People started using eventfd in a semaphore-like way where before they
were using pipes.

That is, counter-based resource access.  Where a "wait()" returns
immediately by decrementing the counter by one, if counter is greater than
zero.  Otherwise will wait.  And where a "post(count)" will add count to
the counter releasing the appropriate amount of waiters.  If eventfd the
"post" (write) part is fine, while the "wait" (read) does not dequeue 1,
but the whole counter value.

The problem with eventfd is that a read() on the fd returns and wipes the
whole counter, making the use of it as semaphore a little bit more
cumbersome.  You can do a read() followed by a write() of COUNTER-1, but
IMO it's pretty easy and cheap to make this work w/out extra steps.  This
patch introduces a new eventfd flag that tells eventfd to only dequeue 1
from the counter, allowing simple read/write to make it behave like a
semaphore.  Simple test here:

http://www.xmailserver.org/eventfd-sem.c

To be back-compatible with earlier kernels, userspace applications should
probe for the availability of this feature via

#ifdef EFD_SEMAPHORE
	fd = eventfd2 (CNT, EFD_SEMAPHORE);
	if (fd == -1 && errno == EINVAL)
		<fallback>
#else
		<fallback>
#endif
Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
Cc: <linux-api@vger.kernel.org>
Tested-by: NMichael Kerrisk <mtk.manpages@gmail.com>
Cc: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

eventpoll.c uses void * in one place for no obvious reason; change it to
use the real type instead.
Signed-off-by: NTony Battersby <tonyb@cybernetics.com>
Acked-by: NDavide Libenzi <davidel@xmailserver.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

ep_modify() doesn't need to set event.data from within the ep->lock
spinlock as the comment suggests.  The only place event.data is used is
ep_send_events_proc(), and this is protected by ep->mtx instead of
ep->lock.  Also update the comment for mutex_lock() at the top of
ep_scan_ready_list(), which mentions epoll_ctl(EPOLL_CTL_DEL) but not
epoll_ctl(EPOLL_CTL_MOD).

ep_modify() can also use spin_lock_irq() instead of spin_lock_irqsave().
Signed-off-by: NTony Battersby <tonyb@cybernetics.com>
Acked-by: NDavide Libenzi <davidel@xmailserver.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

xchg in ep_unregister_pollwait() is unnecessary because it is protected by
either epmutex or ep->mtx (the same protection as ep_remove()).

If xchg was necessary, it would be insufficient to protect against
problems: if multiple concurrent calls to ep_unregister_pollwait() were
possible then a second caller that returns without doing anything because
nwait == 0 could return before the waitqueues are removed by the first
caller, which looks like it could lead to problematic races with
ep_poll_callback().

So remove xchg and add comments about the locking.
Signed-off-by: NTony Battersby <tonyb@cybernetics.com>
Acked-by: NDavide Libenzi <davidel@xmailserver.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If epoll_wait returns -EFAULT, the event that was being returned when the
fault was encountered will be forgotten.  This is not a big deal since
EFAULT will happen only if a buggy userspace program passes in a bad
address, in which case what happens later usually doesn't matter.
However, it is easy to remember the event for later, and this patch makes
a simple change to do that.
Signed-off-by: NTony Battersby <tonyb@cybernetics.com>
Acked-by: NDavide Libenzi <davidel@xmailserver.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

ep_call_nested() (formerly ep_poll_safewake()) uses "current" (without
dereferencing it) to detect callback recursion, but it may be called from
irq context where the use of current is generally discouraged.  It would
be better to use get_cpu() and put_cpu() to detect the callback recursion.
Signed-off-by: NTony Battersby <tonyb@cybernetics.com>
Acked-by: NDavide Libenzi <davidel@xmailserver.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove debugging code from epoll.  There's no need for it to be included
into mainline code.
Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
Cc: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix a bug inside the epoll's f_op->poll() code, that returns POLLIN even
though there are no actual ready monitored fds.  The bug shows up if you
add an epoll fd inside another fd container (poll, select, epoll).

