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SubjectRe: [patch 2/4] Configure out file locking features
Le Sat, 2 Aug 2008 12:38:48 -0400,
"J. Bruce Fields" <bfields@fieldses.org> a écrit :

> Out of curiosity, why does the nfs client need disabling, but not
> nfsd, gfs2, fuse, etc.?

Then also need disabling. Updated patch below.

Thanks!

Thomas

---
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

---
fs/Kconfig | 15 ++++++++++++++-
fs/Makefile | 3 ++-
fs/dlm/Kconfig | 1 +
fs/gfs2/Kconfig | 1 +
fs/proc/proc_misc.c | 4 ++++
include/linux/fs.h | 52 +++++++++++++++++++++++++++++++++++++++++++++-------
kernel/sys_ni.c | 1 +
kernel/sysctl.c | 6 +++++-
8 files changed, 73 insertions(+), 10 deletions(-)
Index: linuxdev/fs/Kconfig
===================================================================
--- linuxdev.orig/fs/Kconfig
+++ linuxdev/fs/Kconfig
@@ -427,12 +427,21 @@
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"

config OCFS2_FS
tristate "OCFS2 file system support"
depends on NET && SYSFS
+ depends on FILE_LOCKING
select CONFIGFS_FS
select JBD
select CRC32
@@ -642,6 +651,7 @@

config FUSE_FS
tristate "Filesystem in Userspace support"
+ depends on FILE_LOCKING
help
With FUSE it is possible to implement a fully functional filesystem
in a userspace program.
@@ -1567,7 +1577,7 @@

config NFS_FS
tristate "NFS client support"
- depends on INET
+ depends on INET && FILE_LOCKING
select LOCKD
select SUNRPC
select NFS_ACL_SUPPORT if NFS_V3_ACL
@@ -1735,6 +1745,7 @@

config LOCKD
tristate
+ depends on FILE_LOCKING

config LOCKD_V4
bool
@@ -1870,6 +1881,7 @@
config CIFS
tristate "CIFS support (advanced network filesystem, SMBFS successor)"
depends on INET
+ depends on FILE_LOCKING
select NLS
help
This is the client VFS module for the Common Internet File System
@@ -2059,6 +2071,7 @@
config AFS_FS
tristate "Andrew File System support (AFS) (EXPERIMENTAL)"
depends on INET && EXPERIMENTAL
+ depends on FILE_LOCKING
select AF_RXRPC
help
If you say Y here, you will get an experimental Andrew File System
Index: linuxdev/fs/Makefile
===================================================================
--- linuxdev.orig/fs/Makefile
+++ linuxdev/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 \
seq_file.o xattr.o libfs.o fs-writeback.o \
pnode.o drop_caches.o splice.o sync.o utimes.o \
@@ -28,6 +28,7 @@
obj-$(CONFIG_TIMERFD) += timerfd.o
obj-$(CONFIG_EVENTFD) += eventfd.o
obj-$(CONFIG_AIO) += aio.o
+obj-$(CONFIG_FILE_LOCKING) += locks.o
obj-$(CONFIG_COMPAT) += compat.o compat_ioctl.o

nfsd-$(CONFIG_NFSD) := nfsctl.o
Index: linuxdev/fs/dlm/Kconfig
===================================================================
--- linuxdev.orig/fs/dlm/Kconfig
+++ linuxdev/fs/dlm/Kconfig
@@ -2,6 +2,7 @@
tristate "Distributed Lock Manager (DLM)"
depends on EXPERIMENTAL && INET
depends on SYSFS && (IPV6 || IPV6=n)
+ depends on FILE_LOCKING
select CONFIGFS_FS
select IP_SCTP
help
Index: linuxdev/fs/gfs2/Kconfig
===================================================================
--- linuxdev.orig/fs/gfs2/Kconfig
+++ linuxdev/fs/gfs2/Kconfig
@@ -1,6 +1,7 @@
config GFS2_FS
tristate "GFS2 file system support"
depends on EXPERIMENTAL && (64BIT || (LSF && LBD))
+ depends on FILE_LOCKING
select FS_POSIX_ACL
select CRC32
help
Index: linuxdev/fs/proc/proc_misc.c
===================================================================
--- linuxdev.orig/fs/proc/proc_misc.c
+++ linuxdev/fs/proc/proc_misc.c
@@ -677,6 +677,7 @@
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);
@@ -688,6 +689,7 @@
.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)
@@ -881,7 +883,9 @@
#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
Index: linuxdev/include/linux/fs.h
===================================================================
--- linuxdev.orig/include/linux/fs.h
+++ linuxdev/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 +1025,33 @@
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_remove_posix(a, b)
+#define locks_remove_flock(a)
+#define posix_test_lock(a, b) (0)
+#define posix_lock_file(a, b) (-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 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 +1583,12 @@
/* /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 +1619,6 @@
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 +1639,14 @@
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 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 */

Index: linuxdev/kernel/sys_ni.c
===================================================================
--- linuxdev.orig/kernel/sys_ni.c
+++ linuxdev/kernel/sys_ni.c
@@ -130,6 +130,7 @@
cond_syscall(sys_io_submit);
cond_syscall(sys_io_cancel);
cond_syscall(sys_io_getevents);
+cond_syscall(sys_flock);

/* arch-specific weak syscall entries */
cond_syscall(sys_pciconfig_read);
Index: linuxdev/kernel/sysctl.c
===================================================================
--- linuxdev.orig/kernel/sysctl.c
+++ linuxdev/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

@@ -1260,6 +1260,7 @@
.extra1 = &minolduid,
.extra2 = &maxolduid,
},
+#ifdef CONFIG_FILE_LOCKING
{
.ctl_name = FS_LEASES,
.procname = "leases-enable",
@@ -1268,6 +1269,7 @@
.mode = 0644,
.proc_handler = &proc_dointvec,
},
+#endif
#ifdef CONFIG_DNOTIFY
{
.ctl_name = FS_DIR_NOTIFY,
@@ -1279,6 +1281,7 @@
},
#endif
#ifdef CONFIG_MMU
+#ifdef CONFIG_FILE_LOCKING
{
.ctl_name = FS_LEASE_TIME,
.procname = "lease-break-time",
@@ -1290,6 +1293,7 @@
.extra1 = &zero,
.extra2 = &two,
},
+#endif /* CONFIG_FILE_LOCKING */
#ifdef CONFIG_AIO
{
.procname = "aio-nr",

--
Thomas Petazzoni, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com
--
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