xref: /openbmc/linux/mm/msync.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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 static void msync_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
21 				unsigned long addr, unsigned long end)
22 {
23 	pte_t *pte;
24 	spinlock_t *ptl;
25 	int progress = 0;
26 
27 again:
28 	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
29 	do {
30 		unsigned long pfn;
31 		struct page *page;
32 
33 		if (progress >= 64) {
34 			progress = 0;
35 			if (need_resched() || need_lockbreak(ptl))
36 				break;
37 		}
38 		progress++;
39 		if (!pte_present(*pte))
40 			continue;
41 		if (!pte_maybe_dirty(*pte))
42 			continue;
43 		pfn = pte_pfn(*pte);
44 		if (unlikely(!pfn_valid(pfn))) {
45 			print_bad_pte(vma, *pte, addr);
46 			continue;
47 		}
48 		page = pfn_to_page(pfn);
49 
50 		if (ptep_clear_flush_dirty(vma, addr, pte) ||
51 		    page_test_and_clear_dirty(page))
52 			set_page_dirty(page);
53 		progress += 3;
54 	} while (pte++, addr += PAGE_SIZE, addr != end);
55 	pte_unmap_unlock(pte - 1, ptl);
56 	cond_resched();
57 	if (addr != end)
58 		goto again;
59 }
60 
61 static inline void msync_pmd_range(struct vm_area_struct *vma, pud_t *pud,
62 				unsigned long addr, unsigned long end)
63 {
64 	pmd_t *pmd;
65 	unsigned long next;
66 
67 	pmd = pmd_offset(pud, addr);
68 	do {
69 		next = pmd_addr_end(addr, end);
70 		if (pmd_none_or_clear_bad(pmd))
71 			continue;
72 		msync_pte_range(vma, pmd, addr, next);
73 	} while (pmd++, addr = next, addr != end);
74 }
75 
76 static inline void msync_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
77 				unsigned long addr, unsigned long end)
78 {
79 	pud_t *pud;
80 	unsigned long next;
81 
82 	pud = pud_offset(pgd, addr);
83 	do {
84 		next = pud_addr_end(addr, end);
85 		if (pud_none_or_clear_bad(pud))
86 			continue;
87 		msync_pmd_range(vma, pud, addr, next);
88 	} while (pud++, addr = next, addr != end);
89 }
90 
91 static void msync_page_range(struct vm_area_struct *vma,
92 				unsigned long addr, unsigned long end)
93 {
94 	pgd_t *pgd;
95 	unsigned long next;
96 
97 	/* For hugepages we can't go walking the page table normally,
98 	 * but that's ok, hugetlbfs is memory based, so we don't need
99 	 * to do anything more on an msync().
100 	 * Can't do anything with VM_RESERVED regions either.
101 	 */
102 	if (vma->vm_flags & (VM_HUGETLB|VM_RESERVED))
103 		return;
104 
105 	BUG_ON(addr >= end);
106 	pgd = pgd_offset(vma->vm_mm, addr);
107 	flush_cache_range(vma, addr, end);
108 	do {
109 		next = pgd_addr_end(addr, end);
110 		if (pgd_none_or_clear_bad(pgd))
111 			continue;
112 		msync_pud_range(vma, pgd, addr, next);
113 	} while (pgd++, addr = next, addr != end);
114 }
115 
116 /*
117  * MS_SYNC syncs the entire file - including mappings.
118  *
119  * MS_ASYNC does not start I/O (it used to, up to 2.5.67).  Instead, it just
120  * marks the relevant pages dirty.  The application may now run fsync() to
121  * write out the dirty pages and wait on the writeout and check the result.
122  * Or the application may run fadvise(FADV_DONTNEED) against the fd to start
123  * async writeout immediately.
124  * So my _not_ starting I/O in MS_ASYNC we provide complete flexibility to
125  * applications.
126  */
127 static int msync_interval(struct vm_area_struct *vma,
128 			unsigned long addr, unsigned long end, int flags)
129 {
130 	int ret = 0;
131 	struct file *file = vma->vm_file;
132 
133 	if ((flags & MS_INVALIDATE) && (vma->vm_flags & VM_LOCKED))
134 		return -EBUSY;
135 
136 	if (file && (vma->vm_flags & VM_SHARED)) {
137 		msync_page_range(vma, addr, end);
138 
139 		if (flags & MS_SYNC) {
140 			struct address_space *mapping = file->f_mapping;
141 			int err;
142 
143 			ret = filemap_fdatawrite(mapping);
144 			if (file->f_op && file->f_op->fsync) {
145 				/*
146 				 * We don't take i_sem here because mmap_sem
147 				 * is already held.
148 				 */
149 				err = file->f_op->fsync(file,file->f_dentry,1);
150 				if (err && !ret)
151 					ret = err;
152 			}
153 			err = filemap_fdatawait(mapping);
154 			if (!ret)
155 				ret = err;
156 		}
157 	}
158 	return ret;
159 }
160 
161 asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
162 {
163 	unsigned long end;
164 	struct vm_area_struct *vma;
165 	int unmapped_error, error = -EINVAL;
166 
167 	if (flags & MS_SYNC)
168 		current->flags |= PF_SYNCWRITE;
169 
170 	down_read(&current->mm->mmap_sem);
171 	if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
172 		goto out;
173 	if (start & ~PAGE_MASK)
174 		goto out;
175 	if ((flags & MS_ASYNC) && (flags & MS_SYNC))
176 		goto out;
177 	error = -ENOMEM;
178 	len = (len + ~PAGE_MASK) & PAGE_MASK;
179 	end = start + len;
180 	if (end < start)
181 		goto out;
182 	error = 0;
183 	if (end == start)
184 		goto out;
185 	/*
186 	 * If the interval [start,end) covers some unmapped address ranges,
187 	 * just ignore them, but return -ENOMEM at the end.
188 	 */
189 	vma = find_vma(current->mm, start);
190 	unmapped_error = 0;
191 	for (;;) {
192 		/* Still start < end. */
193 		error = -ENOMEM;
194 		if (!vma)
195 			goto out;
196 		/* Here start < vma->vm_end. */
197 		if (start < vma->vm_start) {
198 			unmapped_error = -ENOMEM;
199 			start = vma->vm_start;
200 		}
201 		/* Here vma->vm_start <= start < vma->vm_end. */
202 		if (end <= vma->vm_end) {
203 			if (start < end) {
204 				error = msync_interval(vma, start, end, flags);
205 				if (error)
206 					goto out;
207 			}
208 			error = unmapped_error;
209 			goto out;
210 		}
211 		/* Here vma->vm_start <= start < vma->vm_end < end. */
212 		error = msync_interval(vma, start, vma->vm_end, flags);
213 		if (error)
214 			goto out;
215 		start = vma->vm_end;
216 		vma = vma->vm_next;
217 	}
218 out:
219 	up_read(&current->mm->mmap_sem);
220 	current->flags &= ~PF_SYNCWRITE;
221 	return error;
222 }
223