On 05/06, Chao Yu wrote: > On 2020/5/6 7:05, Jaegeuk Kim wrote: > > On 05/05, Chao Yu wrote: > >> On 2020-5-4 22:30, Jaegeuk Kim wrote: > >>> From: Daeho Jeong <daehoje...@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 <daehoje...@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); > >> > >> 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. > > > > Could you give it a try compress_log_size=2 and check decompression works? > > I tried some samples before submitting the patch, did you encounter app's data > corruption when using zstd algorithm? If so, let me check this issue.
Daeho reported: 1. cp -a src_file comp_dir/dst_file (comp_dir is a directory for compression) 2. sync comp_dir/dst_file 3. echo 3 > /proc/sys/vm/drop_caches 4. cat comp_dir/dst_file > dump (it returns I/O error depending on the file). > > Thanks, > > > > >> > >>> 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-de...@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > > . > >
