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Date: Sat, 2 Aug 2008 12:38:48 -0400
From: "J. Bruce Fields" <bfields@...ldses.org>
To: Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Cc: linux-kernel@...r.kernel.org, linux-embedded@...r.kernel.org,
michael@...e-electrons.com, Matt Mackall <mpm@...enic.com>,
matthew@....cx, linux-fsdevel@...r.kernel.org,
akpm@...ux-foundation.org
Subject: Re: [patch 2/4] Configure out file locking features
On Thu, Jul 31, 2008 at 11:27:05AM +0200, Thomas Petazzoni wrote:
> 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:
Out of curiosity, why does the nfs client need disabling, but not nfsd,
gfs2, fuse, etc.?
--b.
>
> 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@...enic.com>, and is part of the Linux Tiny project.
>
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
> Signed-off-by: Matt Mackall <mpm@...enic.com>
> Cc: matthew@....cx
> Cc: linux-fsdevel@...r.kernel.org
> Cc: mpm@...enic.com
> Cc: akpm@...ux-foundation.org
>
> ---
> fs/Kconfig | 2 +-
> fs/Makefile | 3 ++-
> fs/proc/proc_misc.c | 4 ++++
> include/linux/fs.h | 52 +++++++++++++++++++++++++++++++++++++++++++++-------
> init/Kconfig | 8 ++++++++
> kernel/sys_ni.c | 1 +
> kernel/sysctl.c | 6 +++++-
> 7 files changed, 66 insertions(+), 10 deletions(-)
>
> Index: linuxdev/fs/Kconfig
> ===================================================================
> --- linuxdev.orig/fs/Kconfig
> +++ linuxdev/fs/Kconfig
> @@ -1559,7 +1559,7 @@
>
> 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
> 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/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/init/Kconfig
> ===================================================================
> --- linuxdev.orig/init/Kconfig
> +++ linuxdev/init/Kconfig
> @@ -732,6 +732,14 @@
> by some high performance threaded applications. Disabling
> this option saves about 7k.
>
> +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.
> +
> config VM_EVENT_COUNTERS
> default y
> bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
> 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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