btrfs: prepare for extensions in compression options (a7164fa4) · Commits · 戴 / test

This is a minimal patch intended to be backported to older kernels. We're going to extend the string specifying the compression method and this would fail on kernels before that change (the string is compared exactly). Relax the string matching only to the prefix, ie. ignoring anything that goes after "zlib" or "lzo", regardless of th format extension we decide to use. This applies to the mount options and properties. That way, patched old kernels could be booted on systems already utilizing the new compression spec. Applicable since commit , v3.14. Signed-off-by:

David Sterba <dsterba@suse.com>

fs/btrfs/props.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -408,9 +408,9 @@ static int prop_compression_apply(struct inode *inode,
		return 0;
		}

		if (!strncmp("lzo", value, len))
		if (!strncmp("lzo", value, 3))
		type = BTRFS_COMPRESS_LZO;
		else if (!strncmp("zlib", value, len))
		else if (!strncmp("zlib", value, 4))
		type = BTRFS_COMPRESS_ZLIB;
		else
		return -EINVAL;

fs/btrfs/super.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -499,14 +499,14 @@ int btrfs_parse_options(struct btrfs_fs_info info, char options,
		btrfs_test_opt(info, FORCE_COMPRESS);
		if (token == Opt_compress \|\|
		token == Opt_compress_force \|\|
		strcmp(args[0].from, "zlib") == 0) {
		strncmp(args[0].from, "zlib", 4) == 0) {
		compress_type = "zlib";
		info->compress_type = BTRFS_COMPRESS_ZLIB;
		btrfs_set_opt(info->mount_opt, COMPRESS);
		btrfs_clear_opt(info->mount_opt, NODATACOW);
		btrfs_clear_opt(info->mount_opt, NODATASUM);
		no_compress = 0;
		} else if (strcmp(args[0].from, "lzo") == 0) {
		} else if (strncmp(args[0].from, "lzo", 3) == 0) {
		compress_type = "lzo";
		info->compress_type = BTRFS_COMPRESS_LZO;
		btrfs_set_opt(info->mount_opt, COMPRESS);

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