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         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         if (is_vmalloc_addr(pages))
  57                 vfree(pages);
  58         else
  59                 kfree(pages);
  60 }
  61 EXPORT_SYMBOL(ceph_put_page_vector);
  62
  63 void ceph_release_page_vector(struct page **pages, int num_pages)
  64 {
  65         int i;
  66
  67         for (i = 0; i < num_pages; i++)
  68                 __free_pages(pages[i], 0);
  69         kfree(pages);
  70 }
  71 EXPORT_SYMBOL(ceph_release_page_vector);
  72
  73 /*
  74  * allocate a vector new pages
  75  */
  76 struct page **ceph_alloc_page_vector(int num_pages, gfp_t flags)
  77 {
  78         struct page **pages;
  79         int i;
  80
  81         pages = kmalloc(sizeof(*pages) * num_pages, flags);
  82         if (!pages)
  83                 return ERR_PTR(-ENOMEM);
  84         for (i = 0; i < num_pages; i++) {
  85                 pages[i] = __page_cache_alloc(flags);
  86                 if (pages[i] == NULL) {
  87                         ceph_release_page_vector(pages, i);
  88                         return ERR_PTR(-ENOMEM);
  89                 }
  90         }
  91         return pages;
  92 }
  93 EXPORT_SYMBOL(ceph_alloc_page_vector);
  94
  95 /*
  96  * copy user data into a page vector
  97  */
  98 int ceph_copy_user_to_page_vector(struct page **pages,
  99                                          const void __user *data,
 100                                          loff_t off, size_t len)
 101 {
 102         int i = 0;
 103         int po = off & ~PAGE_CACHE_MASK;
 104         int left = len;
 105         int l, bad;
 106
 107         while (left > 0) {
 108                 l = min_t(int, PAGE_CACHE_SIZE-po, left);
 109                 bad = copy_from_user(page_address(pages[i]) + po, data, l);
 110                 if (bad == l)
 111                         return -EFAULT;
 112                 data += l - bad;
 113                 left -= l - bad;
 114                 po += l - bad;
 115                 if (po == PAGE_CACHE_SIZE) {
 116                         po = 0;
 117                         i++;
 118                 }
 119         }
 120         return len;
 121 }
 122 EXPORT_SYMBOL(ceph_copy_user_to_page_vector);
 123
 124 void ceph_copy_to_page_vector(struct page **pages,
 125                                     const void *data,
 126                                     loff_t off, size_t len)
 127 {
 128         int i = 0;
 129         size_t po = off & ~PAGE_CACHE_MASK;
 130         size_t left = len;
 131
 132         while (left > 0) {
 133                 size_t l = min_t(size_t, PAGE_CACHE_SIZE-po, left);
 134
 135                 memcpy(page_address(pages[i]) + po, data, l);
 136                 data += l;
 137                 left -= l;
 138                 po += l;
 139                 if (po == PAGE_CACHE_SIZE) {
 140                         po = 0;
 141                         i++;
 142                 }
 143         }
 144 }
 145 EXPORT_SYMBOL(ceph_copy_to_page_vector);
 146
 147 void ceph_copy_from_page_vector(struct page **pages,
 148                                     void *data,
 149                                     loff_t off, size_t len)
 150 {
 151         int i = 0;
 152         size_t po = off & ~PAGE_CACHE_MASK;
 153         size_t left = len;
 154
 155         while (left > 0) {
 156                 size_t l = min_t(size_t, PAGE_CACHE_SIZE-po, left);
 157
 158                 memcpy(data, page_address(pages[i]) + po, l);
 159                 data += l;
 160                 left -= l;
 161                 po += l;
 162                 if (po == PAGE_CACHE_SIZE) {
 163                         po = 0;
 164                         i++;
 165                 }
 166         }
 167 }
 168 EXPORT_SYMBOL(ceph_copy_from_page_vector);
 169
 170 /*
 171  * Zero an extent within a page vector.  Offset is relative to the
 172  * start of the first page.
 173  */
 174 void ceph_zero_page_vector_range(int off, int len, struct page **pages)
 175 {
 176         int i = off >> PAGE_CACHE_SHIFT;
 177
 178         off &= ~PAGE_CACHE_MASK;
 179
 180         dout("zero_page_vector_page %u~%u\n", off, len);
 181
 182         /* leading partial page? */
 183         if (off) {
 184                 int end = min((int)PAGE_CACHE_SIZE, off + len);
 185                 dout("zeroing %d %p head from %d\n", i, pages[i],
 186                      (int)off);
 187                 zero_user_segment(pages[i], off, end);
 188                 len -= (end - off);
 189                 i++;
 190         }
 191         while (len >= PAGE_CACHE_SIZE) {
 192                 dout("zeroing %d %p len=%d\n", i, pages[i], len);
 193                 zero_user_segment(pages[i], 0, PAGE_CACHE_SIZE);
 194                 len -= PAGE_CACHE_SIZE;
 195                 i++;
 196         }
 197         /* trailing partial page? */
 198         if (len) {
 199                 dout("zeroing %d %p tail to %d\n", i, pages[i], (int)len);
 200                 zero_user_segment(pages[i], 0, len);
 201         }
 202 }
 203 EXPORT_SYMBOL(ceph_zero_page_vector_range);
 204