[PATCH] ext4: Add validation to jbd lock inversion patch and split and writepage

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 fs/ext4/inode.c |  180 ++++++++++++++++++++++++++++++++++++++++++++++--------
 1 files changed, 153 insertions(+), 27 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index d099f55..26a7df3 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1479,6 +1479,11 @@ static int jbd2_journal_dirty_data_fn(handle_t *handle, struct buffer_head *bh)
 	return 0;
 }
 
+static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
+{
+	return !buffer_mapped(bh);
+}
+
 /*
  * Note that we don't need to start a transaction unless we're journaling
  * data because we should have holes filled from ext4_page_mkwrite(). If
@@ -1531,18 +1536,26 @@ static int jbd2_journal_dirty_data_fn(handle_t *handle, struct buffer_head *bh)
 static int __ext4_ordered_writepage(struct page *page,
 				struct writeback_control *wbc)
 {
-	struct inode *inode = page->mapping->host;
-	struct buffer_head *page_bufs;
+	int ret = 0, err;
+	unsigned long len;
 	handle_t *handle = NULL;
-	int ret = 0;
-	int err;
+	struct buffer_head *page_bufs;
+	struct inode *inode = page->mapping->host;
+	loff_t size = i_size_read(inode);
 
-	if (!page_has_buffers(page)) {
-		create_empty_buffers(page, inode->i_sb->s_blocksize,
-				(1 << BH_Dirty)|(1 << BH_Uptodate));
-	}
 	page_bufs = page_buffers(page);
-	walk_page_buffers(handle, page_bufs, 0,
+	if (page->index == size >> PAGE_CACHE_SHIFT)
+		len = size & ~PAGE_CACHE_MASK;
+	else
+		len = PAGE_CACHE_SIZE;
+
+	if (walk_page_buffers(NULL, page_bufs, 0,
+					len, NULL, ext4_bh_unmapped)) {
+		printk(KERN_CRIT "%s called with unmapped buffer\n",
+								__func__);
+		BUG();
+	}
+	walk_page_buffers(NULL, page_bufs, 0,
 			PAGE_CACHE_SIZE, NULL, bget_one);
 
 	ret = block_write_full_page(page, ext4_get_block, wbc);
@@ -1574,8 +1587,8 @@ static int __ext4_ordered_writepage(struct page *page,
 			ret = err;
 	}
 out_put:
-	walk_page_buffers(handle, page_bufs, 0, PAGE_CACHE_SIZE, NULL,
-			  bput_one);
+	walk_page_buffers(handle, page_bufs, 0,
+				PAGE_CACHE_SIZE, NULL, bput_one);
 	return ret;
 }
 
@@ -1583,7 +1596,7 @@ static int ext4_ordered_writepage(struct page *page,
 				struct writeback_control *wbc)
 {
 	J_ASSERT(PageLocked(page));
-
+	BUG_ON(!page_has_buffers(page));
 	/*
 	 * We give up here if we're reentered, because it might be for a
 	 * different filesystem.
@@ -1599,18 +1612,34 @@ static int ext4_ordered_writepage(struct page *page,
 static int __ext4_writeback_writepage(struct page *page,
 				struct writeback_control *wbc)
 {
+	unsigned long len;
+	struct buffer_head *page_bufs;
 	struct inode *inode = page->mapping->host;
+	loff_t size = i_size_read(inode);
 
+	page_bufs = page_buffers(page);
+	if (page->index == size >> PAGE_CACHE_SHIFT)
+		len = size & ~PAGE_CACHE_MASK;
+	else
+		len = PAGE_CACHE_SIZE;
+
+	if (walk_page_buffers(NULL, page_bufs, 0,
+					len, NULL, ext4_bh_unmapped)) {
+		printk(KERN_CRIT "%s called with unmapped buffer\n",
+								__func__);
+		BUG();
+	}
 	if (test_opt(inode->i_sb, NOBH))
 		return nobh_writepage(page, ext4_get_block, wbc);
 	else
 		return block_write_full_page(page, ext4_get_block, wbc);
 }
 
-
 static int ext4_writeback_writepage(struct page *page,
 				struct writeback_control *wbc)
 {
+	BUG_ON(!page_has_buffers(page));
+
 	if (!ext4_journal_current_handle())
 		return __ext4_writeback_writepage(page, wbc);
 
@@ -1622,18 +1651,31 @@ static int ext4_writeback_writepage(struct page *page,
 static int __ext4_journalled_writepage(struct page *page,
 				struct writeback_control *wbc)
 {
+	int ret = 0, err;
+	unsigned long len;
+	handle_t *handle = NULL;
 	struct address_space *mapping = page->mapping;
 	struct inode *inode = mapping->host;
 	struct buffer_head *page_bufs;
-	handle_t *handle = NULL;
-	int ret = 0;
-	int err;
+	loff_t size = i_size_read(inode);
+
+	page_bufs = page_buffers(page);
+	if (page->index == size >> PAGE_CACHE_SHIFT)
+		len = size & ~PAGE_CACHE_MASK;
+	else
+		len = PAGE_CACHE_SIZE;
 
+	if (walk_page_buffers(NULL, page_bufs, 0,
+					len, NULL, ext4_bh_unmapped)) {
+		printk(KERN_CRIT "%s called with unmapped buffer\n",
+								__func__);
+		BUG();
+	}
+	/* FIXME!! do we need to call prepare_write for a mapped buffer */
 	ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE, ext4_get_block);
 	if (ret != 0)
 		goto out_unlock;
 
