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Commit ebf3f09c authored by Thomas Petazzoni's avatar Thomas Petazzoni Committed by Linus Torvalds
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Configure out AIO support 



This patchs adds the CONFIG_AIO option which allows to remove support
for asynchronous I/O operations, that are not necessarly used by
applications, particularly on embedded devices. As this is a
size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
save ~7 kilobytes of kernel code/data:

   text	   data	    bss	    dec	    hex	filename
1115067	 119180	 217088	1451335	 162547	vmlinux
1108025	 119048	 217088	1444161	 160941	vmlinux.new
  -7042    -132       0   -7174   -1C06 +/-

This patch has been originally written by Matt Mackall
<mpm@selenic.com>, and is part of the Linux Tiny project.

[randy.dunlap@oracle.com: build fix]
Signed-off-by: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Zach Brown <zach.brown@oracle.com>
Signed-off-by: default avatarMatt Mackall <mpm@selenic.com>
Signed-off-by: default avatarRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d8273674

fs/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -8,7 +8,7 @@ 
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 dcache.o inode.o \

		attr.o bad_inode.o file.o filesystems.o namespace.o aio.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 \

		stack.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_AIO)               += aio.o

obj-$(CONFIG_FILE_LOCKING)      += locks.o

obj-$(CONFIG_COMPAT)		+= compat.o compat_ioctl.o

include/linux/aio.h

+9 −0
Original line number Diff line number Diff line
@@ -204,12 +204,21 @@ struct kioctx { 
/* prototypes */

extern unsigned aio_max_size;



#ifdef CONFIG_AIO

extern ssize_t wait_on_sync_kiocb(struct kiocb *iocb);

extern int aio_put_req(struct kiocb *iocb);

extern void kick_iocb(struct kiocb *iocb);

extern int aio_complete(struct kiocb *iocb, long res, long res2);

struct mm_struct;

extern void exit_aio(struct mm_struct *mm);

#else

static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }

static inline int aio_put_req(struct kiocb *iocb) { return 0; }

static inline void kick_iocb(struct kiocb *iocb) { }

static inline int aio_complete(struct kiocb *iocb, long res, long res2) { return 0; }

struct mm_struct;

static inline void exit_aio(struct mm_struct *mm) { }

#endif /* CONFIG_AIO */



#define io_wait_to_kiocb(wait) container_of(wait, struct kiocb, ki_wait)

init/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -713,6 +713,14 @@ config SHMEM 
	  option replaces shmem and tmpfs with the much simpler ramfs code,

	  which may be appropriate on small systems without swap.



config AIO

	bool "Enable AIO support" if EMBEDDED

	default y

	help

	  This option enables POSIX asynchronous I/O which may by used

          by some high performance threaded applications. Disabling

          this option saves about 7k.



config VM_EVENT_COUNTERS

	default y

	bool "Enable VM event counters for /proc/vmstat" if EMBEDDED

kernel/sys_ni.c

+5 −0
Original line number Diff line number Diff line
@@ -126,6 +126,11 @@ cond_syscall(sys_vm86); 
cond_syscall(compat_sys_ipc);

cond_syscall(compat_sys_sysctl);

cond_syscall(sys_flock);

cond_syscall(sys_io_setup);

cond_syscall(sys_io_destroy);

cond_syscall(sys_io_submit);

cond_syscall(sys_io_cancel);

cond_syscall(sys_io_getevents);



/* arch-specific weak syscall entries */

cond_syscall(sys_pciconfig_read);

kernel/sysctl.c

+2 −0
Original line number Diff line number Diff line
@@ -1281,6 +1281,7 @@ static struct ctl_table fs_table[] = { 
		.extra2		= &two,

	},

#endif

#ifdef CONFIG_AIO

	{

		.procname	= "aio-nr",

		.data		= &aio_nr,
@@ -1295,6 +1296,7 @@ static struct ctl_table fs_table[] = { 
		.mode		= 0644,

		.proc_handler	= &proc_doulongvec_minmax,

	},

#endif /* CONFIG_AIO */

#ifdef CONFIG_INOTIFY_USER

	{

		.ctl_name	= FS_INOTIFY,