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 got = 0;
  20         int rc = 0;
  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         while (got < num_pages) {
  28                 rc = get_user_pages(current, current->mm,
  29                     (unsigned long)data + ((unsigned long)got * PAGE_SIZE),
  30                     num_pages - got, write_page, 0, pages + got, NULL);
  31                 if (rc < 0)
  32                         break;
  33                 BUG_ON(rc == 0);
  34                 got += rc;
  35         }
  36         up_read(&current->mm->mmap_sem);
  37         if (rc < 0)
  38                 goto fail;
  39         return pages;
  40
  41 fail:
  42         ceph_put_page_vector(pages, got, false);
  43         return ERR_PTR(rc);
  44 }
  45 EXPORT_SYMBOL(ceph_get_direct_page_vector);
  46
  47 void ceph_put_page_vector(struct page **pages, int num_pages, bool dirty)
  48 {
  49         int i;
  50
  51         for (i = 0; i < num_pages; i++) {
  52                 if (dirty)
  53                         set_page_dirty_lock(pages[i]);
  54                 put_page(pages[i]);
  55         }
  56         kfree(pages);
  57 }
  58 EXPORT_SYMBOL(ceph_put_page_vector);
  59
  60 void ceph_release_page_vector(struct page **pages, int num_pages)
  61 {
  62         int i;
  63
  64         for (i = 0; i < num_pages; i++)
  65                 __free_pages(pages[i], 0);
  66         kfree(pages);
  67 }
  68 EXPORT_SYMBOL(ceph_release_page_vector);
  69
  70 /*
  71  * allocate a vector new pages
  72  */
  73 struct page **ceph_alloc_page_vector(int num_pages, gfp_t flags)
  74 {
  75         struct page **pages;
  76         int i;
  77
  78         pages = kmalloc(sizeof(*pages) * num_pages, flags);
  79         if (!pages)
  80                 return ERR_PTR(-ENOMEM);
  81         for (i = 0; i < num_pages; i++) {
  82                 pages[i] = __page_cache_alloc(flags);
  83                 if (pages[i] == NULL) {
  84                         ceph_release_page_vector(pages, i);
  85                         return ERR_PTR(-ENOMEM);
  86                 }
  87         }
  88         return pages;
  89 }
  90 EXPORT_SYMBOL(ceph_alloc_page_vector);
  91
  92 /*
  93  * copy user data into a page vector
  94  */
  95 int ceph_copy_user_to_page_vector(struct page **pages,
  96                                          const char __user *data,
  97                                          loff_t off, size_t len)
  98 {
  99         int i = 0;
 100         int po = off & ~PAGE_CACHE_MASK;
 101         int left = len;
 102         int l, bad;
 103
 104         while (left > 0) {
 105                 l = min_t(int, PAGE_CACHE_SIZE-po, left);
 106                 bad = copy_from_user(page_address(pages[i]) + po, data, l);
 107                 if (bad == l)
 108                         return -EFAULT;
 109                 data += l - bad;
 110                 left -= l - bad;
 111                 po += l - bad;
 112                 if (po == PAGE_CACHE_SIZE) {
 113                         po = 0;
 114                         i++;
 115                 }
 116         }
 117         return len;
 118 }
 119 EXPORT_SYMBOL(ceph_copy_user_to_page_vector);
 120
 121 int ceph_copy_to_page_vector(struct page **pages,
 122                                     const char *data,
 123                                     loff_t off, size_t len)
 124 {
 125         int i = 0;
 126         size_t po = off & ~PAGE_CACHE_MASK;
 127         size_t left = len;
 128         size_t l;
 129
 130         while (left > 0) {
 131                 l = min_t(size_t, PAGE_CACHE_SIZE-po, left);
 132                 memcpy(page_address(pages[i]) + po, data, l);
 133                 data += l;
 134                 left -= l;
 135                 po += l;
 136                 if (po == PAGE_CACHE_SIZE) {
 137                         po = 0;
 138                         i++;
 139                 }
 140         }
 141         return len;
 142 }
 143 EXPORT_SYMBOL(ceph_copy_to_page_vector);
 144
 145 int ceph_copy_from_page_vector(struct page **pages,
 146                                     char *data,
 147                                     loff_t off, size_t len)
 148 {
 149         int i = 0;
 150         size_t po = off & ~PAGE_CACHE_MASK;
 151         size_t left = len;
 152         size_t l;
 153
 154         while (left > 0) {
 155                 l = min_t(size_t, PAGE_CACHE_SIZE-po, left);
 156                 memcpy(data, page_address(pages[i]) + po, l);
 157                 data += l;
 158                 left -= l;
 159                 po += l;
 160                 if (po == PAGE_CACHE_SIZE) {
 161                         po = 0;
 162                         i++;
 163                 }
 164         }
 165         return len;
 166 }
 167 EXPORT_SYMBOL(ceph_copy_from_page_vector);
 168
 169 /*
 170  * copy user data from a page vector into a user pointer
 171  */
 172 int ceph_copy_page_vector_to_user(struct page **pages,
 173                                          char __user *data,
 174                                          loff_t off, size_t len)
 175 {
 176         int i = 0;
 177         int po = off & ~PAGE_CACHE_MASK;
 178         int left = len;
 179         int l, bad;
 180
 181         while (left > 0) {
 182                 l = min_t(int, left, PAGE_CACHE_SIZE-po);
 183                 bad = copy_to_user(data, page_address(pages[i]) + po, l);
 184                 if (bad == l)
 185                         return -EFAULT;
 186                 data += l - bad;
 187                 left -= l - bad;
 188                 if (po) {
 189                         po += l - bad;
 190                         if (po == PAGE_CACHE_SIZE)
 191                                 po = 0;
 192                 }
 193                 i++;
 194         }
 195         return len;
 196 }
 197 EXPORT_SYMBOL(ceph_copy_page_vector_to_user);
 198
 199 /*
 200  * Zero an extent within a page vector.  Offset is relative to the
 201  * start of the first page.
 202  */
 203 void ceph_zero_page_vector_range(int off, int len, struct page **pages)
 204 {
 205         int i = off >> PAGE_CACHE_SHIFT;
 206
 207         off &= ~PAGE_CACHE_MASK;
 208
 209         dout("zero_page_vector_page %u~%u\n", off, len);
 210
 211         /* leading partial page? */
 212         if (off) {
 213                 int end = min((int)PAGE_CACHE_SIZE, off + len);
 214                 dout("zeroing %d %p head from %d\n", i, pages[i],
 215                      (int)off);
 216                 zero_user_segment(pages[i], off, end);
 217                 len -= (end - off);
 218                 i++;
 219         }
 220         while (len >= PAGE_CACHE_SIZE) {
 221                 dout("zeroing %d %p len=%d\n", i, pages[i], len);
 222                 zero_user_segment(pages[i], 0, PAGE_CACHE_SIZE);
 223                 len -= PAGE_CACHE_SIZE;
 224                 i++;
 225         }
 226         /* trailing partial page? */
 227         if (len) {
 228                 dout("zeroing %d %p tail to %d\n", i, pages[i], (int)len);
 229                 zero_user_segment(pages[i], 0, len);
 230         }
 231 }
 232 EXPORT_SYMBOL(ceph_zero_page_vector_range);
 233