-	page_bufs = page_buffers(page);
 	walk_page_buffers(handle, page_bufs, 0, PAGE_CACHE_SIZE, NULL,
 								bget_one);
 	/* As soon as we unlock the page, it can go away, but we have
@@ -1671,14 +1713,13 @@ static int __ext4_journalled_writepage(struct page *page,
 static int ext4_journalled_writepage(struct page *page,
 				struct writeback_control *wbc)
 {
+	BUG_ON(!page_has_buffers(page));
+
 	if (ext4_journal_current_handle())
 		goto no_write;
 
-	if (!page_has_buffers(page) || PageChecked(page)) {
-		/*
-		 * It's mmapped pagecache.  Add buffers and journal it.  There
-		 * doesn't seem much point in redirtying the page here.
-		 */
+	if (PageChecked(page)) {
+		/* dirty pages in data=journal mode */
 		ClearPageChecked(page);
 		return __ext4_journalled_writepage(page, wbc);
 	} else {
@@ -3520,9 +3561,94 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
 	return err;
 }
 
-static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
+static int __ext4_journalled_allocpage(struct page *page,
+				struct writeback_control *wbc)
 {
-	return !buffer_mapped(bh);
+	int ret = 0, err;
+	handle_t *handle = NULL;
+	struct address_space *mapping = page->mapping;
+	struct inode *inode = mapping->host;
+	struct buffer_head *page_bufs;
+
+	/* if alloc we are called after statring a journal */
+	handle = ext4_journal_current_handle();
+	BUG_ON(!handle);
+
+	ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE, ext4_get_block);
+	if (ret != 0)
+		goto out_unlock;
+
+	/* FIXME!! should we do a bget_one */
+	page_bufs = page_buffers(page);
+	ret = walk_page_buffers(handle, page_bufs, 0,
+			PAGE_CACHE_SIZE, NULL, do_journal_get_write_access);
+
+	err = walk_page_buffers(handle, page_bufs, 0,
+				PAGE_CACHE_SIZE, NULL, write_end_fn);
+	if (ret == 0)
+		ret = err;
+	EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
+
+out_unlock:
+	unlock_page(page);
+	return ret;
+}
+
+static int __ext4_ordered_allocpage(struct page *page,
+				struct writeback_control *wbc)
+{
+	int ret = 0;
+	handle_t *handle = NULL;
+	struct buffer_head *page_bufs;
+	struct inode *inode = page->mapping->host;
+
+	/* if alloc we are called after statring a journal */
+	handle = ext4_journal_current_handle();
+	BUG_ON(!handle);
+	if (!page_has_buffers(page)) {
+		create_empty_buffers(page, inode->i_sb->s_blocksize,
+				(1 << BH_Dirty)|(1 << BH_Uptodate));
+	}
+	page_bufs = page_buffers(page);
+	walk_page_buffers(handle, page_bufs, 0,
+			PAGE_CACHE_SIZE, NULL, bget_one);
+
+	ret = block_write_full_page(page, ext4_get_block, wbc);
+
+	/*
+	 * The page can become unlocked at any point now, and
+	 * truncate can then come in and change things.  So we
+	 * can't touch *page from now on.  But *page_bufs is
+	 * safe due to elevated refcount.
+	 */
+
+	/*
+	 * And attach them to the current transaction.  But only if
+	 * block_write_full_page() succeeded.  Otherwise they are unmapped,
+	 * and generally junk.
+	 */
+	if (ret == 0) {
+		ret = walk_page_buffers(handle, page_bufs, 0, PAGE_CACHE_SIZE,
+					NULL, jbd2_journal_dirty_data_fn);
+	}
+	walk_page_buffers(handle, page_bufs, 0,
+				PAGE_CACHE_SIZE, NULL, bput_one);
+	return ret;
+}
+
+static int __ext4_writeback_allocpage(struct page *page,
+				struct writeback_control *wbc)
+{
+	handle_t *handle = NULL;
+	struct inode *inode = page->mapping->host;
+	/* if alloc we are called after statring a journal */
+	handle = ext4_journal_current_handle();
+	BUG_ON(!handle);
+
+	if (test_opt(inode->i_sb, NOBH))
+		return nobh_writepage(page, ext4_get_block, wbc);
+	else
+		return block_write_full_page(page, ext4_get_block, wbc);
 }
 
 int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page)
@@ -3578,11 +3704,11 @@ int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page)
 	wbc.range_start = page_offset(page);
 	wbc.range_end = page_offset(page) + PAGE_CACHE_SIZE;
 	if (ext4_should_writeback_data(inode))
-		ret = __ext4_writeback_writepage(page, &wbc);
+		ret = __ext4_writeback_allocpage(page, &wbc);
 	else if (ext4_should_order_data(inode))
-		ret = __ext4_ordered_writepage(page, &wbc);
+		ret = __ext4_ordered_allocpage(page, &wbc);
 	else
-		ret = __ext4_journalled_writepage(page, &wbc);
+		ret = __ext4_journalled_allocpage(page, &wbc);
 	/* Page got unlocked in writepage */
 	err = ext4_journal_stop(handle);
 	if (!ret)
-- 
1.5.5.1.211.g65ea3.dirty