On Tue, Aug 05 2025, Miklos Szeredi wrote: > The FUSE protocol uses struct fuse_write_out to convey the return value of > copy_file_range, which is restricted to uint32_t. But the COPY_FILE_RANGE > interface supports a 64-bit size copies. > > Currently the number of bytes copied is silently truncated to 32-bit, which > is unfortunate at best. > > Introduce a new op COPY_FILE_RANGE_64, which is identical, except the > number of bytes copied is returned in a 64-bit value. > > If the fuse server does not support COPY_FILE_RANGE_64, fall back to > COPY_FILE_RANGE and truncate the size to UINT_MAX - 4096. I was wondering if it wouldn't make more sense to truncate the size to MAX_RW_COUNT instead. My reasoning is that, if I understand the code correctly (which is probably a big 'if'!), the VFS will fallback to splice() if the file system does not implement copy_file_range. And in this case splice() seems to limit the operation to MAX_RW_COUNT. Cheers, -- Luís > Reported-by: Florian Weimer <fweimer@xxxxxxxxxx> > Closes: https://lore.kernel.org/all/lhuh5ynl8z5.fsf@xxxxxxxxxxxxxxxxxxxxxxxx/ > Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx> > --- > fs/fuse/file.c | 34 ++++++++++++++++++++++++++-------- > fs/fuse/fuse_i.h | 3 +++ > include/uapi/linux/fuse.h | 12 +++++++++++- > 3 files changed, 40 insertions(+), 9 deletions(-) > > diff --git a/fs/fuse/file.c b/fs/fuse/file.c > index adc4aa6810f5..bd6624885855 100644 > --- a/fs/fuse/file.c > +++ b/fs/fuse/file.c > @@ -3017,6 +3017,8 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in, > .flags = flags > }; > struct fuse_write_out outarg; > + struct fuse_copy_file_range_out outarg_64; > + u64 bytes_copied; > ssize_t err; > /* mark unstable when write-back is not used, and file_out gets > * extended */ > @@ -3066,30 +3068,46 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in, > if (is_unstable) > set_bit(FUSE_I_SIZE_UNSTABLE, &fi_out->state); > > - args.opcode = FUSE_COPY_FILE_RANGE; > + args.opcode = FUSE_COPY_FILE_RANGE_64; > args.nodeid = ff_in->nodeid; > args.in_numargs = 1; > args.in_args[0].size = sizeof(inarg); > args.in_args[0].value = &inarg; > args.out_numargs = 1; > - args.out_args[0].size = sizeof(outarg); > - args.out_args[0].value = &outarg; > + args.out_args[0].size = sizeof(outarg_64); > + args.out_args[0].value = &outarg_64; > + if (fc->no_copy_file_range_64) { > +fallback: > + /* Fall back to old op that can't handle large copy length */ > + args.opcode = FUSE_COPY_FILE_RANGE; > + args.out_args[0].size = sizeof(outarg); > + args.out_args[0].value = &outarg; > + inarg.len = min_t(size_t, len, 0xfffff000); > + } > err = fuse_simple_request(fm, &args); > if (err == -ENOSYS) { > - fc->no_copy_file_range = 1; > - err = -EOPNOTSUPP; > + if (fc->no_copy_file_range_64) { > + fc->no_copy_file_range = 1; > + err = -EOPNOTSUPP; > + } else { > + fc->no_copy_file_range_64 = 1; > + goto fallback; > + } > } > if (err) > goto out; > > + bytes_copied = fc->no_copy_file_range_64 ? > + outarg.size : outarg_64.bytes_copied; > + > truncate_inode_pages_range(inode_out->i_mapping, > ALIGN_DOWN(pos_out, PAGE_SIZE), > - ALIGN(pos_out + outarg.size, PAGE_SIZE) - 1); > + ALIGN(pos_out + bytes_copied, PAGE_SIZE) - 1); > > file_update_time(file_out); > - fuse_write_update_attr(inode_out, pos_out + outarg.size, outarg.size); > + fuse_write_update_attr(inode_out, pos_out + bytes_copied, bytes_copied); > > - err = outarg.size; > + err = bytes_copied; > out: > if (is_unstable) > clear_bit(FUSE_I_SIZE_UNSTABLE, &fi_out->state); > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h > index b54f4f57789f..a8be19f686b1 100644 > --- a/fs/fuse/fuse_i.h > +++ b/fs/fuse/fuse_i.h > @@ -850,6 +850,9 @@ struct fuse_conn { > /** Does the filesystem support copy_file_range? */ > unsigned no_copy_file_range:1; > > + /** Does the filesystem support copy_file_range_64? */ > + unsigned no_copy_file_range_64:1; > + > /* Send DESTROY request */ > unsigned int destroy:1; > > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h > index 122d6586e8d4..94621f68a5cc 100644 > --- a/include/uapi/linux/fuse.h > +++ b/include/uapi/linux/fuse.h > @@ -235,6 +235,10 @@ > * > * 7.44 > * - add FUSE_NOTIFY_INC_EPOCH > + * > + * 7.45 > + * - add FUSE_COPY_FILE_RANGE_64 > + * - add struct fuse_copy_file_range_out > */ > > #ifndef _LINUX_FUSE_H > @@ -270,7 +274,7 @@ > #define FUSE_KERNEL_VERSION 7 > > /** Minor version number of this interface */ > -#define FUSE_KERNEL_MINOR_VERSION 44 > +#define FUSE_KERNEL_MINOR_VERSION 45 > > /** The node ID of the root inode */ > #define FUSE_ROOT_ID 1 > @@ -657,6 +661,7 @@ enum fuse_opcode { > FUSE_SYNCFS = 50, > FUSE_TMPFILE = 51, > FUSE_STATX = 52, > + FUSE_COPY_FILE_RANGE_64 = 53, > > /* CUSE specific operations */ > CUSE_INIT = 4096, > @@ -1148,6 +1153,11 @@ struct fuse_copy_file_range_in { > uint64_t flags; > }; > > +/* For FUSE_COPY_FILE_RANGE_64 */ > +struct fuse_copy_file_range_out { > + uint64_t bytes_copied; > +}; > + > #define FUSE_SETUPMAPPING_FLAG_WRITE (1ull << 0) > #define FUSE_SETUPMAPPING_FLAG_READ (1ull << 1) > struct fuse_setupmapping_in { > -- > 2.49.0 >
