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[70.77.216.213]) by smtp.gmail.com with ESMTPSA id j1sm1622049pfg.64.2020.04.10.05.12.11 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 10 Apr 2020 05:12:11 -0700 (PDT) From: Andreas Dilger Message-Id: Content-Type: multipart/signed; boundary="Apple-Mail=_A59F6264-73B6-4739-86B7-EB880DD1914F"; protocol="application/pgp-signature"; micalg=pgp-sha256 Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) Subject: Re: [PATCH v6 03/20] ext4, jbd2: add fast commit initialization routines Date: Fri, 10 Apr 2020 06:12:09 -0600 In-Reply-To: <20200408215530.25649-3-harshads@google.com> Cc: linux-ext4@vger.kernel.org, tytso@mit.edu To: Harshad Shirwadkar References: <20200408215530.25649-1-harshads@google.com> <20200408215530.25649-3-harshads@google.com> X-Mailer: Apple Mail (2.3273) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org --Apple-Mail=_A59F6264-73B6-4739-86B7-EB880DD1914F Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii On Apr 8, 2020, at 3:55 PM, Harshad Shirwadkar = wrote: >=20 > From: Harshad Shirwadkar >=20 > Define feature flags for fast commits and add routines to allow ext4 = to > initialize fast commits. Note that we allow 128 blocks to be used for > fast commits. As of now, that's the default constant value. >=20 > Signed-off-by: Harshad Shirwadkar > +static inline int ext4_should_fast_commit(struct super_block *sb) > +{ > + if (!ext4_has_feature_fast_commit(sb)) > + return 0; > + if (!test_opt2(sb, JOURNAL_FAST_COMMIT)) > + return 0; > + if (test_opt(sb, QUOTA)) > + return 0; > + return 1; > +} This function seems more complex than it should be. In this patch the ext4_should_fast_commit() function is only called once during mount, but in later patches it looks like it is called many times per file/inode. Why not just check JOURNAL_FAST_COMMIT, and clear it at mount/remount time if the other conditions prevent fast commits being used at all? It seems that JOURNAL_FAST_COMMIT is only set if the FAST_COMMIT feature is already in the superblock, so always doing both checks seems = redundant. Also, maybe I missed the discussion, but why does having quotas enabled on the filesystem disable fast commits entirely? I see in patch 11/20 that EXT4_FC_REASON_QUOTA is a reason not to do fast commit on the quota inodes themselves, which seems like a reasonable limitation if needed, but the above check disables FC for any filesystem with quota, and I can't find anywhere that this line is later removed in this series. Cheers, Andreas --Apple-Mail=_A59F6264-73B6-4739-86B7-EB880DD1914F Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org iQIzBAEBCAAdFiEEDb73u6ZejP5ZMprvcqXauRfMH+AFAl6QYpkACgkQcqXauRfM H+CZEBAAtyHEdx6GtauLjtOxpXpqYP772ViwP1iWCAY3ZgjTR8+nuQgwGeEIu9oe bcKkKDeNnTcF+G01rCedLX4N7mpZglKFf6j8M/SHBX9yGLEFF3Hu+1yZ3DHZH8tx f0TANgVRHvtbOfLVXHlilCYma1Ao5MqhJziwfC28JjuyFIlC31PMRfCQ73yM8kQk Vd4YR1tsIKcAw5UD7SoZK5Lt+9uq2N27ZLpnox0TfHZbrKvn1VL3yeCz+GXexwu/ ZiiElPD46AzNGMM9hsE2LRgiMK8Rr+XElsvrA2iAjntLGLzkVJjrM9zNCom8oCfE RWEmDhfiU+lsM24xCjJOWnbvsx9nm6O4cGV2SPrqsQCsfVdNb/YAwrbYf33Zb2wN TrpMjKwX8dZQoZlKnGzNZ04EHeR6zykBKQtOdkp6JDO7uwgQwsq2FMa8MigbSE9g Te/FJXIxbEjjn0w4cjigdvisYh9Ng572Gp4wXze/9cNzT9K94S3tJdmnucRqoWMs YxuYAgN4EAs/cBUTxp7UkmBIPp8hMmUdq7O9CKl+uaLqeVrQS+2OCic7+LiD9jN/ QR09b2N2KzwCUEGIcHYHHuWYSdrL7MvTG2PxJWYtQ4yPRB4dGWfzGOydQFEKa1ju btX6RKPJVROst2f+Uxo11A3B1X6MuHNFFBggKeN6qn9x6I5lkmc= =hcjI -----END PGP SIGNATURE----- --Apple-Mail=_A59F6264-73B6-4739-86B7-EB880DD1914F--