Configure out file locking features

This patch adds the CONFIG_FILE_LOCKING option which allows to remove support for advisory locks. With this patch enabled, the flock() system call, the F_GETLK, F_SETLK and F_SETLKW operations of fcntl() and NFS support are disabled. These features are not necessarly needed on embedded systems. It allows to save ~11 Kb of kernel code and data: text data bss dec hex filename 1125436 118764 212992 1457192 163c28 vmlinux.old 1114299 118564 212992 1445855 160fdf vmlinux -11137 -200 0 -11337 -2C49 +/- This patch has originally been written by Matt Mackall <mpm@selenic.com>, and is part of the Linux Tiny project. Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Signed-off-by: Matt Mackall <mpm@selenic.com> Cc: matthew@wil.cx Cc: linux-fsdevel@vger.kernel.org Cc: mpm@selenic.com Cc: akpm@linux-foundation.org Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

Configure out file locking features
This patch adds the CONFIG_FILE_LOCKING option which allows to remove support for advisory locks. With this patch enabled, the flock() system call, the F_GETLK, F_SETLK and F_SETLKW operations of fcntl() and NFS support are disabled. These features are not necessarly needed on embedded systems. It allows to save ~11 Kb of kernel code and data: text data bss dec hex filename 1125436 118764 212992 1457192 163c28 vmlinux.old 1114299 118564 212992 1445855 160fdf vmlinux -11137 -200 0 -11337 -2C49 +/- This patch has originally been written by Matt Mackall <mpm@selenic.com>, and is part of the Linux Tiny project. Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Signed-off-by: Matt Mackall <mpm@selenic.com> Cc: matthew@wil.cx Cc: linux-fsdevel@vger.kernel.org Cc: mpm@selenic.com Cc: akpm@linux-foundation.org Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Thomas Petazzoni · J. Bruce Fields
1 parent 04716e6621
Showing 6 changed files with 70 additions and 9 deletions Side-by-side Diff
fs/Kconfig
fs/Makefile
fs/proc/proc_misc.c
include/linux/fs.h
kernel/sys_ni.c
kernel/sysctl.c
@@ -419,6 +419,14 @@
 	bool
 	default n
  
+config FILE_LOCKING
+	bool "Enable POSIX file locking API" if EMBEDDED
+	default y
+	help
+	  This option enables standard file locking support, required
+          for filesystems like NFS and for the flock() system
+          call. Disabling this option saves about 11k.
+
 source "fs/xfs/Kconfig"
 source "fs/gfs2/Kconfig"
  
@@ -7,7 +7,7 @@
  
 obj-y :=	open.o read_write.o file_table.o super.o \
 		char_dev.o stat.o exec.o pipe.o namei.o fcntl.o \
-		ioctl.o readdir.o select.o fifo.o locks.o dcache.o inode.o \
+		ioctl.o readdir.o select.o fifo.o dcache.o inode.o \
 		attr.o bad_inode.o file.o filesystems.o namespace.o aio.o \
 		seq_file.o xattr.o libfs.o fs-writeback.o \
 		pnode.o drop_caches.o splice.o sync.o utimes.o \
@@ -27,6 +27,7 @@
 obj-$(CONFIG_SIGNALFD)		+= signalfd.o
 obj-$(CONFIG_TIMERFD)		+= timerfd.o
 obj-$(CONFIG_EVENTFD)		+= eventfd.o
+obj-$(CONFIG_FILE_LOCKING)      += locks.o
 obj-$(CONFIG_COMPAT)		+= compat.o compat_ioctl.o
  
 nfsd-$(CONFIG_NFSD)		:= nfsctl.o
@@ -684,6 +684,7 @@
 	return proc_calc_metrics(page, start, off, count, eof, len);
 }
  
+#ifdef CONFIG_FILE_LOCKING
 static int locks_open(struct inode *inode, struct file *filp)
 {
 	return seq_open(filp, &locks_seq_operations);
@@ -695,6 +696,7 @@
 	.llseek		= seq_lseek,
 	.release	= seq_release,
 };
+#endif /* CONFIG_FILE_LOCKING */
  
 static int execdomains_read_proc(char *page, char **start, off_t off,
 				 int count, int *eof, void *data)
  
