[PATCH] f2fs: fix to avoid GC/mmap race with f2fs_truncate()

[Chao Yu]

It missed to hold i_gc_rwsem and i_map_sem around f2fs_truncate()
in f2fs_file_write_iter() to avoid racing with background GC and
mmap, fix it.

Signed-off-by: Chao Yu <yuch...@huawei.com>
---
 fs/f2fs/file.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index dc79694e512c..f3ca63b55843 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -4443,8 +4443,13 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, 
struct iov_iter *from)
                clear_inode_flag(inode, FI_NO_PREALLOC);
 
                /* if we couldn't write data, we should deallocate blocks. */
-               if (preallocated && i_size_read(inode) < target_size)
+               if (preallocated && i_size_read(inode) < target_size) {
+                       down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+                       down_write(&F2FS_I(inode)->i_mmap_sem);
                        f2fs_truncate(inode);
+                       up_write(&F2FS_I(inode)->i_mmap_sem);
+                       up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+               }
 
                if (ret > 0)
                        f2fs_update_iostat(F2FS_I_SB(inode), APP_WRITE_IO, ret);
-- 
2.29.2