Linux 3.5 compat, end_writeback() changed to clear_inode()

[zfs.git] / config / kernel-clear-inode.m4

diff --git a/config/kernel-clear-inode.m4 b/config/kernel-clear-inode.m4
new file mode 100644 (file)
index 0000000..e3eace2
--- /dev/null
+++ b/config/kernel-clear-inode.m4
@@ -0,0 +1,29 @@
+dnl #
+dnl # 3.5.0 API change
+dnl # torvalds/linux@dbd5768f87ff6fb0a4fe09c4d7b6c4a24de99430 and
+dnl # torvalds/linux@7994e6f7254354e03028a11f98a27bd67dace9f1 reworked
+dnl # where inode_sync_wait() is called.
+dnl #
+dnl # Prior to these changes it would occur in end_writeback() but due
+dnl # to various issues (described in the above commits) it has been
+dnl # moved to evict().   This changes the ordering is which sync occurs
+dnl # but otherwise doesn't impact the zpl implementation.
+dnl #
+dnl # The major impact here is the renaming of end_writeback() to
+dnl # clear_inode().  However, care must be taken when detecting this
+dnl # API change because as recently as 2.6.35 there was a clear_inode()
+dnl # function.  However, it was made obsolete by the evict_inode() API
+dnl # change at the same time.
+dnl #
+dnl # Therefore, to ensure we have the correct API we only allow the
+dnl # clear_inode() compatibility code to be defined iff the evict_inode()
+dnl # functionality is also detected.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_CLEAR_INODE], [
+       ZFS_CHECK_SYMBOL_EXPORT(
+               [clear_inode],
+               [fs/inode.c],
+               [AC_DEFINE(HAVE_CLEAR_INODE, 1,
+               [clear_inode() is available])],
+               [])
+])