1 files changed, 14 insertions, 1 deletions

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 596ec71da00e..79670869d436 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1516,13 +1516,26 @@ xfs_vm_write_failed(
         loff_t                  pos,
         unsigned                len)
 {
-        loff_t                  block_offset = pos & PAGE_MASK;
+        loff_t                  block_offset;
         loff_t                  block_start;
         loff_t                  block_end;
         loff_t                  from = pos & (PAGE_CACHE_SIZE - 1);
         loff_t                  to = from + len;
         struct buffer_head      *bh, *head;
 
+        /*
+         * The request pos offset might be 32 or 64 bit, this is all fine
+         * on 64-bit platform.  However, for 64-bit pos request on 32-bit
+         * platform, the high 32-bit will be masked off if we evaluate the
+         * block_offset via (pos & PAGE_MASK) because the PAGE_MASK is
+         * 0xfffff000 as an unsigned long, hence the result is incorrect
+         * which could cause the following ASSERT failed in most cases.
+         * In order to avoid this, we can evaluate the block_offset of the
+         * start of the page by using shifts rather than masks the mismatch
+         * problem.
+         */
+        block_offset = (pos >> PAGE_CACHE_SHIFT) << PAGE_CACHE_SHIFT;
+
         ASSERT(block_offset + from == pos);
 
         head = page_buffers(page);