Revision 8874e812feb4926f4a51a82c4fca75c7daa05fc5 authored by Linus Torvalds on 21 June 2012, 20:41:07 UTC, committed by Linus Torvalds on 21 June 2012, 20:41:07 UTC
Pull btrfs fixes from Chris Mason: "This is a small pull with btrfs fixes. The biggest of the bunch is another fix for the new backref walking code. We're still hammering out one btrfs dio vs buffered reads problem, but that one will have to wait for the next rc." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: Btrfs: delay iput with async extents Btrfs: add a missing spin_lock Btrfs: don't assume to be on the correct extent in add_all_parents Btrfs: introduce btrfs_next_old_item
mmu_context.c
/* Copyright (C) 2009 Red Hat, Inc.
*
* See ../COPYING for licensing terms.
*/
#include <linux/mm.h>
#include <linux/mmu_context.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <asm/mmu_context.h>
/*
* use_mm
* Makes the calling kernel thread take on the specified
* mm context.
* Called by the retry thread execute retries within the
* iocb issuer's mm context, so that copy_from/to_user
* operations work seamlessly for aio.
* (Note: this routine is intended to be called only
* from a kernel thread context)
*/
void use_mm(struct mm_struct *mm)
{
struct mm_struct *active_mm;
struct task_struct *tsk = current;
task_lock(tsk);
active_mm = tsk->active_mm;
if (active_mm != mm) {
atomic_inc(&mm->mm_count);
tsk->active_mm = mm;
}
tsk->mm = mm;
switch_mm(active_mm, mm, tsk);
task_unlock(tsk);
if (active_mm != mm)
mmdrop(active_mm);
}
EXPORT_SYMBOL_GPL(use_mm);
/*
* unuse_mm
* Reverses the effect of use_mm, i.e. releases the
* specified mm context which was earlier taken on
* by the calling kernel thread
* (Note: this routine is intended to be called only
* from a kernel thread context)
*/
void unuse_mm(struct mm_struct *mm)
{
struct task_struct *tsk = current;
task_lock(tsk);
sync_mm_rss(mm);
tsk->mm = NULL;
/* active_mm is still 'mm' */
enter_lazy_tlb(mm, tsk);
task_unlock(tsk);
}
EXPORT_SYMBOL_GPL(unuse_mm);
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