f2fs: fix to wait page writeback before setting gcing flag

[ Upstream commit a4d7f2b3238fd5f76b9e6434a0bd5d2e29049cff ]

Soft IRQ				Thread
- f2fs_write_end_io
					- f2fs_defragment_range
					 - set_page_private_gcing
 - type = WB_DATA_TYPE(page, false);
 : assign type w/ F2FS_WB_CP_DATA
 due to page_private_gcing() is true
  - dec_page_count() w/ wrong type
  - end_page_writeback()

Value of F2FS_WB_CP_DATA reference count may become negative under above
race condition, the root cause is we missed to wait page writeback before
setting gcing page private flag, let's fix it.

Fixes: 2d1fe8a86bf5 ("f2fs: fix to tag gcing flag on page during file defragment")
Fixes: 4961acdd65c9 ("f2fs: fix to tag gcing flag on page during block migration")
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 19da00ab31aebba4857ebfd548ff7ea7d795c795..8425fc33ea403c66494183e6e095756f446c51c8 100644 (file)
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -2791,6 +2791,8 @@ do_map:
                                goto clear_out;
                        }
 
+                       f2fs_wait_on_page_writeback(page, DATA, true, true);
+
                        set_page_dirty(page);
                        set_page_private_gcing(page);
                        f2fs_put_page(page, 1);
@@ -4184,6 +4186,8 @@ static int redirty_blocks(struct inode *inode, pgoff_t page_idx, int len)
                /* It will never fail, when page has pinned above */
                f2fs_bug_on(F2FS_I_SB(inode), !page);
 
+               f2fs_wait_on_page_writeback(page, DATA, true, true);
+
                set_page_dirty(page);
                set_page_private_gcing(page);
                f2fs_put_page(page, 1);