The problem is that callback-based wake ups used by epoll does not carry
(patches will follow, to fix this) any information about the events that
actually happened.  So the callback code, since it can't call the file*
->poll() inside the callback, chains the file* into a ready-list.

So, suppose you added an fd with EPOLLOUT only, and some data shows up on
the fd, the file* mapped by the fd will be added into the ready-list (via
wakeup callback).  During normal epoll_wait() use, this condition is
sorted out at the time we're actually able to call the file*'s
f_op->poll().

Inside the old epoll's f_op->poll() though, only a quick check
!list_empty(ready-list) was performed, and this could have led to
reporting POLLIN even though no ready fds would show up at a following
epoll_wait().  In order to correctly report the ready status for an epoll
fd, the ready-list must be checked to see if any really available fd+event
would be ready in a following epoll_wait().

Operation (calling f_op->poll() from inside f_op->poll()) that, like wake
ups, must be handled with care because of the fact that epoll fds can be
added to other epoll fds.

Test code:

/*
 *  epoll_test by Davide Libenzi (Simple code to test epoll internals)
 *  Copyright (C) 2008  Davide Libenzi
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  Davide Libenzi <davidel@xmailserver.org>
 *
 */

#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <signal.h>
#include <limits.h>
#include <poll.h>
#include <sys/epoll.h>
#include <sys/wait.h>

#define EPWAIT_TIMEO	(1 * 1000)
#ifndef POLLRDHUP
#define POLLRDHUP 0x2000
#endif

#define EPOLL_MAX_CHAIN	100L

#define EPOLL_TF_LOOP (1 << 0)

struct epoll_test_cfg {
	long size;
	long flags;
};

static int xepoll_create(int n) {
	int epfd;

	if ((epfd = epoll_create(n)) == -1) {
		perror("epoll_create");
		exit(2);
	}

	return epfd;
}

static void xepoll_ctl(int epfd, int cmd, int fd, struct epoll_event *evt) {
	if (epoll_ctl(epfd, cmd, fd, evt) < 0) {
		perror("epoll_ctl");
		exit(3);
	}
}

static void xpipe(int *fds) {
	if (pipe(fds)) {
		perror("pipe");
		exit(4);
	}
}

static pid_t xfork(void) {
	pid_t pid;

	if ((pid = fork()) == (pid_t) -1) {
		perror("pipe");
		exit(5);
	}

	return pid;
}

static int run_forked_proc(int (*proc)(void *), void *data) {
	int status;
	pid_t pid;

	if ((pid = xfork()) == 0)
		exit((*proc)(data));
	if (waitpid(pid, &status, 0) != pid) {
		perror("waitpid");
		return -1;
	}

	return WIFEXITED(status) ? WEXITSTATUS(status): -2;
}

static int check_events(int fd, int timeo) {
	struct pollfd pfd;

	fprintf(stdout, "Checking events for fd %d\n", fd);
	memset(&pfd, 0, sizeof(pfd));
	pfd.fd = fd;
	pfd.events = POLLIN | POLLOUT;
	if (poll(&pfd, 1, timeo) < 0) {
		perror("poll()");
		return 0;
	}
	if (pfd.revents & POLLIN)
		fprintf(stdout, "\tPOLLIN\n");
	if (pfd.revents & POLLOUT)
		fprintf(stdout, "\tPOLLOUT\n");
	if (pfd.revents & POLLERR)
		fprintf(stdout, "\tPOLLERR\n");
	if (pfd.revents & POLLHUP)
		fprintf(stdout, "\tPOLLHUP\n");
	if (pfd.revents & POLLRDHUP)
		fprintf(stdout, "\tPOLLRDHUP\n");

	return pfd.revents;
}

static int epoll_test_tty(void *data) {
	int epfd, ifd = fileno(stdin), res;
	struct epoll_event evt;

