mirror of
https://github.com/torvalds/linux.git
synced 2024-12-17 16:43:08 +00:00
b4955ce3dd
It's common practice to msync a large address range regularly, in which often only a few ptes have actually been dirtied since the previous pass. sync_pte_range then goes much faster if it tests whether pte is dirty before locating and accessing each struct page cacheline; and it is hardly slowed by ptep_clear_flush_dirty repeating that test in the opposite case, when every pte actually is dirty. But beware, s390's pte_dirty always says false, since its dirty bit is kept in the storage key, located via the struct page address. So skip this optimization in its case: use a pte_maybe_dirty macro which just says true if page_test_and_clear_dirty is implemented. Signed-off-by: Abhijit Karmarkar <abhijitk@veritas.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
239 lines
5.6 KiB
C
239 lines
5.6 KiB
C
/*
|
|
* linux/mm/msync.c
|
|
*
|
|
* Copyright (C) 1994-1999 Linus Torvalds
|
|
*/
|
|
|
|
/*
|
|
* The msync() system call.
|
|
*/
|
|
#include <linux/slab.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/mman.h>
|
|
#include <linux/hugetlb.h>
|
|
#include <linux/syscalls.h>
|
|
|
|
#include <asm/pgtable.h>
|
|
#include <asm/tlbflush.h>
|
|
|
|
/*
|
|
* Called with mm->page_table_lock held to protect against other
|
|
* threads/the swapper from ripping pte's out from under us.
|
|
*/
|
|
|
|
static void sync_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
|
|
unsigned long addr, unsigned long end)
|
|
{
|
|
pte_t *pte;
|
|
|
|
pte = pte_offset_map(pmd, addr);
|
|
do {
|
|
unsigned long pfn;
|
|
struct page *page;
|
|
|
|
if (!pte_present(*pte))
|
|
continue;
|
|
if (!pte_maybe_dirty(*pte))
|
|
continue;
|
|
pfn = pte_pfn(*pte);
|
|
if (!pfn_valid(pfn))
|
|
continue;
|
|
page = pfn_to_page(pfn);
|
|
if (PageReserved(page))
|
|
continue;
|
|
|
|
if (ptep_clear_flush_dirty(vma, addr, pte) ||
|
|
page_test_and_clear_dirty(page))
|
|
set_page_dirty(page);
|
|
} while (pte++, addr += PAGE_SIZE, addr != end);
|
|
pte_unmap(pte - 1);
|
|
}
|
|
|
|
static inline void sync_pmd_range(struct vm_area_struct *vma, pud_t *pud,
|
|
unsigned long addr, unsigned long end)
|
|
{
|
|
pmd_t *pmd;
|
|
unsigned long next;
|
|
|
|
pmd = pmd_offset(pud, addr);
|
|
do {
|
|
next = pmd_addr_end(addr, end);
|
|
if (pmd_none_or_clear_bad(pmd))
|
|
continue;
|
|
sync_pte_range(vma, pmd, addr, next);
|
|
} while (pmd++, addr = next, addr != end);
|
|
}
|
|
|
|
static inline void sync_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
|
|
unsigned long addr, unsigned long end)
|
|
{
|
|
pud_t *pud;
|
|
unsigned long next;
|
|
|
|
pud = pud_offset(pgd, addr);
|
|
do {
|
|
next = pud_addr_end(addr, end);
|
|
if (pud_none_or_clear_bad(pud))
|
|
continue;
|
|
sync_pmd_range(vma, pud, addr, next);
|
|
} while (pud++, addr = next, addr != end);
|
|
}
|
|
|
|
static void sync_page_range(struct vm_area_struct *vma,
|
|
unsigned long addr, unsigned long end)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
pgd_t *pgd;
|
|
unsigned long next;
|
|
|
|
/* 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 (is_vm_hugetlb_page(vma))
|
|
return;
|
|
|
|
BUG_ON(addr >= end);
|
|
pgd = pgd_offset(mm, addr);
|
|
flush_cache_range(vma, addr, end);
|
|
spin_lock(&mm->page_table_lock);
