f2fs: avoid race for summary information

In order to do GC more reliably, I'd like to lock the vicitm summary page
until its GC is completed, and also prevent any checkpoint process.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

3 files changed, 7 insertions, 10 deletions

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 136c0f7a670b..e97f30157aa6 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -642,12 +642,6 @@ static void do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
         if (IS_ERR(sum_page))
                 return;
 
-        /*
-         * CP needs to lock sum_page. In this time, we don't need
-         * to lock this page, because this summary page is not gone anywhere.
-         * Also, this page is not gonna be updated before GC is done.
-         */
-        unlock_page(sum_page);
         sum = page_address(sum_page);
 
         switch (GET_SUM_TYPE((&sum->footer))) {
@@ -661,7 +655,7 @@ static void do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
         stat_inc_seg_count(sbi, GET_SUM_TYPE((&sum->footer)));
         stat_inc_call_count(sbi->stat_info);
 
-        f2fs_put_page(sum_page, 0);
+        f2fs_put_page(sum_page, 1);
 }
 
 int f2fs_gc(struct f2fs_sb_info *sbi)
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 8510c5ed402e..95298ef68262 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1149,7 +1149,7 @@ static int f2fs_write_node_pages(struct address_space *mapping,
 
         /* First check balancing cached NAT entries */
         if (try_to_free_nats(sbi, NAT_ENTRY_PER_BLOCK)) {
-                write_checkpoint(sbi, false);
+                f2fs_sync_fs(sbi->sb, true);
                 return 0;
         }
 
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 728c20a8e456..ca5413346653 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -137,10 +137,13 @@ int f2fs_sync_fs(struct super_block *sb, int sync)
         if (!sbi->s_dirty && !get_pages(sbi, F2FS_DIRTY_NODES))
                 return 0;
 
-        if (sync)
+        if (sync) {
+                mutex_lock(&sbi->gc_mutex);
                 write_checkpoint(sbi, false);
-        else
+                mutex_unlock(&sbi->gc_mutex);
+        } else {
                 f2fs_balance_fs(sbi);
+        }
 
         return 0;
 }