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From: Eric Sandeen <sandeen@redhat.com>
To: ext4 development <linux-ext4@vger.kernel.org>
Subject: Bigalloc ENOSPC woes
Date: Mon, 30 Jan 2012 15:19:05 -0600	[thread overview]
Message-ID: <4F270949.30800@redhat.com> (raw)

I got nervous when I tried this on an -O bigalloc -C 65536 fs:

# echo foo > blah; du -hc blah; sync; du -hc blah
4.0K blah
4.0K total
64K blah
64K total

Seems that du should never report less than the cluster size, should it?

And that made me wonder about ENOSPC handling - are we tracing delalloc allocations correctly?

>From running xfstest 204 on a similarly-created fs, it really seems that we are not.

A manual test of creating 4-byte files until ENOSPC (which was really when I ran out of inodes) and then issuing a sync led to a storm of kernel messages about allocation failures:

[  482.154538] EXT4-fs (sdb6): delayed block allocation failed for inode 1664 at logical offset 0 with max blocks 1 with error -28
[  482.154540] EXT4-fs (sdb6): This should not happen!! Data will be lost

<ad infinitum, or at least 600 or so in my case>

and an end result of a bunch of 4 byte long files with no extents.  Almost like files full of NULLs.  Careful - that is hard to live down.  :)

Ted, are you aware of those issues in bigalloc?

-Eric

             reply	other threads:[~2012-01-30 21:19 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-30 21:19 Eric Sandeen [this message]
2012-01-30 22:31 ` Bigalloc ENOSPC woes Ted Ts'o
2012-01-31 16:03 ` Tao Ma

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