btrfs-progs: image: use embedded array for metadump cluster buffer

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/btrfs-image.c b/btrfs-image.c
index e54e3fc..066baf9 100644 (file)
--- a/btrfs-image.c
+++ b/btrfs-image.c
@@ -97,7 +97,10 @@ struct metadump_struct {
        struct btrfs_root *root;
        FILE *out;
 
-       struct meta_cluster *cluster;
+       union {
+               struct meta_cluster cluster;
+               char meta_cluster_bytes[BLOCK_SIZE];
+       };
 
        pthread_t threads[MAX_WORKER_THREADS];
        size_t num_threads;
@@ -705,7 +708,7 @@ static void meta_cluster_init(struct metadump_struct *md, u64 start)
 
        md->num_items = 0;
        md->num_ready = 0;
-       header = &md->cluster->header;
+       header = &md->cluster.header;
        header->magic = cpu_to_le64(HEADER_MAGIC);
        header->bytenr = cpu_to_le64(start);
        header->nritems = cpu_to_le32(0);
@@ -738,7 +741,6 @@ static void metadump_destroy(struct metadump_struct *md, int num_threads)
                free(name->sub);
                free(name);
        }
-       free(md->cluster);
 }
 
 static int metadump_init(struct metadump_struct *md, struct btrfs_root *root,
@@ -748,9 +750,6 @@ static int metadump_init(struct metadump_struct *md, struct btrfs_root *root,
        int i, ret = 0;
 
        memset(md, 0, sizeof(*md));
-       md->cluster = calloc(1, BLOCK_SIZE);
-       if (!md->cluster)
-               return -ENOMEM;
        INIT_LIST_HEAD(&md->list);
        INIT_LIST_HEAD(&md->ordered);
        md->root = root;
@@ -790,7 +789,7 @@ static int write_zero(FILE *out, size_t size)
 
 static int write_buffers(struct metadump_struct *md, u64 *next)
 {
-       struct meta_cluster_header *header = &md->cluster->header;
+       struct meta_cluster_header *header = &md->cluster.header;
        struct meta_cluster_item *item;
        struct async_work *async;
        u64 bytenr = 0;
@@ -820,14 +819,14 @@ static int write_buffers(struct metadump_struct *md, u64 *next)
 
        /* setup and write index block */
        list_for_each_entry(async, &md->ordered, ordered) {
-               item = md->cluster->items + nritems;
+               item = &md->cluster.items[nritems];
                item->bytenr = cpu_to_le64(async->start);
                item->size = cpu_to_le32(async->bufsize);
                nritems++;
        }
        header->nritems = cpu_to_le32(nritems);
 
-       ret = fwrite(md->cluster, BLOCK_SIZE, 1, md->out);
+       ret = fwrite(&md->cluster, BLOCK_SIZE, 1, md->out);
        if (ret != 1) {
                error("unable to write out cluster: %s", strerror(errno));
                return -errno;