Commit fdbd0df9 authored by Zhang Yi's avatar Zhang Yi Committed by Theodore Ts'o
Browse files

ext4: make ext4_mpage_readpages() support large folios 



ext4_mpage_readpages() currently assumes that each folio is the size of
PAGE_SIZE. Modify it to atomically calculate the number of blocks per
folio and iterate through the blocks in each folio, which would allow
for support of larger folios.

Signed-off-by: default avatarZhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250512063319.3539411-2-yi.zhang@huaweicloud.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 1a77a028

fs/ext4/readpage.c

+17 −11
Original line number Diff line number Diff line
@@ -227,24 +227,30 @@ int ext4_mpage_readpages(struct inode *inode, 
	int length;

	unsigned relative_block = 0;

	struct ext4_map_blocks map;

	unsigned int nr_pages = rac ? readahead_count(rac) : 1;

	unsigned int nr_pages, folio_pages;



	map.m_pblk = 0;

	map.m_lblk = 0;

	map.m_len = 0;

	map.m_flags = 0;



	for (; nr_pages; nr_pages--) {

	nr_pages = rac ? readahead_count(rac) : folio_nr_pages(folio);

	for (; nr_pages; nr_pages -= folio_pages) {

		int fully_mapped = 1;

		unsigned first_hole = blocks_per_page;

		unsigned int first_hole;

		unsigned int blocks_per_folio;



		if (rac)

			folio = readahead_folio(rac);



		folio_pages = folio_nr_pages(folio);

		prefetchw(&folio->flags);



		if (folio_buffers(folio))

			goto confused;



		blocks_per_folio = folio_size(folio) >> blkbits;

		first_hole = blocks_per_folio;

		block_in_file = next_block =

			(sector_t)folio->index << (PAGE_SHIFT - blkbits);

		last_block = block_in_file + nr_pages * blocks_per_page;
@@ -270,7 +276,7 @@ int ext4_mpage_readpages(struct inode *inode, 
					map.m_flags &= ~EXT4_MAP_MAPPED;

					break;

				}

				if (page_block == blocks_per_page)

				if (page_block == blocks_per_folio)

					break;

				page_block++;

				block_in_file++;
@@ -281,7 +287,7 @@ int ext4_mpage_readpages(struct inode *inode, 
		 * Then do more ext4_map_blocks() calls until we are

		 * done with this folio.

		 */

		while (page_block < blocks_per_page) {

		while (page_block < blocks_per_folio) {

			if (block_in_file < last_block) {

				map.m_lblk = block_in_file;

				map.m_len = last_block - block_in_file;
@@ -296,13 +302,13 @@ int ext4_mpage_readpages(struct inode *inode, 
			}

			if ((map.m_flags & EXT4_MAP_MAPPED) == 0) {

				fully_mapped = 0;

				if (first_hole == blocks_per_page)

				if (first_hole == blocks_per_folio)

					first_hole = page_block;

				page_block++;

				block_in_file++;

				continue;

			}

			if (first_hole != blocks_per_page)

			if (first_hole != blocks_per_folio)

				goto confused;		/* hole -> non-hole */



			/* Contiguous blocks? */
@@ -315,13 +321,13 @@ int ext4_mpage_readpages(struct inode *inode, 
					/* needed? */

					map.m_flags &= ~EXT4_MAP_MAPPED;

					break;

				} else if (page_block == blocks_per_page)

				} else if (page_block == blocks_per_folio)

					break;

				page_block++;

				block_in_file++;

			}

		}

		if (first_hole != blocks_per_page) {

		if (first_hole != blocks_per_folio) {

			folio_zero_segment(folio, first_hole << blkbits,

					  folio_size(folio));

			if (first_hole == 0) {
@@ -367,11 +373,11 @@ int ext4_mpage_readpages(struct inode *inode, 


		if (((map.m_flags & EXT4_MAP_BOUNDARY) &&

		     (relative_block == map.m_len)) ||

		    (first_hole != blocks_per_page)) {

		    (first_hole != blocks_per_folio)) {

			submit_bio(bio);

			bio = NULL;

		} else

			last_block_in_bio = first_block + blocks_per_page - 1;

			last_block_in_bio = first_block + blocks_per_folio - 1;

		continue;

	confused:

		if (bio) {