btrfs: Deduplicate extent_buffer init code

When a new extent buffer is allocated there are a few mandatory fields
which need to be set in order for the buffer to be sane: level,
generation, bytenr, backref_rev, owner and FSID/UUID. Currently this
is open coded in the callers of btrfs_alloc_tree_block, meaning it's
fairly high in the abstraction hierarchy of operations. This patch
solves this by simply moving this init code in btrfs_init_new_buffer,
since this is the function which initializes a newly allocated
extent buffer. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

4 files changed, 13 insertions, 54 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 18fd80e2f278..18f1ca1c5bd9 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -3358,17 +3358,7 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
 
         root_add_used(root, fs_info->nodesize);
 
-        memzero_extent_buffer(c, 0, sizeof(struct btrfs_header));
         btrfs_set_header_nritems(c, 1);
-        btrfs_set_header_level(c, level);
-        btrfs_set_header_bytenr(c, c->start);
-        btrfs_set_header_generation(c, trans->transid);
-        btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
-        btrfs_set_header_owner(c, root->root_key.objectid);
-
-        write_extent_buffer_fsid(c, fs_info->fsid);
-        write_extent_buffer_chunk_tree_uuid(c, fs_info->chunk_tree_uuid);
-
         btrfs_set_node_key(c, &lower_key, 0);
         btrfs_set_node_blockptr(c, 0, lower->start);
         lower_gen = btrfs_header_generation(lower);
@@ -3497,15 +3487,7 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
                 return PTR_ERR(split);
 
         root_add_used(root, fs_info->nodesize);
-
-        memzero_extent_buffer(split, 0, sizeof(struct btrfs_header));
-        btrfs_set_header_level(split, btrfs_header_level(c));
-        btrfs_set_header_bytenr(split, split->start);
-        btrfs_set_header_generation(split, trans->transid);
-        btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
-        btrfs_set_header_owner(split, root->root_key.objectid);
-        write_extent_buffer_fsid(split, fs_info->fsid);
-        write_extent_buffer_chunk_tree_uuid(split, fs_info->chunk_tree_uuid);
+        ASSERT(btrfs_header_level(c) == level);
 
         ret = tree_mod_log_eb_copy(fs_info, split, c, 0, mid, c_nritems - mid);
         if (ret) {
@@ -4291,15 +4273,6 @@ again:
 
         root_add_used(root, fs_info->nodesize);
 
-        memzero_extent_buffer(right, 0, sizeof(struct btrfs_header));
-        btrfs_set_header_bytenr(right, right->start);
-        btrfs_set_header_generation(right, trans->transid);
-        btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
-        btrfs_set_header_owner(right, root->root_key.objectid);
-        btrfs_set_header_level(right, 0);
-        write_extent_buffer_fsid(right, fs_info->fsid);
-        write_extent_buffer_chunk_tree_uuid(right, fs_info->chunk_tree_uuid);
-
         if (split == 0) {
                 if (mid <= slot) {
                         btrfs_set_header_nritems(right, 0);
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index f3224e23d5fa..6318ac2539d3 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1292,15 +1292,7 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
                 goto fail;
         }
 
-        memzero_extent_buffer(leaf, 0, sizeof(struct btrfs_header));
-        btrfs_set_header_bytenr(leaf, leaf->start);
-        btrfs_set_header_generation(leaf, trans->transid);
-        btrfs_set_header_backref_rev(leaf, BTRFS_MIXED_BACKREF_REV);
-        btrfs_set_header_owner(leaf, objectid);
         root->node = leaf;
-
-        write_extent_buffer_fsid(leaf, fs_info->fsid);
-        write_extent_buffer_chunk_tree_uuid(leaf, fs_info->chunk_tree_uuid);
         btrfs_mark_buffer_dirty(leaf);
 
         root->commit_root = btrfs_root_node(root);
@@ -1374,14 +1366,8 @@ static struct btrfs_root *alloc_log_tree(struct btrfs_trans_handle *trans,
                 return ERR_CAST(leaf);
         }
 
