From: Dan Williams <dan.j.williams@intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Mike Snitzer <snitzer@redhat.com>,
Ira Weiny <ira.weiny@intel.com>,
device-mapper development <dm-devel@redhat.com>,
linux-xfs <linux-xfs@vger.kernel.org>,
Linux NVDIMM <nvdimm@lists.linux.dev>,
linux-s390 <linux-s390@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-erofs@lists.ozlabs.org,
linux-ext4 <linux-ext4@vger.kernel.org>,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 04/11] dax: remove the pgmap sanity checks in generic_fsdax_supported
Date: Wed, 27 Oct 2021 16:02:22 -0700 [thread overview]
Message-ID: <CAPcyv4gUU1D25XSY32oDEbpLXRCvQ_q34sL86xmQ_cH0q5PjZQ@mail.gmail.com> (raw)
In-Reply-To: <20211018044054.1779424-5-hch@lst.de>
On Sun, Oct 17, 2021 at 9:41 PM Christoph Hellwig <hch@lst.de> 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 <hch@lst.de>
> ---
> 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
>
next prev parent reply other threads:[~2021-10-27 23:02 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-18 4:40 futher decouple DAX from block devices Christoph Hellwig
2021-10-18 4:40 ` [PATCH 01/11] dm: make the DAX support dependend on CONFIG_FS_DAX Christoph Hellwig
2021-10-27 20:53 ` Dan Williams
2021-11-01 16:12 ` Mike Snitzer
2021-10-18 4:40 ` [PATCH 02/11] dax: remove CONFIG_DAX_DRIVER Christoph Hellwig
2021-10-27 20:54 ` Dan Williams
2021-10-18 4:40 ` [PATCH 03/11] dax: simplify the dax_device <-> gendisk association Christoph Hellwig
2021-10-27 22:03 ` Dan Williams
2021-10-29 4:57 ` Ira Weiny
2021-11-01 16:28 ` Mike Snitzer
2021-10-18 4:40 ` [PATCH 04/11] dax: remove the pgmap sanity checks in generic_fsdax_supported Christoph Hellwig
2021-10-27 23:02 ` Dan Williams [this message]
2021-10-18 4:40 ` [PATCH 05/11] dax: move the partition alignment check into fs_dax_get_by_bdev Christoph Hellwig
2021-10-27 23:07 ` Dan Williams
2021-10-18 4:40 ` [PATCH 06/11] xfs: factor out a xfs_setup_dax helper Christoph Hellwig
2021-10-18 16:43 ` Darrick J. Wong
2021-10-19 7:23 ` Christoph Hellwig
2021-10-27 23:37 ` Dan Williams
2021-10-18 4:40 ` [PATCH 07/11] dax: remove dax_capable Christoph Hellwig
2021-10-18 12:25 ` Gao Xiang
2021-10-19 15:44 ` [dm-devel] " Darrick J. Wong
2021-10-28 0:20 ` Dan Williams
2021-10-28 0:16 ` Dan Williams
2021-11-01 16:17 ` Mike Snitzer
2021-10-18 4:40 ` [PATCH 08/11] dm-linear: add a linear_dax_pgoff helper Christoph Hellwig
2021-10-28 1:32 ` Dan Williams
2021-11-01 16:18 ` Mike Snitzer
2021-10-18 4:40 ` [PATCH 09/11] dm-log-writes: add a log_writes_dax_pgoff helper Christoph Hellwig
2021-10-28 1:36 ` Dan Williams
2021-11-01 16:19 ` Mike Snitzer
2021-10-18 4:40 ` [PATCH 10/11] dm-stripe: add a stripe_dax_pgoff helper Christoph Hellwig
2021-10-28 1:41 ` Dan Williams
2021-11-01 16:21 ` Mike Snitzer
2021-10-18 4:40 ` [PATCH 11/11] dax: move bdev_dax_pgoff to fs/dax.c Christoph Hellwig
2021-10-28 1:44 ` Dan Williams
2021-10-27 20:46 ` futher decouple DAX from block devices Dan Williams
2021-10-28 23:51 ` Stephen Rothwell
2021-10-29 15:42 ` Dan Williams
2021-10-29 15:55 ` Darrick J. Wong
2021-10-29 16:16 ` Dan Williams
2021-11-03 17:59 ` Eric Sandeen
2021-11-04 8:17 ` Christoph Hellwig
2021-11-04 17:34 ` Darrick J. Wong
2021-11-04 17:35 ` Christoph Hellwig
2021-11-04 18:10 ` Dan Williams
2021-11-04 19:04 ` Darrick J. Wong
2021-11-05 3:09 ` Theodore Ts'o
2021-11-05 3:30 ` Matthew Wilcox
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