|
|
do {
|
|
next = pgd_addr_end(addr, end);
|
|
if (pgd_none_or_clear_bad(pgd))
|
|
continue;
|
|
sync_pud_range(vma, pgd, addr, next);
|
|
} while (pgd++, addr = next, addr != end);
|
|
spin_unlock(&mm->page_table_lock);
|
|
}
|
|
|
|
#ifdef CONFIG_PREEMPT
|
|
static inline void filemap_sync(struct vm_area_struct *vma,
|
|
unsigned long addr, unsigned long end)
|
|
{
|
|
const size_t chunk = 64 * 1024; /* bytes */
|
|
unsigned long next;
|
|
|
|
do {
|
|
next = addr + chunk;
|
|
if (next > end || next < addr)
|
|
next = end;
|
|
sync_page_range(vma, addr, next);
|
|
cond_resched();
|
|
} while (addr = next, addr != end);
|
|
}
|
|
#else
|
|
static inline void filemap_sync(struct vm_area_struct *vma,
|
|
unsigned long addr, unsigned long end)
|
|
{
|
|
sync_page_range(vma, addr, end);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* 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
|
|
* 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 my _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)
|
|
{
|
|
int ret = 0;
|
|
struct file *file = vma->vm_file;
|
|
|
|
if ((flags & MS_INVALIDATE) && (vma->vm_flags & VM_LOCKED))
|
|
return -EBUSY;
|
|
|
|
if (file && (vma->vm_flags & VM_SHARED)) {
|
|
filemap_sync(vma, addr, end);
|
|
|
|
if (flags & MS_SYNC) {
|
|
struct address_space *mapping = file->f_mapping;
|
|
int err;
|
|
|
|
ret = filemap_fdatawrite(mapping);
|
|
if (file->f_op && file->f_op->fsync) {
|
|
/*
|
|
* We don't take i_sem here because mmap_sem
|
|
* is already held.
|
|
*/
|
|
err = file->f_op->fsync(file,file->f_dentry,1);
|
|
if (err && !ret)
|
|
ret = err;
|
|
}
|
|
err = filemap_fdatawait(mapping);
|
|
if (!ret)
|
|
ret = err;
|
|
}
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
|
|
{
|
|
unsigned long end;
|
|
struct vm_area_struct *vma;
|
|
int unmapped_error, error = -EINVAL;
|
|
|
|
if (flags & MS_SYNC)
|
|
current->flags |= PF_SYNCWRITE;
|
|
|
|
down_read(¤t->mm->mmap_sem);
|
|
if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
|
|
goto out;
|
|
if (start & ~PAGE_MASK)
|
|
goto out;
|
|
if ((flags & MS_ASYNC) && (flags & MS_SYNC))
|
|
goto out;
|
|
error = -ENOMEM;
|
|
len = (len + ~PAGE_MASK) & PAGE_MASK;
|
|
end = start + len;
|
|
if (end < start)
|
|
goto out;
|
|
error = 0;
|
|
if (end == start)
|
|
goto out;
|
|
/*
|
|
* If the interval [start,end) covers some unmapped address ranges,
|
|
* just ignore them, but return -ENOMEM at the end.
|
|
*/
|
|
vma = find_vma(current->mm, start);
|
|
unmapped_error = 0;
|
|
for (;;) {
|
|
/* Still start < end. */
|
|
error = -ENOMEM;
|
|
if (!vma)
|
|
goto out;
|
|
/* Here start < vma->vm_end. */
|
|
if (start < vma->vm_start) {
|
|
unmapped_error = -ENOMEM;
|
|
start = vma->vm_start;
|
|
}
|
|
/* Here vma->vm_start <= start < vma->vm_end. */
|
|
if (end <= vma->vm_end) {
|
|
if (start < end) {
|
|
error = msync_interval(vma, start, end, flags);
|
|
if (error)
|
|
goto out;
|
|
}
|
|
error = unmapped_error;
|
|
goto out;
|
|
}
|
|
/* Here vma->vm_start <= start < vma->vm_end < end. */
|
|
error = msync_interval(vma, start, vma->vm_end, flags);
|
|
if (error)
|
|
goto out;
|
|
start = vma->vm_end;
|
|
vma = vma->vm_next;
|
|
}
|
|
out:
|
|
up_read(¤t->mm->mmap_sem);
|
|
current->flags &= ~PF_SYNCWRITE;
|
|
return error;
|
|
}
|