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 25 static 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 if (!pte_maybe_dirty(*pte)) 38 continue; 39 pfn = pte_pfn(*pte); 40 if (!pfn_valid(pfn)) 41 continue; 42 page = pfn_to_page(pfn); 43 if (PageReserved(page)) 44 continue; 45 46 if (ptep_clear_flush_dirty(vma, addr, pte) || 47 page_test_and_clear_dirty(page)) 48 set_page_dirty(page); 49 } while (pte++, addr += PAGE_SIZE, addr != end); 50 pte_unmap(pte - 1); 51 } 52 53 static inline void sync_pmd_range(struct vm_area_struct *vma, pud_t *pud, 54 unsigned long addr, unsigned long end) 55 { 56 pmd_t *pmd; 57 unsigned long next; 58 59 pmd = pmd_offset(pud, addr); 60 do { 61 next = pmd_addr_end(addr, end); 62 if (pmd_none_or_clear_bad(pmd)) 63 continue; 64 sync_pte_range(vma, pmd, addr, next); 65 } while (pmd++, addr = next, addr != end); 66 } 67 68 static inline void sync_pud_range(struct vm_area_struct *vma, pgd_t *pgd, 69 unsigned long addr, unsigned long end) 70 { 71 pud_t *pud; 72 unsigned long next; 73 74 pud = pud_offset(pgd, addr); 75 do { 76 next = pud_addr_end(addr, end); 77 if (pud_none_or_clear_bad(pud)) 78 continue; 79 sync_pmd_range(vma, pud, addr, next); 80 } while (pud++, addr = next, addr != end); 81 } 82 83 static void sync_page_range(struct vm_area_struct *vma, 84 unsigned long addr, unsigned long end) 85 { 86 struct mm_struct *mm = vma->vm_mm; 87 pgd_t *pgd; 88 unsigned long next; 89 90 /* For hugepages we can't go walking the page table normally, 91 * but that's ok, hugetlbfs is memory based, so we don't need 92 * to do anything more on an msync() */ 93 if (is_vm_hugetlb_page(vma)) 94 return; 95 96 BUG_ON(addr >= end); 97 pgd = pgd_offset(mm, addr); 98 flush_cache_range(vma, addr, end); 99 spin_lock(&mm->page_table_lock); 100 do { 101 next = pgd_addr_end(addr, end); 102 if (pgd_none_or_clear_bad(pgd)) 103 continue; 104 sync_pud_range(vma, pgd, addr, next); 105 } while (pgd++, addr = next, addr != end); 106 spin_unlock(&mm->page_table_lock); 107 } 108 109 #ifdef CONFIG_PREEMPT 110 static inline void filemap_sync(struct vm_area_struct *vma, 111 unsigned long addr, unsigned long end) 112 { 113 const size_t chunk = 64 * 1024; /* bytes */ 114 unsigned long next; 115 116 do { 117 next = addr + chunk; 118 if (next > end || next < addr) 119 next = end; 120 sync_page_range(vma, addr, next); 121 cond_resched(); 122 } while (addr = next, addr != end); 123 } 124 #else 125 static inline void filemap_sync(struct vm_area_struct *vma, 126 unsigned long addr, unsigned long end) 127 { 128 sync_page_range(vma, addr, end); 129 } 130 #endif 131 132 /* 133 * MS_SYNC syncs the entire file - including mappings. 134 * 135 * MS_ASYNC does not start I/O (it used to, up to 2.5.67). Instead, it just 136 * marks the relevant pages dirty. The application may now run fsync() to 137 * write out the dirty pages and wait on the writeout and check the result. 138 * Or the application may run fadvise(FADV_DONTNEED) against the fd to start 139 * async writeout immediately. 140 * So my _not_ starting I/O in MS_ASYNC we provide complete flexibility to 141 * applications. 142 */ 143 static int msync_interval(struct vm_area_struct *vma, 144 unsigned long addr, unsigned long end, int flags) 145 { 146 int ret = 0; 147 struct file *file = vma->vm_file; 148 149 if ((flags & MS_INVALIDATE) && (vma->vm_flags & VM_LOCKED)) 150 return -EBUSY; 151 152 if (file && (vma->vm_flags & VM_SHARED)) { 153 filemap_sync(vma, addr, end); 154 155 if (flags & MS_SYNC) { 156 struct address_space *mapping = file->f_mapping; 157 int err; 158 159 ret = filemap_fdatawrite(mapping); 160 if (file->f_op && file->f_op->fsync) { 161 /* 162 * We don't take i_sem here because mmap_sem 163 * is already held. 164 */ 165 err = file->f_op->fsync(file,file->f_dentry,1); 166 if (err && !ret) 167 ret = err; 168 } 169 err = filemap_fdatawait(mapping); 170 if (!ret) 171 ret = err; 172 } 173 } 174 return ret; 175 } 176 177 asmlinkage long sys_msync(unsigned long start, size_t len, int flags) 178 { 179 unsigned long end; 180 struct vm_area_struct *vma; 181 int unmapped_error, error = -EINVAL; 182 183 if (flags & MS_SYNC) 184 current->flags |= PF_SYNCWRITE; 185 186 down_read(¤t->mm->mmap_sem); 187 if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC)) 188 goto out; 189 if (start & ~PAGE_MASK) 190 goto out; 191 if ((flags & MS_ASYNC) && (flags & MS_SYNC)) 192 goto out; 193 error = -ENOMEM; 194 len = (len + ~PAGE_MASK) & PAGE_MASK; 195 end = start + len; 196 if (end < start) 197 goto out; 198 error = 0; 199 if (end == start) 200 goto out; 201 /* 202 * If the interval [start,end) covers some unmapped address ranges, 203 * just ignore them, but return -ENOMEM at the end. 204 */ 205 vma = find_vma(current->mm, start); 206 unmapped_error = 0; 207 for (;;) { 208 /* Still start < end. */ 209 error = -ENOMEM; 210 if (!vma) 211 goto out; 212 /* Here start < vma->vm_end. */ 213 if (start < vma->vm_start) { 214 unmapped_error = -ENOMEM; 215 start = vma->vm_start; 216 } 217 /* Here vma->vm_start <= start < vma->vm_end. */ 218 if (end <= vma->vm_end) { 219 if (start < end) { 220 error = msync_interval(vma, start, end, flags); 221 if (error) 222 goto out; 223 } 224 error = unmapped_error; 225 goto out; 226 } 227 /* Here vma->vm_start <= start < vma->vm_end < end. */ 228 error = msync_interval(vma, start, vma->vm_end, flags); 229 if (error) 230 goto out; 231 start = vma->vm_end; 232 vma = vma->vm_next; 233 } 234 out: 235 up_read(¤t->mm->mmap_sem); 236 current->flags &= ~PF_SYNCWRITE; 237 return error; 238 } 239