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Mon, 29 Apr 2024 17:48:10 +0000 Received: from DM6PR10MB4313.namprd10.prod.outlook.com ([fe80::4f45:f4ab:121:e088]) by DM6PR10MB4313.namprd10.prod.outlook.com ([fe80::4f45:f4ab:121:e088%4]) with mapi id 15.20.7519.031; Mon, 29 Apr 2024 17:48:10 +0000 From: John Garry To: david@fromorbit.com, djwong@kernel.org, hch@lst.de, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, chandan.babu@oracle.com, willy@infradead.org Cc: axboe@kernel.dk, martin.petersen@oracle.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, tytso@mit.edu, jbongio@google.com, ojaswin@linux.ibm.com, ritesh.list@gmail.com, mcgrof@kernel.org, p.raghav@samsung.com, linux-xfs@vger.kernel.org, catherine.hoang@oracle.com, Dave Chinner , John Garry Subject: [PATCH v3 03/21] xfs: always tail align maxlen allocations Date: Mon, 29 Apr 2024 17:47:28 +0000 Message-Id: <20240429174746.2132161-4-john.g.garry@oracle.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20240429174746.2132161-1-john.g.garry@oracle.com> References: <20240429174746.2132161-1-john.g.garry@oracle.com> X-ClientProxiedBy: SJ0P220CA0006.NAMP220.PROD.OUTLOOK.COM (2603:10b6:a03:41b::29) To DM6PR10MB4313.namprd10.prod.outlook.com (2603:10b6:5:212::20) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM6PR10MB4313:EE_|SA1PR10MB6389:EE_ X-MS-Office365-Filtering-Correlation-Id: 4e4398b3-6973-4c29-1ade-08dc687488f4 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230031|7416005|1800799015|376005|366007; 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However, this assumes that nothing modifies args->maxlen between the original allocation context setup and trimming the selected free space extent to size. This assumption has recently been found to be invalid - xfs_alloc_space_available() modifies args->maxlen in low space situations - and there may be more situations we haven't yet found like this. Force aligned allocation introduces the requirement that extents are correctly tail aligned, resulting in this occasional latent alignment failure to e reclassified from an unimportant curiousity to a must-fix bug. Removing the assumption about args->maxlen allocations always being tail aligned is trivial, and should not impact anything because args->maxlen for inodes with extent size hints configured are already aligned. Hence all this change does it avoid weird corner cases that would have resulted in unaligned extent sizes by always trimming the extent down to an aligned size. Signed-off-by: Dave Chinner Signed-off-by: John Garry --- fs/xfs/libxfs/xfs_alloc.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c index 215265e0f68f..e21fd5c1f802 100644 --- a/fs/xfs/libxfs/xfs_alloc.c +++ b/fs/xfs/libxfs/xfs_alloc.c @@ -432,20 +432,18 @@ xfs_alloc_compute_diff( * Fix up the length, based on mod and prod. * len should be k * prod + mod for some k. * If len is too small it is returned unchanged. - * If len hits maxlen it is left alone. */ -STATIC void +static void xfs_alloc_fix_len( - xfs_alloc_arg_t *args) /* allocation argument structure */ + struct xfs_alloc_arg *args) { - xfs_extlen_t k; - xfs_extlen_t rlen; + xfs_extlen_t k; + xfs_extlen_t rlen = args->len; ASSERT(args->mod < args->prod); - rlen = args->len; ASSERT(rlen >= args->minlen); ASSERT(rlen <= args->maxlen); - if (args->prod <= 1 || rlen < args->mod || rlen == args->maxlen || + if (args->prod <= 1 || rlen < args->mod || (args->mod == 0 && rlen < args->prod)) return; k = rlen % args->prod;