[XFS] Fix a 32 bit value wraparound when providing a mapping for a large

direct write.

SGI-PV: 944820
SGI-Modid: xfs-linux-melb:xfs-kern:24351a

Signed-off-by: Nathan Scott <nathans@sgi.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index c6108971b4e6..94d3cdfbf9b8 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -941,13 +941,12 @@ __linvfs_get_block(
         int                     retpbbm = 1;
         int                     error;
 
-        if (blocks) {
-                offset = blocks << inode->i_blkbits;    /* 64 bit goodness */
-                size = (ssize_t) min_t(xfs_off_t, offset, LONG_MAX);
-        } else {
-                size = 1 << inode->i_blkbits;
-        }
         offset = (xfs_off_t)iblock << inode->i_blkbits;
+        if (blocks)
+                size = (ssize_t) min_t(xfs_off_t, LONG_MAX,
+                                        (xfs_off_t)blocks << inode->i_blkbits);
+        else
+                size = 1 << inode->i_blkbits;
 
         VOP_BMAP(vp, offset, size,
                 create ? flags : BMAPI_READ, &iomap, &retpbbm, error);
@@ -1007,7 +1006,7 @@ __linvfs_get_block(
                 ASSERT(iomap.iomap_bsize - iomap.iomap_delta > 0);
                 offset = min_t(xfs_off_t,
                                 iomap.iomap_bsize - iomap.iomap_delta,
-                                blocks << inode->i_blkbits);
+                                (xfs_off_t)blocks << inode->i_blkbits);
                 bh_result->b_size = (u32) min_t(xfs_off_t, UINT_MAX, offset);
         }