When defragging a very large file, the cluster variable can wrap its 32-bit
signed int type and become negative, which eventually gets passed to
btrfs_force_ra() as a very large unsigned long value. On 32-bit platforms,
this eventually results in an Oops from the SLAB allocator.
Change the cluster and max_cluster signed int variables to unsigned long to
match the readahead functions. This also allows the min() comparison in
btrfs_defrag_file() to work as intended.
---
fs/btrfs/ioctl.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 21da576..22e9837 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1011,7 +1011,7 @@ out:
static int cluster_pages_for_defrag(struct inode *inode,
struct page **pages,
unsigned long start_index,
- int num_pages)
+ unsigned long num_pages)
{
unsigned long file_end;
u64 isize = i_size_read(inode);
@@ -1169,8 +1169,8 @@ int btrfs_defrag_file(struct inode *inode, struct file
*file,
int defrag_count = 0;
int compress_type = BTRFS_COMPRESS_ZLIB;
int extent_thresh = range->extent_thresh;
- int max_cluster = (256 * 1024) >> PAGE_CACHE_SHIFT;
- int cluster = max_cluster;
+ unsigned long max_cluster = (256 * 1024) >> PAGE_CACHE_SHIFT;
+ unsigned long cluster = max_cluster;
u64 new_align = ~((u64)128 * 1024 - 1);
struct page **pages = NULL;
--
1.7.9.5
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