Btrfs: use signed integer instead of unsigned long integer for log transid

The log trans id is initialized to be 0 every time we create a log tree,
and the log tree need be re-created after a new transaction is started,
it means the log trans id is unlikely to be a huge number, so we can use
signed integer instead of unsigned long integer to save a bit space.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 8fed212..c9a2444 100644 (file)
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -109,14 +109,17 @@ struct btrfs_inode {
        u64 last_trans;
 
        /*
-        * log transid when this inode was last modified
+        * transid that last logged this inode
         */
-       u64 last_sub_trans;
+       u64 logged_trans;
 
        /*
-        * transid that last logged this inode
+        * log transid when this inode was last modified
         */
-       u64 logged_trans;
+       int last_sub_trans;
+
+       /* a local copy of root's last_log_commit */
+       int last_log_commit;
 
        /* total number of bytes pending delalloc, used by stat to calc the
         * real block usage of the file
@@ -155,9 +158,6 @@ struct btrfs_inode {
        /* flags field from the on disk inode */
        u32 flags;
 
-       /* a local copy of root's last_log_commit */
-       unsigned long last_log_commit;
-
        /*
         * Counters to keep track of the number of extent item's we may use due
         * to delalloc and such.  outstanding_extents is the number of extent

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index dac6653..70c03f5 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1721,8 +1721,8 @@ struct btrfs_root {
        atomic_t log_writers;
        atomic_t log_commit[2];
        atomic_t log_batch;
-       unsigned long log_transid;
-       unsigned long last_log_commit;
+       int log_transid;
+       int last_log_commit;
        pid_t log_start_pid;
        bool log_multiple_pids;
 

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 285c168..128a904 100644 (file)
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2362,7 +2362,7 @@ static int update_log_root(struct btrfs_trans_handle *trans,
 }
 
 static int wait_log_commit(struct btrfs_trans_handle *trans,
-                          struct btrfs_root *root, unsigned long transid)
+                          struct btrfs_root *root, int transid)
 {
        DEFINE_WAIT(wait);
        int index = transid % 2;
@@ -2434,7 +2434,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
        int ret;
        struct btrfs_root *log = root->log_root;
        struct btrfs_root *log_root_tree = root->fs_info->log_root_tree;
-       unsigned long log_transid = 0;
+       int log_transid = 0;
        struct blk_plug plug;
 
        mutex_lock(&root->log_mutex);