Patchwork [4/6] ext4: fix wrong m_len value after unwritten extent conversion

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Submitter Zheng Liu
Date Feb. 28, 2013, 6:26 p.m.
Message ID <1362076004-10087-5-git-send-email-wenqing.lz@taobao.com>
Download mbox | patch
Permalink /patch/224128/
State Superseded
Headers show

Comments

Zheng Liu - Feb. 28, 2013, 6:26 p.m.
From: Zheng Liu <wenqing.lz@taobao.com>

We always assume that the return value of ext4_ext_map_blocks is equal
to map->m_len but when we try to convert an unwritten extent 'm_len'
value will break this assumption.  It is harmless until we use status
tree as a extent cache because we need to update status tree according
to 'm_len' value.

Meanwhile this commit marks EXT4_MAP_MAPPED flag after unwritten extent
conversion.  It shouldn't cause a bug because we update status tree
according to checking EXT4_MAP_UNWRITTEN flag.  But it should be fixed.

After applied this commit, the following error message from self-testing
infrastructure disappears.

    ...
    kernel: ES len assertation failed for inode: 230 retval 1 !=
    map->m_len 3 in ext4_map_blocks (allocation)
    ...

Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Dmitry Monakhov <dmonakhov@openvz.org>
---
 fs/ext4/extents.c | 4 ++++
 1 file changed, 4 insertions(+)

Patch

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 372b2cb..0793a13 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3626,6 +3626,10 @@  ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
 						 path, map->m_len);
 		} else
 			err = ret;
+		map->m_flags |= EXT4_MAP_MAPPED;
+		if (allocated > map->m_len)
+			allocated = map->m_len;
+		map->m_len = allocated;
 		goto out2;
 	}
 	/* buffered IO case */