Linux 6.5 compat: blkdev changes

Multiple changes to the blkdev API were introduced in Linux 6.5. This
includes passing (void* holder) to blkdev_put, adding a new
blk_holder_ops* arg to blkdev_get_by_path, adding a new blk_mode_t type
that replaces uses of fmode_t, and removing an argument from the release
handler on block_device_operations that we weren't using. The open
function definition has also changed to take gendisk* and blk_mode_t, so
update it accordingly, too.

Implement local wrappers for blkdev_get_by_path() and
vdev_blkdev_put() so that the in-line calls are cleaner, and place the
conditionally-compiled implementation details inside of both of these
local wrappers. Both calls are exclusively used within vdev_disk.c, at
this time.

Add blk_mode_is_open_write() to test FMODE_WRITE / BLK_OPEN_WRITE
The wrapper function is now used for testing using the appropriate
method for the kernel, whether the open mode is writable or not.

Emphasize fmode_t arg in zvol_release is not used

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Coleman Kane <ckane@colemankane.org>
Closes #15099

config/kernel-blkdev.m4

@@ -16,12 +16,63 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_BLKDEV_GET_BY_PATH], [
 	])
 ])
 
+dnl #
+dnl # 6.5.x API change,
+dnl # blkdev_get_by_path() takes 4 args
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BLKDEV_GET_BY_PATH_4ARG], [
+	ZFS_LINUX_TEST_SRC([blkdev_get_by_path_4arg], [
+		#include <linux/fs.h>
+		#include <linux/blkdev.h>
+	], [
+		struct block_device *bdev __attribute__ ((unused)) = NULL;
+		const char *path = "path";
+		fmode_t mode = 0;
+		void *holder = NULL;
+		struct blk_holder_ops h;
+
+		bdev = blkdev_get_by_path(path, mode, holder, &h);
+	])
+])
+
 AC_DEFUN([ZFS_AC_KERNEL_BLKDEV_GET_BY_PATH], [
-	AC_MSG_CHECKING([whether blkdev_get_by_path() exists])
+	AC_MSG_CHECKING([whether blkdev_get_by_path() exists and takes 3 args])
 	ZFS_LINUX_TEST_RESULT([blkdev_get_by_path], [
 		AC_MSG_RESULT(yes)
 	], [
-		ZFS_LINUX_TEST_ERROR([blkdev_get_by_path()])
+		AC_MSG_RESULT(no)
+		AC_MSG_CHECKING([whether blkdev_get_by_path() exists and takes 4 args])
+		ZFS_LINUX_TEST_RESULT([blkdev_get_by_path_4arg], [
+			AC_DEFINE(HAVE_BLKDEV_GET_BY_PATH_4ARG, 1,
+				[blkdev_get_by_path() exists and takes 4 args])
+			AC_MSG_RESULT(yes)
+		], [
+			ZFS_LINUX_TEST_ERROR([blkdev_get_by_path()])
+		])
+	])
+])
+
+dnl #
+dnl # 6.5.x API change
+dnl # blk_mode_t was added as a type to supercede some places where fmode_t
+dnl # is used
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BLKDEV_BLK_MODE_T], [
+	ZFS_LINUX_TEST_SRC([blk_mode_t], [
+		#include <linux/fs.h>
+		#include <linux/blkdev.h>
+	], [
+		blk_mode_t m __attribute((unused)) = (blk_mode_t)0;
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BLKDEV_BLK_MODE_T], [
+	AC_MSG_CHECKING([whether blk_mode_t is defined])
+	ZFS_LINUX_TEST_RESULT([blk_mode_t], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_BLK_MODE_T, 1, [blk_mode_t is defined])
+	], [
+		AC_MSG_RESULT(no)
 	])
 ])
 
@@ -41,12 +92,35 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_BLKDEV_PUT], [
 	])
 ])
 
+dnl #
+dnl # 6.5.x API change.
+dnl # blkdev_put() takes (void* holder) as arg 2
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BLKDEV_PUT_HOLDER], [
+	ZFS_LINUX_TEST_SRC([blkdev_put_holder], [
+		#include <linux/fs.h>
+		#include <linux/blkdev.h>
+	], [
+		struct block_device *bdev = NULL;
+		void *holder = NULL;
+
+		blkdev_put(bdev, holder);
+	])
+])
+
 AC_DEFUN([ZFS_AC_KERNEL_BLKDEV_PUT], [
 	AC_MSG_CHECKING([whether blkdev_put() exists])
 	ZFS_LINUX_TEST_RESULT([blkdev_put], [
 		AC_MSG_RESULT(yes)
 	], [
-		ZFS_LINUX_TEST_ERROR([blkdev_put()])
+		AC_MSG_CHECKING([whether blkdev_put() accepts void* as arg 2])
+		ZFS_LINUX_TEST_RESULT([blkdev_put_holder], [
+			AC_MSG_RESULT(yes)
+			AC_DEFINE(HAVE_BLKDEV_PUT_HOLDER, 1,
+				[blkdev_put() accepts void* as arg 2])
+		], [
+			ZFS_LINUX_TEST_ERROR([blkdev_put()])
+		])
 	])
 ])
 
@@ -495,7 +569,9 @@ AC_DEFUN([ZFS_AC_KERNEL_BLKDEV_BLK_STS_RESV_CONFLICT], [
 
 AC_DEFUN([ZFS_AC_KERNEL_SRC_BLKDEV], [
 	ZFS_AC_KERNEL_SRC_BLKDEV_GET_BY_PATH
+	ZFS_AC_KERNEL_SRC_BLKDEV_GET_BY_PATH_4ARG
 	ZFS_AC_KERNEL_SRC_BLKDEV_PUT
+	ZFS_AC_KERNEL_SRC_BLKDEV_PUT_HOLDER
 	ZFS_AC_KERNEL_SRC_BLKDEV_REREAD_PART
 	ZFS_AC_KERNEL_SRC_BLKDEV_INVALIDATE_BDEV
 	ZFS_AC_KERNEL_SRC_BLKDEV_LOOKUP_BDEV
@@ -510,6 +586,7 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_BLKDEV], [
 	ZFS_AC_KERNEL_SRC_BLKDEV_PART_TO_DEV
 	ZFS_AC_KERNEL_SRC_BLKDEV_DISK_CHECK_MEDIA_CHANGE
 	ZFS_AC_KERNEL_SRC_BLKDEV_BLK_STS_RESV_CONFLICT
+	ZFS_AC_KERNEL_SRC_BLKDEV_BLK_MODE_T
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_BLKDEV], [
@@ -530,4 +607,5 @@ AC_DEFUN([ZFS_AC_KERNEL_BLKDEV], [
 	ZFS_AC_KERNEL_BLKDEV_PART_TO_DEV
 	ZFS_AC_KERNEL_BLKDEV_DISK_CHECK_MEDIA_CHANGE
 	ZFS_AC_KERNEL_BLKDEV_BLK_STS_RESV_CONFLICT
+	ZFS_AC_KERNEL_BLKDEV_BLK_MODE_T
 ])

config/kernel-block-device-operations.m4

@@ -49,12 +49,42 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_BLOCK_DEVICE_OPERATIONS_RELEASE_VOID], [
 	], [], [])
 ])
 
