From: Qu Wenruo wqu@suse.com
commit 42c16da6d684391db83788eb680accd84f6c2083 upstream.
As btrfs(5) specified:
Note If nodatacow or nodatasum are enabled, compression is disabled.
If NODATASUM or NODATACOW set, we should not compress the extent.
Normally NODATACOW is detected properly in run_delalloc_range() so compression won't happen for NODATACOW.
However for NODATASUM we don't have any check, and it can cause compressed extent without csum pretty easily, just by: mkfs.btrfs -f $dev mount $dev $mnt -o nodatasum touch $mnt/foobar mount -o remount,datasum,compress $mnt xfs_io -f -c "pwrite 0 128K" $mnt/foobar
And in fact, we have a bug report about corrupted compressed extent without proper data checksum so even RAID1 can't recover the corruption. (https://bugzilla.kernel.org/show_bug.cgi?id=199707)
Running compression without proper checksum could cause more damage when corruption happens, as compressed data could make the whole extent unreadable, so there is no need to allow compression for NODATACSUM.
The fix will refactor the inode compression check into two parts:
- inode_can_compress() As the hard requirement, checked at btrfs_run_delalloc_range(), so no compression will happen for NODATASUM inode at all.
- inode_need_compress() As the soft requirement, checked at btrfs_run_delalloc_range() and compress_file_range().
Reported-by: James Harvey jamespharvey20@gmail.com CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Qu Wenruo wqu@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/btrfs/inode.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-)
--- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -405,10 +405,31 @@ static noinline int add_async_extent(str return 0; }
+/* + * Check if the inode has flags compatible with compression + */ +static inline bool inode_can_compress(struct inode *inode) +{ + if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW || + BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) + return false; + return true; +} + +/* + * Check if the inode needs to be submitted to compression, based on mount + * options, defragmentation, properties or heuristics. + */ static inline int inode_need_compress(struct inode *inode, u64 start, u64 end) { struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+ if (!inode_can_compress(inode)) { + WARN(IS_ENABLED(CONFIG_BTRFS_DEBUG), + KERN_ERR "BTRFS: unexpected compression for ino %llu\n", + btrfs_ino(BTRFS_I(inode))); + return 0; + } /* force compress */ if (btrfs_test_opt(fs_info, FORCE_COMPRESS)) return 1; @@ -1626,7 +1647,8 @@ static int run_delalloc_range(void *priv } else if (BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC && !force_cow) { ret = run_delalloc_nocow(inode, locked_page, start, end, page_started, 0, nr_written); - } else if (!inode_need_compress(inode, start, end)) { + } else if (!inode_can_compress(inode) || + !inode_need_compress(inode, start, end)) { ret = cow_file_range(inode, locked_page, start, end, end, page_started, nr_written, 1, NULL); } else {