On Mon, 2017-06-26 at 09:21 -0400, Anna Schumaker wrote:
>
> On 06/24/2017 09:23 AM, Jeff Layton wrote:
> > On Wed, 2017-06-14 at 13:06 -0400, Olga Kornievskaia wrote:
> > > This is a proposal to allow 64bit count to copy and return as
> > > a result of a copy_file_range. No attempt was made to share code
> > > with the 32bit function because 32bit interface should probably
> > > get depreciated.
> > >
> > > Why use 64bit? Current uses of 32bit are by clone_file_range()
> > > which could use 64bit count and NFS copy_file_range also supports
> > > 64bit count value.
> > >
> > > Also with this proposal off-the-bet allow the userland to copy
> > > between different mount points.
> > >
> > > Signed-off-by: Olga Kornievskaia <kolga@xxxxxxxxxx>
> > > ---
> > > arch/x86/entry/syscalls/syscall_32.tbl | 1 +
> > > arch/x86/entry/syscalls/syscall_64.tbl | 1 +
> > > fs/read_write.c | 136 +++++++++++++++++++++++++++++++++
> > > include/linux/fs.h | 4 +
> > > include/linux/syscalls.h | 3 +
> > > include/uapi/asm-generic/unistd.h | 4 +-
> > > kernel/sys_ni.c | 1 +
> > > 7 files changed, 149 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
> > > index 448ac21..1f5f1e7 100644
> > > --- a/arch/x86/entry/syscalls/syscall_32.tbl
> > > +++ b/arch/x86/entry/syscalls/syscall_32.tbl
> > > @@ -391,3 +391,4 @@
> > > 382 i386 pkey_free sys_pkey_free
> > > 383 i386 statx sys_statx
> > > 384 i386 arch_prctl sys_arch_prctl compat_sys_arch_prctl
> > > +385 i386 copy_file_range64 sys_copy_file_range64
> > > diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
> > > index 5aef183..e658bbe 100644
> > > --- a/arch/x86/entry/syscalls/syscall_64.tbl
> > > +++ b/arch/x86/entry/syscalls/syscall_64.tbl
> > > @@ -339,6 +339,7 @@
> > > 330 common pkey_alloc sys_pkey_alloc
> > > 331 common pkey_free sys_pkey_free
> > > 332 common statx sys_statx
> > > +333 64 copy_file_range64 sys_copy_file_range64
> > >
> > > #
> > > # x32-specific system call numbers start at 512 to avoid cache impact
> > > diff --git a/fs/read_write.c b/fs/read_write.c
> > > index 47c1d44..e2665c1 100644
> > > --- a/fs/read_write.c
> > > +++ b/fs/read_write.c
> > > @@ -1700,6 +1700,142 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> > > return ret;
> > > }
> > >
> > > +u64 vfs_copy_file_range64(struct file *file_in, loff_t pos_in,
> > > + struct file *file_out, loff_t pos_out,
> > > + u64 len, unsigned int flags)
> > > +{
> > > + struct inode *inode_in = file_inode(file_in);
> > > + struct inode *inode_out = file_inode(file_out);
> > > + u64 ret;
> > > +
> > > + if (flags != 0)
> > > + return -EINVAL;
> > > +
> > > + if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
> > > + return -EISDIR;
> > > + if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
> > > + return -EINVAL;
> > > +
> > > + ret = rw_verify_area(READ, file_in, &pos_in, len);
> > > + if (unlikely(ret))
> > > + return ret;
> > > +
> > > + ret = rw_verify_area(WRITE, file_out, &pos_out, len);
> > > + if (unlikely(ret))
> > > + return ret;
> > > +
> > > + if (!(file_in->f_mode & FMODE_READ) ||
> > > + !(file_out->f_mode & FMODE_WRITE) ||
> > > + (file_out->f_flags & O_APPEND))
> > > + return -EBADF;
> > > +
> > > + if (len == 0)
> > > + return 0;
> > > +
> > > + file_start_write(file_out);
> > > +
> > > + /*
> > > + * Try cloning first, this is supported by more file systems, and
> > > + * more efficient if both clone and copy are supported (e.g. NFS).
