Commit f705bf84 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

mm/filemap: Add folio_mkwrite_check_truncate() 



This is the folio equivalent of page_mkwrite_check_truncate().

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarDavid Howells <dhowells@redhat.com>
parent 9eb7c76d

include/linux/pagemap.h

+28 −0
Original line number Diff line number Diff line
@@ -1120,6 +1120,34 @@ static inline unsigned long dir_pages(struct inode *inode) 
			       PAGE_SHIFT;

}



/**

 * folio_mkwrite_check_truncate - check if folio was truncated

 * @folio: the folio to check

 * @inode: the inode to check the folio against

 *

 * Return: the number of bytes in the folio up to EOF,

 * or -EFAULT if the folio was truncated.

 */

static inline ssize_t folio_mkwrite_check_truncate(struct folio *folio,

					      struct inode *inode)

{

	loff_t size = i_size_read(inode);

	pgoff_t index = size >> PAGE_SHIFT;

	size_t offset = offset_in_folio(folio, size);



	if (!folio->mapping)

		return -EFAULT;



	/* folio is wholly inside EOF */

	if (folio_next_index(folio) - 1 < index)

		return folio_size(folio);

	/* folio is wholly past EOF */

	if (folio->index > index || !offset)

		return -EFAULT;

	/* folio is partially inside EOF */

	return offset;

}



/**

 * page_mkwrite_check_truncate - check if page was truncated

 * @page: the page to check