[mirror_ubuntu-bionic-kernel.git] / mm / msync.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;

	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.
	 */
	down_read(&mm->mmap_sem);
	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) {
			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);
			up_read(&mm->mmap_sem);
			error = vfs_fsync_range(file, fstart, fend, 1);
			fput(file);
			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;
		}
	}
out_unlock:
	up_read(&mm->mmap_sem);
out:
	return error ? : unmapped_error;
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
1da177e4 LT	2	/*
	3	* linux/mm/msync.c
	4	*
	5	* Copyright (C) 1994-1999 Linus Torvalds
	6	*/
	7
	8	/*
	9	* The msync() system call.
	10	*/
8f2e9f15	11	#include <linux/fs.h>
1da177e4 LT	12	#include <linux/mm.h>
1da177e4 LT	13	#include <linux/mman.h>
9c50823e	14	#include <linux/file.h>
1da177e4	15	#include <linux/syscalls.h>
e8edc6e0	16	#include <linux/sched.h>
1da177e4	17
1da177e4 LT	18	/*
	19	* MS_SYNC syncs the entire file - including mappings.
	20	*
204ec841 PZ	21	* MS_ASYNC does not start I/O (it used to, up to 2.5.67).
	22	* Nor does it marks the relevant pages dirty (it used to up to 2.6.17).
	23	* Now it doesn't do anything, since dirty pages are properly tracked.
	24	*
	25	* The application may now run fsync() to
1da177e4 LT	26	* write out the dirty pages and wait on the writeout and check the result.
	27	* Or the application may run fadvise(FADV_DONTNEED) against the fd to start
	28	* async writeout immediately.
16538c40	29	* So by _not_ starting I/O in MS_ASYNC we provide complete flexibility to
1da177e4 LT	30	* applications.
1da177e4 LT	31	*/
6a6160a7	32	SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
1da177e4 LT	33	{
1da177e4 LT	34	unsigned long end;
204ec841	35	struct mm_struct *mm = current->mm;
1da177e4	36	struct vm_area_struct *vma;
676758bd AM	37	int unmapped_error = 0;
676758bd AM	38	int error = -EINVAL;
1da177e4	39
1da177e4 LT	40	if (flags & ~(MS_ASYNC \| MS_INVALIDATE \| MS_SYNC))
1da177e4 LT	41	goto out;
b0d61c7e	42	if (offset_in_page(start))
1da177e4 LT	43	goto out;
	44	if ((flags & MS_ASYNC) && (flags & MS_SYNC))
	45	goto out;
	46	error = -ENOMEM;
	47	len = (len + ~PAGE_MASK) & PAGE_MASK;
	48	end = start + len;
	49	if (end < start)
	50	goto out;
	51	error = 0;
	52	if (end == start)
	53	goto out;
	54	/*
	55	* If the interval [start,end) covers some unmapped address ranges,
	56	* just ignore them, but return -ENOMEM at the end.
	57	*/
204ec841 PZ	58	down_read(&mm->mmap_sem);
	59	vma = find_vma(mm, start);
	60	for (;;) {
9c50823e	61	struct file *file;
7fc34a62	62	loff_t fstart, fend;
9c50823e	63
204ec841 PZ	64	/* Still start < end. */
	65	error = -ENOMEM;
	66	if (!vma)
	67	goto out_unlock;
1da177e4 LT	68	/* Here start < vma->vm_end. */
1da177e4 LT	69	if (start < vma->vm_start) {
1da177e4	70	start = vma->vm_start;
204ec841 PZ	71	if (start >= end)
	72	goto out_unlock;
	73	unmapped_error = -ENOMEM;
1da177e4 LT	74	}
1da177e4 LT	75	/* Here vma->vm_start <= start < vma->vm_end. */
204ec841 PZ	76	if ((flags & MS_INVALIDATE) &&
	77	(vma->vm_flags & VM_LOCKED)) {
	78	error = -EBUSY;
	79	goto out_unlock;
1da177e4	80	}
9c50823e	81	file = vma->vm_file;
496a8e68 NJ	82	fstart = (start - vma->vm_start) +
496a8e68 NJ	83	((loff_t)vma->vm_pgoff << PAGE_SHIFT);
7fc34a62	84	fend = fstart + (min(end, vma->vm_end) - start) - 1;
1da177e4	85	start = vma->vm_end;
204ec841	86	if ((flags & MS_SYNC) && file &&
707c21c8	87	(vma->vm_flags & VM_SHARED)) {
707c21c8	88	get_file(file);
204ec841	89	up_read(&mm->mmap_sem);
0661a336	90	error = vfs_fsync_range(file, fstart, fend, 1);
707c21c8	91	fput(file);
204ec841 PZ	92	if (error \|\| start >= end)
	93	goto out;
	94	down_read(&mm->mmap_sem);
	95	vma = find_vma(mm, start);
9c50823e	96	} else {
204ec841 PZ	97	if (start >= end) {
	98	error = 0;
	99	goto out_unlock;
	100	}
9c50823e AM	101	vma = vma->vm_next;
9c50823e AM	102	}
204ec841	103	}
9c50823e	104	out_unlock:
204ec841	105	up_read(&mm->mmap_sem);
9c50823e	106	out:
204ec841	107	return error ? : unmapped_error;
1da177e4	108	}