From: Theodore Ts'o <tytso@mit.edu>
To: Jan Kara <jack@suse.cz>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>,
viro@ZenIV.linux.org.uk
Subject: Re: [PATCH 5/5] ext4: add locking for O_APPEND writes
Date: Tue, 15 Apr 2014 15:36:41 -0400 [thread overview]
Message-ID: <20140415193641.GF4456@thunk.org> (raw)
In-Reply-To: <20140415170540.GC10144@quack.suse.cz>
On Tue, Apr 15, 2014 at 07:05:40PM +0200, Jan Kara wrote:
> On Sat 12-04-14 13:02:41, Ted Tso wrote:
> > Al Viro pointed out that we need to make sure we only allow one
> > O_APPEND write to proceed at a time so that the the s_bitmap_maxbytes
> > check can be properly checked.
> But this introduces lock inversion between aio_mutex and i_mutex, doesn't
> it?
Doh! Thanks for pointing that out. Fortunately, we don't need to
care about optimizing the AIO/DIO O_APPEND write case, so probably the
best thing to do is to unconditionally take aio_mutex and call
ext4_unwritten_wait() early, before we grab i_mutex. So in effect
we'll treat all O_APPEND writes as being unaligned in and in need of
serialization.
I'll send out a revised version for this last patch.
- Ted
prev parent reply other threads:[~2014-04-15 19:36 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-12 17:02 [RFC PATCH 0/5] Clean up ext4_file_write() Theodore Ts'o
2014-04-12 17:02 ` [PATCH 1/5] ext4: inline generic_file_aio_write() into ext4_file_write() Theodore Ts'o
2014-04-15 17:06 ` Jan Kara
2014-04-12 17:02 ` [PATCH 2/5] ext4: move ext4_file_dio_write() " Theodore Ts'o
2014-04-15 17:06 ` Jan Kara
2014-04-12 17:02 ` [PATCH 3/5] ext4: drop aio_mutex after grabbing i_mutex in ext4_file_write() Theodore Ts'o
2014-04-15 17:06 ` Jan Kara
2014-04-12 17:02 ` [PATCH 4/5] ext4: factor out common code " Theodore Ts'o
2014-04-15 17:07 ` Jan Kara
2014-04-12 17:02 ` [PATCH 5/5] ext4: add locking for O_APPEND writes Theodore Ts'o
2014-04-15 17:05 ` Jan Kara
2014-04-15 19:36 ` Theodore Ts'o [this message]
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