Commit 90275a77 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: zstd: make the compression path to handle sector size < page size 



Inside zstd_compress_folios(), after exhausted one input page, we need
to switch to the next page as input.

However when counting the total input bytes (@tot_in), we always increase
it by PAGE_SIZE.

For the following case, it can cause incorrect value:

        0          32K         64K          96K
        |          |///////////||///////////|

After compressing range [32K, 64K), we switch to the next page, and
increasing @tot_in by 64K, while we only read 32K.

This will cause the @total_in to return a value larger than the input
length.

Fix it by only increase @tot_in by the input size.

Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent f6ebedb0

fs/btrfs/zstd.c

+1 −1
Original line number Diff line number Diff line
@@ -495,7 +495,7 @@ int zstd_compress_folios(struct list_head *ws, struct address_space *mapping, 


		/* Check if we need more input */

		if (workspace->in_buf.pos == workspace->in_buf.size) {

			tot_in += PAGE_SIZE;

			tot_in += workspace->in_buf.size;

			kunmap_local(workspace->in_buf.src);

			workspace->in_buf.src = NULL;

			folio_put(in_folio);