virtio_blk: set the zone write granularitygrafted

virtblk_read_zoned_limits() reads the write granularity that the device
reports in virtio_blk_zoned_characteristics and assigns it to the
physical block size and to io_min, but never to the limit that is named
after it. queue_limits.zone_write_granularity is left at zero, so
blk_validate_zoned_limits() raises it to the logical block size:

	if (lim->zone_write_granularity < lim->logical_block_size)
		lim->zone_write_granularity = lim->logical_block_size;

A device that reports a granularity coarser than its logical block size,
which is what the field exists to express, therefore has it silently
reduced. A 512e host managed disk passed through to a guest reports a
logical block size of 512 and a write granularity of 4096, and the guest
ends up with a zone write granularity of 512.

bio_split_alignment() returns lim->zone_write_granularity if it is non-zero
and bio_split_io_at() may split a bio with as per bio_split_alignment().
This can real to the write getting rejected by the host drive, as the write
is not aligned to the physical block size.

zonefs also takes its block size from bdev_zone_write_granularity(), so it
would incorrectly use 512 on a disk that requires 4096.

sd_zbc_read_zones() sets the limit from the physical block size for the
same reason. NVMe ZNS and null_blk leave it unset, but the fallback
gives the right answer for them, as their write granularity is the
logical block size. virtio carries a separate value that may exceed it.

Set the zone write granularity from the value that the device reports.

Fixes: 95bfec41bd3d ("virtio-blk: add support for zoned block devices")
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Link: https://patch.msgid.link/20260918140641.2031075-2-cassel@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 161 insertions, 0 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
new file mode 100644
index 000000000..ffdcd4153
--- /dev/null
+++ b/fs/sysfs/dir.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * fs/sysfs/dir.c - sysfs core and dir operation implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
+ *
+ * Please see Documentation/filesystems/sysfs.rst for more information.
+ */
+
+#define pr_fmt(fmt)	"sysfs: " fmt
+
+#include <linux/fs.h>
+#include <linux/kobject.h>
+#include <linux/slab.h>
+#include "sysfs.h"
+
+DEFINE_SPINLOCK(sysfs_symlink_target_lock);
+
+void sysfs_warn_dup(struct kernfs_node *parent, const char *name)
+{
+	char *buf;
+
+	buf = kzalloc(PATH_MAX, GFP_KERNEL);
+	if (buf)
+		kernfs_path(parent, buf, PATH_MAX);
+
+	pr_warn("cannot create duplicate filename '%s/%s'\n", buf, name);
+	dump_stack();
+
+	kfree(buf);
+}
+
+/**
+ * sysfs_create_dir_ns - create a directory for an object with a namespace tag
+ * @kobj: object we're creating directory for
+ * @ns: the namespace tag to use
+ */
+int sysfs_create_dir_ns(struct kobject *kobj, const struct ns_common *ns)
+{
+	struct kernfs_node *parent, *kn;
+	kuid_t uid;
+	kgid_t gid;
+
+	if (WARN_ON(!kobj))
+		return -EINVAL;
+
+	if (kobj->parent)
+		parent = kobj->parent->sd;
+	else
+		parent = sysfs_root_kn;
+
+	if (!parent)
+		return -ENOENT;
+
+	kobject_get_ownership(kobj, &uid, &gid);
+
+	kn = kernfs_create_dir_ns(parent, kobject_name(kobj), 0755, uid, gid,
+				  kobj, ns);
+	if (IS_ERR(kn)) {
+		if (PTR_ERR(kn) == -EEXIST)
+			sysfs_warn_dup(parent, kobject_name(kobj));
+		return PTR_ERR(kn);
+	}
+
+	kobj->sd = kn;
+	return 0;
+}
+
+/**
+ *	sysfs_remove_dir - remove an object's directory.
+ *	@kobj:	object.
+ *
+ *	The only thing special about this is that we remove any files in
+ *	the directory before we remove the directory, and we've inlined
+ *	what used to be sysfs_rmdir() below, instead of calling separately.
+ */
+void sysfs_remove_dir(struct kobject *kobj)
+{
+	struct kernfs_node *kn = kobj->sd;
+
+	/*
+	 * In general, kobject owner is responsible for ensuring removal
+	 * doesn't race with other operations and sysfs doesn't provide any
+	 * protection; however, when @kobj is used as a symlink target, the
+	 * symlinking entity usually doesn't own @kobj and thus has no
+	 * control over removal.  @kobj->sd may be removed anytime
+	 * and symlink code may end up dereferencing an already freed node.
+	 *
+	 * sysfs_symlink_target_lock synchronizes @kobj->sd
+	 * disassociation against symlink operations so that symlink code
+	 * can safely dereference @kobj->sd.
+	 */
+	spin_lock(&sysfs_symlink_target_lock);
+	kobj->sd = NULL;
+	spin_unlock(&sysfs_symlink_target_lock);
+
+	if (kn) {
+		WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
+		kernfs_remove(kn);
+	}
+}
+
+int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
+			const struct ns_common *new_ns)
+{
+	struct kernfs_node *parent;
+	int ret;
+
+	parent = kernfs_get_parent(kobj->sd);
+	ret = kernfs_rename_ns(kobj->sd, parent, new_name, new_ns);
+	kernfs_put(parent);
+	return ret;
+}
+
+int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
+		      const struct ns_common *new_ns)
+{
+	struct kernfs_node *kn = kobj->sd;
+	struct kernfs_node *new_parent;
+
+	new_parent = new_parent_kobj && new_parent_kobj->sd ?
+		new_parent_kobj->sd : sysfs_root_kn;
+
+	return kernfs_rename_ns(kn, new_parent, NULL, new_ns);
+}
+
+/**
+ * sysfs_create_mount_point - create an always empty directory
+ * @parent_kobj:  kobject that will contain this always empty directory
+ * @name: The name of the always empty directory to add
+ */
+int sysfs_create_mount_point(struct kobject *parent_kobj, const char *name)
+{
+	struct kernfs_node *kn, *parent = parent_kobj->sd;
+
+	kn = kernfs_create_empty_dir(parent, name);
+	if (IS_ERR(kn)) {
+		if (PTR_ERR(kn) == -EEXIST)
+			sysfs_warn_dup(parent, name);
+		return PTR_ERR(kn);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(sysfs_create_mount_point);
+
+/**
+ *	sysfs_remove_mount_point - remove an always empty directory.
+ *	@parent_kobj: kobject that will contain this always empty directory
+ *	@name: The name of the always empty directory to remove
+ *
+ */
+void sysfs_remove_mount_point(struct kobject *parent_kobj, const char *name)
+{
+	struct kernfs_node *parent = parent_kobj->sd;
+
+	kernfs_remove_by_name_ns(parent, name, NULL);
+}
+EXPORT_SYMBOL_GPL(sysfs_remove_mount_point);