	if (check_events(ifd, 0) != POLLOUT) {
		fprintf(stderr, "Something is cooking on STDIN (%d)\n", ifd);
		return 1;
	}
	epfd = xepoll_create(1);
	fprintf(stdout, "Created epoll fd (%d)\n", epfd);
	memset(&evt, 0, sizeof(evt));
	evt.events = EPOLLIN;
	xepoll_ctl(epfd, EPOLL_CTL_ADD, ifd, &evt);
	if (check_events(epfd, 0) & POLLIN) {
		res = epoll_wait(epfd, &evt, 1, 0);
		if (res == 0) {
			fprintf(stderr, "Epoll fd (%d) is ready when it shouldn't!\n",
				epfd);
			return 2;
		}
	}

	return 0;
}

static int epoll_wakeup_chain(void *data) {
	struct epoll_test_cfg *tcfg = data;
	int i, res, epfd, bfd, nfd, pfds[2];
	pid_t pid;
	struct epoll_event evt;

	memset(&evt, 0, sizeof(evt));
	evt.events = EPOLLIN;

	epfd = bfd = xepoll_create(1);

	for (i = 0; i < tcfg->size; i++) {
		nfd = xepoll_create(1);
		xepoll_ctl(bfd, EPOLL_CTL_ADD, nfd, &evt);
		bfd = nfd;
	}
	xpipe(pfds);
	if (tcfg->flags & EPOLL_TF_LOOP)
	{
		xepoll_ctl(bfd, EPOLL_CTL_ADD, epfd, &evt);
		/*
		 * If we're testing for loop, we want that the wakeup
		 * triggered by the write to the pipe done in the child
		 * process, triggers a fake event. So we add the pipe
		 * read size with EPOLLOUT events. This will trigger
		 * an addition to the ready-list, but no real events
		 * will be there. The the epoll kernel code will proceed
		 * in calling f_op->poll() of the epfd, triggering the
		 * loop we want to test.
		 */
		evt.events = EPOLLOUT;
	}
	xepoll_ctl(bfd, EPOLL_CTL_ADD, pfds[0], &evt);

	/*
	 * The pipe write must come after the poll(2) call inside
	 * check_events(). This tests the nested wakeup code in
	 * fs/eventpoll.c:ep_poll_safewake()
	 * By having the check_events() (hence poll(2)) happens first,
	 * we have poll wait queue filled up, and the write(2) in the
	 * child will trigger the wakeup chain.
	 */
	if ((pid = xfork()) == 0) {
		sleep(1);
		write(pfds[1], "w", 1);
		exit(0);
	}

	res = check_events(epfd, 2000) & POLLIN;

	if (waitpid(pid, NULL, 0) != pid) {
		perror("waitpid");
		return -1;
	}

	return res;
}

static int epoll_poll_chain(void *data) {
	struct epoll_test_cfg *tcfg = data;
	int i, res, epfd, bfd, nfd, pfds[2];
	pid_t pid;
	struct epoll_event evt;

	memset(&evt, 0, sizeof(evt));
	evt.events = EPOLLIN;

	epfd = bfd = xepoll_create(1);

	for (i = 0; i < tcfg->size; i++) {
		nfd = xepoll_create(1);
		xepoll_ctl(bfd, EPOLL_CTL_ADD, nfd, &evt);
		bfd = nfd;
	}
	xpipe(pfds);
	if (tcfg->flags & EPOLL_TF_LOOP)
	{
		xepoll_ctl(bfd, EPOLL_CTL_ADD, epfd, &evt);
		/*
		 * If we're testing for loop, we want that the wakeup
		 * triggered by the write to the pipe done in the child
		 * process, triggers a fake event. So we add the pipe
		 * read size with EPOLLOUT events. This will trigger
		 * an addition to the ready-list, but no real events
		 * will be there. The the epoll kernel code will proceed
		 * in calling f_op->poll() of the epfd, triggering the
		 * loop we want to test.
		 */
		evt.events = EPOLLOUT;
	}
	xepoll_ctl(bfd, EPOLL_CTL_ADD, pfds[0], &evt);

