1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
|
/*
* linux/mm/msync.c
*
* Copyright (C) 1994-1999 Linus Torvalds
*/
/*
* The msync() system call.
*/
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/hugetlb.h>
#include <linux/syscalls.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
/*
* Called with mm->page_table_lock held to protect against other
* threads/the swapper from ripping pte's out from under us.
*/
static void msync_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end)
{
struct mm_struct *mm = vma->vm_mm;
pte_t *pte;
int progress = 0;
again:
pte = pte_offset_map(pmd, addr);
do {
unsigned long pfn;
struct page *page;
if (progress >= 64) {
progress = 0;
if (need_resched() ||
need_lockbreak(&mm->page_table_lock))
break;
}
progress++;
if (!pte_present(*pte))
continue;
if (!pte_maybe_dirty(*pte))
continue;
pfn = pte_pfn(*pte);
if (unlikely(!pfn_valid(pfn))) {
print_bad_pte(vma, *pte, addr);
continue;
}
page = pfn_to_page(pfn);
if (ptep_clear_flush_dirty(vma, addr, pte) ||
page_test_and_clear_dirty(page))
set_page_dirty(page);
progress += 3;
} while (pte++, addr += PAGE_SIZE, addr != end);
pte_unmap(pte - 1);
cond_resched_lock(&mm->page_table_lock);
if (addr != end)
goto again;
}
static inline void msync_pmd_range(struct vm_area_struct *vma, pud_t *pud,
unsigned long addr, unsigned long end)
{
pmd_t *pmd;
unsigned long next;
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd))
continue;
msync_pte_range(vma, pmd, addr, next);
} while (pmd++, addr = next, addr != end);
}
static inline void msync_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
unsigned long addr, unsigned long end)
{
pud_t *pud;
unsigned long next;
pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
msync_pmd_range(vma, pud, addr, next);
} while (pud++, addr = next, addr != end);
}
static void msync_page_range(struct vm_area_struct *vma,
unsigned long addr, unsigned long end)
{
struct mm_struct *mm = vma->vm_mm;
pgd_t *pgd;
unsigned long next;
/* For hugepages we can't go walking the page table normally,
* but that's ok, hugetlbfs is memory based, so we don't need
* to do anything more on an msync().
* Can't do anything with VM_RESERVED regions either.
*/
if (vma->vm_flags & (VM_HUGETLB|VM_RESERVED))
return;
BUG_ON(addr >= end);
pgd = pgd_offset(mm, addr);
flush_cache_range(vma, addr, end);
spin_lock(&mm->page_table_lock);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
msync_pud_range(vma, pgd, addr, next);
} while (pgd++, addr = next, addr != end);
spin_unlock(&mm->page_table_lock);
}
/*
* MS_SYNC syncs the entire file - including mappings.
*
* MS_ASYNC does not start I/O (it used to, up to 2.5.67). Instead, it just
* marks the relevant pages dirty. 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 my _not_ starting I/O in MS_ASYNC we provide complete flexibility to
* applications.
*/
static int msync_interval(struct vm_area_struct *vma,
unsigned long addr, unsigned long end, int flags)
{
int ret = 0;
struct file *file = vma->vm_file;
if ((flags & MS_INVALIDATE) && (vma->vm_flags & VM_LOCKED))
return -EBUSY;
if (file && (vma->vm_flags & VM_SHARED)) {
msync_page_range(vma, addr, end);
if (flags & MS_SYNC) {
struct address_space *mapping = file->f_mapping;
int err;
ret = filemap_fdatawrite(mapping);
if (file->f_op && file->f_op->fsync) {
/*
* We don't take i_sem here because mmap_sem
* is already held.
*/
err = file->f_op->fsync(file,file->f_dentry,1);
if (err && !ret)
ret = err;
}
err = filemap_fdatawait(mapping);
if (!ret)
ret = err;
}
}
return ret;
}
asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
{
unsigned long end;
struct vm_area_struct *vma;
int unmapped_error, error = -EINVAL;
if (flags & MS_SYNC)
current->flags |= PF_SYNCWRITE;
down_read(¤t->mm->mmap_sem);
if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
goto out;
if (start & ~PAGE_MASK)
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.
*/
vma = find_vma(current->mm, start);
unmapped_error = 0;
for (;;) {
/* Still start < end. */
error = -ENOMEM;
if (!vma)
goto out;
/* Here start < vma->vm_end. */
if (start < vma->vm_start) {
unmapped_error = -ENOMEM;
start = vma->vm_start;
}
/* Here vma->vm_start <= start < vma->vm_end. */
if (end <= vma->vm_end) {
if (start < end) {
error = msync_interval(vma, start, end, flags);
if (error)
goto out;
}
error = unmapped_error;
goto out;
}
/* Here vma->vm_start <= start < vma->vm_end < end. */
error = msync_interval(vma, start, vma->vm_end, flags);
if (error)
goto out;
start = vma->vm_end;
vma = vma->vm_next;
}
out:
up_read(¤t->mm->mmap_sem);
current->flags &= ~PF_SYNCWRITE;
return error;
}
|
