Re: ENOSPC Regression

[Josef Bacik <josef@redhat.com>]

On Fri, Feb 11, 2011 at 07:21:47AM -0600, Mitch Harder wrote:
> I'm encountering premature ENOSPC issues recently where my Btrfs
> testing partition will either prematurely return an ENOSPC, or lock up
> the operations trying to access the partition.
> 
> I have bisected the problem to this commit:
> http://git.kernel.org/?p=linux/kernel/git/mason/btrfs-unstable.git;a=commit;h=914ee295af418e936ec20a08c1663eaabe4cd07a
> (Btrfs: pwrite blocked when writing from the mmaped buffer of the same page)
> 
> I am encountering the problem on a small-ish 3.5 GB Btrfs partition.
> I can replicate the problem with and without compression.  I can also
> replicate the problem with and without reformating the partition.
> 
> For most operations I run on this partition, Btrfs is performing
> without error.  But when I compile openmotif-2.3.3 on a kernel that is
> after the above referenced commit, I'll get either an ENOSPC error or
> the partition locks up.
> 
> When I encounter a lock-up issue, there are no errors in dmesg, and no
> delayed processes are showing (unless I try to run an additional
> operation on that partition, such as 'ls', which will subsequently
> show up as delayed).  However, the build process for openmotif-2.3.3
> appears frozen, and several processes related to the build are shown
> as running, and will not even respond to 'kill -s 9 <pid>'
> 
> The partition only has about 500 MB of data when I encounter the
> problems, and openmotif-2.3.3 typically only requires about 30-60 MB
> to compile.
> 
> However, running 'btrfs fi show' indicates that btrfs has attempted to
> reserve all the space on the disk for data and metadata.  When running
> a kernel prior to the above referenced commit, btrfs will compile
> openmotif-2.3.3 without needing to reserve much extra space on the
> partition.
> 
> Let me know if you would like any additional information or tests.

Can you try my btrfs-work tree and see if you still have the same problem?
Thanks,

Josef