	/*
	 * The pipe write mush come before the poll(2) call inside
	 * check_events(). This tests the nested f_op->poll calls code in
	 * fs/eventpoll.c:ep_eventpoll_poll()
	 * By having the pipe write(2) happen first, we make the kernel
	 * epoll code to load the ready lists, and the following poll(2)
	 * done inside check_events() will test nested poll code in
	 * ep_eventpoll_poll().
	 */
	if ((pid = xfork()) == 0) {
		write(pfds[1], "w", 1);
		exit(0);
	}
	sleep(1);
	res = check_events(epfd, 1000) & POLLIN;

	if (waitpid(pid, NULL, 0) != pid) {
		perror("waitpid");
		return -1;
	}

	return res;
}

int main(int ac, char **av) {
	int error;
	struct epoll_test_cfg tcfg;

	fprintf(stdout, "\n********** Testing TTY events\n");
	error = run_forked_proc(epoll_test_tty, NULL);
	fprintf(stdout, error == 0 ?
		"********** OK\n": "********** FAIL (%d)\n", error);

	tcfg.size = 3;
	tcfg.flags = 0;
	fprintf(stdout, "\n********** Testing short wakeup chain\n");
	error = run_forked_proc(epoll_wakeup_chain, &tcfg);
	fprintf(stdout, error == POLLIN ?
		"********** OK\n": "********** FAIL (%d)\n", error);

	tcfg.size = EPOLL_MAX_CHAIN;
	tcfg.flags = 0;
	fprintf(stdout, "\n********** Testing long wakeup chain (HOLD ON)\n");
	error = run_forked_proc(epoll_wakeup_chain, &tcfg);
	fprintf(stdout, error == 0 ?
		"********** OK\n": "********** FAIL (%d)\n", error);

	tcfg.size = 3;
	tcfg.flags = 0;
	fprintf(stdout, "\n********** Testing short poll chain\n");
	error = run_forked_proc(epoll_poll_chain, &tcfg);
	fprintf(stdout, error == POLLIN ?
		"********** OK\n": "********** FAIL (%d)\n", error);

	tcfg.size = EPOLL_MAX_CHAIN;
	tcfg.flags = 0;
	fprintf(stdout, "\n********** Testing long poll chain (HOLD ON)\n");
	error = run_forked_proc(epoll_poll_chain, &tcfg);
	fprintf(stdout, error == 0 ?
		"********** OK\n": "********** FAIL (%d)\n", error);

	tcfg.size = 3;
	tcfg.flags = EPOLL_TF_LOOP;
	fprintf(stdout, "\n********** Testing loopy wakeup chain (HOLD ON)\n");
	error = run_forked_proc(epoll_wakeup_chain, &tcfg);
	fprintf(stdout, error == 0 ?
		"********** OK\n": "********** FAIL (%d)\n", error);

	tcfg.size = 3;
	tcfg.flags = EPOLL_TF_LOOP;
	fprintf(stdout, "\n********** Testing loopy poll chain (HOLD ON)\n");
	error = run_forked_proc(epoll_poll_chain, &tcfg);
	fprintf(stdout, error == 0 ?
		"********** OK\n": "********** FAIL (%d)\n", error);

	return 0;
}
Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
Cc: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a driver for Intersil's ISL29003 ambient light sensor device plus some
documentation.  Inspired by tsl2550.c, a driver for a similar device.

It is put in drivers/misc for now until the industrial I/O framework gets
merged.
Signed-off-by: NDaniel Mack <daniel@caiaq.de>
Acked-by: NJonathan Cameron <jic23@cam.ac.uk>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Change hpilo open and close logic to spin for 10usec between checking device,
rather than every usec.

