btrfs: fix potential overflow in cluster_pages_for_defrag on 32bit arch

On 32-bit systems, this shift will overflow for files larger than 4GB as
start_index is unsigned long while the calls to btrfs_delalloc_*_space
expect u64.

CC: stable@vger.kernel.org # 4.4+
Fixes: df480633b891 ("btrfs: extent-tree: Switch to new delalloc space reserve and release")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Sterba <dsterba@suse.com>
[ define the variable instead of repeating the shift ]
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index ab408a23ba32dcafccccb741c2c890c538b84708..69a384145dc6fc2d79ac1cd05a2b8f5220686a5b 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1274,6 +1274,7 @@ static int cluster_pages_for_defrag(struct inode *inode,
        u64 page_start;
        u64 page_end;
        u64 page_cnt;
+       u64 start = (u64)start_index << PAGE_SHIFT;
        int ret;
        int i;
        int i_done;
@@ -1290,8 +1291,7 @@ static int cluster_pages_for_defrag(struct inode *inode,
        page_cnt = min_t(u64, (u64)num_pages, (u64)file_end - start_index + 1);
 
        ret = btrfs_delalloc_reserve_space(BTRFS_I(inode), &data_reserved,
-                       start_index << PAGE_SHIFT,
-                       page_cnt << PAGE_SHIFT);
+                       start, page_cnt << PAGE_SHIFT);
        if (ret)
                return ret;
        i_done = 0;
@@ -1380,8 +1380,7 @@ again:
                btrfs_mod_outstanding_extents(BTRFS_I(inode), 1);
                spin_unlock(&BTRFS_I(inode)->lock);
                btrfs_delalloc_release_space(BTRFS_I(inode), data_reserved,
-                               start_index << PAGE_SHIFT,
-                               (page_cnt - i_done) << PAGE_SHIFT, true);
+                               start, (page_cnt - i_done) << PAGE_SHIFT, true);
        }
 
 
@@ -1408,8 +1407,7 @@ out:
                put_page(pages[i]);
        }
        btrfs_delalloc_release_space(BTRFS_I(inode), data_reserved,
-                       start_index << PAGE_SHIFT,
-                       page_cnt << PAGE_SHIFT, true);
+                       start, page_cnt << PAGE_SHIFT, true);
        btrfs_delalloc_release_extents(BTRFS_I(inode), page_cnt << PAGE_SHIFT);
        extent_changeset_free(data_reserved);
        return ret;