[PATCH 3.16 059/129] ext4: add mask of ext4 flags to swap

[Ben Hutchings]

3.16.70-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: yangerkun <yangerkun@xxxxxxxxxx>

commit abdc644e8cbac2e9b19763680e5a7cf9bab2bee7 upstream.

The reason is that while swapping two inode, we swap the flags too.
Some flags such as EXT4_JOURNAL_DATA_FL can really confuse the things
since we're not resetting the address operations structure.  The
simplest way to keep things sane is to restrict the flags that can be
swapped.

Signed-off-by: yangerkun <yangerkun@xxxxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 fs/ext4/ext4.h  | 3 +++
 fs/ext4/ioctl.c | 6 +++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -405,6 +405,9 @@ struct flex_groups {
 /* Flags that are appropriate for non-directories/regular files. */
 #define EXT4_OTHER_FLMASK (EXT4_NODUMP_FL | EXT4_NOATIME_FL)
 
+/* The only flags that should be swapped */
+#define EXT4_FL_SHOULD_SWAP (EXT4_HUGE_FILE_FL | EXT4_EXTENTS_FL)
+
 /* Mask out flags that are inappropriate for the given type of inode. */
 static inline __u32 ext4_mask_flags(umode_t mode, __u32 flags)
 {
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -61,6 +61,7 @@ static void swap_inode_data(struct inode
 	loff_t isize;
 	struct ext4_inode_info *ei1;
 	struct ext4_inode_info *ei2;
+	unsigned long tmp;
 
 	ei1 = EXT4_I(inode1);
 	ei2 = EXT4_I(inode2);
@@ -71,7 +72,10 @@ static void swap_inode_data(struct inode
 	memswap(&inode1->i_mtime, &inode2->i_mtime, sizeof(inode1->i_mtime));
 
 	memswap(ei1->i_data, ei2->i_data, sizeof(ei1->i_data));
-	memswap(&ei1->i_flags, &ei2->i_flags, sizeof(ei1->i_flags));
+	tmp = ei1->i_flags & EXT4_FL_SHOULD_SWAP;
+	ei1->i_flags = (ei2->i_flags & EXT4_FL_SHOULD_SWAP) |
+		(ei1->i_flags & ~EXT4_FL_SHOULD_SWAP);
+	ei2->i_flags = tmp | (ei2->i_flags & ~EXT4_FL_SHOULD_SWAP);
 	memswap(&ei1->i_disksize, &ei2->i_disksize, sizeof(ei1->i_disksize));
 	ext4_es_remove_extent(inode1, 0, EXT_MAX_BLOCKS);
 	ext4_es_remove_extent(inode2, 0, EXT_MAX_BLOCKS);