net/ceph/pagevec.c

   1 #include <linux/ceph/ceph_debug.h>
   2
   3 #include <linux/module.h>
   4 #include <linux/sched.h>
   5 #include <linux/slab.h>
   6 #include <linux/file.h>
   7 #include <linux/namei.h>
   8 #include <linux/writeback.h>
   9
  10 #include <linux/ceph/libceph.h>
  11
  12 /*
  13  * build a vector of user pages
  14  */
  15 struct page **ceph_get_direct_page_vector(const char __user *data,
  16                                           int num_pages, bool write_page)
  17 {
  18         struct page **pages;
  19         int rc;
  20
  21         pages = kmalloc(sizeof(*pages) * num_pages, GFP_NOFS);
  22         if (!pages)
  23                 return ERR_PTR(-ENOMEM);
  24
  25         down_read(&current->mm->mmap_sem);
  26         rc = get_user_pages(current, current->mm, (unsigned long)data,
  27                             num_pages, write_page, 0, pages, NULL);
  28         up_read(&current->mm->mmap_sem);
  29         if (rc < num_pages)
  30                 goto fail;
  31         return pages;
  32
  33 fail:
  34         ceph_put_page_vector(pages, rc > 0 ? rc : 0, false);
  35         return ERR_PTR(rc);
  36 }
  37 EXPORT_SYMBOL(ceph_get_direct_page_vector);
  38
  39 void ceph_put_page_vector(struct page **pages, int num_pages, bool dirty)
  40 {
  41         int i;
  42
  43         for (i = 0; i < num_pages; i++) {
  44                 if (dirty)
  45                         set_page_dirty_lock(pages[i]);
  46                 put_page(pages[i]);
  47         }
  48         kfree(pages);
  49 }
  50 EXPORT_SYMBOL(ceph_put_page_vector);
  51
  52 void ceph_release_page_vector(struct page **pages, int num_pages)
  53 {
  54         int i;
  55
  56         for (i = 0; i < num_pages; i++)
  57                 __free_pages(pages[i], 0);
  58         kfree(pages);
  59 }
  60 EXPORT_SYMBOL(ceph_release_page_vector);
  61
  62 /*
  63  * allocate a vector new pages
  64  */
  65 struct page **ceph_alloc_page_vector(int num_pages, gfp_t flags)
  66 {
  67         struct page **pages;
  68         int i;
  69
  70         pages = kmalloc(sizeof(*pages) * num_pages, flags);
  71         if (!pages)
  72                 return ERR_PTR(-ENOMEM);
  73         for (i = 0; i < num_pages; i++) {
  74                 pages[i] = __page_cache_alloc(flags);
  75                 if (pages[i] == NULL) {
  76                         ceph_release_page_vector(pages, i);
  77                         return ERR_PTR(-ENOMEM);
  78                 }
  79         }
  80         return pages;
  81 }
  82 EXPORT_SYMBOL(ceph_alloc_page_vector);
  83
  84 /*
  85  * copy user data into a page vector
  86  */
  87 int ceph_copy_user_to_page_vector(struct page **pages,
  88                                          const char __user *data,
  89                                          loff_t off, size_t len)
  90 {
  91         int i = 0;
  92         int po = off & ~PAGE_CACHE_MASK;
  93         int left = len;
  94         int l, bad;
  95
  96         while (left > 0) {
  97                 l = min_t(int, PAGE_CACHE_SIZE-po, left);
  98                 bad = copy_from_user(page_address(pages[i]) + po, data, l);
  99                 if (bad == l)
 100                         return -EFAULT;
 101                 data += l - bad;
 102                 left -= l - bad;
 103                 po += l - bad;
 104                 if (po == PAGE_CACHE_SIZE) {
 105                         po = 0;
 106                         i++;
 107                 }
 108         }
 109         return len;
 110 }
 111 EXPORT_SYMBOL(ceph_copy_user_to_page_vector);
 112
 113 int ceph_copy_to_page_vector(struct page **pages,
 114                                     const char *data,
 115                                     loff_t off, size_t len)
 116 {
