add f_flags to struct statfs(64)

Add a flags field to help glibc implementing statvfs(3) efficiently. We copy the flag values from glibc, and add a new ST_VALID flag to denote that f_flags is implemented. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

add f_flags to struct statfs(64)
Add a flags field to help glibc implementing statvfs(3) efficiently. We copy the flag values from glibc, and add a new ST_VALID flag to denote that f_flags is implemented. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Christoph Hellwig · Al Viro
1 parent ebabe9a900
Showing 5 changed files with 89 additions and 13 deletions Side-by-side Diff
arch/mips/include/asm/statfs.h
arch/s390/include/asm/statfs.h
fs/statfs.c
include/asm-generic/statfs.h
include/linux/statfs.h
@@ -33,7 +33,8 @@
 	/* 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 @@
 	__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 @@
 	/* 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 @@
 	__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 */
@@ -33,7 +33,8 @@
 	__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 @@
 	__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 @@
 	__kernel_fsid_t f_fsid;
 	__u32 f_namelen;
 	__u32 f_frsize;
-	__u32 f_spare[5];
+	__u32 f_flags;
+	__u32 f_spare[4];
 };
  
 #endif /* __s390x__ */
@@ -2,11 +2,49 @@
 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/file.h>
+#include <linux/mount.h>
 #include <linux/namei.h>
 #include <linux/statfs.h>
 #include <linux/security.h>
 #include <linux/uaccess.h>
  
+static int flags_by_mnt(int mnt_flags)
+{
+	int flags = 0;
+
+	if (mnt_flags & MNT_READONLY)
+		flags |= ST_RDONLY;
+	if (mnt_flags & MNT_NOSUID)
+		flags |= ST_NOSUID;
+	if (mnt_flags & MNT_NODEV)
+		flags |= ST_NODEV;
+	if (mnt_flags & MNT_NOEXEC)
+		flags |= ST_NOEXEC;
+	if (mnt_flags & MNT_NOATIME)
+		flags |= ST_NOATIME;
+	if (mnt_flags & MNT_NODIRATIME)
+		flags |= ST_NODIRATIME;
+	if (mnt_flags & MNT_RELATIME)
+		flags |= ST_RELATIME;
+	return flags;
+}
+
+static int flags_by_sb(int s_flags)
+{
+	int flags = 0;
+	if (s_flags & MS_SYNCHRONOUS)
+		flags |= ST_SYNCHRONOUS;
+	if (s_flags & MS_MANDLOCK)
+		flags |= ST_MANDLOCK;
+	return flags;
+}
+
+static int calculate_f_flags(struct vfsmount *mnt)
+{
+	return ST_VALID | flags_by_mnt(mnt->mnt_flags) |
+		flags_by_sb(mnt->mnt_sb->s_flags);
+}
+
 int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf)
 {
 	int retval;
@@ -26,7 +64,12 @@
  
 int vfs_statfs(struct path *path, struct kstatfs *buf)
 {
-	return statfs_by_dentry(path->dentry, buf);
+	int error;
+
+	error = statfs_by_dentry(path->dentry, buf);
+	if (!error)
+		buf->f_flags = calculate_f_flags(path->mnt);
+	return error;
 }
 EXPORT_SYMBOL(vfs_statfs);
  
@@ -69,6 +112,7 @@
 		buf->f_fsid = st.f_fsid;
 		buf->f_namelen = st.f_namelen;
 		buf->f_frsize = st.f_frsize;
+		buf->f_flags = st.f_flags;
 		memset(buf->f_spare, 0, sizeof(buf->f_spare));
 	}
 	return 0;
@@ -96,6 +140,7 @@
 		buf->f_fsid = st.f_fsid;
 		buf->f_namelen = st.f_namelen;
 		buf->f_frsize = st.f_frsize;
+		buf->f_flags = st.f_flags;
 		memset(buf->f_spare, 0, sizeof(buf->f_spare));
 	}
 	return 0;
@@ -33,7 +33,8 @@
 	__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 @@
 	__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 @@
 	__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
@@ -2,7 +2,6 @@
 #define _LINUX_STATFS_H
  
 #include <linux/types.h>
-
 #include <asm/statfs.h>
  
 struct kstatfs {
  
@@ -16,8 +15,30 @@
 	__kernel_fsid_t f_fsid;
 	long f_namelen;
 	long f_frsize;
-	long f_spare[5];
+	long f_flags;
+	long f_spare[4];
 };
+
+/*
+ * Definitions for the flag in f_flag.
+ *
+ * Generally these flags are equivalent to the MS_ flags used in the mount
+ * ABI.  The exception is ST_VALID which has the same value as MS_REMOUNT
+ * which doesn't make any sense for statfs.
+ */
+#define ST_RDONLY	0x0001	/* mount read-only */
+#define ST_NOSUID	0x0002	/* ignore suid and sgid bits */
+#define ST_NODEV	0x0004	/* disallow access to device special files */
+#define ST_NOEXEC	0x0008	/* disallow program execution */
+#define ST_SYNCHRONOUS	0x0010	/* writes are synced at once */
+#define ST_VALID	0x0020	/* f_flags support is implemented */
+#define ST_MANDLOCK	0x0040	/* allow mandatory locks on an FS */
+/* 0x0080 used for ST_WRITE in glibc */
+/* 0x0100 used for ST_APPEND in glibc */
+/* 0x0200 used for ST_IMMUTABLE in glibc */
+#define ST_NOATIME	0x0400	/* do not update access times */
+#define ST_NODIRATIME	0x0800	/* do not update directory access times */
+#define ST_RELATIME	0x1000	/* update atime relative to mtime/ctime */
  
