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 70e7af244 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: 70e7af2 ("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>

1 files changed, 8 insertions, 9 deletions

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 7b40e2e7292a..a3aca495e33e 100644
--- a/fs/btrfs/ordered-data.c
+++ b/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);