Btrfs: btrfs_ioctl_clone: Truncate complete page after performing clone operation

In subpagesize-blocksize scenario, the "destination offset" argument passed to
the btrfs_ioctl_clone() can be aligned to sectorsize but may not be
necessarily aligned to the machine's page size. In such cases,
truncate_inode_pages_range() ends up zeroing out the partial page and future
read operations will return incorrect data. Hence this commit explicitly
rounds down the "destination offset" to the machine's page size.

Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 83c9ad3..709419c 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3926,8 +3926,9 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
         * Truncate page cache pages so that future reads will see the cloned
         * data immediately and not the previous data.
         */
-       truncate_inode_pages_range(&inode->i_data, destoff,
-                                  PAGE_CACHE_ALIGN(destoff + len) - 1);
+       truncate_inode_pages_range(&inode->i_data,
+                               round_down(destoff, PAGE_CACHE_SIZE),
+                               round_up(destoff + len, PAGE_CACHE_SIZE) - 1);
 out_unlock:
        if (!same_inode)
                btrfs_double_inode_unlock(src, inode);