Commit 6eaa266b authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

mm: add folio_fill_tail() and use it in iomap 

The iomap code was limited to PAGE_SIZE bytes; generalise it to cover
an arbitrary-sized folio, and move it to be a common helper.

[akpm@linux-foundation.org: fix folio_fill_tail(), per Andreas Gruenbacher]
Link: https://lkml.kernel.org/r/20231107212643.3490372-3-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a4fc4a0c

fs/iomap/buffered-io.c

+2 −12
Original line number Diff line number Diff line
@@ -305,28 +305,18 @@ static int iomap_read_inline_data(const struct iomap_iter *iter, 
{

	const struct iomap *iomap = iomap_iter_srcmap(iter);

	size_t size = i_size_read(iter->inode) - iomap->offset;

	size_t poff = offset_in_page(iomap->offset);

	size_t offset = offset_in_folio(folio, iomap->offset);

	void *addr;



	if (folio_test_uptodate(folio))

		return 0;



	if (WARN_ON_ONCE(size > PAGE_SIZE - poff))

		return -EIO;

	if (WARN_ON_ONCE(size > PAGE_SIZE -

			 offset_in_page(iomap->inline_data)))

		return -EIO;

	if (WARN_ON_ONCE(size > iomap->length))

		return -EIO;

	if (offset > 0)

		ifs_alloc(iter->inode, folio, iter->flags);



	addr = kmap_local_folio(folio, offset);

	memcpy(addr, iomap->inline_data, size);

	memset(addr + size, 0, PAGE_SIZE - poff - size);

	kunmap_local(addr);

	iomap_set_range_uptodate(folio, offset, PAGE_SIZE - poff);

	folio_fill_tail(folio, offset, iomap->inline_data, size);

	iomap_set_range_uptodate(folio, offset, folio_size(folio) - offset);

	return 0;

}

include/linux/highmem.h

+38 −0
Original line number Diff line number Diff line
@@ -521,6 +521,44 @@ static inline __must_check void *folio_zero_tail(struct folio *folio, 
	return kaddr;

}



/**

 * folio_fill_tail - Copy some data to a folio and pad with zeroes.

 * @folio: The destination folio.

 * @offset: The offset into @folio at which to start copying.

 * @from: The data to copy.

 * @len: How many bytes of data to copy.

 *

 * This function is most useful for filesystems which support inline data.

 * When they want to copy data from the inode into the page cache, this

 * function does everything for them.  It supports large folios even on

 * HIGHMEM configurations.

 */

static inline void folio_fill_tail(struct folio *folio, size_t offset,

		const char *from, size_t len)

{

	char *to = kmap_local_folio(folio, offset);



	VM_BUG_ON(offset + len > folio_size(folio));



	if (folio_test_highmem(folio)) {

		size_t max = PAGE_SIZE - offset_in_page(offset);



		while (len > max) {

			memcpy(to, from, max);

			kunmap_local(to);

			len -= max;

			from += max;

			offset += max;

			max = PAGE_SIZE;

			to = kmap_local_folio(folio, offset);

		}

	}



	memcpy(to, from, len);

	to = folio_zero_tail(folio, offset + len, to + len);

	kunmap_local(to);

}



/**

 * memcpy_from_file_folio - Copy some bytes from a file folio.

 * @to: The destination buffer.