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From: Naohiro Aota <naohiro.aota@wdc.com>
To: linux-btrfs@vger.kernel.org, David Sterba <dsterba@suse.com>
Cc: Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
	Nikolay Borisov <nborisov@suse.com>,
	Damien Le Moal <damien.lemoal@wdc.com>,
	Matias Bjorling <Matias.Bjorling@wdc.com>,
	Johannes Thumshirn <jthumshirn@suse.de>,
	Hannes Reinecke <hare@suse.com>,
	linux-fsdevel@vger.kernel.org,
	Naohiro Aota <naohiro.aota@wdc.com>
Subject: [PATCH v3 04/27] btrfs: disallow RAID5/6 in HMZONED mode
Date: Thu,  8 Aug 2019 18:30:15 +0900
Message-ID: <20190808093038.4163421-5-naohiro.aota@wdc.com> (raw)
In-Reply-To: <20190808093038.4163421-1-naohiro.aota@wdc.com>

Supporting the RAID5/6 profile in HMZONED mode is not trivial. For example,
non-full stripe writes will cause overwriting parity blocks. When we do a
non-full stripe write, it writes to the parity block with the data at that
moment. Then, another write to the stripes will try to overwrite the parity
block with new parity value. However, sequential zones do not allow such
parity overwriting.

Furthermore, using RAID5/6 on SMR drives, which usually have a huge
capacity, incur large overhead of rebuild. Such overhead can lead to
higher volume failure rate (e.g. additional drive failure during
rebuild) because of the increased rebuild time.

Thus, let's disable RAID5/6 profile in HMZONED mode for now.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
---
 fs/btrfs/hmzoned.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/btrfs/hmzoned.c b/fs/btrfs/hmzoned.c
index 512674d8f488..641c83f6ea73 100644
--- a/fs/btrfs/hmzoned.c
+++ b/fs/btrfs/hmzoned.c
@@ -222,6 +222,13 @@ int btrfs_check_hmzoned_mode(struct btrfs_fs_info *fs_info)
 		goto out;
 	}
 
+	/* RAID56 is not allowed */
+	if (btrfs_fs_incompat(fs_info, RAID56)) {
+		btrfs_err(fs_info, "HMZONED mode does not support RAID56");
+		ret = -EINVAL;
+		goto out;
+	}
+
 	btrfs_info(fs_info, "HMZONED mode enabled, zone size %llu B",
 		   fs_info->zone_size);
 out:
-- 
2.22.0


  parent reply index

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-08  9:30 [PATCH v3 00/27] btrfs zoned block device support Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 01/27] btrfs: introduce HMZONED feature flag Naohiro Aota
2019-08-16  4:49   ` Anand Jain
2019-08-08  9:30 ` [PATCH v3 02/27] btrfs: Get zone information of zoned block devices Naohiro Aota
2019-08-16  4:44   ` Anand Jain
2019-08-16 14:19     ` Damien Le Moal
2019-08-16 23:47       ` Anand Jain
2019-08-16 23:55         ` Damien Le Moal
2019-08-08  9:30 ` [PATCH v3 03/27] btrfs: Check and enable HMZONED mode Naohiro Aota
2019-08-16  5:46   ` Anand Jain
2019-08-16 14:23     ` Damien Le Moal
2019-08-16 23:56       ` Anand Jain
2019-08-17  0:05         ` Damien Le Moal
2019-08-20  5:07         ` Naohiro Aota
2019-08-20 13:05           ` David Sterba
2019-08-08  9:30 ` Naohiro Aota [this message]
2019-08-08  9:30 ` [PATCH v3 05/27] btrfs: disallow space_cache in " Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 06/27] btrfs: disallow NODATACOW " Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 07/27] btrfs: disable tree-log " Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 08/27] btrfs: disable fallocate " Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 09/27] btrfs: align device extent allocation to zone boundary Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 10/27] btrfs: do sequential extent allocation in HMZONED mode Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 11/27] btrfs: make unmirroed BGs readonly only if we have at least one writable BG Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 12/27] btrfs: ensure metadata space available on/after degraded mount in HMZONED Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 13/27] btrfs: reset zones of unused block groups Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 14/27] btrfs: limit super block locations in HMZONED mode Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 15/27] btrfs: redirty released extent buffers in sequential BGs Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 16/27] btrfs: serialize data allocation and submit IOs Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 17/27] btrfs: implement atomic compressed IO submission Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 18/27] btrfs: support direct write IO in HMZONED Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 19/27] btrfs: serialize meta IOs on HMZONED mode Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 20/27] btrfs: wait existing extents before truncating Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 21/27] btrfs: avoid async checksum/submit on HMZONED mode Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 22/27] btrfs: disallow mixed-bg in " Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 23/27] btrfs: disallow inode_cache " Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 24/27] btrfs: support dev-replace " Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 25/27] btrfs: enable relocation " Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 26/27] btrfs: relocate block group to repair IO failure in HMZONED Naohiro Aota
2019-08-08  9:30 ` [PATCH v3 27/27] btrfs: enable to mount HMZONED incompat flag Naohiro Aota

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