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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115// 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 = find_vma(mm, vma->vm_end); } }out_unlock: mmap_read_unlock(mm);out: return error ? : unmapped_error;}