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

[Mark Harmstone]

Signed-off-by: Mark Harmstone <m...@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