btrfs: property: Set incompat flag if lzo/zstd compression is set

Incompat flag of LZO/ZSTD compression should be set at:

 1. mount time (-o compress/compress-force)
 2. when defrag is done
 3. when property is set

Currently 3. is missing and this commit adds this.

This could lead to a filesystem that uses ZSTD but is not marked as
such. If a kernel without a ZSTD support encounteres a ZSTD compressed
extent, it will handle that but this could be confusing to the user.

Typically the filesystem is mounted with the ZSTD option, but the
discrepancy can arise when a filesystem is never mounted with ZSTD and
then the property on some file is set (and some new extents are
written). A simple mount with -o compress=zstd will fix that up on an
unpatched kernel.

Same goes for LZO, but this has been around for a very long time
(2.6.37) so it's unlikely that a pre-LZO kernel would be used.

Fixes: 5c1aab1dd544 ("btrfs: Add zstd support")
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add user visible impact ]
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
index 53a8c95828e33a537525a193dfaf20e030505bbc..dc6140013ae8194739a8aa6a387f12c35794bdf9 100644 (file)
--- a/fs/btrfs/props.c
+++ b/fs/btrfs/props.c
@@ -380,6 +380,7 @@ static int prop_compression_apply(struct inode *inode,
                                  const char *value,
                                  size_t len)
 {
+       struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        int type;
 
        if (len == 0) {
@@ -390,14 +391,17 @@ static int prop_compression_apply(struct inode *inode,
                return 0;
        }
 
-       if (!strncmp("lzo", value, 3))
+       if (!strncmp("lzo", value, 3)) {
                type = BTRFS_COMPRESS_LZO;
-       else if (!strncmp("zlib", value, 4))
+               btrfs_set_fs_incompat(fs_info, COMPRESS_LZO);
+       } else if (!strncmp("zlib", value, 4)) {
                type = BTRFS_COMPRESS_ZLIB;
-       else if (!strncmp("zstd", value, len))
+       } else if (!strncmp("zstd", value, len)) {
                type = BTRFS_COMPRESS_ZSTD;
-       else
+               btrfs_set_fs_incompat(fs_info, COMPRESS_ZSTD);
+       } else {
                return -EINVAL;
+       }
 
        BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
        BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;