Commit e01a83e1 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Revert "btrfs: zstd: fix and simplify the inline extent decompression" 



This reverts commit 1e7f6def.

It causes my machine to not even boot, and Klara Modin reports that the
cause is that small zstd-compressed files return garbage when read.

Reported-by: default avatarKlara Modin <klarasmodin@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CABq1_vj4GpUeZpVG49OHCo-3sdbe2-2ROcu_xDvUG-6-5zPRXg@mail.gmail.com/


Reported-and-bisected-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Acked-by: default avatarDavid Sterba <dsterba@suse.com>
Cc: Qu Wenruo <wqu@suse.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5d9248ee

fs/btrfs/compression.h

+1 −1
Original line number Diff line number Diff line
@@ -169,7 +169,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping, 
		unsigned long *total_in, unsigned long *total_out);

int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb);

int zstd_decompress(struct list_head *ws, const u8 *data_in,

		struct page *dest_page, unsigned long dest_pgoff, size_t srclen,

		struct page *dest_page, unsigned long start_byte, size_t srclen,

		size_t destlen);

void zstd_init_workspace_manager(void);

void zstd_cleanup_workspace_manager(void);

fs/btrfs/zstd.c

+53 −22
Original line number Diff line number Diff line
@@ -20,7 +20,6 @@ 
#include "misc.h"

#include "compression.h"

#include "ctree.h"

#include "super.h"



#define ZSTD_BTRFS_MAX_WINDOWLOG 17

#define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG)
@@ -619,48 +618,80 @@ int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb) 
}



int zstd_decompress(struct list_head *ws, const u8 *data_in,

		struct page *dest_page, unsigned long dest_pgoff, size_t srclen,

		struct page *dest_page, unsigned long start_byte, size_t srclen,

		size_t destlen)

{

	struct workspace *workspace = list_entry(ws, struct workspace, list);

	struct btrfs_fs_info *fs_info = btrfs_sb(dest_page->mapping->host->i_sb);

	const u32 sectorsize = fs_info->sectorsize;

	zstd_dstream *stream;

	int ret = 0;

	unsigned long to_copy = 0;

	size_t ret2;

	unsigned long total_out = 0;

	unsigned long pg_offset = 0;



	stream = zstd_init_dstream(

			ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);

	if (!stream) {

		pr_warn("BTRFS: zstd_init_dstream failed\n");

		ret = -EIO;

		goto finish;

	}



	destlen = min_t(size_t, destlen, PAGE_SIZE);



	workspace->in_buf.src = data_in;

	workspace->in_buf.pos = 0;

	workspace->in_buf.size = srclen;



	workspace->out_buf.dst = workspace->buf;

	workspace->out_buf.pos = 0;

	workspace->out_buf.size = sectorsize;

	workspace->out_buf.size = PAGE_SIZE;



	/*

	 * Since both input and output buffers should not exceed one sector,

	 * one call should end the decompression.

	 */

	ret = zstd_decompress_stream(stream, &workspace->out_buf, &workspace->in_buf);

	if (zstd_is_error(ret)) {

		pr_warn_ratelimited("BTRFS: zstd_decompress_stream return %d\n",

				    zstd_get_error_code(ret));

	ret2 = 1;

	while (pg_offset < destlen

	       && workspace->in_buf.pos < workspace->in_buf.size) {

		unsigned long buf_start;

		unsigned long buf_offset;

		unsigned long bytes;



		/* Check if the frame is over and we still need more input */

		if (ret2 == 0) {

			pr_debug("BTRFS: zstd_decompress_stream ended early\n");

			ret = -EIO;

			goto finish;

		}

	to_copy = workspace->out_buf.pos;

	memcpy_to_page(dest_page, dest_pgoff + to_copy, workspace->out_buf.dst, to_copy);

finish:

	/* Error or early end. */

	if (unlikely(to_copy < destlen)) {

		ret2 = zstd_decompress_stream(stream, &workspace->out_buf,

				&workspace->in_buf);

		if (zstd_is_error(ret2)) {

			pr_debug("BTRFS: zstd_decompress_stream returned %d\n",

					zstd_get_error_code(ret2));

			ret = -EIO;

		memzero_page(dest_page, dest_pgoff + to_copy, destlen - to_copy);

			goto finish;

		}



		buf_start = total_out;

		total_out += workspace->out_buf.pos;

		workspace->out_buf.pos = 0;



		if (total_out <= start_byte)

			continue;



		if (total_out > start_byte && buf_start < start_byte)

			buf_offset = start_byte - buf_start;

		else

			buf_offset = 0;



		bytes = min_t(unsigned long, destlen - pg_offset,

				workspace->out_buf.size - buf_offset);



		memcpy_to_page(dest_page, pg_offset,

			       workspace->out_buf.dst + buf_offset, bytes);



		pg_offset += bytes;

	}

	ret = 0;

finish:

	if (pg_offset < destlen) {

		memzero_page(dest_page, pg_offset, destlen - pg_offset);

	}

	return ret;

}