Commit 9f377622 authored by Gao Xiang's avatar Gao Xiang
Browse files

erofs: fix bio->bi_max_vecs behavior change 

Martin reported an issue that directory read could be hung on the
latest -rc kernel with some certain image. The root cause is that
commit baa2c7c9 ("block: set .bi_max_vecs as actual allocated
vector number") changes .bi_max_vecs behavior. bio->bi_max_vecs
is set as actual allocated vector number rather than the requested
number now.

Let's avoid using .bi_max_vecs completely instead.

Link: https://lore.kernel.org/r/20210306040438.8084-1-hsiangkao@aol.com


Reported-by: default avatarMartin DEVERA <devik@eaxlabs.cz>
Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
[ Gao Xiang: note that <= 5.11 kernels are not impacted. ]
Signed-off-by: default avatarGao Xiang <hsiangkao@redhat.com>
parent a38fd874

fs/erofs/data.c

+11 −17
Original line number Diff line number Diff line
@@ -129,6 +129,7 @@ static inline struct bio *erofs_read_raw_page(struct bio *bio, 
					      struct page *page,

					      erofs_off_t *last_block,

					      unsigned int nblocks,

					      unsigned int *eblks,

					      bool ra)

{

	struct inode *const inode = mapping->host;
@@ -145,8 +146,7 @@ static inline struct bio *erofs_read_raw_page(struct bio *bio, 


	/* note that for readpage case, bio also equals to NULL */

	if (bio &&

	    /* not continuous */

	    *last_block + 1 != current_block) {

	    (*last_block + 1 != current_block || !*eblks)) {

submit_bio_retry:

		submit_bio(bio);

		bio = NULL;
@@ -216,7 +216,8 @@ static inline struct bio *erofs_read_raw_page(struct bio *bio, 
		if (nblocks > DIV_ROUND_UP(map.m_plen, PAGE_SIZE))

			nblocks = DIV_ROUND_UP(map.m_plen, PAGE_SIZE);



		bio = bio_alloc(GFP_NOIO, bio_max_segs(nblocks));

		*eblks = bio_max_segs(nblocks);

		bio = bio_alloc(GFP_NOIO, *eblks);



		bio->bi_end_io = erofs_readendio;

		bio_set_dev(bio, sb->s_bdev);
@@ -229,16 +230,8 @@ static inline struct bio *erofs_read_raw_page(struct bio *bio, 
	/* out of the extent or bio is full */

	if (err < PAGE_SIZE)

		goto submit_bio_retry;



	--*eblks;

	*last_block = current_block;



	/* shift in advance in case of it followed by too many gaps */

	if (bio->bi_iter.bi_size >= bio->bi_max_vecs * PAGE_SIZE) {

		/* err should reassign to 0 after submitting */

		err = 0;

		goto submit_bio_out;

	}



	return bio;



err_out:
@@ -252,7 +245,6 @@ static inline struct bio *erofs_read_raw_page(struct bio *bio, 


	/* if updated manually, continuous pages has a gap */

	if (bio)

submit_bio_out:

		submit_bio(bio);

	return err ? ERR_PTR(err) : NULL;

}
@@ -264,23 +256,26 @@ static inline struct bio *erofs_read_raw_page(struct bio *bio, 
static int erofs_raw_access_readpage(struct file *file, struct page *page)

{

	erofs_off_t last_block;

	unsigned int eblks;

	struct bio *bio;



	trace_erofs_readpage(page, true);



	bio = erofs_read_raw_page(NULL, page->mapping,

				  page, &last_block, 1, false);

				  page, &last_block, 1, &eblks, false);



	if (IS_ERR(bio))

		return PTR_ERR(bio);



	DBG_BUGON(bio);	/* since we have only one bio -- must be NULL */

	if (bio)

		submit_bio(bio);

	return 0;

}



static void erofs_raw_access_readahead(struct readahead_control *rac)

{

	erofs_off_t last_block;

	unsigned int eblks;

	struct bio *bio = NULL;

	struct page *page;
@@ -291,7 +286,7 @@ static void erofs_raw_access_readahead(struct readahead_control *rac) 
		prefetchw(&page->flags);



		bio = erofs_read_raw_page(bio, rac->mapping, page, &last_block,

				readahead_count(rac), true);

				readahead_count(rac), &eblks, true);



		/* all the page errors are ignored when readahead */

		if (IS_ERR(bio)) {
@@ -305,7 +300,6 @@ static void erofs_raw_access_readahead(struct readahead_control *rac) 
		put_page(page);

	}



	/* the rare case (end in gaps) */

	if (bio)

		submit_bio(bio);

}