From: Jason Gunthorpe <jgg@ziepe.ca>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Joao Martins <joao.m.martins@oracle.com>,
Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
Christoph Hellwig <hch@lst.de>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Linux NVDIMM <nvdimm@lists.linux.dev>,
linux-s390 <linux-s390@vger.kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Alex Sierra <alex.sierra@amd.com>,
"Kuehling, Felix" <Felix.Kuehling@amd.com>,
Linux MM <linux-mm@kvack.org>,
Ralph Campbell <rcampbell@nvidia.com>,
Alistair Popple <apopple@nvidia.com>,
Vishal Verma <vishal.l.verma@intel.com>,
Dave Jiang <dave.jiang@intel.com>
Subject: Re: can we finally kill off CONFIG_FS_DAX_LIMITED
Date: Tue, 19 Oct 2021 14:54:08 -0300 [thread overview]
Message-ID: <20211019175408.GJ3686969@ziepe.ca> (raw)
In-Reply-To: <CAPcyv4jAQVSKB7rts5Mfu0JRtB-b1NGFgu03+8-ja8o11d1vQA@mail.gmail.com>
On Tue, Oct 19, 2021 at 10:38:42AM -0700, Dan Williams wrote:
> > So we can just delete the detection of the page size and rely on the
> > zap code to wipe out the entire level, not split it. Which is what we
> > have today already.
>
> As Joao points out, userspace wants to know the blast radius of the
> unmap for historical reasons. I do think it's worth deprecating that
> somehow... providing a better error management interface is part of
> the DAX-reflink enabling.
OK, it makes sense.
I have a less invasive idea though - emulate what zap is doing:
if (!pud_present(*pud))
return 0;
if (pud_leaf(*pud))
return PUD_SHIFT;
if (!pmd_present(*pud))
return 0;
if (pmd_leaf(*pud))
return PMD_SHIFT;
return PAGE_SHIFT;
Which would return the "blast radius" of the unmap_mapping_range()
when it rounds up to the left page level that contains the VA.
Now it doesn't need the pte_devmap test..
And when both DAX's learn to use compound_head this can be deleted.
Jason
next prev parent reply other threads:[~2021-10-19 17:54 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-20 5:43 can we finally kill off CONFIG_FS_DAX_LIMITED Christoph Hellwig
2021-08-20 15:41 ` Dan Williams
2021-08-20 17:42 ` Dan Williams
2021-08-20 19:03 ` Gerald Schaefer
2021-08-24 14:17 ` Joao Martins
2021-08-23 14:05 ` Gerald Schaefer
2021-08-23 19:47 ` Gerald Schaefer
2021-08-23 20:21 ` Dan Williams
2021-08-24 14:09 ` Joao Martins
2021-08-24 14:53 ` Dan Williams
2021-08-24 18:24 ` Gerald Schaefer
2021-08-24 18:44 ` Dan Williams
2021-10-14 23:04 ` Jason Gunthorpe
2021-10-15 0:22 ` Joao Martins
2021-10-18 23:30 ` Jason Gunthorpe
2021-10-19 4:26 ` Dan Williams
2021-10-19 14:20 ` Jason Gunthorpe
2021-10-19 15:20 ` Joao Martins
2021-10-19 15:38 ` Felix Kuehling
2021-10-19 17:38 ` Dan Williams
2021-10-19 17:54 ` Jason Gunthorpe [this message]
2021-08-24 6:49 ` David Hildenbrand
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