f2fs: wait on atomic writes to count F2FS_CP_WB_DATA

Otherwise, we can get wrong counts incurring checkpoint hang.

IO_W (CP:  -24, Data:   24, Flush: (   0    0    1), Discard: (   0    0))

Thread A                        Thread B
- f2fs_write_data_pages
 -  __write_data_page
  - f2fs_submit_page_write
   - inc_page_count(F2FS_WB_DATA)
     type is F2FS_WB_DATA due to file is non-atomic one
- f2fs_ioc_start_atomic_write
 - set_inode_flag(FI_ATOMIC_FILE)
                                - f2fs_write_end_io
                                 - dec_page_count(F2FS_WB_CP_DATA)
                                   type is F2FS_WB_DATA due to file becomes
                                   atomic one

Cc: <stable@vger.kernel.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index bba56b39dcc55a1b15da3a90ddb3c53cb894e7f2..ae2b45e7584738ea4c5dac3eddcfcae525959aa8 100644 (file)
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1750,10 +1750,12 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
 
        down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
 
-       if (!get_dirty_pages(inode))
-               goto skip_flush;
-
-       f2fs_msg(F2FS_I_SB(inode)->sb, KERN_WARNING,
+       /*
+        * Should wait end_io to count F2FS_WB_CP_DATA correctly by
+        * f2fs_is_atomic_file.
+        */
+       if (get_dirty_pages(inode))
+               f2fs_msg(F2FS_I_SB(inode)->sb, KERN_WARNING,
                "Unexpected flush for atomic writes: ino=%lu, npages=%u",
                                        inode->i_ino, get_dirty_pages(inode));
        ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
@@ -1761,7 +1763,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
                up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
                goto out;
        }
-skip_flush:
+
        set_inode_flag(inode, FI_ATOMIC_FILE);
        clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST);
        up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);