linux-ext4 - Re: [PATCH v2] ext4: Gracefully handle ext4_break

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Message-ID: <20190530185931.GF2998@mit.edu>
Date:   Thu, 30 May 2019 14:59:31 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     Jan Kara <jack@...e.cz>
Cc:     linux-ext4@...r.kernel.org, Ira Weiny <ira.weiny@...el.com>
Subject: Re: [PATCH v2] ext4: Gracefully handle ext4_break_layouts() failure
 during truncate

On Tue, May 28, 2019 at 10:05:45AM +0200, Jan Kara wrote:
> ext4_break_layouts() may fail e.g. due to a signal being delivered.
> Thus we need to handle its failure gracefully and not by taking the
> filesystem down. Currently ext4_break_layouts() failure is rare but it
> may become more common once RDMA uses layout leases for handling
> long-term page pins for DAX mappings.
> 
> To handle the failure we need to move ext4_break_layouts() earlier
> during setattr handling before we do hard to undo changes such as
> modifying inode size. To be able to do that we also have to move some
> other checks which are better done without holding i_mmap_sem earlier.
> 
> Reported-and-tested-by: Ira Weiny <ira.weiny@...el.com>
> Reviewed-by: Ira Weiny <ira.weiny@...el.com>
> Signed-off-by: Jan Kara <jack@...e.cz>

Applied, thanks!

					- Ted