Migration code currently does not take a reference to target page
properly, so between unlocking the pte and trying to take a new
reference to the page with isolate_lru_page, anything could happen to
it.

Fix this by holding the pte lock until we get a chance to elevate the
refcount.

Other small cleanups while we're here.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

- Move capable() from sched.h to capability.h;

- Use <linux/capability.h> where capable() is used
	(in include/, block/, ipc/, kernel/, a few drivers/,
	mm/, security/, & sound/;
	many more drivers/ to go)

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

To allow various options to work per-mount instead of per-sb we need a
struct vfsmount when updating ctime and mtime.  This preparation patch
replaces the inode_update_time routine with a file_update_atime routine so
we can easily get at the vfsmount.  (and the file makes more sense in this
context anyway).  Also get rid of the unused second argument - we always
want to update the ctime when calling this routine.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Anton Altaparmakov <aia21@cantab.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

This patch converts the inode semaphore to a mutex. I have tested it on
XFS and compiled as much as one can consider on an ia64. Anyway your
luck with it might be different.

Modified-by: Ingo Molnar <mingo@elte.hu>

(finished the conversion)

Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

This patch add EXPORT_SYMBOL(filemap_write_and_wait) and use it.

See mm/filemap.c:

And changes the filemap_write_and_wait() and filemap_write_and_wait_range().

Current filemap_write_and_wait() doesn't wait if filemap_fdatawrite()
returns error.  However, even if filemap_fdatawrite() returned an
error, it may have submitted the partially data pages to the device.
(e.g. in the case of -ENOSPC)

<quotation>
Andrew Morton writes,

If filemap_fdatawrite() returns an error, this might be due to some
I/O problem: dead disk, unplugged cable, etc.  Given the generally
crappy quality of the kernel's handling of such exceptions, there's a
good chance that the filemap_fdatawait() will get stuck in D state
forever.
</quotation>

So, this patch doesn't wait if filemap_fdatawrite() returns the -EIO.

Trond, could you please review the nfs part?  Especially I'm not sure,
nfs must use the "filemap_fdatawrite(inode->i_mapping) == 0", or not.

Acked-by: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

This exports/changes the sync_page_range/_nolock().  The fatfs needs
sync_page_range/_nolock() for expanding truncate, and changes "size_t count"
to "loff_t count".

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

As find_lock_page() already checks with TestSetPageLocked() that page is
locked, there is no need to call lock_page() that will try-lock page again
(chances of page being unlocked in between are small).  Call __lock_page()
directly, this saves one atomic operation.

Also, mark truncate-while-slept path as unlikely while we are here.

(akpm: ug.  But this is actually a common path for normal old read()s against
a page which is under readahead I/O so ho-hum.)

Signed-off-by: Nikita Danilov <danilov@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

readpage(), prepare_write(), and commit_write() callers are updated to
understand the special return code AOP_TRUNCATED_PAGE in the style of
writepage() and WRITEPAGE_ACTIVATE.  AOP_TRUNCATED_PAGE tells the caller that
the callee has unlocked the page and that the operation should be tried again
with a new page.  OCFS2 uses this to detect and work around a lock inversion in
its aop methods.  There should be no change in behaviour for methods that don't
return AOP_TRUNCATED_PAGE.

WRITEPAGE_ACTIVATE is also prepended with AOP_ for consistency and they are
made enums so that kerneldoc can be used to document their semantics.

Signed-off-by: Zach Brown <zach.brown@oracle.com>

Has been introduced for x86-64 at some point to save memory
in struct page, but has been obsolete for some time. Just
remove it.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

When __generic_file_aio_read() hits an error during reading, it reports the
error iff nothing has successfully been read yet.  This is condition - when
an error occurs, if nothing has been read/written, report the error code;
otherwise, report the amount of bytes successfully transferred upto that
point.

This corner case can be exposed by performing readv(2) with the following
iov.

 iov[0] = len0 @ ptr0
 iov[1] = len1 @ NULL (or any other invalid pointer)
 iov[2] = len2 @ ptr2

When file size is enough, performing above readv(2) results in

 len0 bytes from file_pos @ ptr0
 len2 bytes from file_pos + len0 @ ptr2

And the return value is len0 + len2.  Test program is attached to this
mail.

This patch makes __generic_file_aio_read()'s error handling identical to
other functions.

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/uio.h>
#include <errno.h>
#include <string.h>

int main(int argc, char **argv)
{
	const char *path;
	struct stat stbuf;
	size_t len0, len1;
	void *buf0, *buf1;
	struct iovec iov[3];
	int fd, i;
	ssize_t ret;

	if (argc < 2) {
		fprintf(stderr, "Usage: testreadv path (better be a "
			"small text file)\n");
		return 1;
	}
	path = argv[1];

	if (stat(path, &stbuf) < 0) {
		perror("stat");
		return 1;
	}

	len0 = stbuf.st_size / 2;
	len1 = stbuf.st_size - len0;

	if (!len0 || !len1) {
		fprintf(stderr, "Dude, file is too small\n");
		return 1;
	}

	if ((fd = open(path, O_RDONLY)) < 0) {
		perror("open");
		return 1;
	}

	if (!(buf0 = malloc(len0)) || !(buf1 = malloc(len1))) {
		perror("malloc");
		return 1;
	}

	memset(buf0, 0, len0);
	memset(buf1, 0, len1);

	iov[0].iov_base = buf0;
	iov[0].iov_len = len0;
	iov[1].iov_base = NULL;
	iov[1].iov_len = len1;
	iov[2].iov_base = buf1;
	iov[2].iov_len = len1;

	printf("vector ");
	for (i = 0; i < 3; i++)
		printf("%p:%zu ", iov[i].iov_base, iov[i].iov_len);
	printf("\n");

	ret = readv(fd, iov, 3);
	if (ret < 0)
		perror("readv");

	printf("readv returned %zd\nbuf0 = [%s]\nbuf1 = [%s]\n",
	       ret, (char *)buf0, (char *)buf1);

	return 0;
}

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>