Fix lookup_bdev() on Ubuntu

Ubuntu added support for checking inode permissions to lookup_bdev() in kernel
commit 193fb6a2c94fab8eb8ce70a5da4d21c7d4023bee (merged in 4.4.0-6.21).
Upstream bug: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1636517

This patch adds a test for Ubuntu's variant of lookup_bdev() to configure and
calls the function in the correct way.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Hajo Möller <dasjoe@gmail.com>
Closes #5336

diff --git a/config/kernel-lookup-bdev.m4 b/config/kernel-lookup-bdev.m4
index 245f95f041f805411d461d770e4c6eae0d2d0d1e..abbf55d9bb391a6f57490ae6ec7df3c132cf54a3 100644 (file)
--- a/config/kernel-lookup-bdev.m4
+++ b/config/kernel-lookup-bdev.m4
@@ -1,17 +1,29 @@
 dnl #
-dnl # 2.6.27 API change
-dnl # lookup_bdev() was exported.
+dnl # 2.6.27, lookup_bdev() was exported.
+dnl # 4.4.0-6.21 - x.y on Ubuntu, lookup_bdev() takes 2 arguments.
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_LOOKUP_BDEV],
-       [AC_MSG_CHECKING([whether lookup_bdev() is available])
+       [AC_MSG_CHECKING([whether lookup_bdev() wants 1 arg])
        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_DEFINE(HAVE_1ARG_LOOKUP_BDEV, 1, [lookup_bdev() wants 1 arg])
        ], [
                AC_MSG_RESULT(no)
+               AC_MSG_CHECKING([whether lookup_bdev() wants 2 args])
+               ZFS_LINUX_TRY_COMPILE_SYMBOL([
+                       #include <linux/fs.h>
+               ], [
+                       lookup_bdev(NULL, FMODE_READ);
+               ], [lookup_bdev], [fs/block_dev.c], [
+                       AC_MSG_RESULT(yes)
+                       AC_DEFINE(HAVE_2ARGS_LOOKUP_BDEV, 1,
+                           [lookup_bdev() wants 2 args])
+               ], [
+                       AC_MSG_RESULT(no)
+               ])
        ])
-])
+])
\ No newline at end of file

diff --git a/include/linux/blkdev_compat.h b/include/linux/blkdev_compat.h
index bff93ff542331a3777827dd4681d6b4abe0456ae..1f90b98254798921763c86f7690618cddd9b36b3 100644 (file)
--- a/include/linux/blkdev_compat.h
+++ b/include/linux/blkdev_compat.h
@@ -263,12 +263,21 @@ bio_set_flags_failfast(struct block_device *bdev, int *flags)
 
 /*
  * 2.6.27 API change
- * The function was exported for use, prior to this it existed by the
+ * The function was exported for use, prior to this it existed but the
  * symbol was not exported.
+ *
+ * 4.4.0-6.21 API change for Ubuntu
+ * lookup_bdev() gained a second argument, FMODE_*, to check inode permissions.
  */
-#ifndef HAVE_LOOKUP_BDEV
-#define        lookup_bdev(path)               ERR_PTR(-ENOTSUP)
-#endif
+#ifdef HAVE_1ARG_LOOKUP_BDEV
+#define        vdev_lookup_bdev(path)  lookup_bdev(path)
+#else
+#ifdef HAVE_2ARGS_LOOKUP_BDEV
+#define        vdev_lookup_bdev(path)  lookup_bdev(path, 0)
+#else
+#define        vdev_lookup_bdev(path)  ERR_PTR(-ENOTSUP)
+#endif /* HAVE_2ARGS_LOOKUP_BDEV */
+#endif /* HAVE_1ARG_LOOKUP_BDEV */
 
 /*
  * 2.6.30 API change

diff --git a/module/zfs/zvol.c b/module/zfs/zvol.c
index bf6d59fba5dd954bbdcbee68156ef44f1c11414c..72a6bc5e24bb64ede1cfc1d2e2b471628d7c4d83 100644 (file)
--- a/module/zfs/zvol.c
+++ b/module/zfs/zvol.c
@@ -174,7 +174,7 @@ zvol_is_zvol(const char *device)
        struct block_device *bdev;
        unsigned int major;
 
-       bdev = lookup_bdev(device);
+       bdev = vdev_lookup_bdev(device);
        if (IS_ERR(bdev))
                return (B_FALSE);