> > > + */
> > > + if (file_in->f_op->clone_file_range) {
> > > + ret = file_in->f_op->clone_file_range(file_in, pos_in,
> > > + file_out, pos_out, len);
> > > + if (ret == 0) {
> > > + ret = len;
> > > + goto done;
> > > + }
> > > + }
> > > +
> > > + if (file_out->f_op->copy_file_range64) {
> > > + ret = file_out->f_op->copy_file_range64(file_in, pos_in,
> > > + file_out, pos_out, len, flags);
> > > + if (ret != -EOPNOTSUPP)
> > > + goto done;
> > > + }
> > > +
> > > + ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,
> > > + len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
> > > +
> > > +done:
> > > + if (ret > 0) {
> > > + fsnotify_access(file_in);
> > > + add_rchar(current, ret);
> > > + fsnotify_modify(file_out);
> > > + add_wchar(current, ret);
> > > + }
> > > +
> > > + inc_syscr(current);
> > > + inc_syscw(current);
> > > +
> > > + file_end_write(file_out);
> > > +
> > > + return ret;
> > > +}
> > > +EXPORT_SYMBOL(vfs_copy_file_range64);
> > > +
> > > +SYSCALL_DEFINE6(copy_file_range64, int, fd_in, loff_t __user *, off_in,
> > > + int, fd_out, loff_t __user *, off_out,
> > > + u64, len, unsigned int, flags)
> > > +{
> > > + loff_t pos_in;
> > > + loff_t pos_out;
> > > + struct fd f_in;
> > > + struct fd f_out;
> > > + u64 ret = -EBADF;
> > > +
> > > + f_in = fdget(fd_in);
> > > + if (!f_in.file)
> > > + goto out2;
> > > +
> > > + f_out = fdget(fd_out);
> > > + if (!f_out.file)
> > > + goto out1;
> > > +
> > > + ret = -EFAULT;
> > > + if (off_in) {
> > > + if (copy_from_user(&pos_in, off_in, sizeof(loff_t)))
> > > + goto out;
> > > + } else {
> > > + pos_in = f_in.file->f_pos;
> > > + }
> > > +
> > > + if (off_out) {
> > > + if (copy_from_user(&pos_out, off_out, sizeof(loff_t)))
> > > + goto out;
> > > + } else {
> > > + pos_out = f_out.file->f_pos;
> > > + }
> > > +
> > > + ret = vfs_copy_file_range64(f_in.file, pos_in, f_out.file, pos_out, len,
> > > + flags);
> > > + if (ret > 0) {
> > > + pos_in += ret;
> > > + pos_out += ret;
> > > +
> > > + if (off_in) {
> > > + if (copy_to_user(off_in, &pos_in, sizeof(loff_t)))
> > > + ret = -EFAULT;
> > > + } else {
> > > + f_in.file->f_pos = pos_in;
> > > + }
> > > +
> > > + if (off_out) {
> > > + if (copy_to_user(off_out, &pos_out, sizeof(loff_t)))
> > > + ret = -EFAULT;
> > > + } else {
> > > + f_out.file->f_pos = pos_out;
> > > + }
> > > + }
> > > +
> > > +out:
> > > + fdput(f_out);
> > > +out1:
> > > + fdput(f_in);
> > > +out2:
> > > + return ret;
> > > +}
> > > +
> > > static int clone_verify_area(struct file *file, loff_t pos, u64 len, bool write)
> > > {
> > > struct inode *inode = file_inode(file);
> > > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > > index 803e5a9..2727a98 100644
> > > --- a/include/linux/fs.h
> > > +++ b/include/linux/fs.h
> > > @@ -1690,6 +1690,8 @@ struct file_operations {
> > > u64);
> > > ssize_t (*dedupe_file_range)(struct file *, u64, u64, struct file *,
> > > u64);
> > > + u64 (*copy_file_range64)(struct file *, loff_t, struct file *,
> > > + loff_t, u64, unsigned int);
> > > };
> > >
> > > struct inode_operations {
> > > @@ -1770,6 +1772,8 @@ extern int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> > > loff_t len, bool *is_same);
> > > extern int vfs_dedupe_file_range(struct file *file,
