btrfs: fix integer overflow in calc_reclaim_items_nr

Dave Jones hit a WARN_ON(nr < 0) in btrfs_wait_ordered_roots() with
v4.12-rc6.  This was because commit 70e7af24 made it possible for
calc_reclaim_items_nr() to return a negative number.  It's not really a
bug in that commit, it just didn't go far enough down the stack to find
all the possible 64->32 bit overflows.

This switches calc_reclaim_items_nr() to return a u64 and changes everyone
that uses the results of that math to u64 as well.
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Fixes: 70e7af24 ("Btrfs: fix delalloc accounting leak caused by u32 overflow")
Signed-off-by: Chris Mason <clm@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/dev-replace.c

@@ -388,7 +388,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	if (ret)
 		btrfs_err(fs_info, "kobj add dev failed %d", ret);
 
-	btrfs_wait_ordered_roots(fs_info, -1, 0, (u64)-1);
+	btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 
 	/* force writing the updated state information to disk */
 	trans = btrfs_start_transaction(root, 0);
@@ -507,7 +507,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 		return ret;
 	}
-	btrfs_wait_ordered_roots(fs_info, -1, 0, (u64)-1);
+	btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 
 	trans = btrfs_start_transaction(root, 0);
 	if (IS_ERR(trans)) {

fs/btrfs/extent-tree.c

@@ -4288,7 +4288,7 @@ int btrfs_alloc_data_chunk_ondemand(struct btrfs_inode *inode, u64 bytes)
 
 			if (need_commit > 0) {
 				btrfs_start_delalloc_roots(fs_info, 0, -1);
-				btrfs_wait_ordered_roots(fs_info, -1, 0,
+				btrfs_wait_ordered_roots(fs_info, U64_MAX, 0,
 							 (u64)-1);
 			}
 
@@ -4748,14 +4748,14 @@ static void btrfs_writeback_inodes_sb_nr(struct btrfs_fs_info *fs_info,
 	}
 }
 
-static inline int calc_reclaim_items_nr(struct btrfs_fs_info *fs_info,
+static inline u64 calc_reclaim_items_nr(struct btrfs_fs_info *fs_info,
 					u64 to_reclaim)
 {
 	u64 bytes;
-	int nr;
+	u64 nr;
 
 	bytes = btrfs_calc_trans_metadata_size(fs_info, 1);
-	nr = (int)div64_u64(to_reclaim, bytes);
+	nr = div64_u64(to_reclaim, bytes);
 	if (!nr)
 		nr = 1;
 	return nr;
@@ -4774,15 +4774,15 @@ static void shrink_delalloc(struct btrfs_fs_info *fs_info, u64 to_reclaim,
 	struct btrfs_trans_handle *trans;
 	u64 delalloc_bytes;
 	u64 max_reclaim;
+	u64 items;
 	long time_left;
 	unsigned long nr_pages;
 	int loops;
-	int items;
 	enum btrfs_reserve_flush_enum flush;
 
 	/* Calc the number of the pages we need flush for space reservation */
 	items = calc_reclaim_items_nr(fs_info, to_reclaim);
-	to_reclaim = (u64)items * EXTENT_SIZE_PER_ITEM;
+	to_reclaim = items * EXTENT_SIZE_PER_ITEM;
 
 	trans = (struct btrfs_trans_handle *)current->journal_info;
 	block_rsv = &fs_info->delalloc_block_rsv;

fs/btrfs/ioctl.c

@@ -689,7 +689,7 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
 	if (ret)
 		goto dec_and_free;
 
-	btrfs_wait_ordered_extents(root, -1, 0, (u64)-1);
+	btrfs_wait_ordered_extents(root, U64_MAX, 0, (u64)-1);
 
 	btrfs_init_block_rsv(&pending_snapshot->block_rsv,
 			     BTRFS_BLOCK_RSV_TEMP);

fs/btrfs/ordered-data.c

@@ -663,7 +663,7 @@ static void btrfs_run_ordered_extent_work(struct btrfs_work *work)
  * wait for all the ordered extents in a root.  This is done when balancing
  * space between drives.
  */
-int btrfs_wait_ordered_extents(struct btrfs_root *root, int nr,
+u64 btrfs_wait_ordered_extents(struct btrfs_root *root, u64 nr,
 			       const u64 range_start, const u64 range_len)
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;
@@ -671,7 +671,7 @@ int btrfs_wait_ordered_extents(struct btrfs_root *root, int nr,
 	LIST_HEAD(skipped);
 	LIST_HEAD(works);
 	struct btrfs_ordered_extent *ordered, *next;
-	int count = 0;
+	u64 count = 0;
 	const u64 range_end = range_start + range_len;
 
 	mutex_lock(&root->ordered_extent_mutex);
@@ -701,7 +701,7 @@ int btrfs_wait_ordered_extents(struct btrfs_root *root, int nr,
 
 		cond_resched();
 		spin_lock(&root->ordered_extent_lock);
-		if (nr != -1)
+		if (nr != U64_MAX)
 			nr--;
 		count++;
 	}
@@ -720,13 +720,13 @@ int btrfs_wait_ordered_extents(struct btrfs_root *root, int nr,
 	return count;
 }
 
