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Configure out file locking features

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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>
This commit is contained in:
Thomas Petazzoni 2008-08-06 15:12:22 +02:00 committed by J. Bruce Fields
parent 04716e6621
commit bfcd17a6c5
6 changed files with 70 additions and 9 deletions
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8
fs/Kconfig
View file

@ -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"

3
fs/Makefile
View file

@ -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

4
fs/proc/proc_misc.c
View file

@ -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

57
include/linux/fs.h
View file

@ -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 */

1
kernel/sys_ni.c
View file

@ -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);

6
kernel/sysctl.c
View file

@ -97,7 +97,7 @@ static int sixty = 60;
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 @@ static struct ctl_table fs_table[] = {
.extra1 = &minolduid,
.extra2 = &maxolduid,
},
#ifdef CONFIG_FILE_LOCKING
{
.ctl_name = FS_LEASES,
.procname = "leases-enable",
@ -1269,6 +1270,7 @@ static struct ctl_table fs_table[] = {
.mode = 0644,
.proc_handler = &proc_dointvec,
},
#endif
#ifdef CONFIG_DNOTIFY
{
.ctl_name = FS_DIR_NOTIFY,
@ -1280,6 +1282,7 @@ static struct ctl_table fs_table[] = {
},
#endif
#ifdef CONFIG_MMU
#ifdef CONFIG_FILE_LOCKING
{
.ctl_name = FS_LEASE_TIME,
.procname = "lease-break-time",
@ -1291,6 +1294,7 @@ static struct ctl_table fs_table[] = {
.extra1 = &zero,
.extra2 = &two,
},
#endif
{
.procname = "aio-nr",
.data = &aio_nr,