mm/msync.c

   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 }