From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Biggers Date: Fri, 09 Oct 2020 21:34:34 +0000 Subject: Re: [PATCH RFC PKS/PMEM 22/58] fs/f2fs: Utilize new kmap_thread() Message-Id: <20201009213434.GA839@sol.localdomain> List-Id: References: <20201009195033.3208459-1-ira.weiny@intel.com> <20201009195033.3208459-23-ira.weiny@intel.com> In-Reply-To: <20201009195033.3208459-23-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ira.weiny@intel.com Cc: linux-aio@kvack.org, linux-efi@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, Peter Zijlstra , linux-mmc@vger.kernel.org, Dave Hansen , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, target-devel@vger.kernel.org, linux-mtd@lists.infradead.org, linux-kselftest@vger.kernel.org, Thomas Gleixner , drbd-dev@lists.linbit.com, devel@driverdev.osuosl.org, linux-cifs@vger.kernel.org, linux-nilfs@vger.kernel.org, linux-scsi@vger.kernel.org, linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, x86@kernel.org, amd-gfx@lists.freedesktop.org, linux-afs@lists.infradead.org, cluster-devel@redhat.com, Ingo Molnar , intel-wired-lan@lists.osuosl.org, kexec@lists.infradead.org, xen-devel@lists.xenproject.org, linux-ext4@vger.kernel.org, bpf@vger.kernel.org, Dan Williams , Fenghua Yu , intel-gfx@lists.freedesktop.org, ecryptfs@vger.kernel.org, linux-um@lists.infradead.org, reiserfs-devel@vger.kernel.org, linux-block@vger.kernel.org, linux-bcache@vger.kernel.org, Borislav Petkov , Andy Lutomirski , Jaegeuk Kim , ceph-devel@vger.kernel.org, io-uring@vger.kernel.org, linux-cachefs@redhat.com, linux-nfs@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net, netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, samba-technical@lists.samba.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, Andrew Morton , linux-erofs@lists.ozlabs.org, linux-btrfs@vger.kernel.org On Fri, Oct 09, 2020 at 12:49:57PM -0700, ira.weiny@intel.com wrote: > From: Ira Weiny > > The kmap() calls in this FS are localized to a single thread. To avoid > the over head of global PKRS updates use the new kmap_thread() call. > > Cc: Jaegeuk Kim > Cc: Chao Yu > Signed-off-by: Ira Weiny > --- > fs/f2fs/f2fs.h | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > index d9e52a7f3702..ff72a45a577e 100644 > --- a/fs/f2fs/f2fs.h > +++ b/fs/f2fs/f2fs.h > @@ -2410,12 +2410,12 @@ static inline struct page *f2fs_pagecache_get_page( > > static inline void f2fs_copy_page(struct page *src, struct page *dst) > { > - char *src_kaddr = kmap(src); > - char *dst_kaddr = kmap(dst); > + char *src_kaddr = kmap_thread(src); > + char *dst_kaddr = kmap_thread(dst); > > memcpy(dst_kaddr, src_kaddr, PAGE_SIZE); > - kunmap(dst); > - kunmap(src); > + kunmap_thread(dst); > + kunmap_thread(src); > } Wouldn't it make more sense to switch cases like this to kmap_atomic()? The pages are only mapped to do a memcpy(), then they're immediately unmapped. - Eric