f2fs: validate before set/clear free nat bitmap

In flush_nat_entries, all dirty nats will be flushed and if
their new address isn't NULL_ADDR, their bitmaps will be updated,
the free_nid_count of the bitmaps will be increaced regardless
of whether the nats have already been occupied before.
This could lead to wrong free_nid_count.
So this patch checks the status of the bits beforeactually
set/clear them.

Fixes: 586d1492f301 ("f2fs: skip scanning free nid bitmap of full NAT blocks")
Signed-off-by: Fan li <fanofcode.li@samsung.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index d253017..9abfdbb 100644 (file)
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1906,15 +1906,18 @@ static void update_free_nid_bitmap(struct f2fs_sb_info *sbi, nid_t nid,
        if (!test_bit_le(nat_ofs, nm_i->nat_block_bitmap))
                return;
 
-       if (set)
+       if (set) {
+               if (test_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]))
+                       return;
                __set_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);
-       else
-               __clear_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);
-
-       if (set)
                nm_i->free_nid_count[nat_ofs]++;
-       else if (!build)
-               nm_i->free_nid_count[nat_ofs]--;
+       } else {
+               if (!test_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]))
+                       return;
+               __clear_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);
+               if (!build)
+                       nm_i->free_nid_count[nat_ofs]--;
+       }
 }
 
 static void scan_nat_page(struct f2fs_sb_info *sbi,