> > > struct file_dedupe_range *same);
> > > +extern u64 vfs_copy_file_range64(struct file *, loff_t, struct file *,
> > > + loff_t, u64, unsigned int);
> > >
> > > struct super_operations {
> > > struct inode *(*alloc_inode)(struct super_block *sb);
> > > diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> > > index 980c3c9..f7ea78e 100644
> > > --- a/include/linux/syscalls.h
> > > +++ b/include/linux/syscalls.h
> > > @@ -905,5 +905,8 @@ asmlinkage long sys_pkey_mprotect(unsigned long start, size_t len,
> > > asmlinkage long sys_pkey_free(int pkey);
> > > asmlinkage long sys_statx(int dfd, const char __user *path, unsigned flags,
> > > unsigned mask, struct statx __user *buffer);
> > > +asmlinkage long sys_copy_file_range64(int fd_in, loff_t __user *off_in,
> > > + int fd_out, loff_t __user *off_out,
> > > + u64 len, unsigned int flags);
> > >
> > > #endif
> > > diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
> > > index 061185a..e385a76 100644
> > > --- a/include/uapi/asm-generic/unistd.h
> > > +++ b/include/uapi/asm-generic/unistd.h
> > > @@ -731,9 +731,11 @@
> > > __SYSCALL(__NR_pkey_free, sys_pkey_free)
> > > #define __NR_statx 291
> > > __SYSCALL(__NR_statx, sys_statx)
> > > +#define __NR_copy_file_range64 292
> > > +__SYSCALL(__NR_copy_file_range64, sys_copy_file_range64)
> > >
> > > #undef __NR_syscalls
> > > -#define __NR_syscalls 292
> > > +#define __NR_syscalls 293
> > >
> > > /*
> > > * All syscalls below here should go away really,
> > > diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
> > > index 8acef85..8e0cfd4 100644
> > > --- a/kernel/sys_ni.c
> > > +++ b/kernel/sys_ni.c
> > > @@ -178,6 +178,7 @@ asmlinkage long sys_ni_syscall(void)
> > > cond_syscall(sys_capget);
> > > cond_syscall(sys_capset);
> > > cond_syscall(sys_copy_file_range);
> > > +cond_syscall(sys_copy_file_range64);
> > >
> > > /* arch-specific weak syscall entries */
> > > cond_syscall(sys_pciconfig_read);
> >
> > Hi Olga,
> >
> > We discussed this a bit privately, but I'll note it here too.
> >
> > Server-to-server copy seems like a nice thing to me as well. There are
> > several filesystems that can likely make use of that ability.
> >
> > I don't have a real opinion on the API change either, but you're making
> > a very subtle change with this patch. Prior to this, the existing
> > copy_file_range calls could count on the superblocks being the same.
> > Now, it looks like you can pass them any old file pointer.
>
> What if we add a new file op for xdev copy that gets called when
> superblocks are different, but filesystem type is the same? We could
> keep the current copy_file_range fop to fall back on if superblocks
> are the same.
I don't think that would really help much. There are only two
filesystems with copy_file_range operations -- nfsv4 and cifs. I don't
think we really need another special case op for this.
What I would probably suggest is to just push the check for the same
superblock down into the copy_file_range ops in one patch (with no
functional change). Then, you could go and lift that restriction in the
NFSv4 operation without regressing cifs. The CIFS folks could eventually
do the same for theirs.
--
Jeff Layton <jlayton@xxxxxxxxxx>
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