Commit bfcd17a6 authored by Thomas Petazzoni's avatar Thomas Petazzoni Committed by J. Bruce Fields
Browse files

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: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: default avatarMatt 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: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
parent 04716e66

fs/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -419,6 +419,14 @@ config FS_POSIX_ACL 
	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"

fs/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -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-$(CONFIG_ANON_INODES) += anon_inodes.o 
obj-$(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

fs/proc/proc_misc.c

+4 −0
Original line number Diff line number Diff line
@@ -684,6 +684,7 @@ static int cmdline_read_proc(char *page, char **start, off_t off, 
	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 @@ static const struct file_operations proc_locks_operations = { 
	.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 @@ void __init proc_misc_init(void) 
#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

include/linux/fs.h

+50 −7
Original line number Diff line number Diff line
@@ -983,6 +983,13 @@ struct file_lock { 


#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 @@ extern int fcntl_setlk64(unsigned int, struct file *, unsigned int, 
			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 *);
@@ -1023,6 +1025,37 @@ extern int lease_modify(struct file_lock **, int); 
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;
@@ -1554,9 +1587,12 @@ extern int vfs_statfs(struct dentry *, struct kstatfs *); 
/* /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 @@ static inline int locks_verify_locked(struct inode *inode) 
	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 @@ static inline int break_lease(struct inode *inode, unsigned int mode) 
		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 */

kernel/sys_ni.c

+1 −0
Original line number Diff line number Diff line
@@ -125,6 +125,7 @@ cond_syscall(sys_vm86old); 
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);

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