diff options
| author | Calvin Owens <calvin@wbinvd.org> | 2025-08-25 18:32:04 +0930 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2025-09-02 20:45:19 +0200 |
| commit | 6db1df415d73fcad12134a54f97dc6c8a64ab181 (patch) | |
| tree | 6d98a9b3f78c6a9da4368bda59c762ef74a668be | |
| parent | de134cb54c3a67644ff95b1c9bffe545e752c912 (diff) | |
btrfs: accept and ignore compression level for lzo
The compression level is meaningless for lzo, but before commit
3f093ccb95f30 ("btrfs: harden parsing of compression mount options"),
it was silently ignored if passed.
After that commit, passing a level with lzo fails to mount:
BTRFS error: unrecognized compression value lzo:1
It seems reasonable for users to expect that lzo would permit a numeric
level option, as all the other algos do, even though the kernel's
implementation of LZO currently only supports a single level. Because it
has always worked to pass a level, it seems likely to me that users in
the real world are relying on doing so.
This patch restores the old behavior, giving "lzo:N" the same semantics
as all of the other compression algos.
To be clear, silly variants like "lzo:one", "lzo:the_first_option", or
"lzo:armageddon" also used to work. This isn't meant to suggest that
any possible mis-interpretation of mount options that once worked must
continue to work forever. This is an exceptional case where it makes
sense to preserve compatibility, both because the mis-interpretation is
reasonable, and because nothing tangible is sacrificed.
Finally update btrfs_show_options() to ignore the level of LZO, as it
is only the default level without any extra meaning.
Fixes: 3f093ccb95f30 ("btrfs: harden parsing of compression mount options")
Reviewed-by: Daniel Vacek <neelx@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Calvin Owens <calvin@wbinvd.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
| -rw-r--r-- | fs/btrfs/super.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 7f31f8bd63ba..e708faf1892f 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -299,9 +299,12 @@ static int btrfs_parse_compress(struct btrfs_fs_context *ctx, btrfs_set_opt(ctx->mount_opt, COMPRESS); btrfs_clear_opt(ctx->mount_opt, NODATACOW); btrfs_clear_opt(ctx->mount_opt, NODATASUM); - } else if (btrfs_match_compress_type(string, "lzo", false)) { + } else if (btrfs_match_compress_type(string, "lzo", true)) { ctx->compress_type = BTRFS_COMPRESS_LZO; - ctx->compress_level = 0; + ctx->compress_level = btrfs_compress_str2level(BTRFS_COMPRESS_LZO, + string + 3); + if (string[3] == ':' && string[4]) + btrfs_warn(NULL, "Compression level ignored for LZO"); btrfs_set_opt(ctx->mount_opt, COMPRESS); btrfs_clear_opt(ctx->mount_opt, NODATACOW); btrfs_clear_opt(ctx->mount_opt, NODATASUM); @@ -1079,7 +1082,7 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry) seq_printf(seq, ",compress-force=%s", compress_type); else seq_printf(seq, ",compress=%s", compress_type); - if (info->compress_level) + if (info->compress_level && info->compress_type != BTRFS_COMPRESS_LZO) seq_printf(seq, ":%d", info->compress_level); } if (btrfs_test_opt(info, NOSSD)) |