On Mon, Sep 18, 2023 at 01:04:54PM +0200, Hannes Reinecke wrote: > @@ -161,7 +161,7 @@ static struct bio *do_mpage_readpage(struct mpage_readpage_args *args) > struct folio *folio = args->folio; > struct inode *inode = folio->mapping->host; > const unsigned blkbits = inode->i_blkbits; > - const unsigned blocks_per_page = PAGE_SIZE >> blkbits; > + const unsigned blocks_per_folio = folio_size(folio) >> blkbits; > const unsigned blocksize = 1 << blkbits; > struct buffer_head *map_bh = &args->map_bh; > sector_t block_in_file; > @@ -169,7 +169,7 @@ static struct bio *do_mpage_readpage(struct mpage_readpage_args *args) > sector_t last_block_in_file; > sector_t blocks[MAX_BUF_PER_PAGE]; > unsigned page_block; > - unsigned first_hole = blocks_per_page; > + unsigned first_hole = blocks_per_folio; > struct block_device *bdev = NULL; > int length; > int fully_mapped = 1; I feel like we need an assertion that blocks_per_folio <= MAX_BUF_PER_PAGE. Otherwise this function runs off the end of the 'blocks' array. Or (and I tried to do this once before getting bogged down), change this function to not need the blocks array. We need (first_block, length), because this function will punt to 'confused' if theree is an on-disk discontiguity. ie this line needs to change: - if (page_block && blocks[page_block-1] != map_bh->b_blocknr-1) + if (page_block == 0) + first_block = map_bh->b_blocknr; + else if (first_block + page_block != map_bh->b_blocknr) goto confused; > @@ -474,12 +474,12 @@ static int __mpage_writepage(struct folio *folio, struct writeback_control *wbc, > struct address_space *mapping = folio->mapping; > struct inode *inode = mapping->host; > const unsigned blkbits = inode->i_blkbits; > - const unsigned blocks_per_page = PAGE_SIZE >> blkbits; > + const unsigned blocks_per_folio = folio_size(folio) >> blkbits; > sector_t last_block; > sector_t block_in_file; > sector_t blocks[MAX_BUF_PER_PAGE]; > unsigned page_block; > - unsigned first_unmapped = blocks_per_page; > + unsigned first_unmapped = blocks_per_folio; > struct block_device *bdev = NULL; > int boundary = 0; > sector_t boundary_block = 0; Similarly, this function needss an assert. Or remove blocks[].
