From 2b90883c561ddcc641741c2e4df1f702a4f2acb8 Mon Sep 17 00:00:00 2001 From: Johnny Chang Date: Fri, 26 Apr 2019 11:01:05 +0800 Subject: btrfs: Check the compression level before getting a workspace When a file's compression property is set as zlib or zstd but leave the compression mount option not be set, that means btrfs will try to compress the file with default compression level. But in btrfs_compress_pages(), it calls get_workspace() with level = 0. This will return a workspace with a wrong compression level. For zlib, the compression level in the workspace will be 0 (that means "store only"). And for zstd, the compression in the workspace will be 1, not the default level 3. How to reproduce: mkfs -t btrfs /dev/sdb mount /dev/sdb /mnt/ mkdir /mnt/zlib btrfs property set /mnt/zlib/ compression zlib dd if=/dev/zero of=/mnt/zlib/compression-friendly-file-10M bs=1M count=10 sync btrfs-debugfs -f /mnt/zlib/compression-friendly-file-10M btrfs-debugfs output: * before: ... (258 9961472): ram 524288 disk 1106247680 disk_size 524288 file: ... extents 20 disk size 10485760 logical size 10485760 ratio 1.00 * after: ... (258 10354688): ram 131072 disk 14217216 disk_size 4096 file: ... extents 80 disk size 327680 logical size 10485760 ratio 32.00 The steps for zstd are similar, but need to put a debugging message to show the level of the return workspace in zstd_get_workspace(). This commit adds a check of the compression level before getting a workspace by set_level(). CC: stable@vger.kernel.org # 5.1+ Signed-off-by: Johnny Chang Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/compression.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index 1463e14af2fb..4ec1df369e47 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -1009,6 +1009,7 @@ int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping, struct list_head *workspace; int ret; + level = btrfs_compress_op[type]->set_level(level); workspace = get_workspace(type, level); ret = btrfs_compress_op[type]->compress_pages(workspace, mapping, start, pages, -- cgit v1.2.3