Signed-off-by: David Woodhouse <dwmw2@infradead.org>

We're about to call this from a bunch of places which already hold
c->erase_completion_lock, so add an assertion and change its existing
callers to do the same.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

Move the jffs2 garbage collecting thread to the new kthread API.

Signed-off-by: Gerard Lledo <gerard.lledo@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

I've noticed some pretty poor behavior on OLPC machines after bootup, when
gdm/X are starting.  The GCD monopolizes the scheduler (which in turns
means it gets to do more nand i/o), which results in processes taking much
much longer than they should to start.

As an example, on an OLPC machine going from OFW to a usable X (via
auto-login gdm) takes 2m 30s.  The majority of this time is consumed by
the switch into graphical mode.  With this patch, we cut a full 60s off of
bootup time.  After bootup, things are much snappier as well.

Note that we have seen a CRC node error with this patch that causes the machine
to fail to boot, but we've also seen that problem without this patch.

Signed-off-by: Andres Salomon <dilinger@debian.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

The thread_should_wake() function trawls through the list of 'very
dirty' eraseblocks, determining whether the background GC thread should
wake. Doing this without holding the appropriate locks is a bad idea.

OLPC Trac #8615

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: stable@kernel.org

Fix breakage caused by commit d5d8c5976d6adeddb8208c240460411e2198b393
"freezer: do not send signals to kernel threads" in
jffs2_garbage_collect_thread() that assumed it would be sent signals
by the freezer.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Pete MacKay <armlinux@architechnical.net>
Signed-off-by: Len Brown <len.brown@intel.com>

Currently, the freezer treats all tasks as freezable, except for the kernel
threads that explicitly set the PF_NOFREEZE flag for themselves.  This
approach is problematic, since it requires every kernel thread to either
set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't
care for the freezing of tasks at all.

It seems better to only require the kernel threads that want to or need to
be frozen to use some freezer-related code and to remove any
freezer-related code from the other (nonfreezable) kernel threads, which is
done in this patch.

The patch causes all kernel threads to be nonfreezable by default (ie.  to
have PF_NOFREEZE set by default) and introduces the set_freezable()
function that should be called by the freezable kernel threads in order to
unset PF_NOFREEZE.  It also makes all of the currently freezable kernel
threads call set_freezable(), so it shouldn't cause any (intentional)
change of behaviour to appear.  Additionally, it updates documentation to
describe the freezing of tasks more accurately.

[akpm@linux-foundation.org: build fixes]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Convert many spaces to tabs; one or two other minor cosmetic fixes.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

The try_to_freeze() call was in the wrong place; we need it in the
signal-pending loop now that a pending freeze also makes
signal_pending() return true.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>