+dnl #
+dnl # 5.9.x API change
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BLOCK_DEVICE_OPERATIONS_RELEASE_1ARG], [
+	ZFS_LINUX_TEST_SRC([block_device_operations_release_void_1arg], [
+		#include <linux/blkdev.h>
+
+		void blk_release(struct gendisk *g) {
+			(void) g;
+			return;
+		}
+
+		static const struct block_device_operations
+		    bops __attribute__ ((unused)) = {
+			.open		= NULL,
+			.release	= blk_release,
+			.ioctl		= NULL,
+			.compat_ioctl	= NULL,
+		};
+	], [], [])
+])
+
 AC_DEFUN([ZFS_AC_KERNEL_BLOCK_DEVICE_OPERATIONS_RELEASE_VOID], [
-	AC_MSG_CHECKING([whether bops->release() is void])
+	AC_MSG_CHECKING([whether bops->release() is void and takes 2 args])
 	ZFS_LINUX_TEST_RESULT([block_device_operations_release_void], [
 		AC_MSG_RESULT(yes)
 	],[
-		ZFS_LINUX_TEST_ERROR([bops->release()])
+		AC_MSG_RESULT(no)
+		AC_MSG_CHECKING([whether bops->release() is void and takes 1 arg])
+		ZFS_LINUX_TEST_RESULT([block_device_operations_release_void_1arg], [
+			AC_MSG_RESULT(yes)
+			AC_DEFINE([HAVE_BLOCK_DEVICE_OPERATIONS_RELEASE_1ARG], [1],
+				[Define if release() in block_device_operations takes 1 arg])
+		],[
+			ZFS_LINUX_TEST_ERROR([bops->release()])
+		])
 	])
 ])
 
@@ -92,6 +122,7 @@ AC_DEFUN([ZFS_AC_KERNEL_BLOCK_DEVICE_OPERATIONS_REVALIDATE_DISK], [
 AC_DEFUN([ZFS_AC_KERNEL_SRC_BLOCK_DEVICE_OPERATIONS], [
 	ZFS_AC_KERNEL_SRC_BLOCK_DEVICE_OPERATIONS_CHECK_EVENTS
 	ZFS_AC_KERNEL_SRC_BLOCK_DEVICE_OPERATIONS_RELEASE_VOID
+	ZFS_AC_KERNEL_SRC_BLOCK_DEVICE_OPERATIONS_RELEASE_1ARG
 	ZFS_AC_KERNEL_SRC_BLOCK_DEVICE_OPERATIONS_REVALIDATE_DISK
 ])
 

include/os/linux/kernel/linux/blkdev_compat.h

@@ -398,6 +398,12 @@ vdev_lookup_bdev(const char *path, dev_t *dev)
 #endif
 }
 
+#if defined(HAVE_BLK_MODE_T)
+#define	blk_mode_is_open_write(flag)	((flag) & BLK_OPEN_WRITE)
+#else
+#define	blk_mode_is_open_write(flag)	((flag) & FMODE_WRITE)
+#endif
+
 /*
  * Kernels without bio_set_op_attrs use bi_rw for the bio flags.
  */

module/os/linux/zfs/vdev_disk.c

@@ -80,9 +80,22 @@ typedef struct dio_request {
 
 static unsigned int zfs_vdev_failfast_mask = 1;
 
+#ifdef HAVE_BLK_MODE_T
+static blk_mode_t
+#else
 static fmode_t
+#endif
 vdev_bdev_mode(spa_mode_t spa_mode)
 {
+#ifdef HAVE_BLK_MODE_T
+	blk_mode_t mode = 0;
+
+	if (spa_mode & SPA_MODE_READ)
+		mode |= BLK_OPEN_READ;
+
+	if (spa_mode & SPA_MODE_WRITE)
+		mode |= BLK_OPEN_WRITE;
+#else
 	fmode_t mode = 0;
 
 	if (spa_mode & SPA_MODE_READ)
@@ -90,6 +103,7 @@ vdev_bdev_mode(spa_mode_t spa_mode)
 
 	if (spa_mode & SPA_MODE_WRITE)
 		mode |= FMODE_WRITE;
+#endif
 
 	return (mode);
 }
@@ -197,12 +211,47 @@ vdev_disk_kobj_evt_post(vdev_t *v)
 	}
 }
 
