[PATCH 02/11] fs: provide unlocked helper thaw_super()

[Luis R. Rodriguez]

thaw_super() hold a write lock, however we wish to also enable
callers which already hold the write lock. To do this provide a helper
and make thaw_super() use it. This way, all that thaw_super() does
now is lock handling and active count management.

This change has no functional changes.

Suggested-by: Dave Chinner <da...@fromorbit.com>
Signed-off-by: Luis R. Rodriguez <mcg...@kernel.org>
---
 fs/super.c | 39 ++++++++++++++++++++++++++-------------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/fs/super.c b/fs/super.c
index a7650ff22f0e..cecc279beecd 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1493,21 +1493,13 @@ int freeze_super(struct super_block *sb)
 }
 EXPORT_SYMBOL(freeze_super);
 
-/**
- * thaw_super -- unlock filesystem
- * @sb: the super to thaw
- *
- * Unlocks the filesystem and marks it writeable again after freeze_super().
- */
-int thaw_super(struct super_block *sb)
+/* Caller takes lock and handles active count */
+static int thaw_locked_super(struct super_block *sb)
 {
        int error;
 
-       down_write(&sb->s_umount);
-       if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) {
-               up_write(&sb->s_umount);
+       if (sb->s_writers.frozen != SB_FREEZE_COMPLETE)
                return -EINVAL;
-       }
 
        if (sb_rdonly(sb)) {
                sb->s_writers.frozen = SB_UNFROZEN;
@@ -1522,7 +1514,6 @@ int thaw_super(struct super_block *sb)
                        printk(KERN_ERR
                                "VFS:Filesystem thaw failed\n");
                        lockdep_sb_freeze_release(sb);
-                       up_write(&sb->s_umount);
                        return error;
                }
        }
@@ -1531,7 +1522,29 @@ int thaw_super(struct super_block *sb)
        sb_freeze_unlock(sb);
 out:
        wake_up(&sb->s_writers.wait_unfrozen);
-       deactivate_locked_super(sb);
        return 0;
 }
+
+/**
+ * thaw_super -- unlock filesystem
+ * @sb: the super to thaw
+ *
+ * Unlocks the filesystem and marks it writeable again after freeze_super().
+ */
+int thaw_super(struct super_block *sb)
+{
+       int error;
+
+       down_write(&sb->s_umount);
+       error = thaw_locked_super(sb);
+       if (error) {
+               up_write(&sb->s_umount);
+               goto out;
+       }
+
+       deactivate_locked_super(sb);
+
+out:
+       return error;
+}
 EXPORT_SYMBOL(thaw_super);
-- 
2.15.0