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Date: Sat, 21 Oct 2023 06:08:37 +0100
From: Matthew Wilcox <willy@infradead.org>
To: Hannes Reinecke <hare@suse.de>
Cc: Luis Chamberlain <mcgrof@kernel.org>, Christoph Hellwig <hch@lst.de>,
	Jens Axboe <axboe@kernel.dk>, Pankaj Raghav <p.raghav@samsung.com>,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 04/18] fs/buffer.c: use accessor function to translate
 page index to sectors
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In-Reply-To: <ZTLW9jOJ0Crt/ZD3@casper.infradead.org>

On Fri, Oct 20, 2023 at 08:37:26PM +0100, Matthew Wilcox wrote:
> On Mon, Sep 18, 2023 at 01:04:56PM +0200, Hannes Reinecke wrote:
> > Use accessor functions block_index_to_sector() and block_sector_to_index()
> > to translate the page index into the block sector and vice versa.
> 
> You missed two in grow_dev_page() (which I just happened upon):

I have fixes here.  The key part of the first patch is:

 static sector_t folio_init_buffers(struct folio *folio,
-               struct block_device *bdev, sector_t block, int size)
+               struct block_device *bdev, int size)
 {
        struct buffer_head *head = folio_buffers(folio);
        struct buffer_head *bh = head;
        bool uptodate = folio_test_uptodate(folio);
+       sector_t block = folio_pos(folio) / size;
        sector_t end_block = blkdev_max_block(bdev, size);

(and then there's the cruft of removing the arguments from
folio_init_buffers)

The second patch is:

 static bool grow_buffers(struct block_device *bdev, sector_t block,
                unsigned size, gfp_t gfp)
 {
-       pgoff_t index;
-       int sizebits;
-
-       sizebits = PAGE_SHIFT - __ffs(size);
-       index = block >> sizebits;
+       loff_t pos;
[...]
-       if (unlikely(index != block >> sizebits)) {
+       if (check_mul_overflow(block, size, &pos) || pos > MAX_LFS_FILESIZE) {

I'll send a proper patch series tomorrow once the fstests are done
running.