+static int reiserfs_write_begin(struct file *file,
+ struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata)
+{
+ struct inode *inode;
+ struct page *page;
+ pgoff_t index;
+ int ret;
+ int old_ref = 0;
+
+ inode = mapping->host;
+ *fsdata = 0;
+ if (flags & AOP_FLAG_CONT_EXPAND &&
+ (pos & (inode->i_sb->s_blocksize - 1)) == 0) {
+ pos ++;
+ *fsdata = (void *)(unsigned long)flags;
+ }
+
+ index = pos >> PAGE_CACHE_SHIFT;
+ page = grab_cache_page_write_begin(mapping, index, flags);
+ if (!page)
+ return -ENOMEM;
+ *pagep = page;
+
+ reiserfs_wait_on_write_block(inode->i_sb);
+ fix_tail_page_for_writing(page);
+ if (reiserfs_transaction_running(inode->i_sb)) {
+ struct reiserfs_transaction_handle *th;
+ th = (struct reiserfs_transaction_handle *)current->
+ journal_info;
+ BUG_ON(!th->t_refcount);
+ BUG_ON(!th->t_trans_id);
+ old_ref = th->t_refcount;
+ th->t_refcount++;
+ }
+ ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
+ reiserfs_get_block);
+ if (ret && reiserfs_transaction_running(inode->i_sb)) {
+ struct reiserfs_transaction_handle *th = current->journal_info;
+ /* this gets a little ugly. If reiserfs_get_block returned an
+ * error and left a transacstion running, we've got to close it,
+ * and we've got to free handle if it was a persistent transaction.
+ *
+ * But, if we had nested into an existing transaction, we need
+ * to just drop the ref count on the handle.
+ *
+ * If old_ref == 0, the transaction is from reiserfs_get_block,
+ * and it was a persistent trans. Otherwise, it was nested above.
+ */
+ if (th->t_refcount > old_ref) {
+ if (old_ref)
+ th->t_refcount--;
+ else {
+ int err;
+ reiserfs_write_lock(inode->i_sb);
+ err = reiserfs_end_persistent_transaction(th);
+ reiserfs_write_unlock(inode->i_sb);
+ if (err)
+ ret = err;
+ }
+ }
+ }
+ if (ret) {
+ unlock_page(page);
+ page_cache_release(page);
+ }
+ return ret;
+}
+
+int reiserfs_prepare_write(struct file *f, struct page *page,
+ unsigned from, unsigned to)