From: Adam Borowski <kilobyte@angband.pl>
To: Omar Sandoval <osandov@osandov.com>
Cc: linux-btrfs@vger.kernel.org, David Sterba <dsterba@suse.com>,
Christoph Anton Mitterer <calestyo@scientia.net>,
Nikolay Borisov <nborisov@suse.com>,
kernel-team@fb.com, stable@vger.kernel.org
Subject: Re: [PATCH RESEND] Btrfs: fix early ENOSPC due to delalloc
Date: Sat, 22 Jul 2017 00:00:05 +0200 [thread overview]
Message-ID: <20170721220005.idoz25yegjo5sgbb@angband.pl> (raw)
In-Reply-To: <33ac56aa74691de6109709168939cfe9f56cbd70.1500588286.git.osandov@fb.com>
On Thu, Jul 20, 2017 at 03:10:35PM -0700, Omar Sandoval wrote:
> If a lot of metadata is reserved for outstanding delayed allocations, we
> rely on shrink_delalloc() to reclaim metadata space in order to fulfill
> reservation tickets. However, shrink_delalloc() has a shortcut where if
> it determines that space can be overcommitted, it will stop early. This
> made sense before the ticketed enospc system, but now it means that
> shrink_delalloc() will often not reclaim enough space to fulfill any
> tickets, leading to an early ENOSPC.
This happens a lot (like, 1/4 to 1/3 tries) when populating a freshly made
small filesystem, that makes running tests I've been recently doing (like
those degraded raid corruptions) really unfun. These unexplained random
ENOSPCes were driving me mad — thanks for explaining those! Now my tests
properly corrupt data as they should :þ.
--
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⣾⠁⢠⠒⠀⣿⡁ A dumb species has no way to open a tuna can.
⢿⡄⠘⠷⠚⠋⠀ A smart species invents a can opener.
⠈⠳⣄⠀⠀⠀⠀ A master species delegates.
prev parent reply other threads:[~2017-07-21 22:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-20 22:10 [PATCH RESEND] Btrfs: fix early ENOSPC due to delalloc Omar Sandoval
2017-07-21 19:10 ` Josef Bacik
2017-07-21 22:00 ` Adam Borowski [this message]
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