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

This reverts commit 1e7f6def8b.

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: Klara 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: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: David Sterba <dsterba@suse.com>
Cc: Qu Wenruo <wqu@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2024-01-22 15:39:01 -08:00
parent 5d9248eed4
commit e01a83e126
2 changed files with 53 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/btrfs/compression.h
View File

@ -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);

73
fs/btrfs/zstd.c
View File

@ -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 @@ done:
}
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));
goto finish;
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;
}
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;
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;
}
to_copy = workspace->out_buf.pos;
memcpy_to_page(dest_page, dest_pgoff + to_copy, workspace->out_buf.dst, to_copy);
ret = 0;
finish:
/* Error or early end. */
if (unlikely(to_copy < destlen)) {
ret = -EIO;
memzero_page(dest_page, dest_pgoff + to_copy, destlen - to_copy);
if (pg_offset < destlen) {
memzero_page(dest_page, pg_offset, destlen - pg_offset);
}
return ret;
}