115 lines
2.8 KiB
C
115 lines
2.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/mm/msync.c
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*
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* Copyright (C) 1994-1999 Linus Torvalds
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*/
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/*
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* The msync() system call.
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*/
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/file.h>
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#include <linux/syscalls.h>
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#include <linux/sched.h>
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/*
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* MS_SYNC syncs the entire file - including mappings.
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*
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* MS_ASYNC does not start I/O (it used to, up to 2.5.67).
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* Nor does it marks the relevant pages dirty (it used to up to 2.6.17).
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* Now it doesn't do anything, since dirty pages are properly tracked.
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*
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* The application may now run fsync() to
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* write out the dirty pages and wait on the writeout and check the result.
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* Or the application may run fadvise(FADV_DONTNEED) against the fd to start
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* async writeout immediately.
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* So by _not_ starting I/O in MS_ASYNC we provide complete flexibility to
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* applications.
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*/
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SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
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{
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unsigned long end;
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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int unmapped_error = 0;
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int error = -EINVAL;
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start = untagged_addr(start);
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if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
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goto out;
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if (offset_in_page(start))
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goto out;
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if ((flags & MS_ASYNC) && (flags & MS_SYNC))
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goto out;
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error = -ENOMEM;
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len = (len + ~PAGE_MASK) & PAGE_MASK;
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end = start + len;
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if (end < start)
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goto out;
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error = 0;
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if (end == start)
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goto out;
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/*
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* If the interval [start,end) covers some unmapped address ranges,
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* just ignore them, but return -ENOMEM at the end. Besides, if the
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* flag is MS_ASYNC (w/o MS_INVALIDATE) the result would be -ENOMEM
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* anyway and there is nothing left to do, so return immediately.
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*/
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mmap_read_lock(mm);
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vma = find_vma(mm, start);
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for (;;) {
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struct file *file;
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loff_t fstart, fend;
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/* Still start < end. */
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error = -ENOMEM;
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if (!vma)
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goto out_unlock;
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/* Here start < vma->vm_end. */
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if (start < vma->vm_start) {
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if (flags == MS_ASYNC)
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goto out_unlock;
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start = vma->vm_start;
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if (start >= end)
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goto out_unlock;
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unmapped_error = -ENOMEM;
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}
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/* Here vma->vm_start <= start < vma->vm_end. */
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if ((flags & MS_INVALIDATE) &&
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(vma->vm_flags & VM_LOCKED)) {
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error = -EBUSY;
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goto out_unlock;
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}
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file = vma->vm_file;
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fstart = (start - vma->vm_start) +
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((loff_t)vma->vm_pgoff << PAGE_SHIFT);
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fend = fstart + (min(end, vma->vm_end) - start) - 1;
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start = vma->vm_end;
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if ((flags & MS_SYNC) && file &&
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(vma->vm_flags & VM_SHARED)) {
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get_file(file);
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mmap_read_unlock(mm);
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error = vfs_fsync_range(file, fstart, fend, 1);
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fput(file);
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if (error || start >= end)
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goto out;
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mmap_read_lock(mm);
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vma = find_vma(mm, start);
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} else {
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if (start >= end) {
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error = 0;
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goto out_unlock;
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}
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vma = vma->vm_next;
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}
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}
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out_unlock:
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mmap_read_unlock(mm);
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out:
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return error ? : unmapped_error;
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}
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