linux-kernel - Re: [PATCH v2 6/6] super: add filesystem freezing helpers for suspend and hibernate

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Message-ID: <k2xbbfnkklbndjbrrnp5lpyrajp3uuw4oxe6xksbtskb2p4myy@o4ypfbabhuu5>
Date: Mon, 31 Mar 2025 12:23:04 +0200
From: Jan Kara <jack@...e.cz>
To: Christian Brauner <brauner@...nel.org>
Cc: linux-fsdevel@...r.kernel.org, jack@...e.cz, 
	linux-kernel@...r.kernel.org, James Bottomley <James.Bottomley@...senpartnership.com>, 
	mcgrof@...nel.org, hch@...radead.org, david@...morbit.com, rafael@...nel.org, 
	djwong@...nel.org, pavel@...nel.org, peterz@...radead.org, mingo@...hat.com, 
	will@...nel.org, boqun.feng@...il.com
Subject: Re: [PATCH v2 6/6] super: add filesystem freezing helpers for
 suspend and hibernate

On Sat 29-03-25 09:42:19, Christian Brauner wrote:
> Allow the power subsystem to support filesystem freeze for
> suspend and hibernate.
> 
> Signed-off-by: Christian Brauner <brauner@...nel.org>

One comment below. Otherwise feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

> +void filesystems_thaw(bool hibernate)
> +{
> +	__iterate_supers(filesystems_thaw_callback, NULL,
> +			 SUPER_ITER_UNLOCKED | SUPER_ITER_REVERSE);
> +}

I think we should thaw in normal superblock order, not in reverse one? To
thaw the bottommost filesystem first? The filesystem thaw callback can
write to the underlying device and this could cause deadlocks...

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR