ext4: Fix ext4_should_writeback_data() for no-journal mode (441c8508) · Commits · 戴 / test

ext4_should_writeback_data() had an incorrect sequence of tests to determine if it should return 0 or 1: in particular, even in no-journal mode, 0 was being returned for a non-regular-file inode. This meant that, in non-journal mode, we would use ext4_journalled_aops for directories, symlinks, and other non-regular files. However, calling journalled aop callbacks when there is no valid handle, can cause problems. This would cause a kernel crash with Jan Kara's commit ("ext4: fix data corruption in inodes with journalled data"), because we now dereference 'handle' in ext4_journalled_write_end(). I also added BUG_ONs to check for a valid handle in the obviously journal-only aops callbacks. I tested this running xfstests with a scratch device in these modes: - no-journal - data=ordered - data=writeback - data=journal All work fine; the data=journal run has many failures and a crash in xfstests 074, but this is no different from a vanilla kernel. Signed-off-by:

Curt Wohlgemuth <curtw@google.com> Signed-off-by:

"Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org

fs/ext4/ext4_jbd2.h

+2 −2

Original line number	Original line	Diff line number	Diff line
	@@ -289,10 +289,10 @@ static inline int ext4_should_order_data(struct inode *inode)

	static inline int ext4_should_writeback_data(struct inode *inode)		static inline int ext4_should_writeback_data(struct inode *inode)
	{		{
	if (!S_ISREG(inode->i_mode))
	return 0;
	if (EXT4_JOURNAL(inode) == NULL)		if (EXT4_JOURNAL(inode) == NULL)
	return 1;		return 1;
			if (!S_ISREG(inode->i_mode))
			return 0;
	if (ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA))		if (ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA))
	return 0;		return 0;
	if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_WRITEBACK_DATA)		if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_WRITEBACK_DATA)

fs/ext4/inode.c

+4 −0

Original line number	Original line	Diff line number	Diff line
	@@ -983,6 +983,8 @@ static int ext4_journalled_write_end(struct file *file,
	from = pos & (PAGE_CACHE_SIZE - 1);		from = pos & (PAGE_CACHE_SIZE - 1);
	to = from + len;		to = from + len;

			BUG_ON(!ext4_handle_valid(handle));

	if (copied < len) {		if (copied < len) {
	if (!PageUptodate(page))		if (!PageUptodate(page))
	copied = 0;		copied = 0;
	@@ -1699,6 +1701,8 @@ static int __ext4_journalled_writepage(struct page *page,
	goto out;		goto out;
	}		}

			BUG_ON(!ext4_handle_valid(handle));

	ret = walk_page_buffers(handle, page_bufs, 0, len, NULL,		ret = walk_page_buffers(handle, page_bufs, 0, len, NULL,
	do_journal_get_write_access);		do_journal_get_write_access);

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