@@ -888,7 +890,9 @@
 #ifdef CONFIG_PRINTK
 	proc_create("kmsg", S_IRUSR, NULL, &proc_kmsg_operations);
 #endif
+#ifdef CONFIG_FILE_LOCKING
 	proc_create("locks", 0, NULL, &proc_locks_operations);
+#endif
 	proc_create("devices", 0, NULL, &proc_devinfo_operations);
 	proc_create("cpuinfo", 0, NULL, &proc_cpuinfo_operations);
 #ifdef CONFIG_BLOCK
@@ -983,6 +983,13 @@
  
 #include <linux/fcntl.h>
  
+extern void send_sigio(struct fown_struct *fown, int fd, int band);
+
+/* fs/sync.c */
+extern int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
+			loff_t endbyte, unsigned int flags);
+
+#ifdef CONFIG_FILE_LOCKING
 extern int fcntl_getlk(struct file *, struct flock __user *);
 extern int fcntl_setlk(unsigned int, struct file *, unsigned int,
 			struct flock __user *);
  
@@ -993,14 +1000,9 @@
 			struct flock64 __user *);
 #endif
  
-extern void send_sigio(struct fown_struct *fown, int fd, int band);
 extern int fcntl_setlease(unsigned int fd, struct file *filp, long arg);
 extern int fcntl_getlease(struct file *filp);
  
-/* fs/sync.c */
-extern int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
-			loff_t endbyte, unsigned int flags);
-
 /* fs/locks.c */
 extern void locks_init_lock(struct file_lock *);
 extern void locks_copy_lock(struct file_lock *, struct file_lock *);
  
@@ -1023,7 +1025,38 @@
 extern int lock_may_read(struct inode *, loff_t start, unsigned long count);
 extern int lock_may_write(struct inode *, loff_t start, unsigned long count);
 extern struct seq_operations locks_seq_operations;
+#else /* !CONFIG_FILE_LOCKING */
+#define fcntl_getlk(a, b) ({ -EINVAL; })
+#define fcntl_setlk(a, b, c, d) ({ -EACCES; })
+#if BITS_PER_LONG == 32
+#define fcntl_getlk64(a, b) ({ -EINVAL; })
+#define fcntl_setlk64(a, b, c, d) ({ -EACCES; })
+#endif
+#define fcntl_setlease(a, b, c) ({ 0; })
+#define fcntl_getlease(a) ({ 0; })
+#define locks_init_lock(a) ({ })
+#define __locks_copy_lock(a, b) ({ })
+#define locks_copy_lock(a, b) ({ })
+#define locks_remove_posix(a, b) ({ })
+#define locks_remove_flock(a) ({ })
+#define posix_test_lock(a, b) ({ 0; })
+#define posix_lock_file(a, b, c) ({ -ENOLCK; })
+#define posix_lock_file_wait(a, b) ({ -ENOLCK; })
+#define posix_unblock_lock(a, b) (-ENOENT)
+#define vfs_test_lock(a, b) ({ 0; })
+#define vfs_lock_file(a, b, c, d) (-ENOLCK)
+#define vfs_cancel_lock(a, b) ({ 0; })
+#define flock_lock_file_wait(a, b) ({ -ENOLCK; })
+#define __break_lease(a, b) ({ 0; })
+#define lease_get_mtime(a, b) ({ })
+#define generic_setlease(a, b, c) ({ -EINVAL; })
+#define vfs_setlease(a, b, c) ({ -EINVAL; })
+#define lease_modify(a, b) ({ -EINVAL; })
+#define lock_may_read(a, b, c) ({ 1; })
+#define lock_may_write(a, b, c) ({ 1; })
+#endif /* !CONFIG_FILE_LOCKING */
  
+
 struct fasync_struct {
 	int	magic;
 	int	fa_fd;
  
@@ -1554,9 +1587,12 @@
 /* /sys/fs */
 extern struct kobject *fs_kobj;
  
+extern int rw_verify_area(int, struct file *, loff_t *, size_t);
+
 #define FLOCK_VERIFY_READ  1
 #define FLOCK_VERIFY_WRITE 2
  
+#ifdef CONFIG_FILE_LOCKING
 extern int locks_mandatory_locked(struct inode *);
 extern int locks_mandatory_area(int, struct inode *, struct file *, loff_t, size_t);
  
