Re: [rfc] new stat*fs-like syscall?

[Linus Torvalds <torvalds@linux-foundation.org>]

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On Mon, Jul 5, 2010 at 5:45 PM, Brad Boyer <flar@allandria.com> wrote:
> On Tue, Jul 06, 2010 at 08:31:30AM +0900, J. R. Okajima wrote:
>> For negative dentry, it should be supported as long as some
>> standard/specification doesn't prohibit explicitly. So I still think
>> statfs is the best place to implement _PC_LINK_MAX.
>
> If we're going to be changing statfs (or adding a new system call)
> anyway, that does seem like a reasonable place to export this data
> along with whatever else gets added. With the various things that
> have been suggested, maybe we need something more like the stat
> replacement that has been getting discussed with the room for some
> larger optional fields and a way to request a specific set of fields.

Let's not overdesign things. Just do something like the attached
patch, which is the obvious and straightforward thing to do.

Overdesigning is a disease. It's fundamentally wrong.

(Yeah, yeah,. the patch is untested, and doesn't actually _fill_ the
new f_flags value, but that's left as a trivial exercise for the
reader.)

                                Linus

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 arch/ia64/include/asm/compat.h |    3 ++-
 arch/mips/include/asm/statfs.h |   12 ++++++++----
 arch/s390/include/asm/statfs.h |    9 ++++++---
 arch/x86/include/asm/compat.h  |    3 ++-
 fs/compat.c                    |    5 +++--
 include/asm-generic/statfs.h   |    9 ++++++---
 include/linux/statfs.h         |    3 ++-
 7 files changed, 29 insertions(+), 15 deletions(-)

diff --git a/arch/ia64/include/asm/compat.h b/arch/ia64/include/asm/compat.h
index f90edc8..ab15469 100644
--- a/arch/ia64/include/asm/compat.h
+++ b/arch/ia64/include/asm/compat.h
@@ -105,7 +105,8 @@ struct compat_statfs {
 	compat_fsid_t	f_fsid;
 	int		f_namelen;	/* SunOS ignores this field. */
 	int		f_frsize;
-	int		f_spare[5];
+	int		f_flags;
+	int		f_spare[4];
 };
 
 #define COMPAT_RLIM_OLD_INFINITY       0x7fffffff
diff --git a/arch/mips/include/asm/statfs.h b/arch/mips/include/asm/statfs.h
index c3ddf97..0f805c7 100644
--- a/arch/mips/include/asm/statfs.h
+++ b/arch/mips/include/asm/statfs.h
@@ -33,7 +33,8 @@ struct statfs {
 	/* Linux specials */
 	__kernel_fsid_t	f_fsid;
 	long		f_namelen;
-	long		f_spare[6];
+	long		f_flags;
+	long		f_spare[5];
 };
 
 #if (_MIPS_SIM == _MIPS_SIM_ABI32) || (_MIPS_SIM == _MIPS_SIM_NABI32)
@@ -53,7 +54,8 @@ struct statfs64 {
 	__u64	f_bavail;
 	__kernel_fsid_t f_fsid;
 	__u32	f_namelen;
-	__u32	f_spare[6];
+	__u32	f_flags;
+	__u32	f_spare[5];
 };
 
 #endif /* _MIPS_SIM == _MIPS_SIM_ABI32 */
@@ -73,7 +75,8 @@ struct statfs64 {			/* Same as struct statfs */
 	/* Linux specials */
 	__kernel_fsid_t	f_fsid;
 	long		f_namelen;
-	long		f_spare[6];
+	long		f_flags;
+	long		f_spare[5];
 };
 
 struct compat_statfs64 {
@@ -88,7 +91,8 @@ struct compat_statfs64 {
 	__u64	f_bavail;
 	__kernel_fsid_t f_fsid;
 	__u32	f_namelen;
-	__u32	f_spare[6];
+	__u32	f_flags;
+	__u32	f_spare[5];
 };
 
