Btrfs: kill trans in run_delalloc_nocow and btrfs_cross_ref_exist

run_delalloc_nocow has used trans in two places where they don't
actually need @trans.

For btrfs_lookup_file_extent, we search for file extents without COWing
anything, and for btrfs_cross_ref_exist, the only place where we need
@trans is deferencing it in order to get running_transaction which we
could easily get from the global fs_info.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

3 files changed, 16 insertions, 47 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 56b8595eacbb..1692ebb05955 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2584,8 +2584,7 @@ int btrfs_pin_extent_for_log_replay(struct btrfs_fs_info *fs_info,
                                     u64 bytenr, u64 num_bytes);
 int btrfs_exclude_logged_extents(struct btrfs_fs_info *fs_info,
                                  struct extent_buffer *eb);
-int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans,
-                          struct btrfs_root *root,
+int btrfs_cross_ref_exist(struct btrfs_root *root,
                           u64 objectid, u64 offset, u64 bytenr);
 struct btrfs_block_group_cache *btrfs_lookup_block_group(
                                                  struct btrfs_fs_info *info,
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index be235b30a798..0992cd1393a6 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3028,8 +3028,7 @@ int btrfs_set_disk_extent_flags(struct btrfs_trans_handle *trans,
         return ret;
 }
 
-static noinline int check_delayed_ref(struct btrfs_trans_handle *trans,
-                                      struct btrfs_root *root,
+static noinline int check_delayed_ref(struct btrfs_root *root,
                                       struct btrfs_path *path,
                                       u64 objectid, u64 offset, u64 bytenr)
 {
@@ -3037,9 +3036,14 @@ static noinline int check_delayed_ref(struct btrfs_trans_handle *trans,
         struct btrfs_delayed_ref_node *ref;
         struct btrfs_delayed_data_ref *data_ref;
         struct btrfs_delayed_ref_root *delayed_refs;
+        struct btrfs_transaction *cur_trans;
         int ret = 0;
 
-        delayed_refs = &trans->transaction->delayed_refs;
+        cur_trans = root->fs_info->running_transaction;
+        if (!cur_trans)
+                return 0;
+
+        delayed_refs = &cur_trans->delayed_refs;
         spin_lock(&delayed_refs->lock);
         head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
         if (!head) {
@@ -3090,8 +3094,7 @@ static noinline int check_delayed_ref(struct btrfs_trans_handle *trans,
         return ret;
 }
 
-static noinline int check_committed_ref(struct btrfs_trans_handle *trans,
-                                        struct btrfs_root *root,
+static noinline int check_committed_ref(struct btrfs_root *root,
                                         struct btrfs_path *path,
                                         u64 objectid, u64 offset, u64 bytenr)
 {
@@ -3162,9 +3165,8 @@ out:
         return ret;
 }
 
-int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans,
-                          struct btrfs_root *root,
-                          u64 objectid, u64 offset, u64 bytenr)
+int btrfs_cross_ref_exist(struct btrfs_root *root, u64 objectid, u64 offset,
+                          u64 bytenr)
 {
         struct btrfs_path *path;
         int ret;
@@ -3175,12 +3177,12 @@ int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans,
                 return -ENOENT;
 
         do {
-                ret = check_committed_ref(trans, root, path, objectid,
+                ret = check_committed_ref(root, path, objectid,
                                           offset, bytenr);
                 if (ret && ret != -ENOENT)
                         goto out;
 
-                ret2 = check_delayed_ref(trans, root, path, objectid,
+                ret2 = check_delayed_ref(root, path, objectid,
                                          offset, bytenr);
         } while (ret2 == -EAGAIN);
 
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ac5f8c404268..92416f3ea9a8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1247,7 +1247,6 @@ static noinline int run_delalloc_nocow(struct inode *inode,
 {
         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
         struct btrfs_root *root = BTRFS_I(inode)->root;
-        struct btrfs_trans_handle *trans;
         struct extent_buffer *leaf;
         struct btrfs_path *path;
         struct btrfs_file_extent_item *fi;
@@ -1283,30 +1282,10 @@ static noinline int run_delalloc_nocow(struct inode *inode,
 
         nolock = btrfs_is_free_space_inode(inode);
 
-        if (nolock)
-                trans = btrfs_join_transaction_nolock(root);
-        else
-                trans = btrfs_join_transaction(root);
-
-        if (IS_ERR(trans)) {
-                extent_clear_unlock_delalloc(inode, start, end, end,
-                                             locked_page,
-                                             EXTENT_LOCKED | EXTENT_DELALLOC |
-                                             EXTENT_DO_ACCOUNTING |
-                                             EXTENT_DEFRAG, PAGE_UNLOCK |
-                                             PAGE_CLEAR_DIRTY |
-                                             PAGE_SET_WRITEBACK |
-                                             PAGE_END_WRITEBACK);
-                btrfs_free_path(path);
-                return PTR_ERR(trans);
-        }
-
-        trans->block_rsv = &fs_info->delalloc_block_rsv;
-
         cow_start = (u64)-1;
         cur_offset = start;
         while (1) {
-                ret = btrfs_lookup_file_extent(trans, root, path, ino,
+                ret = btrfs_lookup_file_extent(NULL, root, path, ino,
                                                cur_offset, 0);
                 if (ret < 0)
                         goto error;
@@ -1379,7 +1358,7 @@ next_slot:
                                 goto out_check;
                         if (btrfs_extent_readonly(fs_info, disk_bytenr))
                                 goto out_check;
-                        if (btrfs_cross_ref_exist(trans, root, ino,
+                        if (btrfs_cross_ref_exist(root, ino,
                                                   found_key.offset -
                                                   extent_offset, disk_bytenr))
                                 goto out_check;
@@ -1531,10 +1510,6 @@ out_check:
         }
 
 error:
-        err = btrfs_end_transaction(trans);
-        if (!ret)
-                ret = err;
-
         if (ret && cur_offset < end)
                 extent_clear_unlock_delalloc(inode, cur_offset, end, end,
                                              locked_page, EXTENT_LOCKED |
@@ -7290,7 +7265,6 @@ noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,
                               u64 *ram_bytes)
 {
         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
-        struct btrfs_trans_handle *trans;
         struct btrfs_path *path;
         int ret;
         struct extent_buffer *leaf;
@@ -7393,15 +7367,9 @@ noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,
          * look for other files referencing this extent, if we
          * find any we must cow
          */
-        trans = btrfs_join_transaction(root);
-        if (IS_ERR(trans)) {
-                ret = 0;
-                goto out;
-        }
 
-        ret = btrfs_cross_ref_exist(trans, root, btrfs_ino(BTRFS_I(inode)),
+        ret = btrfs_cross_ref_exist(root, btrfs_ino(BTRFS_I(inode)),
                                     key.offset - backref_offset, disk_bytenr);
-        btrfs_end_transaction(trans);
         if (ret) {
                 ret = 0;
                 goto out;