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

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

From: Chao Yu <[email protected]>

[ Upstream commit 27319ba4044c0c67d62ae39e53c0118c89f0a029 ]

Thread                                  GC thread
- f2fs_ioc_start_atomic_write
 - get_dirty_pages
 - filemap_write_and_wait_range
                                        - f2fs_gc
                                         - do_garbage_collect
                                          - gc_data_segment
                                           - move_data_page
                                            - f2fs_is_atomic_file
                                            - set_page_dirty
 - set_inode_flag(, FI_ATOMIC_FILE)

Dirty data page can still be generated by GC in race condition as
above call stack.

This patch adds fi->dio_rwsem[WRITE] in f2fs_ioc_start_atomic_write
to avoid such race.

Signed-off-by: Chao Yu <[email protected]>
Signed-off-by: Jaegeuk Kim <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 fs/f2fs/file.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1670,6 +1670,8 @@ static int f2fs_ioc_start_atomic_write(s
 
        inode_lock(inode);
 
+       down_write(&F2FS_I(inode)->dio_rwsem[WRITE]);
+
        if (f2fs_is_atomic_file(inode))
                goto out;
 
@@ -1699,6 +1701,7 @@ inc_stat:
        stat_inc_atomic_write(inode);
        stat_update_max_atomic_write(inode);
 out:
+       up_write(&F2FS_I(inode)->dio_rwsem[WRITE]);
        inode_unlock(inode);
        mnt_drop_write_file(filp);
        return ret;


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