[PATCH 2/3] fs: make thaw_super_locked() really just a helper

[Luis R. Rodriguez]

thaw_super_locked() was added via commit 08fdc8a0138a ("buffer.c: call
thaw_super during emergency thaw") merged on v4.17 to help with the
ability so that the caller can take charge of handling the s_umount lock,
however, it has left all* of the failure handling including unlocking
lock of s_umount inside thaw_super_locked().

This does not make thaw_super_locked() flexible. For instance we may
later want to use it with the abilty to handle unfolding of the locks
ourselves.

Change thaw_super_locked() to really just be a helper, and let the
callers deal with all the error handling.

This commit introeuces no functional changes.

Signed-off-by: Luis R. Rodriguez <mcg...@kernel.org>
---
 fs/super.c | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/fs/super.c b/fs/super.c
index 9d0eb5e20a1f..82bc74a16f06 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -937,10 +937,15 @@ void emergency_remount(void)
 
 static void do_thaw_all_callback(struct super_block *sb)
 {
+       int error;
+
        down_write(&sb->s_umount);
        if (sb->s_root && sb->s_flags & MS_BORN) {
                emergency_thaw_bdev(sb);
-               thaw_super_locked(sb);
+               error = thaw_super_locked(sb);
+               if (error)
+                       up_write(&sb->s_umount);
+               deactivate_locked_super(sb);
        } else {
                up_write(&sb->s_umount);
        }
@@ -1532,14 +1537,13 @@ int freeze_super(struct super_block *sb)
 }
 EXPORT_SYMBOL(freeze_super);
 
+/* Caller takes the sb->s_umount rw_semaphore lock and handles active count */
 static int thaw_super_locked(struct super_block *sb)
 {
        int error;
 
-       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;
@@ -1554,7 +1558,6 @@ static int thaw_super_locked(struct super_block *sb)
                        printk(KERN_ERR
                                "VFS:Filesystem thaw failed\n");
                        lockdep_sb_freeze_release(sb);
-                       up_write(&sb->s_umount);
                        return error;
                }
        }
@@ -1563,7 +1566,6 @@ static int thaw_super_locked(struct super_block *sb)
        sb_freeze_unlock(sb);
 out:
        wake_up(&sb->s_writers.wait_unfrozen);
-       deactivate_locked_super(sb);
        return 0;
 }
 
@@ -1575,7 +1577,18 @@ static int thaw_super_locked(struct super_block *sb)
  */
 int thaw_super(struct super_block *sb)
 {
+       int error;
+
        down_write(&sb->s_umount);
-       return thaw_super_locked(sb);
+       error = thaw_super_locked(sb);
+       if (error) {
+               up_write(&sb->s_umount);
+               goto out;
+       }
+
+       deactivate_locked_super(sb);
+
+out:
+       return error;
 }
 EXPORT_SYMBOL(thaw_super);
-- 
2.16.3