Linux 5.11 compat: bdev_whole()

The bd_contains member was removed from the block_device structure.
Callers needing to determine if a vdev is a whole block device should
use the new bdev_whole() wrapper.  For older kernels we provide our
own bdev_whole() wrapper which relies on bd_contains for compatibility.

Reviewed-by: Rafael Kitover <[email protected]>
Reviewed-by: Coleman Kane <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #11387
Closes #11390

2 files changed, 37 insertions, 4 deletions

diff --git a/config/kernel-blkdev.m4 b/config/kernel-blkdev.m4
index 622a1af5d..4b80d4dd2 100644
--- a/config/kernel-blkdev.m4
+++ b/config/kernel-blkdev.m4
@@ -271,6 +271,29 @@ AC_DEFUN([ZFS_AC_KERNEL_BLKDEV_BDEV_LOGICAL_BLOCK_SIZE], [
 	])
 ])
 
+dnl #
+dnl # 5.11 API change
+dnl # Added bdev_whole() helper.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BLKDEV_BDEV_WHOLE], [
+	ZFS_LINUX_TEST_SRC([bdev_whole], [
+		#include <linux/blkdev.h>
+	],[
+		struct block_device *bdev = NULL;
+		bdev = bdev_whole(bdev);
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BLKDEV_BDEV_WHOLE], [
+	AC_MSG_CHECKING([whether bdev_whole() is available])
+	ZFS_LINUX_TEST_RESULT([bdev_whole], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_BDEV_WHOLE, 1, [bdev_whole() is available])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
 AC_DEFUN([ZFS_AC_KERNEL_SRC_BLKDEV], [
 	ZFS_AC_KERNEL_SRC_BLKDEV_GET_BY_PATH
 	ZFS_AC_KERNEL_SRC_BLKDEV_PUT
@@ -281,6 +304,7 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_BLKDEV], [
 	ZFS_AC_KERNEL_SRC_BLKDEV_BDEV_PHYSICAL_BLOCK_SIZE
 	ZFS_AC_KERNEL_SRC_BLKDEV_CHECK_DISK_CHANGE
 	ZFS_AC_KERNEL_SRC_BLKDEV_BDEV_CHECK_MEDIA_CHANGE
+	ZFS_AC_KERNEL_SRC_BLKDEV_BDEV_WHOLE
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_BLKDEV], [
@@ -293,4 +317,5 @@ AC_DEFUN([ZFS_AC_KERNEL_BLKDEV], [
 	ZFS_AC_KERNEL_BLKDEV_BDEV_PHYSICAL_BLOCK_SIZE
 	ZFS_AC_KERNEL_BLKDEV_CHECK_DISK_CHANGE
 	ZFS_AC_KERNEL_BLKDEV_BDEV_CHECK_MEDIA_CHANGE
+	ZFS_AC_KERNEL_BLKDEV_BDEV_WHOLE
 ])
diff --git a/module/os/linux/zfs/vdev_disk.c b/module/os/linux/zfs/vdev_disk.c
index 12117655b..4bd27d1b5 100644
--- a/module/os/linux/zfs/vdev_disk.c
+++ b/module/os/linux/zfs/vdev_disk.c
@@ -94,6 +94,14 @@ bdev_capacity(struct block_device *bdev)
 	return (i_size_read(bdev->bd_inode));
 }
 
+#if !defined(HAVE_BDEV_WHOLE)
+static inline struct block_device *
+bdev_whole(struct block_device *bdev)
+{
+	return (bdev->bd_contains);
+}
+#endif
+
 /*
  * Returns the maximum expansion capacity of the block device (in bytes).
  *
@@ -118,7 +126,7 @@ bdev_max_capacity(struct block_device *bdev, uint64_t wholedisk)
 	uint64_t psize;
 	int64_t available;
 
-	if (wholedisk && bdev->bd_part != NULL && bdev != bdev->bd_contains) {
+	if (wholedisk && bdev != bdev_whole(bdev)) {
 		/*
 		 * When reporting maximum expansion capacity for a wholedisk
 		 * deduct any capacity which is expected to be lost due to
@@ -132,7 +140,7 @@ bdev_max_capacity(struct block_device *bdev, uint64_t wholedisk)
 		 * "reserved" EFI partition: in such cases return the device
 		 * usable capacity.
 		 */
-		available = i_size_read(bdev->bd_contains->bd_inode) -
+		available = i_size_read(bdev_whole(bdev)->bd_inode) -
 		    ((EFI_MIN_RESV_SIZE + NEW_START_BLOCK +
 		    PARTITION_END_ALIGNMENT) << SECTOR_BITS);
 		psize = MAX(available, bdev_capacity(bdev));
@@ -192,8 +200,8 @@ vdev_disk_open(vdev_t *v, uint64_t *psize, uint64_t *max_psize,
 		vd->vd_bdev = NULL;
 
 		if (bdev) {
-			if (v->vdev_expanding && bdev != bdev->bd_contains) {
-				bdevname(bdev->bd_contains, disk_name + 5);
+			if (v->vdev_expanding && bdev != bdev_whole(bdev)) {
+				bdevname(bdev_whole(bdev), disk_name + 5);
 				/*
 				 * If userland has BLKPG_RESIZE_PARTITION,
 				 * then it should have updated the partition