1 // SPDX-License-Identifier: GPL-2.0
21  * - encountering a page which has buffers
22  * - encountering a page which has a non-hole after a hole
23  * - encountering a page with non-contiguous blocks
25  * then this code just gives up and calls the buffer_head-based read function.
26  * It does handle a page which has holes at the end - that is a common case:
27  * the end-of-file on blocksize < PAGE_SIZE setups.
44 #include <linux/backing-dev.h>
74 		folio_end_read(fi.folio, bio->bi_status == 0);  in __read_end_io()
75 	if (bio->bi_private)  in __read_end_io()
76 		mempool_free(bio->bi_private, bio_post_read_ctx_pool);  in __read_end_io()
86 	struct bio *bio = ctx->bio;  in decrypt_work()
98 	struct bio *bio = ctx->bio;  in verity_work()
105 	 * This is safe because verity is the last post-read step.  in verity_work()
109 	bio->bi_private = NULL;  in verity_work()
123 	switch (++ctx->cur_step) {  in bio_post_read_processing()
125 		if (ctx->enabled_steps & (1 << STEP_DECRYPT)) {  in bio_post_read_processing()
126 			INIT_WORK(&ctx->work, decrypt_work);  in bio_post_read_processing()
127 			fscrypt_enqueue_decrypt_work(&ctx->work);  in bio_post_read_processing()
130 		ctx->cur_step++;  in bio_post_read_processing()
133 		if (ctx->enabled_steps & (1 << STEP_VERITY)) {  in bio_post_read_processing()
134 			INIT_WORK(&ctx->work, verity_work);  in bio_post_read_processing()
135 			fsverity_enqueue_verify_work(&ctx->work);  in bio_post_read_processing()
138 		ctx->cur_step++;  in bio_post_read_processing()
141 		__read_end_io(ctx->bio);  in bio_post_read_processing()
147 	return bio->bi_private && !bio->bi_status;  in bio_post_read_required()
153  * The mpage code never puts partial pages into a BIO (except for end-of-file).
154  * If a page does not map to a contiguous run of blocks then it simply falls
165 		struct bio_post_read_ctx *ctx = bio->bi_private;  in mpage_end_io()
167 		ctx->cur_step = STEP_INITIAL;  in mpage_end_io()
177 	       idx < DIV_ROUND_UP(inode->i_size, PAGE_SIZE);  in ext4_need_verity()
197 		ctx->bio = bio;  in ext4_set_bio_post_read_ctx()
198 		ctx->enabled_steps = post_read_steps;  in ext4_set_bio_post_read_ctx()
199 		bio->bi_private = ctx;  in ext4_set_bio_post_read_ctx()
206 		return inode->i_sb->s_maxbytes;  in ext4_readpage_limit()
217 	const unsigned blkbits = inode->i_blkbits;  in ext4_mpage_readpages()
226 	struct block_device *bdev = inode->i_sb->s_bdev;  in ext4_mpage_readpages()
237 	for (; nr_pages; nr_pages--) {  in ext4_mpage_readpages()
243 		prefetchw(&folio->flags);  in ext4_mpage_readpages()
249 			(sector_t)folio->index << (PAGE_SHIFT - blkbits);  in ext4_mpage_readpages()
252 				      blocksize - 1) >> blkbits;  in ext4_mpage_readpages()
263 			unsigned map_offset = block_in_file - map.m_lblk;  in ext4_mpage_readpages()
264 			unsigned last = map.m_len - map_offset;  in ext4_mpage_readpages()
287 				map.m_len = last_block - block_in_file;  in ext4_mpage_readpages()
306 				goto confused;		/* hole -> non-hole */  in ext4_mpage_readpages()
308 			/* Contiguous blocks? */  in ext4_mpage_readpages()
328 				if (ext4_need_verity(inode, folio->index) &&  in ext4_mpage_readpages()
342 		if (bio && (last_block_in_bio != first_block - 1 ||  in ext4_mpage_readpages()
357 			ext4_set_bio_post_read_ctx(bio, inode, folio->index);  in ext4_mpage_readpages()
358 			bio->bi_iter.bi_sector = first_block << (blkbits - 9);  in ext4_mpage_readpages()
359 			bio->bi_end_io = mpage_end_io;  in ext4_mpage_readpages()
361 				bio->bi_opf |= REQ_RAHEAD;  in ext4_mpage_readpages()
374 			last_block_in_bio = first_block + blocks_per_page - 1;  in ext4_mpage_readpages()
409 	return -ENOMEM;  in ext4_init_post_read_processing()