um/hostfs: define HOSTFS_ATTR_* via asm-offsets

The HOSTFS_ATTR_* values were meant to be standalone for
communication between hostfs's kernel and user code parts.
However, it's easy to forget that HOSTFS_ATTR_* should be
used even on the kernel side, and that wasn't consistently
done. As a result, the values need to match ATTR_* values,
which is not useful to maintain by hand. Instead, generate
them via asm-offsets like other constants that UML needs
in user-side code that aren't otherwise available in any
header files that can be included there.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Hongbo Li <lihongbo22@huawei.com>
Link: https://patch.msgid.link/20251007071452.367989-3-johannes@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 12 insertions, 33 deletions

diff --git a/arch/um/include/shared/common-offsets.h b/arch/um/include/shared/common-offsets.h
index 8ca66a1918c3..fcec75a93e0c 100644
--- a/arch/um/include/shared/common-offsets.h
+++ b/arch/um/include/shared/common-offsets.h
@@ -18,3 +18,13 @@ DEFINE(UM_NSEC_PER_USEC, NSEC_PER_USEC);
 DEFINE(UM_KERN_GDT_ENTRY_TLS_ENTRIES, GDT_ENTRY_TLS_ENTRIES);
 
 DEFINE(UM_SECCOMP_ARCH_NATIVE, SECCOMP_ARCH_NATIVE);
+
+DEFINE(HOSTFS_ATTR_MODE, ATTR_MODE);
+DEFINE(HOSTFS_ATTR_UID, ATTR_UID);
+DEFINE(HOSTFS_ATTR_GID, ATTR_GID);
+DEFINE(HOSTFS_ATTR_SIZE, ATTR_SIZE);
+DEFINE(HOSTFS_ATTR_ATIME, ATTR_ATIME);
+DEFINE(HOSTFS_ATTR_MTIME, ATTR_MTIME);
+DEFINE(HOSTFS_ATTR_CTIME, ATTR_CTIME);
+DEFINE(HOSTFS_ATTR_ATIME_SET, ATTR_ATIME_SET);
+DEFINE(HOSTFS_ATTR_MTIME_SET, ATTR_MTIME_SET);
diff --git a/arch/x86/um/shared/sysdep/kernel-offsets.h b/arch/x86/um/shared/sysdep/kernel-offsets.h
index 6fd1ed400399..ee6b44ef2217 100644
--- a/arch/x86/um/shared/sysdep/kernel-offsets.h
+++ b/arch/x86/um/shared/sysdep/kernel-offsets.h
@@ -5,6 +5,7 @@
 #include <linux/crypto.h>
 #include <linux/kbuild.h>
 #include <linux/audit.h>
+#include <linux/fs.h>
 #include <asm/mman.h>
 #include <asm/seccomp.h>
 
diff --git a/fs/hostfs/hostfs.h b/fs/hostfs/hostfs.h
index 15b2f094d36e..aa02599b770f 100644
--- a/fs/hostfs/hostfs.h
+++ b/fs/hostfs/hostfs.h
@@ -3,40 +3,8 @@
 #define __UM_FS_HOSTFS
 
 #include <os.h>
+#include <generated/asm-offsets.h>
 
-/*
- * These are exactly the same definitions as in fs.h, but the names are
- * changed so that this file can be included in both kernel and user files.
- */
-
-#define HOSTFS_ATTR_MODE	1
-#define HOSTFS_ATTR_UID 	2
-#define HOSTFS_ATTR_GID 	4
-#define HOSTFS_ATTR_SIZE	8
-#define HOSTFS_ATTR_ATIME	16
-#define HOSTFS_ATTR_MTIME	32
-#define HOSTFS_ATTR_CTIME	64
-#define HOSTFS_ATTR_ATIME_SET	128
-#define HOSTFS_ATTR_MTIME_SET	256
-
-/* This one is unused by hostfs. */
-#define HOSTFS_ATTR_FORCE	512	/* Not a change, but a change it */
-#define HOSTFS_ATTR_ATTR_FLAG	1024
-
-/*
- * If you are very careful, you'll notice that these two are missing:
- *
- * #define ATTR_KILL_SUID	2048
- * #define ATTR_KILL_SGID	4096
- *
- * and this is because they were added in 2.5 development.
- * Actually, they are not needed by most ->setattr() methods - they are set by
- * callers of notify_change() to notify that the setuid/setgid bits must be
- * dropped.
- * notify_change() will delete those flags, make sure attr->ia_valid & ATTR_MODE
- * is on, and remove the appropriate bits from attr->ia_mode (attr is a
- * "struct iattr *"). -BlaisorBlade
- */
 struct hostfs_timespec {
 	long long tv_sec;
 	long long tv_nsec;