It's doubtful many people were impacted by this but commit 6c28567
accidentally broke ZFS builds for 2.6.26 and earlier kernels. This
commit depends on the lookup_bdev() function which exists in 2.6.26
but wasn't exported until 2.6.27.
The availability of the function isn't critical so a wrapper is
introduced which returns ERR_PTR(-ENOTSUP) when the function isn't
defined. This will have the effect of causing zvol_is_zvol() to
always fail for 2.6.26 kernels. This in turn means vdevs will
always get opened concurrently which is good for normal usage.
This will only become an issue if your using a zvol as a vdev in
another pool. In which case you really should be using a newer
kernel anyway.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1205
--- /dev/null
+dnl #
+dnl # 2.6.27 API change
+dnl # lookup_bdev() was exported.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_LOOKUP_BDEV],
+ [AC_MSG_CHECKING([whether lookup_bdev() is available])
+ ZFS_LINUX_TRY_COMPILE_SYMBOL([
+ #include <linux/fs.h>
+ ], [
+ lookup_bdev(NULL);
+ ], [lookup_bdev], [fs/block_dev.c], [
+ AC_MSG_RESULT(yes)
+ AC_DEFINE(HAVE_LOOKUP_BDEV, 1, [lookup_bdev() is available])
+ ], [
+ AC_MSG_RESULT(no)
+ ])
+])
ZFS_AC_KERNEL_3ARG_BLKDEV_GET
ZFS_AC_KERNEL_BLKDEV_GET_BY_PATH
ZFS_AC_KERNEL_OPEN_BDEV_EXCLUSIVE
+ ZFS_AC_KERNEL_LOOKUP_BDEV
ZFS_AC_KERNEL_INVALIDATE_BDEV_ARGS
ZFS_AC_KERNEL_BDEV_LOGICAL_BLOCK_SIZE
ZFS_AC_KERNEL_BDEV_PHYSICAL_BLOCK_SIZE
#endif /* HAVE_1ARG_INVALIDATE_BDEV */
/*
+ * 2.6.27 API change
+ * The function was exported for use, prior to this it existed by the
+ * symbol was not exported.
+ */
+#ifndef HAVE_LOOKUP_BDEV
+# define lookup_bdev(path) ERR_PTR(-ENOTSUP)
+#endif
+
+/*
* 2.6.30 API change
* To ensure good performance preferentially use the physical block size
* for proper alignment. The physical size is supposed to be the internal