From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp2130.oracle.com (userp2130.oracle.com [156.151.31.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 87940212733F9 for ; Tue, 21 May 2019 10:46:41 -0700 (PDT) Date: Tue, 21 May 2019 10:46:25 -0700 From: "Darrick J. Wong" Subject: Re: [PATCH 08/18] dax: memcpy page in case of IOMAP_DAX_COW for mmap faults Message-ID: <20190521174625.GF5125@magnolia> References: <20190429172649.8288-1-rgoldwyn@suse.de> <20190429172649.8288-9-rgoldwyn@suse.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190429172649.8288-9-rgoldwyn@suse.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Goldwyn Rodrigues Cc: kilobyte@angband.pl, jack@suse.cz, linux-nvdimm@lists.01.org, nborisov@suse.com, david@fromorbit.com, dsterba@suse.cz, willy@infradead.org, Goldwyn Rodrigues , linux-fsdevel@vger.kernel.org, hch@lst.de, linux-btrfs@vger.kernel.org List-ID: On Mon, Apr 29, 2019 at 12:26:39PM -0500, Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues > > Change dax_iomap_pfn to return the address as well in order to > use it for performing a memcpy in case the type is IOMAP_DAX_COW. > We don't handle PMD because btrfs does not support hugepages. > > Question: > The sequence of bdev_dax_pgoff() and dax_direct_access() is > used multiple times to calculate address and pfn's. Would it make > sense to call it while calculating address as well to reduce code? > > Signed-off-by: Goldwyn Rodrigues > --- > fs/dax.c | 19 +++++++++++++++---- > 1 file changed, 15 insertions(+), 4 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 610bfa861a28..718b1632a39d 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -984,7 +984,7 @@ static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos) > } > > static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size, > - pfn_t *pfnp) > + pfn_t *pfnp, void **addr) > { > const sector_t sector = dax_iomap_sector(iomap, pos); > pgoff_t pgoff; > @@ -996,7 +996,7 @@ static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size, > return rc; > id = dax_read_lock(); > length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size), > - NULL, pfnp); > + addr, pfnp); > if (length < 0) { > rc = length; > goto out; > @@ -1286,6 +1286,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, > XA_STATE(xas, &mapping->i_pages, vmf->pgoff); > struct inode *inode = mapping->host; > unsigned long vaddr = vmf->address; > + void *addr; > loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT; > struct iomap iomap = { 0 }; Ugh, I had forgotten that fs/dax.c open-codes iomap_apply, probably because the actor returns vm_fault_t, not bytes copied. I guess that makes it a tiny bit more complicated to pass in two (struct iomap *) to the iomap_begin function... > unsigned flags = IOMAP_FAULT; > @@ -1375,16 +1376,26 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, > sync = dax_fault_is_synchronous(flags, vma, &iomap); > > switch (iomap.type) { > + case IOMAP_DAX_COW: > case IOMAP_MAPPED: > if (iomap.flags & IOMAP_F_NEW) { > count_vm_event(PGMAJFAULT); > count_memcg_event_mm(vma->vm_mm, PGMAJFAULT); > major = VM_FAULT_MAJOR; > } > - error = dax_iomap_pfn(&iomap, pos, PAGE_SIZE, &pfn); > + error = dax_iomap_pfn(&iomap, pos, PAGE_SIZE, &pfn, &addr); > if (error < 0) > goto error_finish_iomap; > > + if (iomap.type == IOMAP_DAX_COW) { > + if (iomap.inline_data) { > + error = memcpy_mcsafe(addr, iomap.inline_data, > + PAGE_SIZE); > + if (error < 0) > + goto error_finish_iomap; > + } else > + memset(addr, 0, PAGE_SIZE); This memcpy_mcsafe/memset chunk shows up a lot in this series. Maybe it should be a static inline within dax.c? --D > + } > entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn, > 0, write && !sync); > > @@ -1597,7 +1608,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, > > switch (iomap.type) { > case IOMAP_MAPPED: > - error = dax_iomap_pfn(&iomap, pos, PMD_SIZE, &pfn); > + error = dax_iomap_pfn(&iomap, pos, PMD_SIZE, &pfn, NULL); > if (error < 0) > goto finish_iomap; > > -- > 2.16.4 > _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm