-static int empty_write_end(struct page *page, unsigned from,
- unsigned to, int mode)
-{
- struct inode *inode = page->mapping->host;
- struct gfs2_inode *ip = GFS2_I(inode);
- struct buffer_head *bh;
- unsigned offset, blksize = 1 << inode->i_blkbits;
- pgoff_t end_index = i_size_read(inode) >> PAGE_CACHE_SHIFT;
-
- zero_user(page, from, to-from);
- mark_page_accessed(page);
-
- if (page->index < end_index || !(mode & FALLOC_FL_KEEP_SIZE)) {
- if (!gfs2_is_writeback(ip))
- gfs2_page_add_databufs(ip, page, from, to);
-
- block_commit_write(page, from, to);
- return 0;
- }
-
- offset = 0;
- bh = page_buffers(page);
- while (offset < to) {
- if (offset >= from) {
- set_buffer_uptodate(bh);
- mark_buffer_dirty(bh);
- clear_buffer_new(bh);
- write_dirty_buffer(bh, WRITE);
- }
- offset += blksize;
- bh = bh->b_this_page;
- }
-
- offset = 0;
- bh = page_buffers(page);
- while (offset < to) {
- if (offset >= from) {
- wait_on_buffer(bh);
- if (!buffer_uptodate(bh))
- return -EIO;
- }
- offset += blksize;
- bh = bh->b_this_page;
- }
- return 0;
-}
-
-static int needs_empty_write(sector_t block, struct inode *inode)
-{
- int error;
- struct buffer_head bh_map = { .b_state = 0, .b_blocknr = 0 };
-
- bh_map.b_size = 1 << inode->i_blkbits;
- error = gfs2_block_map(inode, block, &bh_map, 0);
- if (unlikely(error))
- return error;
- return !buffer_mapped(&bh_map);
-}
-
-static int write_empty_blocks(struct page *page, unsigned from, unsigned to,
- int mode)
-{
- struct inode *inode = page->mapping->host;
- unsigned start, end, next, blksize;
- sector_t block = page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
- int ret;
-
- blksize = 1 << inode->i_blkbits;
- next = end = 0;
- while (next < from) {
- next += blksize;
- block++;
- }
- start = next;
- do {
- next += blksize;
- ret = needs_empty_write(block, inode);
- if (unlikely(ret < 0))
- return ret;
- if (ret == 0) {
- if (end) {
- ret = __block_write_begin(page, start, end - start,
- gfs2_block_map);
- if (unlikely(ret))
- return ret;
- ret = empty_write_end(page, start, end, mode);
- if (unlikely(ret))
- return ret;
- end = 0;
- }
- start = next;
- }
- else
- end = next;
- block++;
- } while (next < to);
-
- if (end) {
- ret = __block_write_begin(page, start, end - start, gfs2_block_map);
- if (unlikely(ret))
- return ret;
- ret = empty_write_end(page, start, end, mode);
- if (unlikely(ret))
- return ret;
- }
-
- return 0;
-}
-