-int btrfs_wait_ordered_roots(struct btrfs_fs_info *fs_info, int nr,
-			      const u64 range_start, const u64 range_len)
+u64 btrfs_wait_ordered_roots(struct btrfs_fs_info *fs_info, u64 nr,
+			     const u64 range_start, const u64 range_len)
 {
 	struct btrfs_root *root;
 	struct list_head splice;
-	int done;
-	int total_done = 0;
+	u64 total_done = 0;
+	u64 done;
 
 	INIT_LIST_HEAD(&splice);
 
@@ -748,9 +748,8 @@ int btrfs_wait_ordered_roots(struct btrfs_fs_info *fs_info, int nr,
 		total_done += done;
 
 		spin_lock(&fs_info->ordered_root_lock);
-		if (nr != -1) {
+		if (nr != U64_MAX) {
 			nr -= done;
-			WARN_ON(nr < 0);
 		}
 	}
 	list_splice_tail(&splice, &fs_info->ordered_roots);

fs/btrfs/ordered-data.h

@@ -200,9 +200,9 @@ int btrfs_ordered_update_i_size(struct inode *inode, u64 offset,
 				struct btrfs_ordered_extent *ordered);
 int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u64 disk_bytenr,
 			   u32 *sum, int len);
-int btrfs_wait_ordered_extents(struct btrfs_root *root, int nr,
+u64 btrfs_wait_ordered_extents(struct btrfs_root *root, u64 nr,
 			       const u64 range_start, const u64 range_len);
-int btrfs_wait_ordered_roots(struct btrfs_fs_info *fs_info, int nr,
+u64 btrfs_wait_ordered_roots(struct btrfs_fs_info *fs_info, u64 nr,
 			      const u64 range_start, const u64 range_len);
 void btrfs_get_logged_extents(struct btrfs_inode *inode,
 			      struct list_head *logged_list,

fs/btrfs/qgroup.c

@@ -2405,7 +2405,7 @@ static int qgroup_reserve(struct btrfs_root *root, u64 num_bytes, bool enforce)
 				ret = btrfs_start_delalloc_inodes(root, 0);
 				if (ret)
 					return ret;
-				btrfs_wait_ordered_extents(root, -1, 0, (u64)-1);
+				btrfs_wait_ordered_extents(root, U64_MAX, 0, (u64)-1);
 				trans = btrfs_join_transaction(root);
 				if (IS_ERR(trans))
 					return PTR_ERR(trans);

fs/btrfs/relocation.c

@@ -4373,7 +4373,7 @@ int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start)
 
 	btrfs_wait_block_group_reservations(rc->block_group);
 	btrfs_wait_nocow_writers(rc->block_group);
-	btrfs_wait_ordered_roots(fs_info, -1,
+	btrfs_wait_ordered_roots(fs_info, U64_MAX,
 				 rc->block_group->key.objectid,
 				 rc->block_group->key.offset);
 

fs/btrfs/scrub.c

@@ -3836,7 +3836,7 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
 			 */
 			btrfs_wait_block_group_reservations(cache);
 			btrfs_wait_nocow_writers(cache);
-			ret = btrfs_wait_ordered_roots(fs_info, -1,
+			ret = btrfs_wait_ordered_roots(fs_info, U64_MAX,
 						       cache->key.objectid,
 						       cache->key.offset);
 			if (ret > 0) {

fs/btrfs/super.c

@@ -1177,7 +1177,7 @@ int btrfs_sync_fs(struct super_block *sb, int wait)
 		return 0;
 	}
 
-	btrfs_wait_ordered_roots(fs_info, -1, 0, (u64)-1);
+	btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 
 	trans = btrfs_attach_transaction_barrier(root);
 	if (IS_ERR(trans)) {

fs/btrfs/transaction.c

@@ -1923,7 +1923,7 @@ static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
 static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
 {
 	if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
-		btrfs_wait_ordered_roots(fs_info, -1, 0, (u64)-1);
+		btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 }
 
 static inline void