Ping? This patch should fix the problem of compressed extent even when nodatasum is set.
It has been one year but we still didn't get a conclusion on where force_compress should behave. But at least to me, NODATASUM is a strong exclusion for compress, no matter whatever option we use, we should NEVER compress data without datasum/datacow. So I still want to push this patch as is. Thanks, Qu On 2018/5/15 下午3:36, Qu Wenruo wrote: > 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 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, so there is no need to allow compression for > NODATACSUM. > > Reported-by: James Harvey <jamespharve...@gmail.com> > Signed-off-by: Qu Wenruo <w...@suse.com> > --- > fs/btrfs/inode.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index d241285a0d2a..dbef3f404559 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -396,6 +396,14 @@ static inline int inode_need_compress(struct inode > *inode, u64 start, u64 end) > { > struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); > > + /* > + * Btrfs doesn't support compression without csum or CoW. > + * This should have the highest priority. > + */ > + if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW || > + BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) > + return 0; > + > /* force compress */ > if (btrfs_test_opt(fs_info, FORCE_COMPRESS)) > return 1; >
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