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(¤t->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(¤t->mm->mmap_sem); 220 current->flags &= ~PF_SYNCWRITE; 221 return error; 222 } 223