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authorMiao Xie <miaox@cn.fujitsu.com>2013-05-15 11:48:20 +0400
committerJosef Bacik <jbacik@fusionio.com>2013-06-14 19:29:38 +0400
commitb0feb9d96e71a88d7eec56f41b8f23e92af889b0 (patch)
treee808deeb4f3b33636d6481ff1bc88ae269880fa3 /fs/btrfs/disk-io.h
parentcb517eabba4f109810dba2e5f37b0dcf22103065 (diff)
downloadlinux-b0feb9d96e71a88d7eec56f41b8f23e92af889b0.tar.xz
Btrfs: introduce grab/put functions for the root of the fs/file tree
The grab/put funtions will be used in the next patch, which need grab the root object and ensure it is not freed. We use reference counter instead of the srcu lock is to aovid blocking the memory reclaim task, which invokes synchronize_srcu(). Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Diffstat (limited to 'fs/btrfs/disk-io.h')
-rw-r--r--fs/btrfs/disk-io.h21
1 files changed, 21 insertions, 0 deletions
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index 534d583e609d..b71acd6e1e5b 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -76,6 +76,27 @@ void btrfs_btree_balance_dirty_nodelay(struct btrfs_root *root);
void btrfs_drop_and_free_fs_root(struct btrfs_fs_info *fs_info,
struct btrfs_root *root);
void btrfs_free_fs_root(struct btrfs_root *root);
+
+/*
+ * This function is used to grab the root, and avoid it is freed when we
+ * access it. But it doesn't ensure that the tree is not dropped.
+ *
+ * If you want to ensure the whole tree is safe, you should use
+ * fs_info->subvol_srcu
+ */
+static inline struct btrfs_root *btrfs_grab_fs_root(struct btrfs_root *root)
+{
+ if (atomic_inc_not_zero(&root->refs))
+ return root;
+ return NULL;
+}
+
+static inline void btrfs_put_fs_root(struct btrfs_root *root)
+{
+ if (atomic_dec_and_test(&root->refs))
+ kfree(root);
+}
+
void btrfs_mark_buffer_dirty(struct extent_buffer *buf);
int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid,
int atomic);