[PATCH] btrfs: use helper functions to check if a string has a given prefix

[George Hu <integral@archlinux.org>]

Replace strncmp() prefix checks with strstarts() when only a boolean result
is needed, and with str_has_prefix() when the prefix length is needed after
a successful match.

This makes prefix checks clearer and more concise.

Signed-off-by: George Hu <integral@archlinux.org>
---
 fs/btrfs/compression.c | 15 ++++-----------
 fs/btrfs/compression.h |  2 +-
 fs/btrfs/props.c       |  2 +-
 fs/btrfs/super.c       |  5 ++---
 fs/btrfs/xattr.c       |  3 +--
 5 files changed, 9 insertions(+), 18 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index c62b5148d5ac..82d0413e6236 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -70,19 +70,12 @@ 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)
 {
-	int i;
-
-	for (i = 1; i < ARRAY_SIZE(btrfs_compress_types); i++) {
-		size_t comp_len = strlen(btrfs_compress_types[i]);
-
-		if (len < comp_len)
-			continue;
-
-		if (!strncmp(btrfs_compress_types[i], str, comp_len))
+	for (int i = 1; i < ARRAY_SIZE(btrfs_compress_types); i++)
+		if (strstarts(str, btrfs_compress_types[i]))
 			return true;
-	}
+
 	return false;
 }
 
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index 1022dc53ec51..1d8e12fcd488 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -131,7 +131,7 @@ 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);
 
diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
index bb77d46376d4..c33930c58802 100644
--- a/fs/btrfs/props.c
+++ b/fs/btrfs/props.c
@@ -301,7 +301,7 @@ static int prop_compression_validate(const struct btrfs_inode *inode,
 	if (!value)
 		return 0;
 
-	if (btrfs_compress_is_valid_type(value, len))
+	if (btrfs_compress_is_valid_type(value))
 		return 0;
 
 	if ((len == 2 && strncmp("no", value, 2) == 0) ||
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index ddb620ac241b..287cdc45bef8 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -263,10 +263,9 @@ static const struct fs_parameter_spec btrfs_fs_parameters[] = {
 
 static bool btrfs_match_compress_type(const char *string, const char *type, bool may_have_level)
 {
-	const int len = strlen(type);
+	const size_t len = str_has_prefix(string, type);
 
-	return (strncmp(string, type, len) == 0) &&
-		((may_have_level && string[len] == ':') || string[len] == '\0');
+	return len && ((may_have_level && string[len] == ':') || string[len] == '\0');
 }
 
 static int btrfs_parse_compress(struct btrfs_fs_context *ctx,
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index ab55d10bd71f..9011d8096e2d 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -239,8 +239,7 @@ int btrfs_setxattr_trans(struct inode *inode, const char *name,
 		 * block_rsv of the handle and trigger a warning for the start
 		 * case.
 		 */
-		ASSERT(strncmp(name, XATTR_SECURITY_PREFIX,
-			       XATTR_SECURITY_PREFIX_LEN) == 0);
+		ASSERT(strstarts(name, XATTR_SECURITY_PREFIX));
 		trans = current->journal_info;
 	}
 
-- 
2.55.0