forked from Minki/linux
[PATCH] mm: msync() cleanup
With the tracking of dirty pages properly done now, msync doesn't need to scan the PTEs anymore to determine the dirty status. From: Hugh Dickins <hugh@veritas.com> In looking to do that, I made some other tidyups: can remove several #includes, and sys_msync loop termination not quite right. Most of those points are criticisms of the existing sys_msync, not of your patch. In particular, the loop termination errors were introduced in 2.6.17: I did notice this shortly before it came out, but decided I was more likely to get it wrong myself, and make matters worse if I tried to rush a last-minute fix in. And it's not terribly likely to go wrong, nor disastrous if it does go wrong (may miss reporting an unmapped area; may also fsync file of a following vma). Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Peter Zijlstra
Linus Torvalds
parent
ee6a645788
commit
204ec841fb
196
mm/msync.c
196
mm/msync.c
@ -7,149 +7,33 @@
|
||||
/*
|
||||
* The msync() system call.
|
||||
*/
|
||||
#include <linux/slab.h>
|
||||
#include <linux/pagemap.h>
|
||||
#include <linux/fs.h>
|
||||
#include <linux/mm.h>
|
||||
#include <linux/mman.h>
|
||||
#include <linux/hugetlb.h>
|
||||
#include <linux/writeback.h>
|
||||
#include <linux/file.h>
|
||||
#include <linux/syscalls.h>
|
||||
|
||||
#include <asm/pgtable.h>
|
||||
#include <asm/tlbflush.h>
|
||||
|
||||
static unsigned long msync_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
|
||||
unsigned long addr, unsigned long end)
|
||||
{
|
||||
pte_t *pte;
|
||||
spinlock_t *ptl;
|
||||
int progress = 0;
|
||||
unsigned long ret = 0;
|
||||
|
||||
again:
|
||||
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
|
||||
do {
|
||||
struct page *page;
|
||||
|
||||
if (progress >= 64) {
|
||||
progress = 0;
|
||||
if (need_resched() || need_lockbreak(ptl))
|
||||
break;
|
||||
}
|
||||
progress++;
|
||||
if (!pte_present(*pte))
|
||||
continue;
|
||||
if (!pte_maybe_dirty(*pte))
|
||||
continue;
|
||||
page = vm_normal_page(vma, addr, *pte);
|
||||
if (!page)
|
||||
continue;
|
||||
if (ptep_clear_flush_dirty(vma, addr, pte) ||
|
||||
page_test_and_clear_dirty(page))
|
||||
ret += set_page_dirty(page);
|
||||
progress += 3;
|
||||
} while (pte++, addr += PAGE_SIZE, addr != end);
|
||||
pte_unmap_unlock(pte - 1, ptl);
|
||||
cond_resched();
|
||||
if (addr != end)
|
||||
goto again;
|
||||
return ret;
|
||||
}
|
||||
|
||||
static inline unsigned long msync_pmd_range(struct vm_area_struct *vma,
|
||||
pud_t *pud, unsigned long addr, unsigned long end)
|
||||
{
|
||||
pmd_t *pmd;
|
||||
unsigned long next;
|
||||
unsigned long ret = 0;
|
||||
|
||||
pmd = pmd_offset(pud, addr);
|
||||
do {
|
||||
next = pmd_addr_end(addr, end);
|
||||
if (pmd_none_or_clear_bad(pmd))
|
||||
continue;
|
||||
ret += msync_pte_range(vma, pmd, addr, next);
|
||||
} while (pmd++, addr = next, addr != end);
|
||||
return ret;
|
||||
}
|
||||
|
||||
static inline unsigned long msync_pud_range(struct vm_area_struct *vma,
|
||||
pgd_t *pgd, unsigned long addr, unsigned long end)
|
||||
{
|
||||
pud_t *pud;
|
||||
unsigned long next;
|
||||
unsigned long ret = 0;
|
||||
|
||||
pud = pud_offset(pgd, addr);
|
||||
do {
|
||||
next = pud_addr_end(addr, end);
|
||||
if (pud_none_or_clear_bad(pud))
|
||||
continue;
|
||||
ret += msync_pmd_range(vma, pud, addr, next);
|
||||
} while (pud++, addr = next, addr != end);
|
||||
return ret;
|
||||
}
|
||||
|
||||
static unsigned long msync_page_range(struct vm_area_struct *vma,
|
||||
unsigned long addr, unsigned long end)
|
||||
{
|
||||
pgd_t *pgd;
|
||||
unsigned long next;
|
||||
unsigned long ret = 0;
|
||||
|
||||
/* For hugepages we can't go walking the page table normally,
|
||||
* but that's ok, hugetlbfs is memory based, so we don't need
|
||||
* to do anything more on an msync().
|
||||
*/
|
||||
if (vma->vm_flags & VM_HUGETLB)
|
||||
return 0;
|
||||
|
||||
BUG_ON(addr >= end);
|
||||
pgd = pgd_offset(vma->vm_mm, addr);
|
||||
flush_cache_range(vma, addr, end);
|
||||
do {
|
||||
next = pgd_addr_end(addr, end);
|
||||
if (pgd_none_or_clear_bad(pgd))
|
||||
continue;
|
||||
ret += msync_pud_range(vma, pgd, addr, next);
|
||||
} while (pgd++, addr = next, addr != end);
|
||||
return ret;
|
||||
}
|
||||
|
||||
/*
|
||||
* MS_SYNC syncs the entire file - including mappings.
