From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752292AbeDDVkc (ORCPT ); Wed, 4 Apr 2018 17:40:32 -0400 Received: from mail-he1eur01on0131.outbound.protection.outlook.com ([104.47.0.131]:22432 "EHLO EUR01-HE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752134AbeDDVk3 (ORCPT ); Wed, 4 Apr 2018 17:40:29 -0400 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=avagin@virtuozzo.com; Date: Wed, 4 Apr 2018 14:40:04 -0700 From: Andrei Vagin To: Dan Williams Cc: linux-nvdimm@lists.01.org, Michal Hocko , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Christoph Hellwig , Jan Kara , david@fromorbit.com, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, snitzer@redhat.com Subject: Re: [v8, 11/18] mm, dax: enable filesystems to trigger dev_pagemap ->page_free callbacks Message-ID: <20180404214003.GB12737@outlook.office365.com> References: <152246898837.36038.26895928842345061.stgit@dwillia2-desk3.amr.corp.intel.com> <20180404212340.GA12737@outlook.office365.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180404212340.GA12737@outlook.office365.com> User-Agent: Mutt/1.9.1 (2017-09-22) X-Originating-IP: [4.16.175.162] X-ClientProxiedBy: HE1P192CA0021.EURP192.PROD.OUTLOOK.COM (2603:10a6:3:fe::31) To HE1PR08MB0746.eurprd08.prod.outlook.com (2a01:111:e400:59b1::12) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 7ac3c7cd-ac90-46dd-0f56-08d59a74a5ed X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(5600026)(4604075)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7153060)(7193020);SRVR:HE1PR08MB0746; X-Microsoft-Exchange-Diagnostics: 1;HE1PR08MB0746;3:TvFgV8nBEhuLDufYHwMCi06KV3az02FriW3viMCQUI2a+fcvaLlequU2dE5TYKbojfPE1VfGFRgpgjkFJasWEzNEz+UCtfRarGbfCZuQwQQxw0LiUknZTqJIuF+UDrU1AhW7p/ruPMQys90Kw+ECxU264ts++OXpIsEsJ/u8tlUxpn5phR9hnl9Av0fsp33tdZzTrZauO4WIl4LKi5JaDE7R7ndo8+ob5CvqtOAx3RP6HWUf68FFsZOerDZM5lBb;25:yDeQX3bGVVYR+43IUW99imibXPztvpZJmuQvYy5VxZgloY3EsCZ5b7YTHivFQpcdp+mePrLJtUB/Jy5T1/VPHwNWV8Kb7rMXNMvnJ1gONimCw7ik47TIx0mZIf23A+GtXXm9IRRh9aaV7Bk7dLzlPIIzGGtK27FN4Y2xA1lspwKMaY6Wlu2NH/fu3X9QCtZRWBfEA8k8LAbaNGoMESITMz/ixJLMQhMr9V+CBsdxnrE/4BWKv93Dj7qCpmycnpyy2LzwZaMfXXwiCSUt4LWq5XHCAG6ojOtS9RSpKOEy5+YXLYTAjAAIoKKY/oSwiSvNdpMoSSZvssUGWy7WPJLQCg==;31:o6YvwpOL/mCsxbvunE9wXmQpgnQKPhBENEJ3EI4c2u4psPUl3AajYDA8FRwvgR075GXPZY7z59YRz8sl2knpytwK5dDSBOFD0nFP9RmFnVCeeKGKUmDlaOfc8qj7pDFwaBnlpjlhj9QRB2vjRV+ddUdHl5C1m9GGM9W+rZt1Swq9PXz32POeHl9J+hMgvke2gBSqtqaJhxyK/ktjhIRESTL8NU+XnatKsqPqfaEapMA= X-MS-TrafficTypeDiagnostic: HE1PR08MB0746: X-Microsoft-Exchange-Diagnostics: 1;HE1PR08MB0746;20: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;4:4PSjQk5hhe3YOJgmvxPjgln2RhE9fcgI89VSsi+BfYgZ3KnRoIqRI4bOzXULfib93oZEubt1duPrj3EcNH2ce6/5PnR13NHlgy8VA7vowddq9p16dSTCk7AML4Up1uDBpmUfdRV+5A8rHg5iOvbjxxOKsm1oxlN8lZ4AhFHlHcSBUFWBGiTuFmeDl+ueKVVWJ0mSAAco3rLEfA/dH/oVNJ39MJgyt0Q7Xf7h2EWd6cNEJGmN6+dbP/hE+PFSBNl6wCeEXJVvb/UGmWIJeT8mTvH+qJxA7ReLl9k9329ACVPeY1wKW0SBM5TuIhl3Mc/q