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