@@ -1587,8 +1623,6 @@
 	return 0;
 }
  
-extern int rw_verify_area(int, struct file *, loff_t *, size_t);
-
 static inline int locks_verify_truncate(struct inode *inode,
 				    struct file *filp,
 				    loff_t size)
@@ -1609,6 +1643,15 @@
 		return __break_lease(inode, mode);
 	return 0;
 }
+#else /* !CONFIG_FILE_LOCKING */
+#define locks_mandatory_locked(a) ({ 0; })
+#define locks_mandatory_area(a, b, c, d, e) ({ 0; })
+#define __mandatory_lock(a) ({ 0; })
+#define mandatory_lock(a) ({ 0; })
+#define locks_verify_locked(a) ({ 0; })
+#define locks_verify_truncate(a, b, c) ({ 0; })
+#define break_lease(a, b) ({ 0; })
+#endif /* CONFIG_FILE_LOCKING */
  
 /* fs/open.c */
  
@@ -125,6 +125,7 @@
 cond_syscall(sys_vm86);
 cond_syscall(compat_sys_ipc);
 cond_syscall(compat_sys_sysctl);
+cond_syscall(sys_flock);
  
 /* arch-specific weak syscall entries */
 cond_syscall(sys_pciconfig_read);
@@ -97,7 +97,7 @@
 static int neg_one = -1;
 #endif
  
-#ifdef CONFIG_MMU
+#if defined(CONFIG_MMU) && defined(CONFIG_FILE_LOCKING)
 static int two = 2;
 #endif
  
