KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 68 insertions, 0 deletions

diff --git a/Documentation/admin-guide/ufs.rst b/Documentation/admin-guide/ufs.rst
new file mode 100644
index 000000000..55d15297f
--- /dev/null
+++ b/Documentation/admin-guide/ufs.rst
@@ -0,0 +1,68 @@
+=========
+Using UFS
+=========
+
+mount -t ufs -o ufstype=type_of_ufs device dir
+
+
+UFS Options
+===========
+
+ufstype=type_of_ufs
+	UFS is a file system widely used in different operating systems.
+	The problem are differences among implementations. Features of
+	some implementations are undocumented, so its hard to recognize
+	type of ufs automatically. That's why user must specify type of
+	ufs manually by mount option ufstype. Possible values are:
+
+	old
+                old format of ufs
+		default value, supported as read-only
+
+	44bsd
+                used in FreeBSD, NetBSD, OpenBSD
+		supported as read-write
+
+	ufs2
+                used in FreeBSD 5.x
+		supported as read-write
+
+	5xbsd
+                synonym for ufs2
+
+	sun
+                used in SunOS (Solaris)
+		supported as read-write
+
+	sunx86
+                used in SunOS for Intel (Solarisx86)
+		supported as read-write
+
+	hp
+                used in HP-UX
+		supported as read-only
+
+	nextstep
+		used in NextStep
+		supported as read-only
+
+	nextstep-cd
+		used for NextStep CDROMs (block_size == 2048)
+		supported as read-only
+
+	openstep
+		used in OpenStep
+		supported as read-only
+
+
+Possible Problems
+-----------------
+
+See next section, if you have any.
+
+
+Bug Reports
+-----------
+
+Any ufs bug report you can send to daniel.pirkl@email.cz or
+to dushistov@mail.ru (do not send partition tables bug reports).