Commit 1a63c198 authored May 15, 2018 by Misono Tomohiro Committed by David Sterba May 17, 2018

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: 5c1aab1d ("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>

parent 31d11b83

fs/btrfs/props.c

+8 −4

Original line number	Diff line number	Diff line
		@@ -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;