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(
  28                     (unsigned long)data + ((unsigned long)got * PAGE_SIZE),
  29                     num_pages - got, pages + got, write_page ? FOLL_WRITE : 0);
  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         kvfree(pages);
  55 }
  56 EXPORT_SYMBOL(ceph_put_page_vector);
  57
  58 void ceph_release_page_vector(struct page **pages, int num_pages)
  59 {
  60         int i;
  61
  62         for (i = 0; i < num_pages; i++)
  63                 __free_pages(pages[i], 0);
  64         kfree(pages);
  65 }
  66 EXPORT_SYMBOL(ceph_release_page_vector);
  67
  68 /*
  69  * allocate a vector new pages
  70  */
  71 struct page **ceph_alloc_page_vector(int num_pages, gfp_t flags)
  72 {
  73         struct page **pages;
  74         int i;
  75
  76         pages = kmalloc(sizeof(*pages) * num_pages, flags);
  77         if (!pages)
  78                 return ERR_PTR(-ENOMEM);
  79         for (i = 0; i < num_pages; i++) {
  80                 pages[i] = __page_cache_alloc(flags);
  81                 if (pages[i] == NULL) {
  82                         ceph_release_page_vector(pages, i);
  83                         return ERR_PTR(-ENOMEM);
  84                 }
  85         }
  86         return pages;
  87 }
  88 EXPORT_SYMBOL(ceph_alloc_page_vector);
  89
  90 /*
  91  * copy user data into a page vector
  92  */
  93 int ceph_copy_user_to_page_vector(struct page **pages,
  94                                          const void __user *data,
  95                                          loff_t off, size_t len)
  96 {
  97         int i = 0;
  98         int po = off & ~PAGE_MASK;
  99         int left = len;
 100         int l, bad;
 101
 102         while (left > 0) {
 103                 l = min_t(int, PAGE_SIZE-po, left);
 104                 bad = copy_from_user(page_address(pages[i]) + po, data, l);
 105                 if (bad == l)
 106                         return -EFAULT;
 107                 data += l - bad;
 108                 left -= l - bad;
 109                 po += l - bad;
 110                 if (po == PAGE_SIZE) {
 111                         po = 0;
 112                         i++;
 113                 }
 114         }
 115         return len;
 116 }
 117 EXPORT_SYMBOL(ceph_copy_user_to_page_vector);
 118
 119 void ceph_copy_to_page_vector(struct page **pages,
 120                                     const void *data,
 121                                     loff_t off, size_t len)
 122 {
 123         int i = 0;
 124         size_t po = off & ~PAGE_MASK;
 125         size_t left = len;
 126
 127         while (left > 0) {
 128                 size_t l = min_t(size_t, PAGE_SIZE-po, left);
 129
 130                 memcpy(page_address(pages[i]) + po, data, l);
 131                 data += l;
 132                 left -= l;
 133                 po += l;
 134                 if (po == PAGE_SIZE) {
 135                         po = 0;
 136                         i++;
 137                 }
 138         }
 139 }
 140 EXPORT_SYMBOL(ceph_copy_to_page_vector);
 141
 142 void ceph_copy_from_page_vector(struct page **pages,
 143                                     void *data,
 144                                     loff_t off, size_t len)
 145 {
 146         int i = 0;
 147         size_t po = off & ~PAGE_MASK;
 148         size_t left = len;
 149
 150         while (left > 0) {
 151                 size_t l = min_t(size_t, PAGE_SIZE-po, left);
 152
 153                 memcpy(data, page_address(pages[i]) + po, l);
 154                 data += l;
 155                 left -= l;
 156                 po += l;
 157                 if (po == PAGE_SIZE) {
 158                         po = 0;
 159                         i++;
 160                 }
 161         }
 162 }
 163 EXPORT_SYMBOL(ceph_copy_from_page_vector);
 164
 165 /*
 166  * Zero an extent within a page vector.  Offset is relative to the
 167  * start of the first page.
 168  */
 169 void ceph_zero_page_vector_range(int off, int len, struct page **pages)
 170 {
 171         int i = off >> PAGE_SHIFT;
 172
 173         off &= ~PAGE_MASK;
 174
 175         dout("zero_page_vector_page %u~%u\n", off, len);
 176
 177         /* leading partial page? */
 178         if (off) {
 179                 int end = min((int)PAGE_SIZE, off + len);
 180                 dout("zeroing %d %p head from %d\n", i, pages[i],
 181                      (int)off);
 182                 zero_user_segment(pages[i], off, end);
 183                 len -= (end - off);
 184                 i++;
 185         }
 186         while (len >= PAGE_SIZE) {
 187                 dout("zeroing %d %p len=%d\n", i, pages[i], len);
 188                 zero_user_segment(pages[i], 0, PAGE_SIZE);
 189                 len -= PAGE_SIZE;
 190                 i++;
 191         }
 192         /* trailing partial page? */
 193         if (len) {
 194                 dout("zeroing %d %p tail to %d\n", i, pages[i], (int)len);
 195                 zero_user_segment(pages[i], 0, len);
 196         }
 197 }
 198 EXPORT_SYMBOL(ceph_zero_page_vector_range);
 199