Because the loop is coded to take up to 10ms, it seemed prudent to
increase the interval between polling the device, to reduce the load on
the system and allow more other work to happen.
Signed-off-by: NDavid Altobelli <david.altobelli@hp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The base versions handle constant folding now and are shorter than these
private wrappers, use them directly.
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Cc: Anton Altaparmakov <aia21@cantab.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We cover all log-levels by pr_...  macros except KERN_CONT one.  Add it
for convenience.
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Impact: Attribute function 'init_post' with __releases(...).

Fix these sparse warnings:
  init/main.c:805:21: warning: context imbalance in 'init_post' - unexpected unlock
  init/main.c:899:9: warning: context imbalance in 'kernel_init' - wrong count at exit
Signed-off-by: NHannes Eder <hannes@hanneseder.net>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The GPIO API is supposed to return 0 or a negative error code,
but the SSB GPIO functions return the bitmask of the GPIO register.
Fix this by ignoring the bitmask and always returning 0. The SSB GPIO functions can't fail.
Signed-off-by: NMichael Buesch <mb@bu3sch.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove PARPORT dependency for Auxiliary Display support.

This is not needed since the dependency for the KS0108 driver is
PARPORT_PC.
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Miguel Ojeda Sandonis <miguel.ojeda.sandonis@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Now that the filesystem freeze operation has been elevated to the VFS, and
is just an ioctl away, some sort of safety net for unintentionally frozen
root filesystems may be in order.

The timeout thaw originally proposed did not get merged, but perhaps
something like this would be useful in emergencies.

For example, freeze /path/to/mountpoint may freeze your root filesystem if
you forgot that you had that unmounted.

I chose 'j' as the last remaining character other than 'h' which is sort
of reserved for help (because help is generated on any unknown character).

I've tested this on a non-root fs with multiple (nested) freezers, as well
as on a system rendered unresponsive due to a frozen root fs.

[randy.dunlap@oracle.com: emergency thaw only if CONFIG_BLOCK enabled]
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Cc: Takashi Sato <t-sato@yk.jp.nec.com>
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Tfour 4 redundant if-conditions in function __rb_erase_color() in
lib/rbtree.c are removed.

In pseudo-source-code, the structure of the code is as follows:

if ((!A || B) && (!C || D)) {
	.
	.
	.
} else {
	if (!C || D) {//if this is true, it implies: (A == true) && (B == false)
		if (A) {//hence this always evaluates to 'true'...
			.
		}
		.
		//at this point, C always becomes true, because of:
		__rb_rotate_right/left();
		//and:
		other = parent->rb_right/left;
	}
	.
	.
	if (C) {//...and this too !
		.
	}
}
Signed-off-by: NWolfram Strepp <wstrepp@gmx.de>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add the ability to 'resize' the loop device on the fly.

One practical application is a loop file with XFS filesystem, already
mounted: You can easily enlarge the file (append some bytes) and then call
ioctl(fd, LOOP_SET_CAPACITY, new); The loop driver will learn about the
new size and you can use xfs_growfs later on, which will allow you to use
full capacity of the loop file without the need to unmount.

Test app:

#include <linux/fs.h>
#include <linux/loop.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define _GNU_SOURCE
#include <getopt.h>

char *me;

void usage(FILE *f)
{
	fprintf(f, "%s [options] loop_dev [backend_file]\n"
		"-s, --set new_size_in_bytes\n"
		"\twhen backend_file is given, "
		"it will be expanded too while keeping the original contents\n",
		me);
}

struct option opts[] = {
	{
		.name		= "set",
		.has_arg	= 1,
		.flag		= NULL,
		.val		= 's'
	},
	{
		.name		= "help",
		.has_arg	= 0,
		.flag		= NULL,
		.val		= 'h'
	}
};

void err_size(char *name, __u64 old)
{
	fprintf(stderr, "size must be larger than current %s (%llu)\n",
		name, old);
}

int main(int argc, char *argv[])
{
	int fd, err, c, i, bfd;
	ssize_t ssz;
	size_t sz;
	__u64 old, new, append;
	char a[BUFSIZ];
	struct stat st;
	FILE *out;
	char *backend, *dev;

