Re: [PATCH 04/11] fs, quota: introduce wait_super_thawed() to wait until a superblock is thawed

[Al Viro <viro@xxxxxxxxxxxxxxxxxx>]

On Wed, Aug 14, 2019 at 02:18:27PM +0200, Sascha Hauer wrote:
> quota uses three different functions to get a superblock from a
> block_device. Instead, retrieve the superblock always with get_super()
> and introduce wait_super_thawed() which is then used to wait until the
> superblock is thawed. This way the code can better be shared with the
> code introduced in the next step: We want to add quota support for
> filesystems without a block_device, so here functions around a
> block_device can't be used.

> + *	wait_super_thawed - wait for a superblock being thawed
> + *	@sb: superblock to wait for
> + *	@excl: if true, get s_umount semaphore exclusively
> + *
> + * Wait until the superblock is thawed. s_umount semaphore must be released on
> + * entry and will be held when returning.
> + */

Never expose anything like that - if locking rules depend upon the flags,
it MUST NOT be anything beyond a static helper.  I'm serious - that kind
of stuff ends up with trouble again and again.  Just don't.

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