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>
diff --git a/fs/Kconfig b/fs/Kconfig
index abccb5da..c6ae4d48 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -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"
diff --git a/fs/Makefile b/fs/Makefile
index a1482a5..4b86d43 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -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
diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
index 29e20c6..1aabbe2 100644
--- a/fs/proc/proc_misc.c
+++ b/fs/proc/proc_misc.c
@@ -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
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 580b513..9f54016 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -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 *);
@@ -1023,6 +1025,37 @@
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 @@
/* /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 */
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 08d6e1b..503d8d4 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.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);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 50ec088..4588b2c 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -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,