	err = EINVAL;
	out = stderr;
	me = argv[0];
	new = 0;
	while ((c = getopt_long(argc, argv, "s:h", opts, &i)) != -1) {
		switch (c) {
		case 's':
			errno = 0;
			new = strtoull(optarg, NULL, 0);
			if (errno) {
				err = errno;
				perror(argv[i]);
				goto out;
			}
			break;

		case 'h':
			err = 0;
			out = stdout;
			goto err;

		default:
			perror(argv[i]);
			goto err;
		}
	}

	if (optind < argc)
		dev = argv[optind++];
	else
		goto err;

	fd = open(dev, O_RDONLY);
	if (fd < 0) {
		err = errno;
		perror(dev);
		goto out;
	}

	err = ioctl(fd, BLKGETSIZE64, &old);
	if (err) {
		err = errno;
		perror("ioctl BLKGETSIZE64");
		goto out;
	}

	if (!new) {
		printf("%llu\n", old);
		goto out;
	}

	if (new < old) {
		err = EINVAL;
		err_size(dev, old);
		goto out;
	}

	if (optind < argc) {
		backend = argv[optind++];
		bfd = open(backend, O_WRONLY|O_APPEND);
		if (bfd < 0) {
			err = errno;
			perror(backend);
			goto out;
		}
		err = fstat(bfd, &st);
		if (err) {
			err = errno;
			perror(backend);
			goto out;
		}
		if (new < st.st_size) {
			err = EINVAL;
			err_size(backend, st.st_size);
			goto out;
		}
		append = new - st.st_size;
		sz = sizeof(a);
		while (append > 0) {
			if (append < sz)
				sz = append;
			ssz = write(bfd, a, sz);
			if (ssz != sz) {
				err = errno;
				perror(backend);
				goto out;
			}
			append -= sz;
		}
		err = fsync(bfd);
		if (err) {
			err = errno;
			perror(backend);
			goto out;
		}
	}

	err = ioctl(fd, LOOP_SET_CAPACITY, new);
	if (err) {
		err = errno;
		perror("ioctl LOOP_SET_CAPACITY");
	}
	goto out;

 err:
	usage(out);
 out:
	return err;
}
Signed-off-by: NJ. R. Okajima <hooanon05@yahoo.co.jp>
Signed-off-by: NTomas Matejicek <tomas@slax.org>
Cc: <util-linux-ng@vger.kernel.org>
Cc: Karel Zak <kzak@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: <linux-api@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

These comments are useless now, remove them.
Signed-off-by: NWANG Cong <xiyou.wangcong@gmail.com>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

These error messages are from check_sysemu(), not check_ptrace().
Signed-off-by: NWANG Cong <xiyou.wangcong@gmail.com>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

uml uses a concatenated string literal to store the contents of .config,
but .config file content is varaible, it can be very long.

Use an array of string literals instead.
Signed-off-by: NWANG Cong <xiyou.wangcong@gmail.com>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

MAJOR_NR isn't needed anymore since very early 2.5 kernels.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove unused/duplicate cruft from asm/suspend.h:

 - x86_32: remove unused acpi code
 - powerpc: remove duplicate prototypes, see linux/suspend.h
Signed-off-by: NMagnus Damm <damm@igel.co.jp>
Cc: Paul Mundt <lethal@linux-sh.org>
Acked-by: N"Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make the following header file changes:

 - remove arch ifdefs and asm/suspend.h from linux/suspend.h
 - add asm/suspend.h to disk.c (for arch_prepare_suspend())
 - add linux/io.h to swsusp.c (for ioremap())
 - x86 32/64 bit compile fixes
Signed-off-by: NMagnus Damm <damm@igel.co.jp>
Cc: Paul Mundt <lethal@linux-sh.org>
Acked-by: N"Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Convert alpha architecture to use u64 as unsigned long long.  This is
being done so that (a) all arches use u64 as unsigned long long and (b)
printk of a u64 as %ll[ux] will not generate format warnings by gcc.

