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