1 files changed, 31 insertions, 7 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 8a277505a3be..10b71e4029a0 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1412,7 +1412,7 @@ static void ext4_da_release_space(struct inode *inode, int to_free)
 static void ext4_da_page_release_reservation(struct page *page,
 					     unsigned long offset)
 {
-	int to_release = 0;
+	int to_release = 0, contiguous_blks = 0;
 	struct buffer_head *head, *bh;
 	unsigned int curr_off = 0;
 	struct inode *inode = page->mapping->host;
@@ -1427,14 +1427,23 @@ static void ext4_da_page_release_reservation(struct page *page,
 
 		if ((offset <= curr_off) && (buffer_delay(bh))) {
 			to_release++;
+			contiguous_blks++;
 			clear_buffer_delay(bh);
+		} else if (contiguous_blks) {
+			lblk = page->index <<
+			       (PAGE_CACHE_SHIFT - inode->i_blkbits);
+			lblk += (curr_off >> inode->i_blkbits) -
+				contiguous_blks;
+			ext4_es_remove_extent(inode, lblk, contiguous_blks);
+			contiguous_blks = 0;
 		}
 		curr_off = next_off;
 	} while ((bh = bh->b_this_page) != head);
 
-	if (to_release) {
+	if (contiguous_blks) {
 		lblk = page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
-		ext4_es_remove_extent(inode, lblk, to_release);
+		lblk += (curr_off >> inode->i_blkbits) - contiguous_blks;
+		ext4_es_remove_extent(inode, lblk, contiguous_blks);
 	}
 
 	/* If we have released all the blocks belonging to a cluster, then we
@@ -2099,19 +2108,32 @@ static int __ext4_journalled_writepage(struct page *page,
 		ext4_walk_page_buffers(handle, page_bufs, 0, len,
 				       NULL, bget_one);
 	}
-	/* As soon as we unlock the page, it can go away, but we have
-	 * references to buffers so we are safe */
+	/*
+	 * We need to release the page lock before we start the
+	 * journal, so grab a reference so the page won't disappear
+	 * out from under us.
+	 */
+	get_page(page);
 	unlock_page(page);
 
 	handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
 				    ext4_writepage_trans_blocks(inode));
 	if (IS_ERR(handle)) {
 		ret = PTR_ERR(handle);
-		goto out;
+		put_page(page);
+		goto out_no_pagelock;
 	}
-
 	BUG_ON(!ext4_handle_valid(handle));
 
+	lock_page(page);
+	put_page(page);
+	if (page->mapping != mapping) {
+		/* The page got truncated from under us */
+		ext4_journal_stop(handle);
+		ret = 0;
+		goto out;
+	}
+
 	if (inline_data) {
 		ret = ext4_journal_get_write_access(handle, inode_bh);
 
@@ -2136,6 +2158,8 @@ static int __ext4_journalled_writepage(struct page *page,
 				       NULL, bput_one);
 	ext4_set_inode_state(inode, EXT4_STATE_JDATA);
 out:
+	unlock_page(page);
+out_no_pagelock:
 	brelse(inode_bh);
 	return ret;
 }