[RFC PATCH 08/19] btrfs: change extract in prop_handler to write into string

[Mark Harmstone <mark@harmstone.com>]

Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
 fs/btrfs/props.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
index dc6140013ae8..e57a4edc88c4 100644
--- a/fs/btrfs/props.c
+++ b/fs/btrfs/props.c
@@ -19,7 +19,7 @@ struct prop_handler {
 	const char *xattr_name;
 	int (*validate)(const char *value, size_t len);
 	int (*apply)(struct inode *inode, const char *value, size_t len);
-	const char *(*extract)(struct inode *inode);
+	int (*extract)(struct inode *inode, char *value);
 	int inheritable;
 };
 
@@ -27,7 +27,7 @@ static int prop_compression_validate(const char *value, size_t len);
 static int prop_compression_apply(struct inode *inode,
 				  const char *value,
 				  size_t len);
-static const char *prop_compression_extract(struct inode *inode);
+static int prop_compression_extract(struct inode *inode, char *value);
 
 static struct prop_handler prop_handlers[] = {
 	{
@@ -298,14 +298,14 @@ static int inherit_props(struct btrfs_trans_handle *trans,
 
 	for (i = 0; i < ARRAY_SIZE(prop_handlers); i++) {
 		const struct prop_handler *h = &prop_handlers[i];
-		const char *value;
+		char value[64];
 		u64 num_bytes;
 
 		if (!h->inheritable)
 			continue;
 
-		value = h->extract(parent);
-		if (!value)
+		ret = h->extract(parent, value);
+		if (ret)
 			continue;
 
 		num_bytes = btrfs_calc_trans_metadata_size(fs_info, 1);
@@ -410,18 +410,29 @@ static int prop_compression_apply(struct inode *inode,
 	return 0;
 }
 
-static const char *prop_compression_extract(struct inode *inode)
+static int prop_compression_extract(struct inode *inode, char *value)
 {
 	switch (BTRFS_I(inode)->prop_compress) {
 	case BTRFS_COMPRESS_ZLIB:
 	case BTRFS_COMPRESS_LZO:
 	case BTRFS_COMPRESS_ZSTD:
-		return btrfs_compress_type2str(BTRFS_I(inode)->prop_compress);
+	{
+		const char *v;
+
+		v = btrfs_compress_type2str(BTRFS_I(inode)->prop_compress);
+
+		if (!v)
+			return -EINVAL;
+
+		strcpy(value, v);
+
+		return 0;
+	}
 	default:
 		break;
 	}
 
-	return NULL;
+	return -EINVAL;
 }
 
 
-- 
2.19.2