From 9f377622a484de0818c49ee01e0ab4eedf6acd81 Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Sat, 6 Mar 2021 12:04:38 +0800 Subject: [PATCH] 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 baa2c7c97153 ("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: Martin DEVERA Reviewed-by: Chao Yu [ Gao Xiang: note that <= 5.11 kernels are not impacted. ] Signed-off-by: Gao Xiang --- fs/erofs/data.c | 28 +++++++++++----------------- 1 file changed, 11 insertions(+), 17 deletions(-) diff --git a/fs/erofs/data.c b/fs/erofs/data.c index f88851c5c250..1249e74b3bf0 100644 --- a/fs/erofs/data.c +++ b/fs/erofs/data.c @@ -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 @@ submit_bio_retry: 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 @@ submit_bio_retry: /* 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 @@ has_updated: /* 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 @@ submit_bio_out: 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); }