X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:(228905959029699); X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(6040522)(2401047)(8121501046)(5005006)(3231221)(944501327)(52105095)(93006095)(93001095)(3002001)(10201501046)(6041310)(20161123558120)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123560045)(20161123564045)(20161123562045)(6072148)(201708071742011);SRVR:HE1PR08MB0746;BCL:0;PCL:0;RULEID:;SRVR:HE1PR08MB0746; X-Forefront-PRVS: 0632519F33 X-Forefront-Antispam-Report: SFV:NSPM;SFS:(10019020)(376002)(396003)(39850400004)(39380400002)(366004)(346002)(199004)(189003)(186003)(52146003)(106356001)(55016002)(54906003)(26005)(68736007)(6916009)(8676002)(81156014)(45080400002)(97736004)(7416002)(50466002)(23676004)(2906002)(53936002)(8936002)(486006)(476003)(25786009)(6666003)(5890100001)(81166006)(229853002)(52116002)(7696005)(2870700001)(16526019)(5660300001)(7736002)(956004)(2486003)(59450400001)(76176011)(316002)(9686003)(105586002)(11346002)(47776003)(37156001)(6116002)(58126008)(4326008)(6246003)(386003)(33656002)(69596002)(66066001)(53416004)(575784001)(478600001)(6506007)(1076002)(86362001)(3846002)(446003)(305945005)(18370500001);DIR:OUT;SFP:1102;SCL:1;SRVR:HE1PR08MB0746;H:outlook.office365.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX:1; X-Microsoft-Exchange-Diagnostics: =?utf-8?B?MTtIRTFQUjA4TUIwNzQ2OzIzOjRZQ0NpNDNMVlpXQmR6dDFiTERpWERZUnhr?= =?utf-8?B?NjViUlRUN3FqcXcrNis3N01EVlNPZkFpRG5sQ0doMHlXRGlLZmgySDJDVWht?= =?utf-8?B?ZXU1ajRydlhsZGFESXBVNVczNDlBUE1BbGxGUXJRWC9mNlArQzFVZ3lEc2h4?= =?utf-8?B?c2k2WGFHOTUwZVBiekZoRHE2WlJPK2RXSzl0ZzBpdUg0ZCtOK1V4YXMyV3pF?= =?utf-8?B?WmVYMVZ5RWY1Q044UXFKRnNVSk52cEhPLytJb1podkpmREtRVURLYmxWaUZW?= =?utf-8?B?N2FDRFJxdnF3OGllY1prSytIa3RtNnVrYUJxb0hhbm9HbUU1TzZsczNIRFVa?= =?utf-8?B?bXpPV1c2K3BEZkxMKzBOeUcyOTI1RVJOVEcwK25FV0FXTXpYSDlMRTNCM2pK?= =?utf-8?B?WWdIZElJcnB6eURGRFh0NXl4ZS9teXhpUTBTcEs3Q2FYU0Jwak5SVnJxbktz?= =?utf-8?B?U09KYXd5eVRvQkNhY2MySGZnUEw3TGRJTGJrUWtCV1l5RTlSbGY0QmV2QUhv?= =?utf-8?B?UUZUYys4Z09tdjhLVEE0YlUwYlJBc2M5MG5LazNtK041TXpUSkRWelhFSkhW?= =?utf-8?B?ajdtQzc3TXhSc0tvLyt0WjJMaUtvOXVIVlpnU3RXMWVCM2VTcEdjZmZ6Nzd3?= =?utf-8?B?WHlTTWJCVUFhUnBTWEt6S0NGS3VUc2VNdUJiTzMweGVWNlRUQUpxWjFwSXlP?= =?utf-8?B?dm1ub1FlQW8xb2t5RFNlSHhYd1Q5MkVCRHFTeUxRa1RNM3VoQ0dJMkUwMy9K?= =?utf-8?B?VXB4b0d6cnlxMFRGaXFIUlJsUXBEUW5FVXFXakVSc2tuZW44UW1DcXY2blRx?= =?utf-8?B?TXlFV2VVYkFWTU1RUjUvWlB4c0ZQMnNHMWNGSnBwdWRnTE1sMFg5dkdtVXhF?= =?utf-8?B?S3FYdm1vclEzakhONkxoN0dyS3pBakdsUVhNdU8xb2swSXpqa1V5WDBtRW5I?= =?utf-8?B?dUpseHo4dlFKQ0JUUmNVejArNmtyc3VRMUZJdjNRb2ZaRnhZSkE0Vy9GWURy?= =?utf-8?B?dy9hVkkreHlPeG1PRGVOUHlya2pVa2VqTTh4QnNIb0NHQmYrNFRJUXFBbGp4?= =?utf-8?B?NWV2VlFERTVUNzQ2VFNHWkI1ZjQ5RnA0ZWUzVUhWM1V5dE1IMG1SNkhFTG91?= =?utf-8?B?RGJRaUI2SytudjdUTGJtc2lRQ3ZoVUM3R0E3VGtoYnR6Z0h1ZEY3Mk5pUWRr?