The only gcc cross-compiler that I have is 4.0.2, which generates errors
about miscompiling __weak references, so I have commented out that line in
compiler-gcc4.h so that most of these compile, but more builds and real
machine testing would be Real Good.

[akpm@linux-foundation.org: fix warning]
[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
From: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

- "_local" versions of xchg/cmpxchg functions duplicate code
  of non-local ones (quite a few pages of assembler), except
  memory barriers. We can generate these two variants from a
  single header file using simple macros;

- convert xchg macro back to inline function using always_inline
  attribute;

- use proper argument types for cmpxchg_u8/u16 functions
  to fix a problem with negative arguments.
Signed-off-by: NIvan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NCheng Renquan <crquan@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When this macros isn't called with 'fixup', e.g.  with foo this will
incorectly expand to foo->foo.bits.errreg
Signed-off-by: NRoel Kluin <roel.kluin@gmail.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Synopsis: if shmem_writepage calls swap_writepage directly, most shmem
swap loads benefit, and a catastrophic interaction between SLUB and some
flash storage is avoided.

shmem_writepage() has always been peculiar in making no attempt to write:
it has just transferred a shmem page from file cache to swap cache, then
let that page make its way around the LRU again before being written and
freed.

The idea was that people use tmpfs because they want those pages to stay
in RAM; so although we give it an overflow to swap, we should resist
writing too soon, giving those pages a second chance before they can be
reclaimed.

That was always questionable, and I've toyed with this patch for years;
but never had a clear justification to depart from the original design.

It became more questionable in 2.6.28, when the split LRU patches classed
shmem and tmpfs pages as SwapBacked rather than as file_cache: that in
itself gives them more resistance to reclaim than normal file pages.  I
prepared this patch for 2.6.29, but the merge window arrived before I'd
completed gathering statistics to justify sending it in.

Then while comparing SLQB against SLUB, running SLUB on a laptop I'd
habitually used with SLAB, I found SLUB to run my tmpfs kbuild swapping
tests five times slower than SLAB or SLQB - other machines slower too, but
nowhere near so bad.  Simpler "cp -a" swapping tests showed the same.

slub_max_order=0 brings sanity to all, but heavy swapping is too far from
normal to justify such a tuning.  The crucial factor on that laptop turns
out to be that I'm using an SD card for swap.  What happens is this:

By default, SLUB uses order-2 pages for shmem_inode_cache (and many other
fs inodes), so creating tmpfs files under memory pressure brings lumpy
reclaim into play.  One subpage of the order is chosen from the bottom of
the LRU as usual, then the other three picked out from their random
positions on the LRUs.

In a tmpfs load, many of these pages will be ones which already passed
through shmem_writepage, so already have swap allocated.  And though their
offsets on swap were probably allocated sequentially, now that the pages
are picked off at random, their swap offsets are scattered.

But the flash storage on the SD card is very sensitive to having its
writes merged: once swap is written at scattered offsets, performance
falls apart.  Rotating disk seeks increase too, but less disastrously.

So: stop giving shmem/tmpfs pages a second pass around the LRU, write them
out to swap as soon as their swap has been allocated.

It's surely possible to devise an artificial load which runs faster the
old way, one whose sizing is such that the tmpfs pages on their second
pass are the ones that are wanted again, and other pages not.

But I've not yet found such a load: on all machines, under the loads I've
tried, immediate swap_writepage speeds up shmem swapping: especially when
using the SLUB allocator (and more effectively than slub_max_order=0), but
also with the others; and it also reduces the variance between runs.  How
much faster varies widely: a factor of five is rare, 5% is common.

