f2fs: compress: fix error path of inc_valid_block_count()

If inc_valid_block_count() can not allocate all requested blocks,
it needs to release block count in .total_valid_block_count and
resevation blocks in inode.

Fixes: 5460749 ("f2fs: compress: fix to avoid inconsistence bewteen i_blocks and dnode")
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Author: chaseyu

fs/f2fs/f2fs.h

@@ -2306,7 +2306,7 @@ static inline void f2fs_i_blocks_write(struct inode *, block_t, bool, bool);
 static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
 				 struct inode *inode, blkcnt_t *count, bool partial)
 {
-	blkcnt_t diff = 0, release = 0;
+	long long diff = 0, release = 0;
 	block_t avail_user_block_count;
 	int ret;
 
@@ -2326,26 +2326,27 @@ static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
 	percpu_counter_add(&sbi->alloc_valid_block_count, (*count));
 
 	spin_lock(&sbi->stat_lock);
-	sbi->total_valid_block_count += (block_t)(*count);
-	avail_user_block_count = get_available_block_count(sbi, inode, true);
 
-	if (unlikely(sbi->total_valid_block_count > avail_user_block_count)) {
+	avail_user_block_count = get_available_block_count(sbi, inode, true);
+	diff = (long long)sbi->total_valid_block_count + *count -
+						avail_user_block_count;
+	if (unlikely(diff > 0)) {
 		if (!partial) {
 			spin_unlock(&sbi->stat_lock);
+			release = *count;
 			goto enospc;
 		}
-
-		diff = sbi->total_valid_block_count - avail_user_block_count;
 		if (diff > *count)
 			diff = *count;
 		*count -= diff;
 		release = diff;
-		sbi->total_valid_block_count -= diff;
 		if (!*count) {
 			spin_unlock(&sbi->stat_lock);
 			goto enospc;
 		}
 	}
+	sbi->total_valid_block_count += (block_t)(*count);
+
 	spin_unlock(&sbi->stat_lock);
 
 	if (unlikely(release)) {