f2fs: fix to cover io->bio with io_rwsem

In the f2fs_wait_on_page_writeback, io->bio should be covered by io_rwsem.
Otherwise, the bio pointer can become a dangling pointer due to data races.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index cb49e63..f799c6a 100644 (file)
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1049,15 +1049,14 @@ static inline bool is_merged_page(struct f2fs_sb_info *sbi,
 {
        enum page_type btype = PAGE_TYPE_OF_BIO(type);
        struct f2fs_bio_info *io = &sbi->write_io[btype];
-       struct bio *bio = io->bio;
        struct bio_vec *bvec;
        int i;
 
        down_read(&io->io_rwsem);
-       if (!bio)
+       if (!io->bio)
                goto out;
 
-       bio_for_each_segment_all(bvec, bio, i) {
+       bio_for_each_segment_all(bvec, io->bio, i) {
                if (page == bvec->bv_page) {
                        up_read(&io->io_rwsem);
                        return true;