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-rw-r--r--mm/msync.c236
1 files changed, 236 insertions, 0 deletions
diff --git a/mm/msync.c b/mm/msync.c
new file mode 100644
index 000000000000..090f426bca7d
--- /dev/null
+++ b/mm/msync.c
@@ -0,0 +1,236 @@
1/*
2 * linux/mm/msync.c
3 *
4 * Copyright (C) 1994-1999 Linus Torvalds
5 */
6
7/*
8 * The msync() system call.
9 */
10#include <linux/slab.h>
11#include <linux/pagemap.h>
12#include <linux/mm.h>
13#include <linux/mman.h>
14#include <linux/hugetlb.h>
15#include <linux/syscalls.h>
16
17#include <asm/pgtable.h>
18#include <asm/tlbflush.h>
19
20/*
21 * Called with mm->page_table_lock held to protect against other
22 * threads/the swapper from ripping pte's out from under us.
23 */
24
25static void sync_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
26 unsigned long addr, unsigned long end)
27{
28 pte_t *pte;
29
30 pte = pte_offset_map(pmd, addr);
31 do {
32 unsigned long pfn;
33 struct page *page;
34
35 if (!pte_present(*pte))
36 continue;
37 pfn = pte_pfn(*pte);
38 if (!pfn_valid(pfn))
39 continue;
40 page = pfn_to_page(pfn);
41 if (PageReserved(page))
42 continue;
43
44 if (ptep_clear_flush_dirty(vma, addr, pte) ||
45 page_test_and_clear_dirty(page))
46 set_page_dirty(page);
47 } while (pte++, addr += PAGE_SIZE, addr != end);
48 pte_unmap(pte - 1);
49}
50
51static inline void sync_pmd_range(struct vm_area_struct *vma, pud_t *pud,
52 unsigned long addr, unsigned long end)
53{
54 pmd_t *pmd;
55 unsigned long next;
56
57 pmd = pmd_offset(pud, addr);
58 do {
59 next = pmd_addr_end(addr, end);
60 if (pmd_none_or_clear_bad(pmd))
61 continue;
62 sync_pte_range(vma, pmd, addr, next);
63 } while (pmd++, addr = next, addr != end);
64}
65
66static inline void sync_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
67 unsigned long addr, unsigned long end)
68{
69 pud_t *pud;
70 unsigned long next;
71
72 pud = pud_offset(pgd, addr);
73 do {
74 next = pud_addr_end(addr, end);
75 if (pud_none_or_clear_bad(pud))
76 continue;
77 sync_pmd_range(vma, pud, addr, next);
78 } while (pud++, addr = next, addr != end);
79}
80
81static void sync_page_range(struct vm_area_struct *vma,
82 unsigned long addr, unsigned long end)
83{
84 struct mm_struct *mm = vma->vm_mm;
85 pgd_t *pgd;
86 unsigned long next;
87
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))
92 return;
93
94 BUG_ON(addr >= end);
95 pgd = pgd_offset(mm, addr);
96 flush_cache_range(vma, addr, end);
97 spin_lock(&mm->page_table_lock);
98 do {
99 next = pgd_addr_end(addr, end);
100 if (pgd_none_or_clear_bad(pgd))
101 continue;
102 sync_pud_range(vma, pgd, addr, next);
103 } while (pgd++, addr = next, addr != end);
104 spin_unlock(&mm->page_table_lock);
105}
106
107#ifdef CONFIG_PREEMPT
108static inline void filemap_sync(struct vm_area_struct *vma,
109 unsigned long addr, unsigned long end)
110{
111 const size_t chunk = 64 * 1024; /* bytes */
112 unsigned long next;
113
114 do {
115 next = addr + chunk;
116 if (next > end || next < addr)
117 next = end;
118 sync_page_range(vma, addr, next);
119 cond_resched();
120 } while (addr = next, addr != end);
121}
122#else
123static inline void filemap_sync(struct vm_area_struct *vma,
124 unsigned long addr, unsigned long end)
125{
126 sync_page_range(vma, addr, end);
127}
128#endif
129
130/*
131 * MS_SYNC syncs the entire file - including mappings.
132 *
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
139 * applications.
140 */
141static int msync_interval(struct vm_area_struct *vma,
142 unsigned long addr, unsigned long end, int flags)
143{
144 int ret = 0;
145 struct file *file = vma->vm_file;
146
147 if ((flags & MS_INVALIDATE) && (vma->vm_flags & VM_LOCKED))
148 return -EBUSY;
149
150 if (file && (vma->vm_flags & VM_SHARED)) {
151 filemap_sync(vma, addr, end);
152
153 if (flags & MS_SYNC) {
154 struct address_space *mapping = file->f_mapping;
155 int err;
156
157 ret = filemap_fdatawrite(mapping);
158 if (file->f_op && file->f_op->fsync) {
159 /*
160 * We don't take i_sem here because mmap_sem
161 * is already held.
162 */
163 err = file->f_op->fsync(file,file->f_dentry,1);
164 if (err && !ret)
165 ret = err;
166 }
167 err = filemap_fdatawait(mapping);
168 if (!ret)
169 ret = err;
170 }
171 }
172 return ret;
173}
174
175asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
176{
177 unsigned long end;
178 struct vm_area_struct *vma;
179 int unmapped_error, error = -EINVAL;
180
181 if (flags & MS_SYNC)
182 current->flags |= PF_SYNCWRITE;
183
184 down_read(&current->mm->mmap_sem);
185 if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
186 goto out;
187 if (start & ~PAGE_MASK)
188 goto out;
189 if ((flags & MS_ASYNC) && (flags & MS_SYNC))
190 goto out;
191 error = -ENOMEM;
192 len = (len + ~PAGE_MASK) & PAGE_MASK;
193 end = start + len;
194 if (end < start)
195 goto out;
196 error = 0;
197 if (end == start)
198 goto out;
199 /*
200 * If the interval [start,end) covers some unmapped address ranges,
201 * just ignore them, but return -ENOMEM at the end.
202 */
203 vma = find_vma(current->mm, start);
204 unmapped_error = 0;
205 for (;;) {
206 /* Still start < end. */
207 error = -ENOMEM;
208 if (!vma)
209 goto out;
210 /* Here start < vma->vm_end. */
211 if (start < vma->vm_start) {
212 unmapped_error = -ENOMEM;
213 start = vma->vm_start;
214 }
215 /* Here vma->vm_start <= start < vma->vm_end. */
216 if (end <= vma->vm_end) {
217 if (start < end) {
218 error = msync_interval(vma, start, end, flags);
219 if (error)
220 goto out;
221 }
222 error = unmapped_error;
223 goto out;
224 }
225 /* Here vma->vm_start <= start < vma->vm_end < end. */
226 error = msync_interval(vma, start, vma->vm_end, flags);
227 if (error)
228 goto out;
229 start = vma->vm_end;
230 vma = vma->vm_next;
231 }
232out:
233 up_read(&current->mm->mmap_sem);
234 current->flags &= ~PF_SYNCWRITE;
235 return error;
236}
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