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Open Source and information security mailing list archives
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Date: Tue, 13 Oct 2020 12:41:36 -0700 From: Dan Williams <dan.j.williams@...el.com> To: Matthew Wilcox <willy@...radead.org> Cc: "Weiny, Ira" <ira.weiny@...el.com>, Andrew Morton <akpm@...ux-foundation.org>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Nicolas Pitre <nico@...xnic.net>, X86 ML <x86@...nel.org>, Dave Hansen <dave.hansen@...ux.intel.com>, Fenghua Yu <fenghua.yu@...el.com>, Linux Doc Mailing List <linux-doc@...r.kernel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, linux-nvdimm <linux-nvdimm@...ts.01.org>, linux-fsdevel <linux-fsdevel@...r.kernel.org>, Linux MM <linux-mm@...ck.org>, linux-kselftest@...r.kernel.org, linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>, KVM list <kvm@...r.kernel.org>, Netdev <netdev@...r.kernel.org>, bpf@...r.kernel.org, Kexec Mailing List <kexec@...ts.infradead.org>, linux-bcache@...r.kernel.org, linux-mtd@...ts.infradead.org, devel@...verdev.osuosl.org, linux-efi <linux-efi@...r.kernel.org>, linux-mmc@...r.kernel.org, linux-scsi <linux-scsi@...r.kernel.org>, target-devel@...r.kernel.org, linux-nfs@...r.kernel.org, ceph-devel@...r.kernel.org, linux-ext4 <linux-ext4@...r.kernel.org>, linux-aio@...ck.org, io-uring@...r.kernel.org, linux-erofs@...ts.ozlabs.org, linux-um@...ts.infradead.org, linux-ntfs-dev@...ts.sourceforge.net, reiserfs-devel@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net, linux-nilfs@...r.kernel.org, cluster-devel@...hat.com, ecryptfs@...r.kernel.org, linux-cifs@...r.kernel.org, linux-btrfs <linux-btrfs@...r.kernel.org>, linux-afs@...ts.infradead.org, linux-rdma <linux-rdma@...r.kernel.org>, amd-gfx list <amd-gfx@...ts.freedesktop.org>, Maling list - DRI developers <dri-devel@...ts.freedesktop.org>, intel-gfx@...ts.freedesktop.org, drbd-dev@...ts.linbit.com, linux-block@...r.kernel.org, xen-devel <xen-devel@...ts.xenproject.org>, linux-cachefs@...hat.com, samba-technical@...ts.samba.org, intel-wired-lan@...ts.osuosl.org Subject: Re: [PATCH RFC PKS/PMEM 33/58] fs/cramfs: Utilize new kmap_thread() On Tue, Oct 13, 2020 at 12:37 PM Matthew Wilcox <willy@...radead.org> wrote: > > On Tue, Oct 13, 2020 at 11:44:29AM -0700, Dan Williams wrote: > > On Fri, Oct 9, 2020 at 12:52 PM <ira.weiny@...el.com> wrote: > > > > > > From: Ira Weiny <ira.weiny@...el.com> > > > > > > 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: Nicolas Pitre <nico@...xnic.net> > > > Signed-off-by: Ira Weiny <ira.weiny@...el.com> > > > --- > > > fs/cramfs/inode.c | 10 +++++----- > > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > > > diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c > > > index 912308600d39..003c014a42ed 100644 > > > --- a/fs/cramfs/inode.c > > > +++ b/fs/cramfs/inode.c > > > @@ -247,8 +247,8 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset, > > > struct page *page = pages[i]; > > > > > > if (page) { > > > - memcpy(data, kmap(page), PAGE_SIZE); > > > - kunmap(page); > > > + memcpy(data, kmap_thread(page), PAGE_SIZE); > > > + kunmap_thread(page); > > > > Why does this need a sleepable kmap? This looks like a textbook > > kmap_atomic() use case. > > There's a lot of code of this form. Could we perhaps have: > > static inline void copy_to_highpage(struct page *to, void *vfrom, unsigned int size) > { > char *vto = kmap_atomic(to); > > memcpy(vto, vfrom, size); > kunmap_atomic(vto); > } > > in linux/highmem.h ? Nice, yes, that could also replace the local ones in lib/iov_iter.c (memcpy_{to,from}_page())
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