|
||||
*
|
||||
* MS_ASYNC does not start I/O (it used to, up to 2.5.67). Instead, it just
|
||||
* marks the relevant pages dirty. The application may now run fsync() to
|
||||
* MS_ASYNC does not start I/O (it used to, up to 2.5.67).
|
||||
* Nor does it marks the relevant pages dirty (it used to up to 2.6.17).
|
||||
* Now it doesn't do anything, since dirty pages are properly tracked.
|
||||
*
|
||||
* The application may now run fsync() to
|
||||
* write out the dirty pages and wait on the writeout and check the result.
|
||||
* Or the application may run fadvise(FADV_DONTNEED) against the fd to start
|
||||
* async writeout immediately.
|
||||
* So by _not_ starting I/O in MS_ASYNC we provide complete flexibility to
|
||||
* applications.
|
||||
*/
|
||||
static int msync_interval(struct vm_area_struct *vma, unsigned long addr,
|
||||
unsigned long end, int flags,
|
||||
unsigned long *nr_pages_dirtied)
|
||||
{
|
||||
struct file *file = vma->vm_file;
|
||||
|
||||
if ((flags & MS_INVALIDATE) && (vma->vm_flags & VM_LOCKED))
|
||||
return -EBUSY;
|
||||
|
||||
if (file && (vma->vm_flags & VM_SHARED))
|
||||
*nr_pages_dirtied = msync_page_range(vma, addr, end);
|
||||
return 0;
|
||||
}
|
||||
|
||||
asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
|
||||
{
|
||||
unsigned long end;
|
||||
struct mm_struct *mm = current->mm;
|
||||
struct vm_area_struct *vma;
|
||||
int unmapped_error = 0;
|
||||
int error = -EINVAL;
|
||||
int done = 0;
|
||||
|
||||
if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
|
||||
goto out;
|
||||
@ -169,64 +53,50 @@ asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
|
||||
* If the interval [start,end) covers some unmapped address ranges,
|
||||
* just ignore them, but return -ENOMEM at the end.
|
||||
*/
|
||||
down_read(¤t->mm->mmap_sem);
|
||||
vma = find_vma(current->mm, start);
|
||||
if (!vma) {
|
||||
error = -ENOMEM;
|
||||
goto out_unlock;
|
||||
}
|
||||
do {
|
||||
unsigned long nr_pages_dirtied = 0;
|
||||
down_read(&mm->mmap_sem);
|
||||
vma = find_vma(mm, start);
|
||||
for (;;) {
|
||||
struct file *file;
|
||||
|
||||
/* Still start < end. */
|
||||
error = -ENOMEM;
|
||||
if (!vma)
|
||||
goto out_unlock;
|
||||
/* Here start < vma->vm_end. */
|
||||
if (start < vma->vm_start) {
|
||||
unmapped_error = -ENOMEM;
|
||||
start = vma->vm_start;
|
||||
if (start >= end)
|
||||
goto out_unlock;
|
||||
unmapped_error = -ENOMEM;
|
||||
}
|
||||
/* Here vma->vm_start <= start < vma->vm_end. */
|
||||
if (end <= vma->vm_end) {
|
||||
if (start < end) {
|
||||
error = msync_interval(vma, start, end, flags,
|
||||
&nr_pages_dirtied);
|
||||
if (error)
|
||||
goto out_unlock;
|
||||
}
|
||||
error = unmapped_error;
|
||||
done = 1;
|
||||
} else {
|
||||
/* Here vma->vm_start <= start < vma->vm_end < end. */
|
||||
error = msync_interval(vma, start, vma->vm_end, flags,
|
||||
&nr_pages_dirtied);
|
||||
if (error)
|
||||
goto out_unlock;
|
||||
if ((flags & MS_INVALIDATE) &&
|
||||
(vma->vm_flags & VM_LOCKED)) {
|
||||
error = -EBUSY;
|
||||
goto out_unlock;
|
||||
}
|
||||
file = vma->vm_file;
|
||||
start = vma->vm_end;
|
||||
if ((flags & MS_ASYNC) && file && nr_pages_dirtied) {
|
||||
get_file(file);
|
||||
up_read(¤t->mm->mmap_sem);
|
||||
balance_dirty_pages_ratelimited_nr(file->f_mapping,
|
||||
nr_pages_dirtied);
|
||||
fput(file);
|
||||
down_read(¤t->mm->mmap_sem);
|
||||
vma = find_vma(current->mm, start);
|
||||
} else if ((flags & MS_SYNC) && file &&
|
||||
if ((flags & MS_SYNC) && file &&
|
||||
(vma->vm_flags & VM_SHARED)) {
|
||||
get_file(file);
|
||||
up_read(¤t->mm->mmap_sem);
|
||||
up_read(&mm->mmap_sem);
|
||||
error = do_fsync(file, 0);
|
||||
fput(file);
|
||||
down_read(¤t->mm->mmap_sem);
|
||||
if (error)
|
||||
goto out_unlock;
|
||||
vma = find_vma(current->mm, start);
|
||||
if (error || start >= end)
|
||||
goto out;
|
||||
down_read(&mm->mmap_sem);
|
||||
vma = find_vma(mm, start);
|
||||
} else {
|
||||
if (start >= end) {
|
||||
error = 0;
|
||||
goto out_unlock;
|
||||
}
|
||||
vma = vma->vm_next;
|
||||
}
|
||||
} while (vma && !done);
|
||||
}
|
||||
out_unlock:
|
||||
up_read(¤t->mm->mmap_sem);
|
||||
up_read(&mm->mmap_sem);
|
||||
out:
|
||||
return error;
|
||||
return error ? : unmapped_error;
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user