fs: introduce write_begin, write_end, and perform_write aops
[linux-2.6.git] / drivers / block / loop.c
index b9233a0..a5f993a 100644 (file)
@@ -204,14 +204,13 @@ lo_do_transfer(struct loop_device *lo, int cmd,
  * do_lo_send_aops - helper for writing data to a loop device
  *
  * This is the fast version for backing filesystems which implement the address
- * space operations prepare_write and commit_write.
+ * space operations write_begin and write_end.
  */
 static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
-               int bsize, loff_t pos, struct page *page)
+               int bsize, loff_t pos, struct page *unused)
 {
        struct file *file = lo->lo_backing_file; /* kudos to NFsckingS */
        struct address_space *mapping = file->f_mapping;
-       const struct address_space_operations *aops = mapping->a_ops;
        pgoff_t index;
        unsigned offset, bv_offs;
        int len, ret;
@@ -223,63 +222,47 @@ static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
        len = bvec->bv_len;
        while (len > 0) {
                sector_t IV;
-               unsigned size;
+               unsigned size, copied;
                int transfer_result;
+               struct page *page;
+               void *fsdata;
 
                IV = ((sector_t)index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9);
                size = PAGE_CACHE_SIZE - offset;
                if (size > len)
                        size = len;
-               page = grab_cache_page(mapping, index);
-               if (unlikely(!page))
+
+               ret = pagecache_write_begin(file, mapping, pos, size, 0,
+                                                       &page, &fsdata);
+               if (ret)
                        goto fail;
-               ret = aops->prepare_write(file, page, offset,
-                                         offset + size);
-               if (unlikely(ret)) {
-                       if (ret == AOP_TRUNCATED_PAGE) {
-                               page_cache_release(page);
-                               continue;
-                       }
-                       goto unlock;
-               }
+
                transfer_result = lo_do_transfer(lo, WRITE, page, offset,
                                bvec->bv_page, bv_offs, size, IV);
-               if (unlikely(transfer_result)) {
-                       /*
-                        * The transfer failed, but we still write the data to
-                        * keep prepare/commit calls balanced.
-                        */
-                       printk(KERN_ERR "loop: transfer error block %llu\n",
-                              (unsigned long long)index);
-                       zero_user_page(page, offset, size, KM_USER0);
-               }
-               flush_dcache_page(page);
-               ret = aops->commit_write(file, page, offset,
-                                        offset + size);
-               if (unlikely(ret)) {
-                       if (ret == AOP_TRUNCATED_PAGE) {
-                               page_cache_release(page);
-                               continue;
-                       }
-                       goto unlock;
-               }
+               copied = size;
                if (unlikely(transfer_result))
-                       goto unlock;
-               bv_offs += size;
-               len -= size;
+                       copied = 0;
+
+               ret = pagecache_write_end(file, mapping, pos, size, copied,
+                                                       page, fsdata);
+               if (ret < 0)
+                       goto fail;
+               if (ret < copied)
+                       copied = ret;
+
+               if (unlikely(transfer_result))
+                       goto fail;
+
+               bv_offs += copied;
+               len -= copied;
                offset = 0;
                index++;
-               pos += size;
-               unlock_page(page);
-               page_cache_release(page);
+               pos += copied;
        }
        ret = 0;
 out:
        mutex_unlock(&mapping->host->i_mutex);
        return ret;
-unlock:
-       unlock_page(page);
-       page_cache_release(page);
 fail:
        ret = -1;
        goto out;
@@ -313,7 +296,7 @@ static int __do_lo_send_write(struct file *file,
  * do_lo_send_direct_write - helper for writing data to a loop device
  *
  * This is the fast, non-transforming version for backing filesystems which do
- * not implement the address space operations prepare_write and commit_write.
+ * not implement the address space operations write_begin and write_end.
  * It uses the write file operation which should be present on all writeable
  * filesystems.
  */
@@ -332,7 +315,7 @@ static int do_lo_send_direct_write(struct loop_device *lo,
  * do_lo_send_write - helper for writing data to a loop device
  *
  * This is the slow, transforming version for filesystems which do not
- * implement the address space operations prepare_write and commit_write.  It
+ * implement the address space operations write_begin and write_end.  It
  * uses the write file operation which should be present on all writeable
  * filesystems.
  *
@@ -780,7 +763,7 @@ static int loop_set_fd(struct loop_device *lo, struct file *lo_file,
                 */
                if (!file->f_op->splice_read)
                        goto out_putf;
-               if (aops->prepare_write && aops->commit_write)
+               if (aops->prepare_write || aops->write_begin)
                        lo_flags |= LO_FLAGS_USE_AOPS;
                if (!(lo_flags & LO_FLAGS_USE_AOPS) && !file->f_op->write)
                        lo_flags |= LO_FLAGS_READ_ONLY;