From: Ross Zwisler Subject: Re: [PATCH 10/13] mm: Wire up MAP_SYNC Date: Mon, 21 Aug 2017 15:37:04 -0600 Message-ID: <20170821213704.GG26220@linux.intel.com> References: <20170817160815.30466-1-jack@suse.cz> <20170817160815.30466-11-jack@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org, Andy Lutomirski , linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, Christoph Hellwig , Ross Zwisler , Dan Williams , Boaz Harrosh To: Jan Kara Return-path: Content-Disposition: inline In-Reply-To: <20170817160815.30466-11-jack@suse.cz> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Thu, Aug 17, 2017 at 06:08:12PM +0200, Jan Kara wrote: > Pretty crude for now... > > Signed-off-by: Jan Kara > --- > fs/ext4/file.c | 2 ++ > include/linux/mm.h | 1 + > include/linux/mman.h | 3 ++- > include/uapi/asm-generic/mman.h | 1 + > mm/mmap.c | 5 +++++ > 5 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/fs/ext4/file.c b/fs/ext4/file.c > index f84bb29e941e..850037e140d7 100644 > --- a/fs/ext4/file.c > +++ b/fs/ext4/file.c > @@ -340,6 +340,8 @@ static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma) > vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE; > } else { > vma->vm_ops = &ext4_file_vm_ops; > + if (vma->vm_flags & VM_SYNC) > + return -EOPNOTSUPP; > } > return 0; > } > diff --git a/include/linux/mm.h b/include/linux/mm.h > index fa036093e76c..d0fb385414a4 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -188,6 +188,7 @@ extern unsigned int kobjsize(const void *objp); > #define VM_ACCOUNT 0x00100000 /* Is a VM accounted object */ > #define VM_NORESERVE 0x00200000 /* should the VM suppress accounting */ > #define VM_HUGETLB 0x00400000 /* Huge TLB Page VM */ > +#define VM_SYNC 0x00800000 /* Synchronous page faults */ > #define VM_ARCH_1 0x01000000 /* Architecture-specific flag */ > #define VM_ARCH_2 0x02000000 > #define VM_DONTDUMP 0x04000000 /* Do not include in the core dump */ > diff --git a/include/linux/mman.h b/include/linux/mman.h > index c8367041fafd..c38279b651e5 100644 > --- a/include/linux/mman.h > +++ b/include/linux/mman.h > @@ -86,7 +86,8 @@ calc_vm_flag_bits(unsigned long flags) > { > return _calc_vm_trans(flags, MAP_GROWSDOWN, VM_GROWSDOWN ) | > _calc_vm_trans(flags, MAP_DENYWRITE, VM_DENYWRITE ) | > - _calc_vm_trans(flags, MAP_LOCKED, VM_LOCKED ); > + _calc_vm_trans(flags, MAP_LOCKED, VM_LOCKED ) | > + _calc_vm_trans(flags, MAP_SYNC, VM_SYNC ); > } > > unsigned long vm_commit_limit(void); > diff --git a/include/uapi/asm-generic/mman.h b/include/uapi/asm-generic/mman.h > index 7162cd4cca73..00e55627d2df 100644 > --- a/include/uapi/asm-generic/mman.h > +++ b/include/uapi/asm-generic/mman.h > @@ -12,6 +12,7 @@ > #define MAP_NONBLOCK 0x10000 /* do not block on IO */ > #define MAP_STACK 0x20000 /* give out an address that is best suited for process/thread stacks */ > #define MAP_HUGETLB 0x40000 /* create a huge page mapping */ > +#define MAP_SYNC 0x80000 /* perform synchronous page faults for the mapping */ > > /* Bits [26:31] are reserved, see mman-common.h for MAP_HUGETLB usage */ > > diff --git a/mm/mmap.c b/mm/mmap.c > index f19efcf75418..18453c04b09f 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -1423,12 +1423,17 @@ unsigned long do_mmap(struct file *file, unsigned long addr, > return -ENODEV; > if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) > return -EINVAL; > + if (!(vm_flags & VM_SHARED) && (vm_flags & VM_SYNC)) > + return -EINVAL; I know this will be reworked with Dan's new mmap() interface, but I was curious what the !(vm_flags & VM_SHARED) check here was for. We're in a MAP_PRIVATE case, so is it ever possible for VM_SHARED to be set in vm_flags? I tried to make this happen with some various test scenarios, but wasn't able. > break; > > default: > return -EINVAL; > } > } else { > + if (vm_flags & VM_SYNC) > + return -EINVAL; > + > switch (flags & MAP_TYPE) { > case MAP_SHARED: > if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) > -- > 2.12.3 >