Commit fe181377 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

buffer: convert block_page_mkwrite() to use a folio 

If any page in a folio is dirtied, dirty the entire folio.  Removes a
number of hidden calls to compound_head() and references to page->mapping
and page->index.  Fixes a pre-existing bug where we could mark a folio as
dirty if the file is truncated to a multiple of the page size just as we
take the page fault.  I don't believe this bug has any bad effect, it's
just inefficient.

Link: https://lkml.kernel.org/r/20230612210141.730128-8-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent bb0ea598

fs/buffer.c

+13 −14
Original line number Diff line number Diff line
@@ -2564,38 +2564,37 @@ EXPORT_SYMBOL(block_commit_write); 
int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,

			 get_block_t get_block)

{

	struct page *page = vmf->page;

	struct folio *folio = page_folio(vmf->page);

	struct inode *inode = file_inode(vma->vm_file);

	unsigned long end;

	loff_t size;

	int ret;



	lock_page(page);

	folio_lock(folio);

	size = i_size_read(inode);

	if ((page->mapping != inode->i_mapping) ||

	    (page_offset(page) > size)) {

	if ((folio->mapping != inode->i_mapping) ||

	    (folio_pos(folio) >= size)) {

		/* We overload EFAULT to mean page got truncated */

		ret = -EFAULT;

		goto out_unlock;

	}



	/* page is wholly or partially inside EOF */

	if (((page->index + 1) << PAGE_SHIFT) > size)

		end = size & ~PAGE_MASK;

	else

		end = PAGE_SIZE;

	end = folio_size(folio);

	/* folio is wholly or partially inside EOF */

	if (folio_pos(folio) + end > size)

		end = size - folio_pos(folio);



	ret = __block_write_begin(page, 0, end, get_block);

	ret = __block_write_begin_int(folio, 0, end, get_block, NULL);

	if (!ret)

		ret = block_commit_write(page, 0, end);

		ret = block_commit_write(&folio->page, 0, end);



	if (unlikely(ret < 0))

		goto out_unlock;

	set_page_dirty(page);

	wait_for_stable_page(page);

	folio_mark_dirty(folio);

	folio_wait_stable(folio);

	return 0;

out_unlock:

	unlock_page(page);

	folio_unlock(folio);

	return ret;

}

EXPORT_SYMBOL(block_page_mkwrite);