 117         int i = 0;
 118         size_t po = off & ~PAGE_CACHE_MASK;
 119         size_t left = len;
 120         size_t l;
 121
 122         while (left > 0) {
 123                 l = min_t(size_t, PAGE_CACHE_SIZE-po, left);
 124                 memcpy(page_address(pages[i]) + po, data, l);
 125                 data += l;
 126                 left -= l;
 127                 po += l;
 128                 if (po == PAGE_CACHE_SIZE) {
 129                         po = 0;
 130                         i++;
 131                 }
 132         }
 133         return len;
 134 }
 135 EXPORT_SYMBOL(ceph_copy_to_page_vector);
 136
 137 int ceph_copy_from_page_vector(struct page **pages,
 138                                     char *data,
 139                                     loff_t off, size_t len)
 140 {
 141         int i = 0;
 142         size_t po = off & ~PAGE_CACHE_MASK;
 143         size_t left = len;
 144         size_t l;
 145
 146         while (left > 0) {
 147                 l = min_t(size_t, PAGE_CACHE_SIZE-po, left);
 148                 memcpy(data, page_address(pages[i]) + po, l);
 149                 data += l;
 150                 left -= l;
 151                 po += l;
 152                 if (po == PAGE_CACHE_SIZE) {
 153                         po = 0;
 154                         i++;
 155                 }
 156         }
 157         return len;
 158 }
 159 EXPORT_SYMBOL(ceph_copy_from_page_vector);
 160
 161 /*
 162  * copy user data from a page vector into a user pointer
 163  */
 164 int ceph_copy_page_vector_to_user(struct page **pages,
 165                                          char __user *data,
 166                                          loff_t off, size_t len)
 167 {
 168         int i = 0;
 169         int po = off & ~PAGE_CACHE_MASK;
 170         int left = len;
 171         int l, bad;
 172
 173         while (left > 0) {
 174                 l = min_t(int, left, PAGE_CACHE_SIZE-po);
 175                 bad = copy_to_user(data, page_address(pages[i]) + po, l);
 176                 if (bad == l)
 177                         return -EFAULT;
 178                 data += l - bad;
 179                 left -= l - bad;
 180                 if (po) {
 181                         po += l - bad;
 182                         if (po == PAGE_CACHE_SIZE)
 183                                 po = 0;
 184                 }
 185                 i++;
 186         }
 187         return len;
 188 }
 189 EXPORT_SYMBOL(ceph_copy_page_vector_to_user);
 190
 191 /*
 192  * Zero an extent within a page vector.  Offset is relative to the
 193  * start of the first page.
 194  */
 195 void ceph_zero_page_vector_range(int off, int len, struct page **pages)
 196 {
 197         int i = off >> PAGE_CACHE_SHIFT;
 198
 199         off &= ~PAGE_CACHE_MASK;
 200
 201         dout("zero_page_vector_page %u~%u\n", off, len);
 202
 203         /* leading partial page? */
 204         if (off) {
 205                 int end = min((int)PAGE_CACHE_SIZE, off + len);
 206                 dout("zeroing %d %p head from %d\n", i, pages[i],
 207                      (int)off);
 208                 zero_user_segment(pages[i], off, end);
 209                 len -= (end - off);
 210                 i++;
 211         }
 212         while (len >= PAGE_CACHE_SIZE) {
 213                 dout("zeroing %d %p len=%d\n", i, pages[i], len);
 214                 zero_user_segment(pages[i], 0, PAGE_CACHE_SIZE);
 215                 len -= PAGE_CACHE_SIZE;
 216                 i++;
 217         }
 218         /* trailing partial page? */
 219         if (len) {
 220                 dout("zeroing %d %p tail to %d\n", i, pages[i], (int)len);
 221                 zero_user_segment(pages[i], 0, len);
 222         }
 223 }
 224 EXPORT_SYMBOL(ceph_zero_page_vector_range);
 225