+#if !defined(HAVE_BLKDEV_GET_BY_PATH_4ARG)
+/*
+ * Define a dummy struct blk_holder_ops for kernel versions
+ * prior to 6.5.
+ */
+struct blk_holder_ops {};
+#endif
+
+static struct block_device *
+vdev_blkdev_get_by_path(const char *path, spa_mode_t mode, void *holder,
+    const struct blk_holder_ops *hops)
+{
+#ifdef HAVE_BLKDEV_GET_BY_PATH_4ARG
+	return (blkdev_get_by_path(path,
+	    vdev_bdev_mode(mode) | BLK_OPEN_EXCL, holder, hops));
+#else
+	return (blkdev_get_by_path(path,
+	    vdev_bdev_mode(mode) | FMODE_EXCL, holder));
+#endif
+}
+
+static void
+vdev_blkdev_put(struct block_device *bdev, spa_mode_t mode, void *holder)
+{
+#ifdef HAVE_BLKDEV_PUT_HOLDER
+	return (blkdev_put(bdev, holder));
+#else
+	return (blkdev_put(bdev, vdev_bdev_mode(mode) | FMODE_EXCL));
+#endif
+}
+
 static int
 vdev_disk_open(vdev_t *v, uint64_t *psize, uint64_t *max_psize,
     uint64_t *logical_ashift, uint64_t *physical_ashift)
 {
 	struct block_device *bdev;
+#ifdef HAVE_BLK_MODE_T
+	blk_mode_t mode = vdev_bdev_mode(spa_mode(v->vdev_spa));
+#else
 	fmode_t mode = vdev_bdev_mode(spa_mode(v->vdev_spa));
+#endif
 	hrtime_t timeout = MSEC2NSEC(zfs_vdev_open_timeout_ms);
 	vdev_disk_t *vd;
 
@@ -252,15 +301,15 @@ vdev_disk_open(vdev_t *v, uint64_t *psize, uint64_t *max_psize,
 					reread_part = B_TRUE;
 			}
 
-			blkdev_put(bdev, mode | FMODE_EXCL);
+			vdev_blkdev_put(bdev, mode, zfs_vdev_holder);
 		}
 
 		if (reread_part) {
-			bdev = blkdev_get_by_path(disk_name, mode | FMODE_EXCL,
+			bdev = vdev_blkdev_get_by_path(disk_name, mode,
-			    zfs_vdev_holder);
+			    zfs_vdev_holder, NULL);
 			if (!IS_ERR(bdev)) {
 				int error = vdev_bdev_reread_part(bdev);
-				blkdev_put(bdev, mode | FMODE_EXCL);
+				vdev_blkdev_put(bdev, mode, zfs_vdev_holder);
 				if (error == 0) {
 					timeout = MSEC2NSEC(
 					    zfs_vdev_open_timeout_ms * 2);
@@ -305,8 +354,8 @@ vdev_disk_open(vdev_t *v, uint64_t *psize, uint64_t *max_psize,
 	hrtime_t start = gethrtime();
 	bdev = ERR_PTR(-ENXIO);
 	while (IS_ERR(bdev) && ((gethrtime() - start) < timeout)) {
-		bdev = blkdev_get_by_path(v->vdev_path, mode | FMODE_EXCL,
+		bdev = vdev_blkdev_get_by_path(v->vdev_path, mode,
-		    zfs_vdev_holder);
+		    zfs_vdev_holder, NULL);
 		if (unlikely(PTR_ERR(bdev) == -ENOENT)) {
 			/*
 			 * There is no point of waiting since device is removed
@@ -382,8 +431,8 @@ vdev_disk_close(vdev_t *v)
 		return;
 
 	if (vd->vd_bdev != NULL) {
-		blkdev_put(vd->vd_bdev,
+		vdev_blkdev_put(vd->vd_bdev, spa_mode(v->vdev_spa),
-		    vdev_bdev_mode(spa_mode(v->vdev_spa)) | FMODE_EXCL);
+		    zfs_vdev_holder);
 	}
 
 	rw_destroy(&vd->vd_lock);

module/os/linux/zfs/zfs_vnops_os.c

@@ -186,7 +186,7 @@ zfs_open(struct inode *ip, int mode, int flag, cred_t *cr)
 		return (error);
 
