writeback: Export __inode_attach_wb()

Commit c26339e1df33 ("ext4: Fix data integrity writeout issues in
nojournal mode") made ext4_mark_iloc_dirty() attach the inode to a wb
before marking it for metadata writeback in nojournal mode. This is the
first modular caller of inode_attach_wb() - all users of
__inode_attach_wb() so far were built-in - so with CONFIG_EXT4_FS=m and
CONFIG_CGROUP_WRITEBACK=y the build now fails at the modpost stage:

  ERROR: modpost: "__inode_attach_wb" [fs/ext4/ext4.ko] undefined!

Export the symbol. Use EXPORT_SYMBOL_GPL() to match the other cgroup
writeback exports in this file.

Fixes: c26339e1df33 ("ext4: Fix data integrity writeout issues in nojournal mode")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202607281811.F3c6kRvX-lkp@intel.com/
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 9d96357731a3d4beb6f8b128d47424dc2a82d33a..71dd618db07534312d1d7f5aacbd9a862eada1b8 100644 (file)
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -299,6 +299,7 @@ void __inode_attach_wb(struct inode *inode, struct folio *folio)
        if (unlikely(cmpxchg(&inode->i_wb, NULL, wb)))
                wb_put(wb);
 }
+EXPORT_SYMBOL_GPL(__inode_attach_wb);
 
 /**
  * inode_cgwb_move_to_attached - put the inode onto wb->b_attached list