On Fri 20-04-18 16:59:03, Luis R. Rodriguez wrote:
> 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.
And do you have use for the new thaw_super_locked()? Because the new
semantics with having to deal with deactivate_locked_super() does not seem
ideal either so as a standalone cleanup patch it does not look too
useful.
> This commit introeuces no functional changes.
^^^ introduces
Honza
> ---
> 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
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
