mirror of
https://github.com/torvalds/linux.git
synced 2025-11-03 18:20:25 +02:00
f6899bc03c
If an unmapped region was found and the flag is MS_ASYNC (without MS_INVALIDATE) there is nothing to do and the result would be always -ENOMEM, so return immediately. Link: https://lkml.kernel.org/r/20201025092901.56399-1-sh1r4s3@mail.si-head.nl Signed-off-by: Nikita Ermakov <sh1r4s3@mail.si-head.nl> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
114 lines
2.8 KiB
C
114 lines
2.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* linux/mm/msync.c
|
|
*
|
|
* Copyright (C) 1994-1999 Linus Torvalds
|
|
*/
|
|
|
|
/*
|
|
* The msync() system call.
|
|
*/
|
|
#include <linux/fs.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/mman.h>
|
|
#include <linux/file.h>
|
|
#include <linux/syscalls.h>
|
|
#include <linux/sched.h>
|
|
|
|
/*
|
|
* MS_SYNC syncs the entire file - including mappings.
|
|
*
|
|
* 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.
|
|
*/
|
|
SYSCALL_DEFINE3(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;
|
|
|
|
start = untagged_addr(start);
|
|
|
|
if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
|
|
goto out;
|
|
if (offset_in_page(start))
|
|
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. Besides, if the
|
|
* flag is MS_ASYNC (w/o MS_INVALIDATE) the result would be -ENOMEM
|
|
* anyway and there is nothing left to do, so return immediately.
|
|
*/
|
|
mmap_read_lock(mm);
|
|
vma = find_vma(mm, start);
|
|
for (;;) {
|
|
struct file *file;
|
|
loff_t fstart, fend;
|
|
|
|
/* Still start < end. */
|
|
error = -ENOMEM;
|
|
if (!vma)
|
|
goto out_unlock;
|
|
/* Here start < vma->vm_end. */
|
|
if (start < vma->vm_start) {
|
|
if (flags == MS_ASYNC)
|
|
goto out_unlock;
|
|
start = vma->vm_start;
|
|
if (start >= end)
|
|
goto out_unlock;
|
|
unmapped_error = -ENOMEM;
|
|
}
|
|
/* Here vma->vm_start <= start < vma->vm_end. */
|
|
if ((flags & MS_INVALIDATE) &&
|
|
(vma->vm_flags & VM_LOCKED)) {
|
|
error = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
file = vma->vm_file;
|
|
fstart = (start - vma->vm_start) +
|
|
((loff_t)vma->vm_pgoff << PAGE_SHIFT);
|
|
fend = fstart + (min(end, vma->vm_end) - start) - 1;
|
|
start = vma->vm_end;
|
|
if ((flags & MS_SYNC) && file &&
|
|
(vma->vm_flags & VM_SHARED)) {
|
|
get_file(file);
|
|
mmap_read_unlock(mm);
|
|
error = vfs_fsync_range(file, fstart, fend, 1);
|
|
fput(file);
|
|
if (error || start >= end)
|
|
goto out;
|
|
mmap_read_lock(mm);
|
|
vma = find_vma(mm, start);
|
|
} else {
|
|
if (start >= end) {
|
|
error = 0;
|
|
goto out_unlock;
|
|
}
|
|
vma = vma->vm_next;
|
|
}
|
|
}
|
|
out_unlock:
|
|
mmap_read_unlock(mm);
|
|
out:
|
|
return error ? : unmapped_error;
|
|
}
|