 #endif /* _MIPS_SIM == _MIPS_SIM_ABI64 */
diff --git a/arch/s390/include/asm/statfs.h b/arch/s390/include/asm/statfs.h
index 06cc703..3be7fbd 100644
--- a/arch/s390/include/asm/statfs.h
+++ b/arch/s390/include/asm/statfs.h
@@ -33,7 +33,8 @@ struct statfs {
 	__kernel_fsid_t f_fsid;
 	int  f_namelen;
 	int  f_frsize;
-	int  f_spare[5];
+	int  f_flags;
+	int  f_spare[4];
 };
 
 struct statfs64 {
@@ -47,7 +48,8 @@ struct statfs64 {
 	__kernel_fsid_t f_fsid;
 	int  f_namelen;
 	int  f_frsize;
-	int  f_spare[5];
+	int  f_flags;
+	int  f_spare[4];
 };
 
 struct compat_statfs64 {
@@ -61,7 +63,8 @@ struct compat_statfs64 {
 	__kernel_fsid_t f_fsid;
 	__u32 f_namelen;
 	__u32 f_frsize;
-	__u32 f_spare[5];
+	__u32 f_flags;
+	__u32 f_spare[4];
 };
 
 #endif /* __s390x__ */
diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index 306160e..9f9cdb8 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -108,7 +108,8 @@ struct compat_statfs {
 	compat_fsid_t	f_fsid;
 	int		f_namelen;	/* SunOS ignores this field. */
 	int		f_frsize;
-	int		f_spare[5];
+	int		f_flags;
+	int		f_spare[4];
 };
 
 #define COMPAT_RLIM_OLD_INFINITY	0x7fffffff
diff --git a/fs/compat.c b/fs/compat.c
index 6490d21..fe96e7d 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -245,7 +245,7 @@ static int put_compat_statfs(struct compat_statfs __user *ubuf, struct kstatfs *
 	    __put_user(kbuf->f_fsid.val[0], &ubuf->f_fsid.val[0]) ||
 	    __put_user(kbuf->f_fsid.val[1], &ubuf->f_fsid.val[1]) ||
 	    __put_user(kbuf->f_frsize, &ubuf->f_frsize) ||
-	    __put_user(0, &ubuf->f_spare[0]) || 
+	    __put_user(kbuf->f_flags, &ubuf->f_flags) || 
 	    __put_user(0, &ubuf->f_spare[1]) || 
 	    __put_user(0, &ubuf->f_spare[2]) || 
 	    __put_user(0, &ubuf->f_spare[3]) || 
@@ -318,7 +318,8 @@ static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstat
 	    __put_user(kbuf->f_namelen, &ubuf->f_namelen) ||
 	    __put_user(kbuf->f_fsid.val[0], &ubuf->f_fsid.val[0]) ||
 	    __put_user(kbuf->f_fsid.val[1], &ubuf->f_fsid.val[1]) ||
-	    __put_user(kbuf->f_frsize, &ubuf->f_frsize))
+	    __put_user(kbuf->f_frsize, &ubuf->f_frsize) ||
+	    __put_user(kbuf->f_flags, &ubuf->f_flags))
 		return -EFAULT;
 	return 0;
 }
diff --git a/include/asm-generic/statfs.h b/include/asm-generic/statfs.h
index 3b4fb3e..0fd28e0 100644
--- a/include/asm-generic/statfs.h
+++ b/include/asm-generic/statfs.h
@@ -33,7 +33,8 @@ struct statfs {
 	__kernel_fsid_t f_fsid;
 	__statfs_word f_namelen;
 	__statfs_word f_frsize;
-	__statfs_word f_spare[5];
+	__statfs_word f_flags;
+	__statfs_word f_spare[4];
 };
 
 /*
@@ -55,7 +56,8 @@ struct statfs64 {
 	__kernel_fsid_t f_fsid;
 	__statfs_word f_namelen;
 	__statfs_word f_frsize;
-	__statfs_word f_spare[5];
+	__statfs_word f_flags;
+	__statfs_word f_spare[4];
 } ARCH_PACK_STATFS64;
 
 /* 
@@ -77,7 +79,8 @@ struct compat_statfs64 {
 	__kernel_fsid_t f_fsid;
 	__u32 f_namelen;
 	__u32 f_frsize;
-	__u32 f_spare[5];
+	__u32 f_flags;
+	__u32 f_spare[4];
 } ARCH_PACK_COMPAT_STATFS64;
 
 #endif
diff --git a/include/linux/statfs.h b/include/linux/statfs.h
index b34cc82..dd8b4e7 100644
--- a/include/linux/statfs.h
+++ b/include/linux/statfs.h
@@ -16,7 +16,8 @@ struct kstatfs {
 	__kernel_fsid_t f_fsid;
 	long f_namelen;
 	long f_frsize;
-	long f_spare[5];
+	long f_flags;
+	long f_spare[4];
 };
 
 #endif