= =?utf-8?B?WE5RR05mR1I0c3graGNXOS9MTXQ5NVNEdUd5dkZzMFBBckp0aXRMRlZFNFlk?= =?utf-8?B?aUJwNzlNd2ZLcHJHOTRDOUFOdjJ1eHZuVHkzeDY3UHo3ZGlyQW1naVpHNEdx?= =?utf-8?B?L0UxMjY4aGtUT2l2UHlnSzZqdEE4YkhiR1Nxa2E0cndQeDlCMFIxOFc2bXly?= =?utf-8?B?M0ZFWWpkQzBrblNRSDk3SDdBUWVoNjNCTjFXNlpqTXJqaVlRS25MR3JRQ3ZP?= =?utf-8?B?UmRUanFJeXZoR2lTZlNoMkF1MGRDcjI0MkhYazViVFMvT2xtcEpSem5CVWFO?= =?utf-8?B?a1FOcmdIQjdhaGRaUWEwdUFVdm9GSVpGcDdtQUhHbEI4UzduKzMvNjBqQlVG?= =?utf-8?B?amw2TEJTd29JS3JqTHNJeW5VSFkwdnJsS0gyOEpXdXNPTmV0L0oyMXdYNStN?= =?utf-8?B?eTQxZGZNQXVzSmwwWDJxWDJHZFBNUmlheEYxUTNBc1R3a2hKeDVRZFdLd0pU?= =?utf-8?B?ajY4eGM4Wm5XRHdPS2VybjA3alo3aURPZVM5dy91ZjNRZ25tbU0yQmZpcVJx?= =?utf-8?B?dlNZZzdrRHhka2w0WDZqdXFia0Q3RVZyZjV0WkdxZGlKY0p6ZnFGSkxHbkI3?= =?utf-8?B?WDZHTW52VzE1N3hsZ0c2c1c2ZGV0bWI1ZitCQWxKSW11eEJRdFBZQU9CRUxk?= =?utf-8?B?QS8yUnk4N09URWNLZDRObEVPV3k0djQveWpGaWpMazhqNGpHZlNndFFGNzNJ?= =?utf-8?B?RFlGdDI3Qkl1b1M2QXZQZUlySUVGWkN1aStCMVE5K2ZpMlBoOCtMTGZTMXpo?= =?utf-8?B?R1FpZGl3N3E1L3VuNnlwa1JPNnN1OTQ3NzdYdmpVdVVBWFUrK3hwRzNscjJn?= =?utf-8?Q?v75I=3D?= X-Microsoft-Antispam-Message-Info: jmnUDn0KBNOaMDIXwWX8U5dP74W88MWzcgZ5I9tS1/56gRihYxfogPv60FLKYd1NzEUZ3XgD+qZEsTHkaFyfo42rK/O7dyXdOHMfPgGj4520uspiYjtE1UQyHmoKuXxxX6lsDTVaS7rAqAL63gN7XWk6bCyg640owIT50DUElOQXsa3eoZHBoMREHQP7fZt3 X-Microsoft-Exchange-Diagnostics: 1;HE1PR08MB0746;6:jB6QDOpak09IDiqZV1QyilrHc3Wi2tll/XhZOp3bQgeEUVgxCdYN0pJq5qGOrT602vgnRoHuEoKd+FDseh4ihOwmM46QQMkeKj4hNuhYGryBX8AJu7zK6zi4FYiuQcfsUkgALsaPqchSdcEiCinCxA6OkEpK8lzAJ6hjnxAETnFhSmxnu6GGSW24xKyJokUSEYZGKsLSfEaJ/0NNbFkSbJD8bORybgXNKo8tBSRb1dsgLmP8/PwpO6zNF51EupUFAsiKFQoAMGdMjvs+aAMprd4ZK4f0uZysZjg5w8c1jM3+P/chIDmJfU/pRNuZC1iwaAeI8eupPvOBFVYJpBIA2XJK60T+xaD5OM+f08c0DdiXE6zKXIABaZDiP/CHDoKEb3nYDwLFHTZVYL3dhn5LOgqsFOm7VcKJJe5yo1wStBLGNoCcY/54fdQRf2l7/4za0coWcYWkyAsm1XAk1Kdj4A==;5:cDY6sDJzy2f9hjPHB3OVjPC6SLV9xlHkdbfJUsalSv4ttJgql7QSYiRoiCO0FmH1KeeSCqkVxhaoiQj8g6HiDKWEmi8J3npk14lsjqgGPbK2B7iwSYAQdtGZpgKS3Tp/61601pUXvulovFVZegGg/FifZS3kReZjTp5zGLU5Fbg=;24:ia6Ot2wifH4QgFeWfF2GdvoBBF5UVKViWyACB+cP5mKhHTvGouloAuo9TpRkLY9rh0BJOOiFyMXLoKVivHyZhsK8GUkwMFGGNuXdY1nYrew= SpamDiagnosticOutput: 1:99 SpamDiagnosticMetadata: NSPM X-Microsoft-Exchange-Diagnostics: 1;HE1PR08MB0746;7:C+jueaEgCsoj4PZRWYRJcWOZC64qmmDpzl7xcXxEJ5Np1krzfuD07Khgl3Ev1WaOmeqhmGb2fBTfe7uKxzkH/M/eZiuh6Xj+eWObeNr0RBpXAfFpa12EWeaDXUjT0Siu2zMQ3IijDqIMn9Mspb9FVaf50/7ByHDagaYumwdan8riZ4Q7shTxBSxk+BAKiZPhdXyZX1YFTOJ+/EVNP9wLs5kq+TK7eJjsiVyXmuArensM7nUN+HURo8/2v1gEa1DR;20:cvFMTEMM7+2eMM/4O9AfJQ/pMaY3si3aCq8GRJvHHq54wwJZrOU3IXbHvUG6at6T58f0E26AO/Mj+892aB9LyRD3snjbNMqYRX4h6aRY8silR4l2uQ7upBOiqPIxjnVDKETzVHWXp0DcX6hbTMZ1dmhop2Mz+oYozlQ0ajbyvuI= X-OriginatorOrg: virtuozzo.