4 * Copyright (C) 1994-1999 Linus Torvalds
8 * The msync() system call.
10 #include <linux/slab.h>
11 #include <linux/pagemap.h>
13 #include <linux/mman.h>
14 #include <linux/hugetlb.h>
15 #include <linux/syscalls.h>
17 #include <asm/pgtable.h>
18 #include <asm/tlbflush.h>
21 * Called with mm->page_table_lock held to protect against other
22 * threads/the swapper from ripping pte's out from under us.
25 static void sync_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
26 unsigned long addr, unsigned long end)
30 pte = pte_offset_map(pmd, addr);
35 if (!pte_present(*pte))
40 page = pfn_to_page(pfn);
41 if (PageReserved(page))
44 if (ptep_clear_flush_dirty(vma, addr, pte) ||
45 page_test_and_clear_dirty(page))
47 } while (pte++, addr += PAGE_SIZE, addr != end);
51 static inline void sync_pmd_range(struct vm_area_struct *vma, pud_t *pud,
52 unsigned long addr, unsigned long end)
57 pmd = pmd_offset(pud, addr);
59 next = pmd_addr_end(addr, end);
60 if (pmd_none_or_clear_bad(pmd))
62 sync_pte_range(vma, pmd, addr, next);
63 } while (pmd++, addr = next, addr != end);
66 static inline void sync_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
67 unsigned long addr, unsigned long end)
72 pud = pud_offset(pgd, addr);
74 next = pud_addr_end(addr, end);
75 if (pud_none_or_clear_bad(pud))
77 sync_pmd_range(vma, pud, addr, next);
78 } while (pud++, addr = next, addr != end);
81 static void sync_page_range(struct vm_area_struct *vma,
82 unsigned long addr, unsigned long end)
84 struct mm_struct *mm = vma->vm_mm;
88 /* For hugepages we can't go walking the page table normally,
89 * but that's ok, hugetlbfs is memory based, so we don't need
90 * to do anything more on an msync() */
91 if (is_vm_hugetlb_page(vma))
95 pgd = pgd_offset(mm, addr);
96 flush_cache_range(vma, addr, end);
97 spin_lock(&mm->page_table_lock);
99 next = pgd_addr_end(addr, end);
100 if (pgd_none_or_clear_bad(pgd))
102 sync_pud_range(vma, pgd, addr, next);
103 } while (pgd++, addr = next, addr != end);
104 spin_unlock(&mm->page_table_lock);
107 #ifdef CONFIG_PREEMPT
108 static inline void filemap_sync(struct vm_area_struct *vma,
109 unsigned long addr, unsigned long end)
111 const size_t chunk = 64 * 1024; /* bytes */
116 if (next > end || next < addr)
118 sync_page_range(vma, addr, next);
120 } while (addr = next, addr != end);
123 static inline void filemap_sync(struct vm_area_struct *vma,
124 unsigned long addr, unsigned long end)
126 sync_page_range(vma, addr, end);
131 * MS_SYNC syncs the entire file - including mappings.
133 * MS_ASYNC does not start I/O (it used to, up to 2.5.67). Instead, it just
134 * marks the relevant pages dirty. The application may now run fsync() to
135 * write out the dirty pages and wait on the writeout and check the result.
136 * Or the application may run fadvise(FADV_DONTNEED) against the fd to start
137 * async writeout immediately.
138 * So my _not_ starting I/O in MS_ASYNC we provide complete flexibility to
141 static int msync_interval(struct vm_area_struct *vma,
142 unsigned long addr, unsigned long end, int flags)
145 struct file *file = vma->vm_file;
147 if ((flags & MS_INVALIDATE) && (vma->vm_flags & VM_LOCKED))
150 if (file && (vma->vm_flags & VM_SHARED)) {
151 filemap_sync(vma, addr, end);
153 if (flags & MS_SYNC) {
154 struct address_space *mapping = file->f_mapping;
157 ret = filemap_fdatawrite(mapping);
158 if (file->f_op && file->f_op->fsync) {
160 * We don't take i_sem here because mmap_sem
163 err = file->f_op->fsync(file,file->f_dentry,1);
167 err = filemap_fdatawait(mapping);
175 asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
178 struct vm_area_struct *vma;
179 int unmapped_error, error = -EINVAL;
182 current->flags |= PF_SYNCWRITE;
184 down_read(¤t->mm->mmap_sem);
185 if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
187 if (start & ~PAGE_MASK)
189 if ((flags & MS_ASYNC) && (flags & MS_SYNC))
192 len = (len + ~PAGE_MASK) & PAGE_MASK;
200 * If the interval [start,end) covers some unmapped address ranges,
201 * just ignore them, but return -ENOMEM at the end.
203 vma = find_vma(current->mm, start);
206 /* Still start < end. */
210 /* Here start < vma->vm_end. */
211 if (start < vma->vm_start) {
212 unmapped_error = -ENOMEM;
213 start = vma->vm_start;
215 /* Here vma->vm_start <= start < vma->vm_end. */
216 if (end <= vma->vm_end) {
218 error = msync_interval(vma, start, end, flags);
222 error = unmapped_error;
225 /* Here vma->vm_start <= start < vma->vm_end < end. */
226 error = msync_interval(vma, start, vma->vm_end, flags);
233 up_read(¤t->mm->mmap_sem);
234 current->flags &= ~PF_SYNCWRITE;