[PATCH v9 69/96] mm/filemap: Add folio_mkwrite_check_truncate
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Date: 2021-05-05 16:31:16
Also in:
linux-fsdevel, lkml
Subsystem:
page cache, the rest · Maintainers:
Matthew Wilcox, Linus Torvalds
This is the folio equivalent of page_mkwrite_check_truncate(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> --- include/linux/pagemap.h | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 2f896574aad7..8fd00dc5ebd5 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h@@ -1195,6 +1195,34 @@ 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
--
2.30.2