extern void ext4_set_aops(struct inode *inode);
extern int ext4_writepage_trans_blocks(struct inode *);
extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks);
-extern int ext4_block_truncate_page(handle_t *handle,
- struct address_space *mapping, loff_t from);
-extern int ext4_block_zero_page_range(handle_t *handle,
- struct address_space *mapping, loff_t from, loff_t length);
extern int ext4_discard_partial_page_buffers(handle_t *handle,
struct address_space *mapping, loff_t from,
loff_t length, int flags);
return err;
}
-/*
- * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
- * up to the end of the block which corresponds to `from'.
- * This required during truncate. We need to physically zero the tail end
- * of that block so it doesn't yield old data if the file is later grown.
- */
-int ext4_block_truncate_page(handle_t *handle,
- struct address_space *mapping, loff_t from)
-{
- unsigned offset = from & (PAGE_CACHE_SIZE-1);
- unsigned length;
- unsigned blocksize;
- struct inode *inode = mapping->host;
-
- blocksize = inode->i_sb->s_blocksize;
- length = blocksize - (offset & (blocksize - 1));
-
- return ext4_block_zero_page_range(handle, mapping, from, length);
-}
-
-/*
- * ext4_block_zero_page_range() zeros out a mapping of length 'length'
- * starting from file offset 'from'. The range to be zero'd must
- * be contained with in one block. If the specified range exceeds
- * the end of the block it will be shortened to end of the block
- * that cooresponds to 'from'
- */
-int ext4_block_zero_page_range(handle_t *handle,
- struct address_space *mapping, loff_t from, loff_t length)
-{
- ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
- unsigned offset = from & (PAGE_CACHE_SIZE-1);
- unsigned blocksize, max, pos;
- ext4_lblk_t iblock;
- struct inode *inode = mapping->host;
- struct buffer_head *bh;
- struct page *page;
- int err = 0;
-
- page = find_or_create_page(mapping, from >> PAGE_CACHE_SHIFT,
- mapping_gfp_mask(mapping) & ~__GFP_FS);
- if (!page)
- return -ENOMEM;
-
- blocksize = inode->i_sb->s_blocksize;
- max = blocksize - (offset & (blocksize - 1));
-
- /*
- * correct length if it does not fall between
- * 'from' and the end of the block
- */
- if (length > max || length < 0)
- length = max;
-
- iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
-
- if (!page_has_buffers(page))
- create_empty_buffers(page, blocksize, 0);
-
- /* Find the buffer that contains "offset" */
- bh = page_buffers(page);
- pos = blocksize;
- while (offset >= pos) {
- bh = bh->b_this_page;
- iblock++;
- pos += blocksize;
- }
-
- err = 0;
- if (buffer_freed(bh)) {
- BUFFER_TRACE(bh, "freed: skip");
- goto unlock;
- }
-
- if (!buffer_mapped(bh)) {
- BUFFER_TRACE(bh, "unmapped");
- ext4_get_block(inode, iblock, bh, 0);
- /* unmapped? It's a hole - nothing to do */
- if (!buffer_mapped(bh)) {
- BUFFER_TRACE(bh, "still unmapped");
- goto unlock;
- }
- }
-
- /* Ok, it's mapped. Make sure it's up-to-date */
- if (PageUptodate(page))
- set_buffer_uptodate(bh);
-
- if (!buffer_uptodate(bh)) {
- err = -EIO;
- ll_rw_block(READ, 1, &bh);
- wait_on_buffer(bh);
- /* Uhhuh. Read error. Complain and punt. */
- if (!buffer_uptodate(bh))
- goto unlock;
- }
-
- if (ext4_should_journal_data(inode)) {
- BUFFER_TRACE(bh, "get write access");
- err = ext4_journal_get_write_access(handle, bh);
- if (err)
- goto unlock;
- }
-
- zero_user(page, offset, length);
-
- BUFFER_TRACE(bh, "zeroed end of block");
-
- err = 0;
- if (ext4_should_journal_data(inode)) {
- err = ext4_handle_dirty_metadata(handle, inode, bh);
- } else
- mark_buffer_dirty(bh);
-
-unlock:
- unlock_page(page);
- page_cache_release(page);
- return err;
-}
-
int ext4_can_truncate(struct inode *inode)
{
if (S_ISREG(inode->i_mode))