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Apr 2018 21:40:10.7202 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 7ac3c7cd-ac90-46dd-0f56-08d59a74a5ed X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 0bc7f26d-0264-416e-a6fc-8352af79c58f X-MS-Exchange-Transport-CrossTenantHeadersStamped: HE1PR08MB0746 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 04, 2018 at 02:23:40PM -0700, Andrei Vagin wrote: > Hi Dan, > > I catch the following bug on the linux-next 20180404. git bisect brought me to this commit: The next patch fixes the problem: diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 5b13da127982..a67a7fe75fd5 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -228,6 +228,10 @@ static void __fs_dax_release(struct dax_device *dax_dev, void *owner) void fs_dax_release(struct dax_device *dax_dev, void *owner) { + if (!dax_dev) { + printk("%s:%d: dax_dev == NULL\n", __func__, __LINE__); + return; + } if (dax_dev->ops->fs_release) dax_dev->ops->fs_release(dax_dev, owner); else And here is dmesg from my test vm: [root@fc24 ~]# dmesg | grep -A 2 -B 2 dax [ 14.659318] md: Skipping autodetection of RAID arrays. (raid=autodetect will force) [ 14.662436] EXT4-fs (vda2): couldn't mount as ext3 due to feature incompatibilities [ 14.663983] fs_dax_release:232: dax_dev == NULL [ 14.665646] EXT4-fs (vda2): couldn't mount as ext2 due to feature incompatibilities [ 14.667047] fs_dax_release:232: dax_dev == NULL [ 14.668933] EXT4-fs (vda2): INFO: recovery required on readonly filesystem [ 14.670039] EXT4-fs (vda2): write access will be enabled during recovery > > commit 8e4d1ccc5286d2c3da6515b92323a3529aa64496 (HEAD, refs/bisect/bad) > Author: Dan Williams > Date: Sat Oct 21 14:41:13 2017 -0700 > > mm, dax: enable filesystems to trigger dev_pagemap ->page_free callbacks > > > [ 11.278768] BUG: unable to handle kernel NULL pointer dereference at 0000000000000440 > [ 11.279999] IP: fs_dax_release+0x5/0x90 > [ 11.280587] PGD 0 P4D 0 > [ 11.280973] Oops: 0000 [#1] SMP PTI > [ 11.281500] Modules linked in: > [ 11.281968] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.16.0-rc4-00193-g8e4d1ccc5286 #7 > [ 11.283163] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1.fc26 04/01/2014 > [ 11.284418] RIP: 0010:fs_dax_release+0x5/0x90 > [ 11.285068] RSP: 0000:ffffb1480062fbd8 EFLAGS: 00010287 > [ 11.285845] RAX: 0000000000000001 RBX: ffff9e2cb823c088 RCX: 0000000000000003 > [ 11.286896] RDX: 0000000000000000 RSI: ffff9e2cb823c088 RDI: 0000000000000000 > [ 11.287980] RBP: ffffb1480062fcd8 R08: 0000000000000001 R09: 0000000000000000 > [ 11.289147] R10: ffffb1480062fb20 R11: 0000000000000000 R12: 00000000ffffffea > [ 11.290576] R13: 0000000000000000 R14: 0000000000000000 R15: ffff9e2cb823a048 > [ 11.291630] FS: 0000000000000000(0000) GS:ffff9e2cbfd00000(0000) knlGS:0000000000000000 > [ 11.292781] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 11.293602] CR2: 0000000000000440 CR3: 000000007d21e001 CR4: 00000000003606e0 > [ 11.294817] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 11.296827] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 11.298293] Call