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