[PATCH] btrfs: zstd: add `zstd-fast` alias mount option for fast modes

[Daniel Vacek <neelx@suse.com>]

Now that zstd fast compression levels are allowed with `compress=zstd:-N`
mount option, allow also specifying the same using the `compress=zstd-fast:N`
alias.

Upstream zstd deprecated the negative levels in favor of the `zstd-fast`
label anyways so this is actually the preferred way now. And indeed it also
looks more human friendly.

Signed-off-by: Daniel Vacek <neelx@suse.com>
---
 fs/btrfs/super.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 40709e2a44fce..c1bc8d4db440a 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -368,6 +368,16 @@ static int btrfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
 			btrfs_set_opt(ctx->mount_opt, COMPRESS);
 			btrfs_clear_opt(ctx->mount_opt, NODATACOW);
 			btrfs_clear_opt(ctx->mount_opt, NODATASUM);
+		} else if (strncmp(param->string, "zstd-fast", 9) == 0) {
+			ctx->compress_type = BTRFS_COMPRESS_ZSTD;
+			ctx->compress_level =
+				-btrfs_compress_str2level(BTRFS_COMPRESS_ZSTD,
+							  param->string + 9);
+			if (ctx->compress_level > 0)
+				ctx->compress_level = -ctx->compress_level;
+			btrfs_set_opt(ctx->mount_opt, COMPRESS);
+			btrfs_clear_opt(ctx->mount_opt, NODATACOW);
+			btrfs_clear_opt(ctx->mount_opt, NODATASUM);
 		} else if (strncmp(param->string, "zstd", 4) == 0) {
 			ctx->compress_type = BTRFS_COMPRESS_ZSTD;
 			ctx->compress_level =
-- 
2.47.2