Unionfs: reintroduce a bmap method

This is needed for swapon(2) files in the union.

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>

diff --git a/fs/unionfs/mmap.c b/fs/unionfs/mmap.c
index 3f65e524f0df9ad7adda13800a483aaf8a3e6458..fa358ef3a6df0b6396dda2e359982b78eb746150 100644 (file)
--- a/fs/unionfs/mmap.c
+++ b/fs/unionfs/mmap.c
@@ -304,10 +304,33 @@ out:
        return err;             /* assume all is ok */
 }
 
+/*
+ * Although unionfs isn't a block-based file system, it may stack on one.
+ * ->bmap is needed, for example, to swapon(2) files.
+ */
+sector_t unionfs_bmap(struct address_space *mapping, sector_t block)
+{
+       int err = -EINVAL;
+       struct inode *inode, *lower_inode;
+       sector_t (*bmap)(struct address_space *, sector_t);
+
+       inode = (struct inode *)mapping->host;
+       lower_inode = unionfs_lower_inode(inode);
+       if (!lower_inode)
+               goto out;
+       bmap = lower_inode->i_mapping->a_ops->bmap;
+       if (bmap)
+               err = bmap(lower_inode->i_mapping, block);
+out:
+       return err;
+}
+
+
 struct address_space_operations unionfs_aops = {
        .writepage      = unionfs_writepage,
        .writepages     = unionfs_writepages,
        .readpage       = unionfs_readpage,
        .prepare_write  = unionfs_prepare_write,
        .commit_write   = unionfs_commit_write,
+       .bmap           = unionfs_bmap,
 };