       case S_IFLNK:
-         inode->i_op = &page_symlink_inode_operations;
-         break;
+         BUG();
       }
       spin_lock (&shmem_ilock);
       list_add (&inode->u.shmem_i.list, &shmem_inodes);
@@ -401,6 +419,32 @@
    return 0;
 }
 
+void shmem_lock(struct file * file, int lock)
+{
+   struct inode * inode = file->f_dentry->d_inode;
+   struct shmem_inode_info * info = &inode->u.shmem_i;
+   struct page * page;
+   unsigned long idx, size;
+
+   if (info->locked == lock)
+      return;
+   down(&inode->i_sem);
+   info->locked = lock;
+   size = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+   for (idx = 0; idx < size; idx++) {
+      page = find_lock_page(inode->i_mapping, idx);
+      if (!page)
+         continue;
+      if (!lock) {
+         /* release the extra count and our reference */
+         page_cache_release(page);
+         page_cache_release(page);
+      }
+      UnlockPage(page);
+   }
+   up(&inode->i_sem);
+}
+
 /*
  * Lookup the data. This is trivial - if the dentry didn't already
  * exist, we know it is negative.
@@ -528,19 +572,6 @@
    return error;
 }
 
-static int shmem_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
-{
-   int error;
-
-   error = shmem_mknod(dir, dentry, S_IFLNK | S_IRWXUGO, 0);
-   if (!error) {
-      int l = strlen(symname)+1;
-      struct inode *inode = dentry->d_inode;
-      error = block_symlink(inode, symname, l);
-   }
-   return error;
-}
-
 static int shmem_mmap(struct file * file, struct vm_area_struct * vma)
 {
    struct vm_operations_struct * ops;
@@ -677,7 +708,6 @@
    lookup:      shmem_lookup,
    link:      shmem_link,
    unlink:      shmem_unlink,
-   symlink:   shmem_symlink,
    mkdir:      shmem_mkdir,
    rmdir:      shmem_rmdir,
    mknod:      shmem_mknod,