 #endif
...	...	@@ -33,7 +33,8 @@
33	33	/* Linux specials */
34	34	__kernel_fsid_t f_fsid;
35	35	long f_namelen;
36		- long f_spare[6];
	36	+ long f_flags;
	37	+ long f_spare[5];
37	38	};
38	39
39	40	#if (_MIPS_SIM == _MIPS_SIM_ABI32) \|\| (_MIPS_SIM == _MIPS_SIM_NABI32)
...	...	@@ -53,7 +54,8 @@
53	54	__u64 f_bavail;
54	55	__kernel_fsid_t f_fsid;
55	56	__u32 f_namelen;
56		- __u32 f_spare[6];
	57	+ __u32 f_flags;
	58	+ __u32 f_spare[5];
57	59	};
58	60
59	61	#endif /* _MIPS_SIM == _MIPS_SIM_ABI32 */
...	...	@@ -73,7 +75,8 @@
73	75	/* Linux specials */
74	76	__kernel_fsid_t f_fsid;
75	77	long f_namelen;
76		- long f_spare[6];
	78	+ long f_flags;
	79	+ long f_spare[5];
77	80	};
78	81
79	82	struct compat_statfs64 {
...	...	@@ -88,7 +91,8 @@
88	91	__u64 f_bavail;
89	92	__kernel_fsid_t f_fsid;
90	93	__u32 f_namelen;
91		- __u32 f_spare[6];
	94	+ __u32 f_flags;
	95	+ __u32 f_spare[5];
92	96	};
93	97
94	98	#endif /* _MIPS_SIM == _MIPS_SIM_ABI64 */
...	...	@@ -33,7 +33,8 @@
33	33	__kernel_fsid_t f_fsid;
34	34	int f_namelen;
35	35	int f_frsize;
36		- int f_spare[5];
	36	+ int f_flags;
	37	+ int f_spare[4];
37	38	};
38	39
39	40	struct statfs64 {
...	...	@@ -47,7 +48,8 @@
47	48	__kernel_fsid_t f_fsid;
48	49	int f_namelen;
49	50	int f_frsize;
50		- int f_spare[5];
	51	+ int f_flags;
	52	+ int f_spare[4];
51	53	};
52	54
53	55	struct compat_statfs64 {
...	...	@@ -61,7 +63,8 @@
61	63	__kernel_fsid_t f_fsid;
62	64	__u32 f_namelen;
63	65	__u32 f_frsize;
64		- __u32 f_spare[5];
	66	+ __u32 f_flags;
	67	+ __u32 f_spare[4];
65	68	};
66	69
67	70	#endif /* __s390x__ */
...	...	@@ -2,11 +2,49 @@
2	2	#include <linux/module.h>
3	3	#include <linux/fs.h>
4	4	#include <linux/file.h>
	5	+#include <linux/mount.h>
5	6	#include <linux/namei.h>
6	7	#include <linux/statfs.h>
7	8	#include <linux/security.h>
8	9	#include <linux/uaccess.h>
9	10
	11	+static int flags_by_mnt(int mnt_flags)
	12	+{
	13	+ int flags = 0;
	14	+
	15	+ if (mnt_flags & MNT_READONLY)
	16	+ flags \|= ST_RDONLY;
	17	+ if (mnt_flags & MNT_NOSUID)
	18	+ flags \|= ST_NOSUID;
	19	+ if (mnt_flags & MNT_NODEV)
	20	+ flags \|= ST_NODEV;
	21	+ if (mnt_flags & MNT_NOEXEC)
	22	+ flags \|= ST_NOEXEC;
	23	+ if (mnt_flags & MNT_NOATIME)
	24	+ flags \|= ST_NOATIME;
	25	+ if (mnt_flags & MNT_NODIRATIME)
	26	+ flags \|= ST_NODIRATIME;
	27	+ if (mnt_flags & MNT_RELATIME)
	28	+ flags \|= ST_RELATIME;
	29	+ return flags;
	30	+}
	31	+
	32	+static int flags_by_sb(int s_flags)
	33	+{
	34	+ int flags = 0;
	35	+ if (s_flags & MS_SYNCHRONOUS)
	36	+ flags \|= ST_SYNCHRONOUS;
	37	+ if (s_flags & MS_MANDLOCK)
	38	+ flags \|= ST_MANDLOCK;
	39	+ return flags;
	40	+}
	41	+
	42	+static int calculate_f_flags(struct vfsmount *mnt)
	43	+{
	44	+ return ST_VALID \| flags_by_mnt(mnt->mnt_flags) \|
	45	+ flags_by_sb(mnt->mnt_sb->s_flags);
	46	+}
	47	+
10	48	int statfs_by_dentry(struct dentry dentry, struct kstatfs buf)
11	49	{
12	50	int retval;
...	...	@@ -26,7 +64,12 @@
26	64
27	65	int vfs_statfs(struct path path, struct kstatfs buf)
28	66	{
29		- return statfs_by_dentry(path->dentry, buf);
	67	+ int error;
	68	+
	69	+ error = statfs_by_dentry(path->dentry, buf);
	70	+ if (!error)
	71	+ buf->f_flags = calculate_f_flags(path->mnt);
	72	+ return error;
30	73	}
31	74	EXPORT_SYMBOL(vfs_statfs);
32	75
...	...	@@ -69,6 +112,7 @@
69	112	buf->f_fsid = st.f_fsid;
70	113	buf->f_namelen = st.f_namelen;
71	114	buf->f_frsize = st.f_frsize;
	115	+ buf->f_flags = st.f_flags;
72	116	memset(buf->f_spare, 0, sizeof(buf->f_spare));
73	117	}
74	118	return 0;
...	...	@@ -96,6 +140,7 @@
96	140	buf->f_fsid = st.f_fsid;
97	141	buf->f_namelen = st.f_namelen;
98	142	buf->f_frsize = st.f_frsize;
	143	+ buf->f_flags = st.f_flags;
99	144	memset(buf->f_spare, 0, sizeof(buf->f_spare));
100	145	}
101	146	return 0;
...	...	@@ -33,7 +33,8 @@
33	33	__kernel_fsid_t f_fsid;
34	34	__statfs_word f_namelen;
35	35	__statfs_word f_frsize;
36		- __statfs_word f_spare[5];
	36	+ __statfs_word f_flags;
	37	+ __statfs_word f_spare[4];
37	38	};
38	39
39	40	/*
...	...	@@ -55,7 +56,8 @@
55	56	__kernel_fsid_t f_fsid;
56	57	__statfs_word f_namelen;
57	58	__statfs_word f_frsize;
58		- __statfs_word f_spare[5];
	59	+ __statfs_word f_flags;
	60	+ __statfs_word f_spare[4];
59	61	} ARCH_PACK_STATFS64;
60	62
61	63	/*
...	...	@@ -77,7 +79,8 @@
77	79	__kernel_fsid_t f_fsid;
78	80	__u32 f_namelen;
79	81	__u32 f_frsize;
80		- __u32 f_spare[5];
	82	+ __u32 f_flags;
	83	+ __u32 f_spare[4];
81	84	} ARCH_PACK_COMPAT_STATFS64;
82	85
83	86	#endif
...	...	@@ -2,7 +2,6 @@
2	2	#define _LINUX_STATFS_H
3	3
4	4	#include <linux/types.h>
5		-
6	5	#include <asm/statfs.h>
7	6
8	7	struct kstatfs {
9	8
...	...	@@ -16,8 +15,30 @@
16	15	__kernel_fsid_t f_fsid;
17	16	long f_namelen;
18	17	long f_frsize;
19		- long f_spare[5];
	18	+ long f_flags;
	19	+ long f_spare[4];
20	20	};
	21	+
	22	+/*
	23	+ * Definitions for the flag in f_flag.
	24	+ *
	25	+ * Generally these flags are equivalent to the MS_ flags used in the mount
	26	+ * ABI. The exception is ST_VALID which has the same value as MS_REMOUNT
	27	+ * which doesn't make any sense for statfs.
	28	+ */
	29	+#define ST_RDONLY 0x0001 /* mount read-only */
	30	+#define ST_NOSUID 0x0002 /* ignore suid and sgid bits */
	31	+#define ST_NODEV 0x0004 /* disallow access to device special files */
	32	+#define ST_NOEXEC 0x0008 /* disallow program execution */
	33	+#define ST_SYNCHRONOUS 0x0010 /* writes are synced at once */
	34	+#define ST_VALID 0x0020 /* f_flags support is implemented */
	35	+#define ST_MANDLOCK 0x0040 /* allow mandatory locks on an FS */
	36	+/* 0x0080 used for ST_WRITE in glibc */
	37	+/* 0x0100 used for ST_APPEND in glibc */
	38	+/* 0x0200 used for ST_IMMUTABLE in glibc */
	39	+#define ST_NOATIME 0x0400 /* do not update access times */
	40	+#define ST_NODIRATIME 0x0800 /* do not update directory access times */
	41	+#define ST_RELATIME 0x1000 /* update atime relative to mtime/ctime */
21	42
22	43	#endif