[PATCH 2/4] btrfs: also validate compression levels in btrfs_compress_is_valid_type()

[koraynilay <koray.fra@gmail.com>]

Change btrfs_compress_is_valid_type() to use btrfs_match_compress_type()
and btrfs_compress_str2level() instead of a simple strncmp, which would
validate even incorrect strings (e.g. "zstd:invalid" or "zstdinvalid").

This also makes the function validate levels in the same way the compress=
option gets parsed, allowing bigger or smaller values, but still clamping
them to the min or max supported.

Furthermore, remove the len parameter, since now it requires a
NUL-terminated string because of btrfs_compress_str2level(); this change is
fine because btrfs_compress_is_valid_type() is used only once in props.c

Assisted-by: Gemini:3.1-pro antigravity-cli-1.1.5
Signed-off-by: koraynilay <koray.fra@gmail.com>
---
 fs/btrfs/compression.c | 11 ++++++++---
 fs/btrfs/compression.h |  2 +-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 58138f300b58..833c5f45afec 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -70,18 +70,23 @@ static struct compressed_bio *alloc_compressed_bio(struct btrfs_inode *inode,
 	return to_compressed_bio(bbio);
 }
 
-bool btrfs_compress_is_valid_type(const char *str, size_t len)
+bool btrfs_compress_is_valid_type(const char *str)
 {
+	size_t len = strlen(str);
 	int i;
 
 	for (i = 1; i < ARRAY_SIZE(btrfs_compress_types); i++) {
 		size_t comp_len = strlen(btrfs_compress_types[i]);
+		const char *comp_type = btrfs_compress_types[i];
+		int tmp_level;
 
 		if (len < comp_len)
 			continue;
 
-		if (!strncmp(btrfs_compress_types[i], str, comp_len))
-			return true;
+		if (btrfs_match_compress_type(str, comp_type, true)) {
+			if (btrfs_compress_str2level(i, str + comp_len, &tmp_level) == 0)
+				return true;
+		}
 	}
 	return false;
 }
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index e67ba47b4cdc..c63bed9f4152 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -132,7 +132,7 @@ extern const struct btrfs_compress_levels btrfs_lzo_compress;
 extern const struct btrfs_compress_levels btrfs_zstd_compress;
 
 const char* btrfs_compress_type2str(enum btrfs_compression_type type);
-bool btrfs_compress_is_valid_type(const char *str, size_t len);
+bool btrfs_compress_is_valid_type(const char *str);
 
 int btrfs_compress_heuristic(struct btrfs_inode *inode, u64 start, u64 end);
 
-- 
2.55.0