Trace: > [ 11.298728] ext4_fill_super+0x31b/0x39d0 > [ 11.299441] ? sget_userns+0x155/0x500 > [ 11.300144] ? vsnprintf+0x253/0x4b0 > [ 11.301223] ? ext4_calculate_overhead+0x4a0/0x4a0 > [ 11.301801] ? snprintf+0x45/0x70 > [ 11.302214] ? ext4_calculate_overhead+0x4a0/0x4a0 > [ 11.302822] mount_bdev+0x17b/0x1b0 > [ 11.303332] mount_fs+0x35/0x150 > [ 11.303803] vfs_kern_mount.part.25+0x54/0x150 > [ 11.304443] do_mount+0x620/0xd60 > [ 11.304935] ? memdup_user+0x3e/0x70 > [ 11.305458] SyS_mount+0x80/0xd0 > [ 11.305931] mount_block_root+0x105/0x2b7 > [ 11.306512] ? SyS_mknod+0x16b/0x1f0 > [ 11.307035] ? set_debug_rodata+0x11/0x11 > [ 11.307616] prepare_namespace+0x135/0x16b > [ 11.308215] kernel_init_freeable+0x271/0x297 > [ 11.308838] ? rest_init+0xd0/0xd0 > [ 11.309322] kernel_init+0xa/0x110 > [ 11.309821] ret_from_fork+0x3a/0x50 > [ 11.310347] Code: a5 45 31 ed e8 5d 5e 36 00 eb d7 48 c7 c7 20 48 2f a5 e8 4f 5e 36 00 eb c9 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 <48> 8b 87 40 04 00 00 48 8b 40 18 48 85 c0 74 05 e9 c6 7e 60 00 > [ 11.313168] RIP: fs_dax_release+0x5/0x90 RSP: ffffb1480062fbd8 > [ 11.313991] CR2: 0000000000000440 > [ 11.314475] ---[ end trace 8acbb19b74409665 ]--- > > > On Fri, Mar 30, 2018 at 09:03:08PM -0700, Dan Williams wrote: > > In order to resolve collisions between filesystem operations and DMA to > > DAX mapped pages we need a callback when DMA completes. With a callback > > we can hold off filesystem operations while DMA is in-flight and then > > resume those operations when the last put_page() occurs on a DMA page. > > > > Recall that the 'struct page' entries for DAX memory are created with > > devm_memremap_pages(). That routine arranges for the pages to be > > allocated, but never onlined, so a DAX page is DMA-idle when its > > reference count reaches one. > > > > Also recall that the HMM sub-system added infrastructure to trap the > > page-idle (2-to-1 reference count) transition of the pages allocated by > > devm_memremap_pages() and trigger a callback via the 'struct > > dev_pagemap' associated with the page range. Whereas the HMM callbacks > > are going to a device driver to manage bounce pages in device-memory in > > the filesystem-dax case we will call back to filesystem specified > > callback. > > > > Since the callback is not known at devm_memremap_pages() time we arrange > > for the filesystem to install it at mount time. No functional changes > > are expected as this only registers a nop handler for the ->page_free() > > event for device-mapped pages. > > > > Cc: Michal Hocko > > Reviewed-by: "Jérôme Glisse" > > Reviewed-by: Christoph Hellwig > > Reviewed-by: Jan Kara > > Signed-off-by: Dan Williams > > --- > > drivers/dax/super.c | 21 +++++++++++---------- > > drivers/nvdimm/pmem.c | 3 ++- > > fs/ext2/super.c | 6 +++--- > > fs/ext4/super.c | 6 +++--- > > fs/xfs/xfs_super.c | 20 ++++++++++---------- > > include/linux/dax.h | 23 ++++++++++++++--------- > > 6 files changed, 43 insertions(+), 36 deletions(-) > > > > diff --git a/drivers/dax/super.c b/drivers/dax/super.c > > index c4cf284dfe1c..7d260f118a39 100644 > > --- a/drivers/dax/super.c > > +++ b/drivers/dax/super.c > > @@ -63,16 +63,6 @@ int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size, > > } > > EXPORT_SYMBOL(bdev_dax_pgoff); > > > > -#if IS_ENABLED(CONFIG_FS_DAX) > > -struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev) > > -{ > > - if (!blk_queue_dax(bdev->bd_queue)) > > - return NULL; > > - return fs_dax_get_by_host(bdev->bd_disk->disk_name); > > -} > > -EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev); > > -#endif > > - > > /** > > * __bdev_dax_supported() - Check if the device supports dax for filesystem > > * @sb: The superblock of the device > > @@ -579,6 +569,17 @@ struct dax_device *alloc_dax(void *private, const char *__host, > > } > > EXPORT_SYMBOL_GPL(alloc_dax); > > > > +struct dax_device *alloc_dax_devmap(void *private, const char *host, > > + const struct dax_operations *ops, struct dev_pagemap *pgmap) > > +{ > > + struct dax_device *dax_dev = alloc_dax(private, host, ops); > > + > > + if (dax_dev) > > + dax_dev->pgmap = pgmap; > > + return dax_dev; > > +} > > +EXPORT_SYMBOL_GPL(alloc_dax_devmap); > > + > > void put_dax(struct dax_device *dax_dev) > > { > > if (!dax_dev) > > diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c > > index 06f8dcc52ca6..e6d7351f3379 100644 > > --- a/drivers/nvdimm/pmem.c > > +++ b/drivers/nvdimm/pmem.c > > @@ -408,7 +408,8 @@ static int pmem_attach_disk(struct device *dev, > > nvdimm_badblocks_populate(nd_region, &pmem->bb, &bb_res); > > disk->bb = &pmem->bb; > > > > - dax_dev = alloc_dax(pmem, disk->disk_name, &pmem_dax_ops); > > + dax_dev = alloc_dax_devmap(pmem, disk->disk_name, &pmem_dax_ops, > > + &pmem->pgmap); > > if (!dax_dev) { > > put_disk(disk); > > return -ENOMEM; > > diff --git a/fs/ext2/super.c b/fs/ext2/super.c > > index 7666c065b96f..6ae20e319bc4 100644 > > --- a/fs/ext2/super.c > > +++ b/fs/ext2/super.c > > @@ -172,7 +172,7 @@ static void ext2_put_super (struct super_block * sb) > > brelse (sbi->s_sbh); > > sb->s_fs_info = NULL; > > kfree(sbi->s_blockgroup_lock); > > - fs_put_dax(sbi->s_daxdev); > > + fs_dax_release(sbi->s_daxdev, sb); > > kfree(sbi); > > } > > > > @@ -817,7 +817,7 @@ static unsigned long descriptor_loc(struct super_block *sb, > > > > static int ext2_fill_super(struct super_block *sb, void *data, int silent) > > { > > - struct dax_device *dax_dev = fs_dax_get_by_bdev(sb->s_bdev); > > + struct dax_device *dax_dev = fs_dax_claim_bdev(sb->s_bdev, sb); > > struct buffer_head * bh; > > struct ext2_sb_info * sbi; > > struct ext2_super_block * es; > > @@ -1213,7 +1213,7 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent) > > kfree(sbi->s_blockgroup_lock); > > kfree(sbi); > > failed: > > - fs_put_dax(dax_dev); > > + fs_dax_release(dax_dev, sb); > > return ret; > > } > > > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > > index 39bf464c35f1..315a323729e3 100644 > > --- a/fs/ext4/super.c > > +++ b/fs/ext4/super.c > > @@ -952,7 +952,7 @@ static void ext4_put_super(struct super_block *sb) > > if (sbi->s_chksum_driver) > > crypto_free_shash(sbi->s_chksum_driver); > > kfree(sbi->s_blockgroup_lock); > > - fs_put_dax(sbi->s_daxdev); > > + fs_dax_release(sbi->s_daxdev, sb); > > kfree(sbi); > > } > > > > @@ -3398,7 +3398,7 @@ static void ext4_set_resv_clusters(struct super_block *sb) > > > > static int ext4_fill_super(struct super_block *sb, void *data, int silent) > > { > > - struct dax_device *dax_dev = fs_dax_get_by_bdev(sb->s_bdev); > > + struct dax_device *dax_dev = fs_dax_claim_bdev(sb->s_bdev, sb); > > char *orig_data = kstrdup(data, GFP_KERNEL); > > struct buffer_head *bh; > > struct ext4_super_block *es = NULL; > > @@ -4408,7 +4408,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) > > out_free_base: > > kfree(sbi); > > kfree(orig_data); > > - fs_put_dax(dax_dev); > > + fs_dax_release(dax_dev, sb); > > return err ? err : ret; > > } > > > > diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c > > index 93588ea3d3d2..ef7dd7148c0b 100644 > > --- a/fs/xfs/xfs_super.c > > +++ b/fs/xfs/xfs_super.c > > @@ -724,7 +724,7 @@ xfs_close_devices( > > > > xfs_free_buftarg(mp, mp->m_logdev_targp); > > xfs_blkdev_put(logdev); > > - fs_put_dax(dax_logdev); > > + fs_dax_release(dax_logdev, mp); > > } > > if (mp->m_rtdev_targp) { > > struct block_device *rtdev = mp->m_rtdev_targp->bt_bdev; > > @@ -732,10 +732,10 @@ xfs_close_devices( > > > > xfs_free_buftarg(mp, mp->m_rtdev_targp); > > xfs_blkdev_put(rtdev); > > - fs_put_dax(dax_rtdev); > > + fs_dax_release(dax_rtdev, mp); > > } > > xfs_free_buftarg(mp, mp->m_ddev_targp); > > - fs_put_dax(dax_ddev); > > + fs_dax_release(dax_ddev, mp); > > } > > > > /* > > @@ -753,9 +753,9 @@ xfs_open_devices( > > struct xfs_mount *mp) > > { > > struct block_device *ddev = mp->m_super->s_bdev; > > - struct dax_device *dax_ddev = fs_dax_get_by_bdev(ddev); > > - struct dax_device *dax_logdev = NULL, *dax_rtdev = NULL; > > + struct dax_device *dax_ddev = fs_dax_claim_bdev(ddev, mp); > > struct block_device *logdev = NULL, *rtdev = NULL; > > + struct dax_device *dax_logdev = NULL, *dax_rtdev = NULL; > > int error; > > > > /* > > @@ -765,7 +765,7 @@ xfs_open_devices( > > error = xfs_blkdev_get(mp, mp->m_logname, &logdev); > > if (error) > > goto out; > > - dax_logdev = fs_dax_get_by_bdev(logdev); > > + dax_logdev = fs_dax_claim_bdev(logdev, mp); > > } > > > > if (mp->m_rtname) { > > @@ -779,7 +779,7 @@ xfs_open_devices( > > error = -EINVAL; > > goto out_close_rtdev; > > } > > - dax_rtdev = fs_dax_get_by_bdev(rtdev); > > + dax_rtdev = fs_dax_claim_bdev(rtdev, mp); > > } > > > > /* > > @@ -813,14 +813,14 @@ xfs_open_devices( > > xfs_free_buftarg(mp, mp->m_ddev_targp); > > out_close_rtdev: > > xfs_blkdev_put(rtdev); > > - fs_put_dax(dax_rtdev); > > + fs_dax_release(dax_rtdev, mp); > > out_close_logdev: > > if (logdev && logdev != ddev) { > > xfs_blkdev_put(logdev); > > - fs_put_dax(dax_logdev); > > + fs_dax_release(dax_logdev, mp); > > } > > out: > > - fs_put_dax(dax_ddev); > > + fs_dax_release(dax_ddev, mp); > > return error; > > } > > > > diff --git a/include/linux/dax.h b/include/linux/dax.h > > index e9d59a6b06e1..a88ff009e2a1 100644 > > --- a/include/linux/dax.h > > +++ b/include/linux/dax.h > > @@ -32,6 +32,8 @@ extern struct attribute_group dax_attribute_group; > > struct dax_device *dax_get_by_host(const char *host); > > struct dax_device *alloc_dax(void *private, const char *host, > > const struct dax_operations *ops); > > +struct dax_device *alloc_dax_devmap(void *private, const char *host, > > + const struct dax_operations *ops, struct dev_pagemap *pgmap); > > void put_dax(struct dax_device *dax_dev); > > void kill_dax(struct dax_device *dax_dev); > > void dax_write_cache(struct dax_device *dax_dev, bool wc); > > @@ -50,6 +52,12 @@ static inline struct dax_device *alloc_dax(void *private, const char *host, > > */ > > return NULL; > > } > > +static inline struct dax_device *alloc_dax_devmap(void *private, > > + const char *host, const struct dax_operations *ops, > > + struct dev_pagemap *pgmap) > > +{ > > + return NULL; > > +} > > static inline void put_dax(struct dax_device *dax_dev) > > { > > } > > @@ -79,12 +87,8 @@ static inline struct dax_device *fs_dax_get_by_host(const char *host) > > return dax_get_by_host(host); > > } > > > > -static inline void fs_put_dax(struct dax_device *dax_dev) > > -{ > > - put_dax(dax_dev); > > -} > > - > > -struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev); > > +struct dax_device *fs_dax_claim_bdev(struct block_device *bdev, void *owner); > > +void fs_dax_release(struct dax_device *dax_dev, void *owner); > > int dax_writeback_mapping_range(struct address_space *mapping, > > struct block_device *bdev, struct writeback_control *wbc); > > struct dax_device *fs_dax_claim(struct dax_device *dax_dev, void *owner); > > @@ -100,13 +104,14 @@ static inline struct dax_device *fs_dax_get_by_host(const char *host) > > return NULL; > > } > > > > -static inline void fs_put_dax(struct dax_device *dax_dev) > > +static inline struct dax_device *fs_dax_claim_bdev(struct block_device *bdev, > > + void *owner) > > { > > + return NULL; > > } > > > > -static inline struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev) > > +static inline void fs_dax_release(struct dax_device *dax_dev, void *owner) > > { > > - return NULL; > > } > > > > static inline int dax_writeback_mapping_range(struct address_space *mapping,