linux.git/mm/filemap.c, branch v2.6.24

Do dirty page accounting when removing a page from the page cache

2007-12-19T22:05:13+00:00

Krzysztof Oledzki noticed a dirty page accounting leak on some of his
machines, causing the machine to eventually lock up when the kernel
decided that there was too much dirty data, but nobody could actually
write anything out to fix it.

The culprit turns out to be filesystems (cough ext3 with data=journal
cough) that re-dirty the page when the "->invalidatepage()" callback is
called.

Fix it up by doing a final dirty page accounting check when we actually
remove the page from the page cache.

This fixes bugzilla entry 9182:

	http://bugzilla.kernel.org/show_bug.cgi?id=9182

Tested-by: Ingo Molnar 
Tested-by: Krzysztof Oledzki 
Cc: Andrew Morton 
Cc: Nick Piggin 
Cc: Peter Zijlstra 
Signed-off-by: Linus Torvalds

Remove broken ptrace() special-case code from file mapping

2007-10-31T16:19:46+00:00

The kernel has for random historical reasons allowed ptrace() accesses
to access (and insert) pages into the page cache above the size of the
file.

However, Nick broke that by mistake when doing the new fault handling in
commit 54cb8821de07f2ffcd28c380ce9b93d5784b40d7 ("mm: merge populate and
nopage into fault (fixes nonlinear)".  The breakage caused a hang with
gdb when trying to access the invalid page.

The ptrace "feature" really isn't worth resurrecting, since it really is
wrong both from a portability _and_ from an internal page cache validity
standpoint.  So this removes those old broken remnants, and fixes the
ptrace() hang in the process.

Noticed and bisected by Duane Griffin, who also supplied a test-case
(quoth Nick: "Well that's probably the best bug report I've ever had,
thanks Duane!").

Cc: Duane Griffin 
Acked-by: Nick Piggin 
Signed-off-by: Linus Torvalds

dio: fix cache invalidation after sync writes

2007-10-30T19:14:06+00:00

Commit commit 65b8291c4000e5f38fc94fb2ca0cb7e8683c8a1b ("dio: invalidate
clean pages before dio write") introduced a bug which stopped dio from
ever invalidating the page cache after writes.  It still invalidated it
before writes so most users were fine.

Karl Schendel reported ( http://lkml.org/lkml/2007/10/26/481 ) hitting
this bug when he had a buffered reader immediately reading file data
after an O_DIRECT wirter had written the data.  The kernel issued
read-ahead beyond the position of the reader which overlapped with the
O_DIRECT writer.  The failure to invalidate after writes caused the
reader to see stale data from the read-ahead.

The following patch is originally from Karl.  The following commentary
is his:

	The below 3rd try takes on your suggestion of just invalidating
	no matter what the retval from the direct_IO call.  I ran it
	thru the test-case several times and it has worked every time.
	The post-invalidate is probably still too early for async-directio,
	but I don't have a testcase for that;  just sync.  And, this
	won't be any worse in the async case.

I added a test to the aio-dio-regress repository which mimics Karl's IO
pattern.  It verifed the bad behaviour and that the patch fixed it.  I
agree with Karl, this still doesn't help the case where a buffered
reader follows an AIO O_DIRECT writer.  That will require a bit more
work.

This gives up on the idea of returning EIO to indicate to userspace that
stale data remains if the invalidation failed.

Signed-off-by: Zach Brown 
Cc: Karl Schendel 
Cc: Benjamin LaHaise 
Cc: Andrew Morton 
Cc: Nick Piggin 
Cc: Leonid Ananiev 
Cc: Chris Mason 
Signed-off-by: Linus Torvalds

Fix a build error when BLOCK=n

2007-10-29T10:33:06+00:00

mm/filemap.c: In function '__filemap_fdatawrite_range':
mm/filemap.c:200: error: implicit declaration of function
'mapping_cap_writeback_dirty'

This happens when we don't use/have any block devices and a NFS root
filesystem is used.

mapping_cap_writeback_dirty() is defined in linux/backing-dev.h which
used to be provided in mm/filemap.c by linux/blkdev.h until commit
f5ff8422bbdd59f8c1f699df248e1b7a11073027 (Fix warnings with
!CONFIG_BLOCK).

Signed-off-by: Emil Medve 
Signed-off-by: Jens Axboe

kernel-api docbook: fix content problems

2007-10-19T18:53:35+00:00

Fix kernel-api docbook contents problems.

docproc: linux-2.6.23-git13/include/asm-x86/unaligned_32.h: No such file or directory
Warning(linux-2.6.23-git13//include/linux/list.h:482): bad line: 			of list entry
Warning(linux-2.6.23-git13//mm/filemap.c:864): No description found for parameter 'ra'
Warning(linux-2.6.23-git13//block/ll_rw_blk.c:3760): No description found for parameter 'req'
Warning(linux-2.6.23-git13//include/linux/input.h:1077): No description found for parameter 'private'
Warning(linux-2.6.23-git13//include/linux/input.h:1077): No description found for parameter 'cdev'

Signed-off-by: Randy Dunlap 
Cc: Jens Axboe 
Cc: WU Fengguang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Include in mm/filemap.c

2007-10-18T21:47:32+00:00

It gets it indirectly from blkdev.h when CONFIG_BLOCK is enabled, but it
needs it unconditionally for the definition of mapping_cap_writeback_dirty.

