[PATCH 4.4 02/34] f2fs: fix a bug caused by NULL extent tree

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Yunlei He <heyunlei@huawei.com>

commit dad48e73127ba10279ea33e6dbc8d3905c4d31c0 upstream.

Thread A:					Thread B:

-f2fs_remount
    -sbi->mount_opt.opt = 0;
						<--- -f2fs_iget
						         -do_read_inode
							     -f2fs_init_extent_tree
							         -F2FS_I(inode)->extent_tree is NULL
        -default_options && parse_options
	    -remount return
						<---  -f2fs_map_blocks
						          -f2fs_lookup_extent_tree
                                                              -f2fs_bug_on(sbi, !et);

The same problem with f2fs_new_inode.

Signed-off-by: Yunlei He <heyunlei@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/f2fs/extent_cache.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -172,7 +172,7 @@ void f2fs_drop_largest_extent(struct ino
 	__drop_largest_extent(inode, fofs, 1);
 }
 
-void f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext)
+static void __f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext)
 {
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 	struct extent_tree *et;
@@ -204,6 +204,14 @@ out:
 	write_unlock(&et->lock);
 }
 
+void f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext)
+{
+	__f2fs_init_extent_tree(inode, i_ext);
+
+	if (!F2FS_I(inode)->extent_tree)
+		set_inode_flag(F2FS_I(inode), FI_NO_EXTENT);
+}
+
 static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
 							struct extent_info *ei)
 {