From: Nikolay Borisov <nborisov@suse.com>
To: dsterba@suse.cz, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 6/6] btrfs: Simplify code flow in btrfs_delayed_inode_reserve_metadata
Date: Mon, 1 Mar 2021 18:20:29 +0200 [thread overview]
Message-ID: <7129f1a4-ba72-c35e-7a77-0ead54f7fede@suse.com> (raw)
In-Reply-To: <20210301161532.GV7604@twin.jikos.cz>
On 1.03.21 г. 18:15 ч., David Sterba wrote:
> On Mon, Feb 22, 2021 at 06:40:47PM +0200, Nikolay Borisov wrote:
>> btrfs_block_rsv_add can return only ENOSPC since it's called with
>> NO_FLUSH modifier. This so simplify the logic in
>> btrfs_delayed_inode_reserve_metadata to exploit this invariant.
>
> This seems quite fragile, it's not straightforward to see from the
> context that the NO_FLUSH code will always return ENOSPC. I followed a
> few calls down from btrfs_block_rsv_add and it's well hidden inside
> __reserve_bytes. So in case it's an invariant I'd rather add an
> assertion, ie. ASSERT(ret == 0 || ret == -ENOSPC) so at least we know
> when this gets broken. Otherwise looks ok.
>
Fair enough, I'm fine with it. In any case we no longer return eagain
when reserving. either we succeed or we return ENOSPC - either because
we don't have space and we can't flush or because even after the
flushing machinery did its work a ticket still couldn't be satisfied, in
which case we failed it hence ENOSPC got returned.
next prev parent reply other threads:[~2021-03-01 16:23 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-22 16:40 [PATCH 0/6] Qgroup/delayed node related fixes Nikolay Borisov
2021-02-22 16:40 ` [PATCH 1/6] btrfs: Free correct amount of space in btrfs_delayed_inode_reserve_metadata Nikolay Borisov
2021-02-22 23:41 ` Qu Wenruo
2021-02-22 16:40 ` [PATCH 2/6] btrfs: Export qgroup_reserve_meta Nikolay Borisov
2021-02-22 23:42 ` Qu Wenruo
2021-02-25 16:27 ` David Sterba
2021-02-22 16:40 ` [PATCH 3/6] btrfs: Don't flush from btrfs_delayed_inode_reserve_metadata Nikolay Borisov
2021-02-22 23:45 ` Qu Wenruo
2021-02-22 16:40 ` [PATCH 4/6] btrfs: Cleanup try_flush_qgroup Nikolay Borisov
2021-02-22 23:46 ` Qu Wenruo
2021-02-22 16:40 ` [PATCH 5/6] btrfs: Remove btrfs_inode from btrfs_delayed_inode_reserve_metadata Nikolay Borisov
2021-02-22 23:53 ` Qu Wenruo
2021-02-22 16:40 ` [PATCH 6/6] btrfs: Simplify code flow in btrfs_delayed_inode_reserve_metadata Nikolay Borisov
2021-03-01 16:15 ` David Sterba
2021-03-01 16:20 ` Nikolay Borisov [this message]
2021-03-01 18:54 ` David Sterba
2021-03-01 18:55 ` [PATCH 0/6] Qgroup/delayed node related fixes David Sterba
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