@@ -1261,6 +1261,7 @@
 		.extra1		= &minolduid,
 		.extra2		= &maxolduid,
 	},
+#ifdef CONFIG_FILE_LOCKING
 	{
 		.ctl_name	= FS_LEASES,
 		.procname	= "leases-enable",
@@ -1269,6 +1270,7 @@
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec,
 	},
+#endif
 #ifdef CONFIG_DNOTIFY
 	{
 		.ctl_name	= FS_DIR_NOTIFY,
@@ -1280,6 +1282,7 @@
 	},
 #endif
 #ifdef CONFIG_MMU
+#ifdef CONFIG_FILE_LOCKING
 	{
 		.ctl_name	= FS_LEASE_TIME,
 		.procname	= "lease-break-time",
@@ -1291,6 +1294,7 @@
 		.extra1		= &zero,
 		.extra2		= &two,
 	},
+#endif
 	{
 		.procname	= "aio-nr",
 		.data		= &aio_nr,
...	...	@@ -419,6 +419,14 @@
419	419	bool
420	420	default n
421	421
	422	+config FILE_LOCKING
	423	+ bool "Enable POSIX file locking API" if EMBEDDED
	424	+ default y
	425	+ help
	426	+ This option enables standard file locking support, required
	427	+ for filesystems like NFS and for the flock() system
	428	+ call. Disabling this option saves about 11k.
	429	+
422	430	source "fs/xfs/Kconfig"
423	431	source "fs/gfs2/Kconfig"
424	432
...	...	@@ -7,7 +7,7 @@
7	7
8	8	obj-y := open.o read_write.o file_table.o super.o \
9	9	char_dev.o stat.o exec.o pipe.o namei.o fcntl.o \
10		- ioctl.o readdir.o select.o fifo.o locks.o dcache.o inode.o \
	10	+ ioctl.o readdir.o select.o fifo.o dcache.o inode.o \
11	11	attr.o bad_inode.o file.o filesystems.o namespace.o aio.o \
12	12	seq_file.o xattr.o libfs.o fs-writeback.o \
13	13	pnode.o drop_caches.o splice.o sync.o utimes.o \
...	...	@@ -27,6 +27,7 @@
27	27	obj-$(CONFIG_SIGNALFD) += signalfd.o
28	28	obj-$(CONFIG_TIMERFD) += timerfd.o
29	29	obj-$(CONFIG_EVENTFD) += eventfd.o
	30	+obj-$(CONFIG_FILE_LOCKING) += locks.o
30	31	obj-$(CONFIG_COMPAT) += compat.o compat_ioctl.o
31	32
32	33	nfsd-$(CONFIG_NFSD) := nfsctl.o
...	...	@@ -684,6 +684,7 @@
684	684	return proc_calc_metrics(page, start, off, count, eof, len);
685	685	}
686	686
	687	+#ifdef CONFIG_FILE_LOCKING
687	688	static int locks_open(struct inode inode, struct file filp)
688	689	{
689	690	return seq_open(filp, &locks_seq_operations);
...	...	@@ -695,6 +696,7 @@
695	696	.llseek = seq_lseek,
696	697	.release = seq_release,
697	698	};
	699	+#endif /* CONFIG_FILE_LOCKING */
698	700
699	701	static int execdomains_read_proc(char page, char *start, off_t off,
700	702	int count, int eof, void data)
701	703
...	...	@@ -888,7 +890,9 @@
888	890	#ifdef CONFIG_PRINTK
889	891	proc_create("kmsg", S_IRUSR, NULL, &proc_kmsg_operations);
890	892	#endif
	893	+#ifdef CONFIG_FILE_LOCKING
891	894	proc_create("locks", 0, NULL, &proc_locks_operations);
	895	+#endif
892	896	proc_create("devices", 0, NULL, &proc_devinfo_operations);
893	897	proc_create("cpuinfo", 0, NULL, &proc_cpuinfo_operations);
894	898	#ifdef CONFIG_BLOCK
...	...	@@ -983,6 +983,13 @@
983	983
984	984	#include <linux/fcntl.h>
985	985
	986	+extern void send_sigio(struct fown_struct *fown, int fd, int band);
	987	+
	988	+/* fs/sync.c */
	989	+extern int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
	990	+ loff_t endbyte, unsigned int flags);
	991	+
	992	+#ifdef CONFIG_FILE_LOCKING
986	993	extern int fcntl_getlk(struct file , struct flock __user );
987	994	extern int fcntl_setlk(unsigned int, struct file *, unsigned int,
988	995	struct flock __user *);
989	996
...	...	@@ -993,14 +1000,9 @@
993	1000	struct flock64 __user *);
994	1001	#endif
995	1002
996		-extern void send_sigio(struct fown_struct *fown, int fd, int band);
997	1003	extern int fcntl_setlease(unsigned int fd, struct file *filp, long arg);
998	1004	extern int fcntl_getlease(struct file *filp);
999	1005
1000		-/* fs/sync.c */
1001		-extern int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
1002		- loff_t endbyte, unsigned int flags);
1003		-
1004	1006	/* fs/locks.c */
1005	1007	extern void locks_init_lock(struct file_lock *);
1006	1008	extern void locks_copy_lock(struct file_lock , struct file_lock );
1007	1009
...	...	@@ -1023,7 +1025,38 @@
1023	1025	extern int lock_may_read(struct inode *, loff_t start, unsigned long count);
1024	1026	extern int lock_may_write(struct inode *, loff_t start, unsigned long count);
1025	1027	extern struct seq_operations locks_seq_operations;
