On Thu, Jun 15, 2017 at 4:53 PM, Darrick J. Wong
<darrick.wong@xxxxxxxxxx> wrote:
> On Thu, Jun 15, 2017 at 10:39:42AM -0400, Olga Kornievskaia wrote:
>> On Wed, Jun 14, 2017 at 11:59 PM, Darrick J. Wong
>> <darrick.wong@xxxxxxxxxx> wrote:
>> > On Wed, Jun 14, 2017 at 02:53:35PM -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 | 146 +++++++++++++++++++++++++++++++--
>> >> 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, 154 insertions(+), 6 deletions(-)
>> >>
>> >> 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 e3ee985..c9c072b 100644
>> >> --- a/fs/read_write.c
>> >> +++ b/fs/read_write.c
>> >> @@ -1700,7 +1700,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
>> >> return ret;
>> >> }
>> >>
>> >> -static int clone_verify_area(struct file *file, loff_t pos, u64 len, bool write)
>> >> +static int rw64_verify_area(struct file *file, loff_t pos, u64 len, bool write)
>> >> {
>> >> struct inode *inode = file_inode(file);
>> >>
>> >> @@ -1723,6 +1723,142 @@ static int clone_verify_area(struct file *file, loff_t pos, u64 len, bool write)
>> >> return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
>> >> }
>> >>
>> >> +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)
>> >
>> > AFAICT the difference between vfs_copy_file_range() and
>> > vfs_copy_file_range64() is that you've replaced 'size_t len' with
>> > 'u64 len', correct?
>>
>> That and I'm asking to allow for cross-device copy to be allowed by
>> the system call.
>
> I was fine letting each fs decide if it was going to allow cross-device
> copy or not, but Christoph argued that since we don't generally allow
> operations across mountpoints we shouldn't allow cross-mountpoint
> {clone,copy}_file_range either.
>
> Roughly translated, XFS has no cross-device copy abilities, there aren't
> any plans to add it, so I don't feel motivated to argue for it... but if
> the nfs community is so motivated (it sounds like it) then y'all could
> try one more time.
Yes NFS community does need one for doing a server-to-server copy
(performance) feature.
There was an argument that none of the VFS operations allow for
cross-device operations. What about splice, doesn't it allow to cross
mount points? So why not allow copy_file_range to do it too?
>> > sizeof(size_t) == sizeof(u64) on 64-bit machines, so at least as far as
>> > the userspace interface is concerned, this only makes a difference on
>> > 32-bit userlands, right? So, uh, how many 32-bit user programs need to
>> > c_f_r more than 2GB at a time?
>>
>> Isn't that 4GB? I thought that max of ssize_t is 4GB on 64bit. I'm
>> under the impression that sizeof (ssize_t) != sizeof(u64) on 64bit
>> machine. If I'm wrong, then this patch is indeed not needed.
>
> From include/uapi/asm-generic/posix_types.h:
>
> /*
> * Most 32 bit architectures use "unsigned int" size_t,
> * and all 64 bit architectures use "unsigned long" size_t.
> */
> #ifndef __kernel_size_t
> #if __BITS_PER_LONG != 64
> typedef unsigned int __kernel_size_t;
> typedef int __kernel_ssize_t;
> typedef int __kernel_ptrdiff_t;
> #else
> typedef __kernel_ulong_t __kernel_size_t;
> typedef __kernel_long_t __kernel_ssize_t;
> typedef __kernel_long_t __kernel_ptrdiff_t;
> #endif
> #endif
>
> Note that 'long' is 64-bit, at least on x64.
Ok, thank you for pointing this out. I see now that it's not important
to change the size_t to allow for larger than 4GB copies.
>
>> > Follow up question -- does c_f_r not work for > 2GB of data when
>> > userspace is 64-bit?
>>
>> Current copy_file_range would work for any file size, it would just
>> need to be called in a loop by the application. With the given
>> proposal, there wouldn't be a need for the application to loop due to
>> the API size limitation. It might still loop if a partial copy was
>> done.
>
> ...which is what happens if we fall back to do_splice_direct, since a
> single call won't pagecache-copy more than INT_MAX bytes from one file
> to another. Therefore, any serious user of this syscall has to check
> the arguments and loop if it wants the whole range done, similar to how
> one is (supposed) to call write().
>
> --D
>
>>
>> >
>> > --D
>> >
>> >> +{
>> >> + 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 = rw64_verify_area(file_in, pos_in, len, false);
>> >> + if (unlikely(ret))
>> >> + return ret;
>> >> +
>> >> + ret = rw64_verify_area(file_out, pos_out, len, true);
>> >> + 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;
>> >> +}
>> >> +
>> >> /*
>> >> * Check that the two inodes are eligible for cloning, the ranges make
>> >> * sense, and then flush all dirty data. Caller must ensure that the
>> >> @@ -1860,11 +1996,11 @@ int vfs_clone_file_range(struct file *file_in, loff_t pos_in,
>> >> if (!file_in->f_op->clone_file_range)
>> >> return -EOPNOTSUPP;
>> >>
>> >> - ret = clone_verify_area(file_in, pos_in, len, false);
>> >> + ret = rw64_verify_area(file_in, pos_in, len, false);
>> >> if (ret)
>> >> return ret;
>> >>
>> >> - ret = clone_verify_area(file_out, pos_out, len, true);
>> >> + ret = rw64_verify_area(file_out, pos_out, len, true);
>> >> if (ret)
>> >> return ret;
>> >>
>> >> @@ -2009,7 +2145,7 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
>> >> if (!S_ISREG(src->i_mode))
>> >> goto out;
>> >>
>> >> - ret = clone_verify_area(file, off, len, false);
>> >> + ret = rw64_verify_area(file, off, len, false);
>> >> if (ret < 0)
>> >> goto out;
>> >> ret = 0;
>> >> @@ -2041,7 +2177,7 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
>> >> }
>> >>
>> >> dst_off = info->dest_offset;
>> >> - ret = clone_verify_area(dst_file, dst_off, len, true);
>> >> + ret = rw64_verify_area(dst_file, dst_off, len, true);
>> >> if (ret < 0) {
>> >> info->status = ret;
>> >> goto next_file;
>> >> diff --git a/include/linux/fs.h b/include/linux/fs.h
>> >> index 803e5a9..41fce43 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);
>> >> --
>> >> 1.8.3.1
>> >>
>> > --
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