introduce __sb_writers_{acquired,release}() helpers

Preparation to hide the sb->s_writers internals from xfs and btrfs.
Add 2 trivial define's they can use rather than play with ->s_writers
directly. No changes in btrfs/transaction.o and xfs/xfs_aops.o.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jan Kara <jack@suse.com>

3 files changed, 9 insertions, 10 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index f5021fcb154e..a8ab8f5ef38e 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1638,9 +1638,7 @@ static void do_async_commit(struct work_struct *work)
          * Tell lockdep about it.
          */
         if (ac->newtrans->type & __TRANS_FREEZABLE)
-                rwsem_acquire_read(
-                     &ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
-                     0, 1, _THIS_IP_);
+                __sb_writers_acquired(ac->root->fs_info->sb, SB_FREEZE_FS);
 
         current->journal_info = ac->newtrans;
 
@@ -1679,9 +1677,7 @@ int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
          * async commit thread will be the one to unlock it.
          */
         if (ac->newtrans->type & __TRANS_FREEZABLE)
-                rwsem_release(
-                        &root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
-                        1, _THIS_IP_);
+                __sb_writers_release(root->fs_info->sb, SB_FREEZE_FS);
 
         schedule_work(&ac->work);
 
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 3859f5e27a4d..9bbb3507376a 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -119,8 +119,7 @@ xfs_setfilesize_trans_alloc(
          * We may pass freeze protection with a transaction.  So tell lockdep
          * we released it.
          */
-        rwsem_release(&ioend->io_inode->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
-                      1, _THIS_IP_);
+        __sb_writers_release(ioend->io_inode->i_sb, SB_FREEZE_FS);
         /*
          * We hand off the transaction to the completion thread now, so
          * clear the flag here.
@@ -171,8 +170,7 @@ xfs_setfilesize_ioend(
          * Similarly for freeze protection.
          */
         current_set_flags_nested(&tp->t_pflags, PF_FSTRANS);
-        rwsem_acquire_read(&VFS_I(ip)->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
-                           0, 1, _THIS_IP_);
+        __sb_writers_acquired(VFS_I(ip)->i_sb, SB_FREEZE_FS);
 
         return xfs_setfilesize(ip, tp, ioend->io_offset, ioend->io_size);
 }
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 84b783f277f7..acb7cad84edd 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1391,6 +1391,11 @@ extern struct timespec current_fs_time(struct super_block *sb);
 void __sb_end_write(struct super_block *sb, int level);
 int __sb_start_write(struct super_block *sb, int level, bool wait);
 
+#define __sb_writers_acquired(sb, lev)  \
+        rwsem_acquire_read(&(sb)->s_writers.lock_map[(lev)-1], 0, 1, _THIS_IP_)
+#define __sb_writers_release(sb, lev)   \
+        rwsem_release(&(sb)->s_writers.lock_map[(lev)-1], 1, _THIS_IP_)
+
 /**
  * sb_end_write - drop write access to a superblock
  * @sb: the super we wrote to