linux-kernel - Re: [PATCH 7/8] Revert "ext4: avoid deadlocks in the writeback path by using sb_getblk

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Message-ID: <20170117075450.GC19699@dhcp22.suse.cz>
Date:   Tue, 17 Jan 2017 08:54:51 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Theodore Ts'o <tytso@....edu>
Cc:     linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dave Chinner <david@...morbit.com>, djwong@...nel.org,
        Chris Mason <clm@...com>, David Sterba <dsterba@...e.cz>,
        Jan Kara <jack@...e.cz>, ceph-devel@...r.kernel.org,
        cluster-devel@...hat.com, linux-nfs@...r.kernel.org,
        logfs@...fs.org, linux-xfs@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-btrfs@...r.kernel.org,
        linux-mtd@...ts.infradead.org, reiserfs-devel@...r.kernel.org,
        linux-ntfs-dev@...ts.sourceforge.net,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-afs@...ts.infradead.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 7/8] Revert "ext4: avoid deadlocks in the writeback path
 by using sb_getblk_gfp"

On Mon 16-01-17 22:01:18, Theodore Ts'o wrote:
> On Fri, Jan 06, 2017 at 03:11:06PM +0100, Michal Hocko wrote:
> > From: Michal Hocko <mhocko@...e.com>
> > 
> > This reverts commit c45653c341f5c8a0ce19c8f0ad4678640849cb86 because
> > sb_getblk_gfp is not really needed as
> > sb_getblk
> >   __getblk_gfp
> >     __getblk_slow
> >       grow_buffers
> >         grow_dev_page
> > 	  gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp
> > 
> > so __GFP_FS is cleared unconditionally and therefore the above commit
> > didn't have any real effect in fact.
> > 
> > This patch should not introduce any functional change. The main point
> > of this change is to reduce explicit GFP_NOFS usage inside ext4 code to
> > make the review of the remaining usage easier.
> > 
> > Signed-off-by: Michal Hocko <mhocko@...e.com>
> > Reviewed-by: Jan Kara <jack@...e.cz>
> 
> If I'm not mistaken, this patch is not dependent on any of the other
> patches in this series (and the other patches are not dependent on
> this one).  Hence, I could take this patch via the ext4 tree, correct?

Yes, that is correct

-- 
Michal Hocko
SUSE Labs