 	/* Honor ZFS_APPENDONLY file attribute */
-	if ((mode & FMODE_WRITE) && (zp->z_pflags & ZFS_APPENDONLY) &&
+	if (blk_mode_is_open_write(mode) && (zp->z_pflags & ZFS_APPENDONLY) &&
 	    ((flag & O_APPEND) == 0)) {
 		zfs_exit(zfsvfs, FTAG);
 		return (SET_ERROR(EPERM));

module/os/linux/zfs/zpl_ctldir.c

@@ -42,7 +42,7 @@
 static int
 zpl_common_open(struct inode *ip, struct file *filp)
 {
-	if (filp->f_mode & FMODE_WRITE)
+	if (blk_mode_is_open_write(filp->f_mode))
 		return (-EACCES);
 
 	return (generic_file_open(ip, filp));

module/os/linux/zfs/zvol_os.c

@@ -671,7 +671,11 @@ zvol_request(struct request_queue *q, struct bio *bio)
 }
 
 static int
+#ifdef HAVE_BLK_MODE_T
+zvol_open(struct gendisk *disk, blk_mode_t flag)
+#else
 zvol_open(struct block_device *bdev, fmode_t flag)
+#endif
 {
 	zvol_state_t *zv;
 	int error = 0;
@@ -686,10 +690,14 @@ retry:
 	/*
 	 * Obtain a copy of private_data under the zvol_state_lock to make
 	 * sure that either the result of zvol free code path setting
-	 * bdev->bd_disk->private_data to NULL is observed, or zvol_os_free()
+	 * disk->private_data to NULL is observed, or zvol_os_free()
 	 * is not called on this zv because of the positive zv_open_count.
 	 */
+#ifdef HAVE_BLK_MODE_T
+	zv = disk->private_data;
+#else
 	zv = bdev->bd_disk->private_data;
+#endif
 	if (zv == NULL) {
 		rw_exit(&zvol_state_lock);
 		return (SET_ERROR(-ENXIO));
@@ -769,14 +777,15 @@ retry:
 			}
 		}
 
-		error = -zvol_first_open(zv, !(flag & FMODE_WRITE));
+		error = -zvol_first_open(zv, !(blk_mode_is_open_write(flag)));
 
 		if (drop_namespace)
 			mutex_exit(&spa_namespace_lock);
 	}
 
 	if (error == 0) {
-		if ((flag & FMODE_WRITE) && (zv->zv_flags & ZVOL_RDONLY)) {
+		if ((blk_mode_is_open_write(flag)) &&
+		    (zv->zv_flags & ZVOL_RDONLY)) {
 			if (zv->zv_open_count == 0)
 				zvol_last_close(zv);
 
@@ -791,14 +800,25 @@ retry:
 		rw_exit(&zv->zv_suspend_lock);
 
 	if (error == 0)
+#ifdef HAVE_BLK_MODE_T
+		disk_check_media_change(disk);
+#else
 		zfs_check_media_change(bdev);
+#endif
 
 	return (error);
 }
 
 static void
-zvol_release(struct gendisk *disk, fmode_t mode)
+#ifdef HAVE_BLOCK_DEVICE_OPERATIONS_RELEASE_1ARG
+zvol_release(struct gendisk *disk)
+#else
+zvol_release(struct gendisk *disk, fmode_t unused)
+#endif
 {
+#if !defined(HAVE_BLOCK_DEVICE_OPERATIONS_RELEASE_1ARG)
+	(void) unused;
+#endif
 	zvol_state_t *zv;
 	boolean_t drop_suspend = B_TRUE;