-        memzero_extent_buffer(leaf, 0, sizeof(struct btrfs_header));
-        btrfs_set_header_bytenr(leaf, leaf->start);
-        btrfs_set_header_generation(leaf, trans->transid);
-        btrfs_set_header_backref_rev(leaf, BTRFS_MIXED_BACKREF_REV);
-        btrfs_set_header_owner(leaf, BTRFS_TREE_LOG_OBJECTID);
         root->node = leaf;
 
-        write_extent_buffer_fsid(root->node, fs_info->fsid);
         btrfs_mark_buffer_dirty(root->node);
         btrfs_tree_unlock(root->node);
         return root;
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 472872a6cc27..0ca3999356c7 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -8302,7 +8302,7 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
 
 static struct extent_buffer *
 btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root,
-                      u64 bytenr, int level)
+                      u64 bytenr, int level, u64 owner)
 {
         struct btrfs_fs_info *fs_info = root->fs_info;
         struct extent_buffer *buf;
@@ -8311,7 +8311,6 @@ btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root,
         if (IS_ERR(buf))
                 return buf;
 
-        btrfs_set_header_generation(buf, trans->transid);
         btrfs_set_buffer_lockdep_class(root->root_key.objectid, buf, level);
         btrfs_tree_lock(buf);
         clean_tree_block(fs_info, buf);
@@ -8320,6 +8319,14 @@ btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root,
         btrfs_set_lock_blocking(buf);
         set_extent_buffer_uptodate(buf);
 
+        memzero_extent_buffer(buf, 0, sizeof(struct btrfs_header));
+        btrfs_set_header_level(buf, level);
+        btrfs_set_header_bytenr(buf, buf->start);
+        btrfs_set_header_generation(buf, trans->transid);
+        btrfs_set_header_backref_rev(buf, BTRFS_MIXED_BACKREF_REV);
+        btrfs_set_header_owner(buf, owner);
+        write_extent_buffer_fsid(buf, fs_info->fsid);
+        write_extent_buffer_chunk_tree_uuid(buf, fs_info->chunk_tree_uuid);
         if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
                 buf->log_index = root->log_transid % 2;
                 /*
@@ -8428,7 +8435,7 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
         if (btrfs_is_testing(fs_info)) {
                 buf = btrfs_init_new_buffer(trans, root, root->alloc_bytenr,
-                                            level);
+                                            level, root_objectid);
                 if (!IS_ERR(buf))
                         root->alloc_bytenr += blocksize;
                 return buf;
@@ -8444,7 +8451,8 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
         if (ret)
                 goto out_unuse;
 
-        buf = btrfs_init_new_buffer(trans, root, ins.objectid, level);
+        buf = btrfs_init_new_buffer(trans, root, ins.objectid, level,
+                                    root_objectid);
         if (IS_ERR(buf)) {
                 ret = PTR_ERR(buf);
                 goto out_free_reserved;
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0c4b9f364e84..08b8c0b346b3 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -616,14 +616,6 @@ static noinline int create_subvol(struct inode *dir,
                 goto fail;
         }
 
-        memzero_extent_buffer(leaf, 0, sizeof(struct btrfs_header));
-        btrfs_set_header_bytenr(leaf, leaf->start);
-        btrfs_set_header_generation(leaf, trans->transid);
-        btrfs_set_header_backref_rev(leaf, BTRFS_MIXED_BACKREF_REV);
-        btrfs_set_header_owner(leaf, objectid);
-
-        write_extent_buffer_fsid(leaf, fs_info->fsid);
-        write_extent_buffer_chunk_tree_uuid(leaf, fs_info->chunk_tree_uuid);
         btrfs_mark_buffer_dirty(leaf);
 
         inode_item = &root_item->inode;