Noticed and bisected down to 4af3c9cc4fad54c3627e9afebf905aafde5690ed
("Drop some headers from mm.h") by Avuton Olrich.

Cc: Avuton Olrich 
Cc: Alexey Dobriyan 
Cc: Andrew Morton 
Signed-off-by: Linus Torvalds

Implement file posix capabilities

2007-10-17T15:43:07+00:00

Implement file posix capabilities.  This allows programs to be given a
subset of root's powers regardless of who runs them, without having to use
setuid and giving the binary all of root's powers.

This version works with Kaigai Kohei's userspace tools, found at
http://www.kaigai.gr.jp/index.php.  For more information on how to use this
patch, Chris Friedhoff has posted a nice page at
http://www.friedhoff.org/fscaps.html.

Changelog:
	Nov 27:
	Incorporate fixes from Andrew Morton
	(security-introduce-file-caps-tweaks and
	security-introduce-file-caps-warning-fix)
	Fix Kconfig dependency.
	Fix change signaling behavior when file caps are not compiled in.

	Nov 13:
	Integrate comments from Alexey: Remove CONFIG_ ifdef from
	capability.h, and use %zd for printing a size_t.

	Nov 13:
	Fix endianness warnings by sparse as suggested by Alexey
	Dobriyan.

	Nov 09:
	Address warnings of unused variables at cap_bprm_set_security
	when file capabilities are disabled, and simultaneously clean
	up the code a little, by pulling the new code into a helper
	function.

	Nov 08:
	For pointers to required userspace tools and how to use
	them, see http://www.friedhoff.org/fscaps.html.

	Nov 07:
	Fix the calculation of the highest bit checked in
	check_cap_sanity().

	Nov 07:
	Allow file caps to be enabled without CONFIG_SECURITY, since
	capabilities are the default.
	Hook cap_task_setscheduler when !CONFIG_SECURITY.
	Move capable(TASK_KILL) to end of cap_task_kill to reduce
	audit messages.

	Nov 05:
	Add secondary calls in selinux/hooks.c to task_setioprio and
	task_setscheduler so that selinux and capabilities with file
	cap support can be stacked.

	Sep 05:
	As Seth Arnold points out, uid checks are out of place
	for capability code.

	Sep 01:
	Define task_setscheduler, task_setioprio, cap_task_kill, and
	task_setnice to make sure a user cannot affect a process in which
	they called a program with some fscaps.

	One remaining question is the note under task_setscheduler: are we
	ok with CAP_SYS_NICE being sufficient to confine a process to a
	cpuset?

	It is a semantic change, as without fsccaps, attach_task doesn't
	allow CAP_SYS_NICE to override the uid equivalence check.  But since
	it uses security_task_setscheduler, which elsewhere is used where
	CAP_SYS_NICE can be used to override the uid equivalence check,
	fixing it might be tough.

	     task_setscheduler
		 note: this also controls cpuset:attach_task.  Are we ok with
		     CAP_SYS_NICE being used to confine to a cpuset?
	     task_setioprio
	     task_setnice
		 sys_setpriority uses this (through set_one_prio) for another
		 process.  Need same checks as setrlimit

	Aug 21:
	Updated secureexec implementation to reflect the fact that
	euid and uid might be the same and nonzero, but the process
	might still have elevated caps.

	Aug 15:
	Handle endianness of xattrs.
	Enforce capability version match between kernel and disk.
	Enforce that no bits beyond the known max capability are
	set, else return -EPERM.
	With this extra processing, it may be worth reconsidering
	doing all the work at bprm_set_security rather than
	d_instantiate.

	Aug 10:
	Always call getxattr at bprm_set_security, rather than
	caching it at d_instantiate.

[morgan@kernel.org: file-caps clean up for linux/capability.h]
[bunk@kernel.org: unexport cap_inode_killpriv]
Signed-off-by: Serge E. Hallyn 
Cc: Stephen Smalley 
Cc: James Morris 
Cc: Chris Wright 
Cc: Andrew Morgan 
Signed-off-by: Andrew Morgan 
Signed-off-by: Adrian Bunk 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: document tree_lock->zone.lock lockorder

2007-10-17T15:42:46+00:00

zone->lock is quite an "inner" lock and mostly constrained to page alloc as
well, so like slab locks, it probably isn't something that is critically
important to document here.  However unlike slab locks, zone lock could be
used more widely in future, and page_alloc.c might possibly have more
business to do tricky things with pagecache than does slab.  So...  I don't
think it hurts to document it.

Signed-off-by: Nick Piggin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs: remove some AOP_TRUNCATED_PAGE

2007-10-16T16:42:58+00:00

prepare/commit_write no longer returns AOP_TRUNCATED_PAGE since OCFS2 and
GFS2 were converted to the new aops, so we can make some simplifications
for that.

[michal.k.k.piotrowski@gmail.com: fix warning]
Signed-off-by: Nick Piggin 
Cc: Michael Halcrow 
Cc: Mark Fasheh 
Cc: Steven Whitehouse 
Signed-off-by: Michal Piotrowski 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs: new cont helpers

2007-10-16T16:42:55+00:00

Rework the generic block "cont" routines to handle the new aops.  Supporting
cont_prepare_write would take quite a lot of code to support, so remove it
instead (and we later convert all filesystems to use it).

write_begin gets passed AOP_FLAG_CONT_EXPAND when called from
generic_cont_expand, so filesystems can avoid the old hacks they used.

Signed-off-by: Nick Piggin 
Cc: OGAWA Hirofumi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds