From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f178.google.com (mail-pl1-f178.google.com [209.85.214.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 86EB672 for ; Wed, 27 Oct 2021 23:02:34 +0000 (UTC) Received: by mail-pl1-f178.google.com with SMTP id r5so3099759pls.1 for ; Wed, 27 Oct 2021 16:02:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=TIqjtDMduKwUTBKX+tBygnWIDjEpMEr2bhy/yT20mZY=; b=REyhBK6tQZDsAnyKckv+GTqli7ewznlsn87vyBbY5f9febMQ9OwtuAQWJhdicQr38K K1RmGd24wmhycGjPGNyFLV1NcRjXV0YOMJgCvWwD1u2op9FVS5Ne01Ma8I3/7N/vKG+L Nf/tcy6ZTKg9EdZlESmgy/KdDpwwSItb4MeferFvOhl0fHKDs4iLoNdhifCWx1/jKI7k we4R1sn71TU5C2vgTscBN2f7yTZYEbFO4nfi+2G6AAM+9u32OYSh0jX2w1H4FzdcM3Ry 12G6L2JWGDbLkKio2wNGWYlGKXiSVAEj+xqYbUihB4TpfsaefQ6c0TKQ0AY7vxbKpFnC uryw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=TIqjtDMduKwUTBKX+tBygnWIDjEpMEr2bhy/yT20mZY=; b=EkkbwNJpaoRMw7cjkiKgbQdps6yV0SGesyN2XruCRy00gV0Ges9nNCpnd7avXy3bp8 VgFu/4zRGTA8NYKzShDnnuLlPbWgkd36IjMJcNLrHN0vOxVGPpe5lYwUDc4ZPY53RsdV pGSqKqnkd/na278j3vzvPomQutgh80dPa0aNOeMjOcNKWjgisBUNA3eOWbleOCQY3Bey 1ImOQLHXrkIiztgo4ZwYqK5Ij8gPaxgpbWZGnfJ+4lwThMhsVLD6sb6T0UzeUx6bOlbf I3yEBr1jJRybeZYVt7r0HrJzDRFmRlT/fOTTJy3SJXom95KP2AjjaFHN2cKBKe/MJdJF cxvg== X-Gm-Message-State: AOAM532zOoHX/P9YRBgytPy8U2I5g0ggHN35I7ZLI2PpAeUjR1vqAIG3 h8nFqEY12tzlzSsBkm67+FW+55uE6ClwTWw707SdYQ== X-Google-Smtp-Source: ABdhPJxUwYpsZPDBKuNiovYR0U6XMhxIiDSjLBJJ1e6zz5gkWe8hCvGUK6ph3bxfDtcB6AFtR1bn5v1MGpOhiVcMhIY= X-Received: by 2002:a17:90a:a085:: with SMTP id r5mr8858216pjp.8.1635375753946; Wed, 27 Oct 2021 16:02:33 -0700 (PDT) Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20211018044054.1779424-1-hch@lst.de> <20211018044054.1779424-5-hch@lst.de> In-Reply-To: <20211018044054.1779424-5-hch@lst.de> From: Dan Williams Date: Wed, 27 Oct 2021 16:02:22 -0700 Message-ID: Subject: Re: [PATCH 04/11] dax: remove the pgmap sanity checks in generic_fsdax_supported To: Christoph Hellwig Cc: Mike Snitzer , Ira Weiny , device-mapper development , linux-xfs , Linux NVDIMM , linux-s390 , linux-fsdevel , linux-erofs@lists.ozlabs.org, linux-ext4 , virtualization@lists.linux-foundation.org Content-Type: text/plain; charset="UTF-8" On Sun, Oct 17, 2021 at 9:41 PM Christoph Hellwig wrote: > > Drivers that register a dax_dev should make sure it works, no need > to double check from the file system. > > Signed-off-by: Christoph Hellwig > --- > drivers/dax/super.c | 49 +-------------------------------------------- > 1 file changed, 1 insertion(+), 48 deletions(-) > > diff --git a/drivers/dax/super.c b/drivers/dax/super.c > index 9383c11b21853..04fc680542e8d 100644 > --- a/drivers/dax/super.c > +++ b/drivers/dax/super.c > @@ -107,13 +107,9 @@ bool generic_fsdax_supported(struct dax_device *dax_dev, > struct block_device *bdev, int blocksize, sector_t start, > sector_t sectors) > { > - bool dax_enabled = false; > pgoff_t pgoff, pgoff_end; > - void *kaddr, *end_kaddr; > - pfn_t pfn, end_pfn; > sector_t last_page; > - long len, len2; > - int err, id; > + int err; > > if (blocksize != PAGE_SIZE) { > pr_info("%pg: error: unsupported blocksize for dax\n", bdev); > @@ -138,49 +134,6 @@ bool generic_fsdax_supported(struct dax_device *dax_dev, > return false; > } > > - id = dax_read_lock(); > - len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn); > - len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn); > - > - if (len < 1 || len2 < 1) { > - pr_info("%pg: error: dax access failed (%ld)\n", > - bdev, len < 1 ? len : len2); > - dax_read_unlock(id); > - return false; > - } > - > - if (IS_ENABLED(CONFIG_FS_DAX_LIMITED) && pfn_t_special(pfn)) { > - /* > - * An arch that has enabled the pmem api should also > - * have its drivers support pfn_t_devmap() > - * > - * This is a developer warning and should not trigger in > - * production. dax_flush() will crash since it depends > - * on being able to do (page_address(pfn_to_page())). > - */ > - WARN_ON(IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API)); > - dax_enabled = true; > - } else if (pfn_t_devmap(pfn) && pfn_t_devmap(end_pfn)) { > - struct dev_pagemap *pgmap, *end_pgmap; > - > - pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL); > - end_pgmap = get_dev_pagemap(pfn_t_to_pfn(end_pfn), NULL); > - if (pgmap && pgmap == end_pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX > - && pfn_t_to_page(pfn)->pgmap == pgmap > - && pfn_t_to_page(end_pfn)->pgmap == pgmap > - && pfn_t_to_pfn(pfn) == PHYS_PFN(__pa(kaddr)) > - && pfn_t_to_pfn(end_pfn) == PHYS_PFN(__pa(end_kaddr))) This is effectively a self-test for a regression that was found while manipulating the 'struct page' memmap metadata reservation for PMEM namespaces. I guess it's just serving as a security-blanket now and I should find a way to move it out to a self-test. I'll take a look. > - dax_enabled = true; > - put_dev_pagemap(pgmap); > - put_dev_pagemap(end_pgmap); > - > - } > - dax_read_unlock(id); > - > - if (!dax_enabled) { > - pr_info("%pg: error: dax support not enabled\n", bdev); > - return false; > - } > return true; > } > EXPORT_SYMBOL_GPL(generic_fsdax_supported); > -- > 2.30.2 >