Messages in this thread | | | Subject | Re: [f2fs-dev] [PATCH] f2fs: change maximum zstd compression buffer size | From | Chao Yu <> | Date | Tue, 5 May 2020 10:08:37 +0800 |
| |
On 2020-5-5 9:52, Chao Yu wrote: > On 2020-5-4 22:30, Jaegeuk Kim wrote: >> From: Daeho Jeong <daehojeong@google.com> >> >> Current zstd compression buffer size is one page and header size less >> than cluster size. By this, zstd compression always succeeds even if >> the real compression data is failed to fit into the buffer size, and >> eventually reading the cluster returns I/O error with the corrupted >> compression data. > > What's the root cause of this issue? I didn't get it. > >> >> Signed-off-by: Daeho Jeong <daehojeong@google.com> >> --- >> fs/f2fs/compress.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c >> index 4c7eaeee52336..a9fa8049b295f 100644 >> --- a/fs/f2fs/compress.c >> +++ b/fs/f2fs/compress.c >> @@ -313,7 +313,7 @@ static int zstd_init_compress_ctx(struct compress_ctx *cc) >> cc->private = workspace; >> cc->private2 = stream; >> >> - cc->clen = cc->rlen - PAGE_SIZE - COMPRESS_HEADER_SIZE; >> + cc->clen = ZSTD_compressBound(PAGE_SIZE << cc->log_cluster_size);
Max size of intermediate buffer has been set as below?
- zstd_init_compress_ctx - params = ZSTD_getParams(F2FS_ZSTD_DEFAULT_CLEVEL, cc->rlen, 0) - ZSTD_CStreamWorkspaceBound(params.cParams) - outBuffSize = ZSTD_compressBound(blockSize) + 1; - workspace_size = ... + outBuffSize + ... - workspace = f2fs_kvmalloc(workspace_size)
> > In my machine, the value is 66572 which is much larger than size of dst buffer, > so, in where we can tell the real size of dst buffer to zstd compressor? > Otherwise, if compressed data size is larger than dst buffer size, when we flush > compressed data into dst buffer, we may suffer overflow. > >> return 0; >> } >> >> @@ -330,7 +330,7 @@ static int zstd_compress_pages(struct compress_ctx *cc) >> ZSTD_inBuffer inbuf; >> ZSTD_outBuffer outbuf; >> int src_size = cc->rlen; >> - int dst_size = src_size - PAGE_SIZE - COMPRESS_HEADER_SIZE; >> + int dst_size = cc->clen; >> int ret; >> >> inbuf.pos = 0; >> > > > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
| |