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, 218 insertions, 0 deletions

diff --git a/fs/init.c b/fs/init.c
new file mode 100644
index 000000000..33e312d74
--- /dev/null
+++ b/fs/init.c
@@ -0,0 +1,218 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Routines that mimic syscalls, but don't use the user address space or file
+ * descriptors.  Only for init/ and related early init code.
+ */
+#include <linux/init.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/fs.h>
+#include <linux/fs_struct.h>
+#include <linux/file.h>
+#include <linux/init_syscalls.h>
+#include <linux/security.h>
+#include "internal.h"
+
+int __init init_pivot_root(const char *new_root, const char *put_old)
+{
+	struct path new_path __free(path_put) = {};
+	struct path old_path __free(path_put) = {};
+	int ret;
+
+	ret = kern_path(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &new_path);
+	if (ret)
+		return ret;
+
+	ret = kern_path(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_path);
+	if (ret)
+		return ret;
+
+	return path_pivot_root(&new_path, &old_path);
+}
+
+int __init init_mount(const char *dev_name, const char *dir_name,
+		const char *type_page, unsigned long flags, void *data_page)
+{
+	struct path path;
+	int ret;
+
+	ret = kern_path(dir_name, LOOKUP_FOLLOW, &path);
+	if (ret)
+		return ret;
+	ret = path_mount(dev_name, &path, type_page, flags, data_page);
+	path_put(&path);
+	return ret;
+}
+
+int __init init_umount(const char *name, int flags)
+{
+	int lookup_flags = LOOKUP_MOUNTPOINT;
+	struct path path;
+	int ret;
+
+	if (!(flags & UMOUNT_NOFOLLOW))
+		lookup_flags |= LOOKUP_FOLLOW;
+	ret = kern_path(name, lookup_flags, &path);
+	if (ret)
+		return ret;
+	return path_umount(&path, flags);
+}
+
+int __init init_chdir(const char *filename)
+{
+	struct path path;
+	int error;
+
+	error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
+	if (error)
+		return error;
+	error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
+	if (!error)
+		set_fs_pwd(current->fs, &path);
+	path_put(&path);
+	return error;
+}
+
+int __init init_chroot(const char *filename)
+{
+	struct path path;
+	int error;
+
+	error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
+	if (error)
+		return error;
+	error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
+	if (error)
+		goto dput_and_out;
+	error = -EPERM;
+	if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
+		goto dput_and_out;
+	error = security_path_chroot(&path);
+	if (error)
+		goto dput_and_out;
+	set_fs_root(current->fs, &path);
+dput_and_out:
+	path_put(&path);
+	return error;
+}
+
+int __init init_chown(const char *filename, uid_t user, gid_t group, int flags)
+{
+	int lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
+	struct path path;
+	int error;
+
+	error = kern_path(filename, lookup_flags, &path);
+	if (error)
+		return error;
+	error = mnt_want_write(path.mnt);
+	if (!error) {
+		error = chown_common(&path, user, group);
+		mnt_drop_write(path.mnt);
+	}
+	path_put(&path);
+	return error;
+}
+
+int __init init_chmod(const char *filename, umode_t mode)
+{
+	struct path path;
+	int error;
+
+	error = kern_path(filename, LOOKUP_FOLLOW, &path);
+	if (error)
+		return error;
+	error = chmod_common(&path, mode);
+	path_put(&path);
+	return error;
+}
+
+int __init init_eaccess(const char *filename)
+{
+	struct path path;
+	int error;
+
+	error = kern_path(filename, LOOKUP_FOLLOW, &path);
+	if (error)
+		return error;
+	error = path_permission(&path, MAY_ACCESS);
+	path_put(&path);
+	return error;
+}
+
+int __init init_stat(const char *filename, struct kstat *stat, int flags)
+{
+	int lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
+	struct path path;
+	int error;
+
+	error = kern_path(filename, lookup_flags, &path);
+	if (error)
+		return error;
+	error = vfs_getattr(&path, stat, STATX_BASIC_STATS,
+			    flags | AT_NO_AUTOMOUNT);
+	path_put(&path);
+	return error;
+}
+
+int __init init_mknod(const char *filename, umode_t mode, unsigned int dev)
+{
+	CLASS(filename_kernel, name)(filename);
+	return filename_mknodat(AT_FDCWD, name, mode, dev);
+}
+
+int __init init_link(const char *oldname, const char *newname)
+{
+	CLASS(filename_kernel, old)(oldname);
+	CLASS(filename_kernel, new)(newname);
+	return filename_linkat(AT_FDCWD, old, AT_FDCWD, new, 0);
+}
+
+int __init init_symlink(const char *oldname, const char *newname)
+{
+	CLASS(filename_kernel, old)(oldname);
+	CLASS(filename_kernel, new)(newname);
+	return filename_symlinkat(old, AT_FDCWD, new);
+}
+
+int __init init_unlink(const char *pathname)
+{
+	CLASS(filename_kernel, name)(pathname);
+	return filename_unlinkat(AT_FDCWD, name);
+}
+
+int __init init_mkdir(const char *pathname, umode_t mode)
+{
+	CLASS(filename_kernel, name)(pathname);
+	return filename_mkdirat(AT_FDCWD, name, mode);
+}
+
+int __init init_rmdir(const char *pathname)
+{
+	CLASS(filename_kernel, name)(pathname);
+	return filename_rmdir(AT_FDCWD, name);
+}
+
+int __init init_utimes(char *filename, struct timespec64 *ts)
+{
+	struct path path;
+	int error;
+
+	error = kern_path(filename, 0, &path);
+	if (error)
+		return error;
+	error = vfs_utimes(&path, ts);
+	path_put(&path);
+	return error;
+}
+
+int __init init_dup(struct file *file)
+{
+	int fd;
+
+	fd = get_unused_fd_flags(0);
+	if (fd < 0)
+		return fd;
+	fd_install(fd, get_file(file));
+	return 0;
+}