	1028	+#else /* !CONFIG_FILE_LOCKING */
	1029	+#define fcntl_getlk(a, b) ({ -EINVAL; })
	1030	+#define fcntl_setlk(a, b, c, d) ({ -EACCES; })
	1031	+#if BITS_PER_LONG == 32
	1032	+#define fcntl_getlk64(a, b) ({ -EINVAL; })
	1033	+#define fcntl_setlk64(a, b, c, d) ({ -EACCES; })
	1034	+#endif
	1035	+#define fcntl_setlease(a, b, c) ({ 0; })
	1036	+#define fcntl_getlease(a) ({ 0; })
	1037	+#define locks_init_lock(a) ({ })
	1038	+#define __locks_copy_lock(a, b) ({ })
	1039	+#define locks_copy_lock(a, b) ({ })
	1040	+#define locks_remove_posix(a, b) ({ })
	1041	+#define locks_remove_flock(a) ({ })
	1042	+#define posix_test_lock(a, b) ({ 0; })
	1043	+#define posix_lock_file(a, b, c) ({ -ENOLCK; })
	1044	+#define posix_lock_file_wait(a, b) ({ -ENOLCK; })
	1045	+#define posix_unblock_lock(a, b) (-ENOENT)
	1046	+#define vfs_test_lock(a, b) ({ 0; })
	1047	+#define vfs_lock_file(a, b, c, d) (-ENOLCK)
	1048	+#define vfs_cancel_lock(a, b) ({ 0; })
	1049	+#define flock_lock_file_wait(a, b) ({ -ENOLCK; })
	1050	+#define __break_lease(a, b) ({ 0; })
	1051	+#define lease_get_mtime(a, b) ({ })
	1052	+#define generic_setlease(a, b, c) ({ -EINVAL; })
	1053	+#define vfs_setlease(a, b, c) ({ -EINVAL; })
	1054	+#define lease_modify(a, b) ({ -EINVAL; })
	1055	+#define lock_may_read(a, b, c) ({ 1; })
	1056	+#define lock_may_write(a, b, c) ({ 1; })
	1057	+#endif /* !CONFIG_FILE_LOCKING */
1026	1058
	1059	+
1027	1060	struct fasync_struct {
1028	1061	int magic;
1029	1062	int fa_fd;
1030	1063
...	...	@@ -1554,9 +1587,12 @@
1554	1587	/* /sys/fs */
1555	1588	extern struct kobject *fs_kobj;
1556	1589
	1590	+extern int rw_verify_area(int, struct file , loff_t , size_t);
	1591	+
1557	1592	#define FLOCK_VERIFY_READ 1
1558	1593	#define FLOCK_VERIFY_WRITE 2
1559	1594
	1595	+#ifdef CONFIG_FILE_LOCKING
1560	1596	extern int locks_mandatory_locked(struct inode *);
1561	1597	extern int locks_mandatory_area(int, struct inode , struct file , loff_t, size_t);
1562	1598
...	...	@@ -1587,8 +1623,6 @@
1587	1623	return 0;
1588	1624	}
1589	1625
1590		-extern int rw_verify_area(int, struct file , loff_t , size_t);
1591		-
1592	1626	static inline int locks_verify_truncate(struct inode *inode,
1593	1627	struct file *filp,
1594	1628	loff_t size)
...	...	@@ -1609,6 +1643,15 @@
1609	1643	return __break_lease(inode, mode);
1610	1644	return 0;
1611	1645	}
	1646	+#else /* !CONFIG_FILE_LOCKING */
	1647	+#define locks_mandatory_locked(a) ({ 0; })
	1648	+#define locks_mandatory_area(a, b, c, d, e) ({ 0; })
	1649	+#define __mandatory_lock(a) ({ 0; })
	1650	+#define mandatory_lock(a) ({ 0; })
	1651	+#define locks_verify_locked(a) ({ 0; })
	1652	+#define locks_verify_truncate(a, b, c) ({ 0; })
	1653	+#define break_lease(a, b) ({ 0; })
	1654	+#endif /* CONFIG_FILE_LOCKING */
1612	1655
1613	1656	/* fs/open.c */
1614	1657
...	...	@@ -125,6 +125,7 @@
125	125	cond_syscall(sys_vm86);
126	126	cond_syscall(compat_sys_ipc);
127	127	cond_syscall(compat_sys_sysctl);
	128	+cond_syscall(sys_flock);
128	129
129	130	/* arch-specific weak syscall entries */
130	131	cond_syscall(sys_pciconfig_read);
...	...	@@ -97,7 +97,7 @@
97	97	static int neg_one = -1;
98	98	#endif
99	99
100		-#ifdef CONFIG_MMU
	100	+#if defined(CONFIG_MMU) && defined(CONFIG_FILE_LOCKING)
101	101	static int two = 2;
102	102	#endif
103	103
...	...	@@ -1261,6 +1261,7 @@
1261	1261	.extra1 = &minolduid,
1262	1262	.extra2 = &maxolduid,
1263	1263	},
	1264	+#ifdef CONFIG_FILE_LOCKING
1264	1265	{
1265	1266	.ctl_name = FS_LEASES,
1266	1267	.procname = "leases-enable",
...	...	@@ -1269,6 +1270,7 @@
1269	1270	.mode = 0644,
1270	1271	.proc_handler = &proc_dointvec,
1271	1272	},
	1273	+#endif
1272	1274	#ifdef CONFIG_DNOTIFY
1273	1275	{
1274	1276	.ctl_name = FS_DIR_NOTIFY,
...	...	@@ -1280,6 +1282,7 @@
1280	1282	},
1281	1283	#endif
1282	1284	#ifdef CONFIG_MMU
	1285	+#ifdef CONFIG_FILE_LOCKING
1283	1286	{
1284	1287	.ctl_name = FS_LEASE_TIME,
1285	1288	.procname = "lease-break-time",
...	...	@@ -1291,6 +1294,7 @@
1291	1294	.extra1 = &zero,
1292	1295	.extra2 = &two,
1293	1296	},
	1297	+#endif
1294	1298	{
1295	1299	.procname = "aio-nr",
1296	1300	.data = &aio_nr,