One load which might have suffered: imagine a swapping shmem load in a
limited mem_cgroup on a machine with plenty of memory.  Before 2.6.29 the
swapcache was not charged, and such a load would have run quickest with
the shmem swapcache never written to swap.  But now swapcache is charged,
so even this load benefits from shmem_writepage directly to swap.

Apologies for the #ifndef CONFIG_SWAP swap_writepage() stub in swap.h:
it's silly because that will never get called; but refactoring shmem.c
sensibly according to CONFIG_SWAP will be a separate task.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Acked-by: NPekka Enberg <penberg@cs.helsinki.fi>
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

try_to_free_pages() is used for the direct reclaim of up to
SWAP_CLUSTER_MAX pages when watermarks are low.  The caller to
alloc_pages_nodemask() can specify a nodemask of nodes that are allowed to
be used but this is not passed to try_to_free_pages().  This can lead to
unnecessary reclaim of pages that are unusable by the caller and int the
worst case lead to allocation failure as progress was not been make where
it is needed.

This patch passes the nodemask used for alloc_pages_nodemask() to
try_to_free_pages().
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Instead of open-coding the lru-list-add pagevec batching when expanding a
file mapping from zero, defer to the appropriate page cache function that
also takes care of adding the page to the lru list.

This is cleaner, saves code and reduces the stack footprint by 16 words
worth of pagevec.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NDavid Howells <dhowells@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Acked-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.com>
Cc: MinChan Kim <minchan.kim@gmail.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Greg Ungerer <gerg@snapgear.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When a shrinker has a negative number of objects to delete, the symbol
name of the shrinker should be printed, not shrink_slab.  This also makes
the error message slightly more informative.

Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make CONFIG_UNEVICTABLE_LRU available when CONFIG_MMU=n.  There's no logical
reason it shouldn't be available, and it can be used for ramfs.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Greg Ungerer <gerg@snapgear.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Enrik Berkhan <Enrik.Berkhan@ge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The mlock() facility does not exist for NOMMU since all mappings are
effectively locked anyway, so we don't make the bits available when
they're not useful.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Greg Ungerer <gerg@snapgear.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Enrik Berkhan <Enrik.Berkhan@ge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use debug_kmap_atomic in kmap_atomic, kmap_atomic_pfn, and
iomap_atomic_prot_pfn.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

x86 has debug_kmap_atomic_prot() which is error checking function for
kmap_atomic.  It is usefull for the other architectures, although it needs
CONFIG_TRACE_IRQFLAGS_SUPPORT.

This patch exposes it to the other architectures.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix warnings and return values in sysfs bin_page_mkwrite(), fixing
fs/sysfs/bin.c: In function `bin_page_mkwrite':
fs/sysfs/bin.c:250: warning: passing argument 2 of `bb->vm_ops->page_mkwrite' from incompatible pointer type
fs/sysfs/bin.c: At top level:
fs/sysfs/bin.c:280: warning: initialization from incompatible pointer type

Expects to have my [PATCH next] sysfs: fix some bin_vm_ops errors
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: "Eric W. Biederman" <ebiederm@aristanetworks.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

page_mkwrite is called with neither the page lock nor the ptl held.  This
means a page can be concurrently truncated or invalidated out from
underneath it.  Callers are supposed to prevent truncate races themselves,
however previously the only thing they can do in case they hit one is to
raise a SIGBUS.  A sigbus is wrong for the case that the page has been
invalidated or truncated within i_size (eg.  hole punched).  Callers may
also have to perform memory allocations in this path, where again, SIGBUS
would be wrong.

The previous patch ("mm: page_mkwrite change prototype to match fault")
made it possible to properly specify errors.  Convert the generic buffer.c
code and btrfs to return sane error values (in the case of page removed
from pagecache, VM_FAULT_NOPAGE will cause the fault handler to exit
without doing anything, and the fault will be retried properly).

This fixes core code, and converts btrfs as a template/example.  All other
filesystems defining their own page_mkwrite should be fixed in a similar
manner.
Acked-by: NChris Mason <chris.mason@oracle.com>
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>