Commit 10bc8e4a authored by Amir Goldstein's avatar Amir Goldstein Committed by Al Viro
Browse files

vfs: fix copy_file_range() averts filesystem freeze protection 



Commit 868f9f2f ("vfs: fix copy_file_range() regression in cross-fs
copies") removed fallback to generic_copy_file_range() for cross-fs
cases inside vfs_copy_file_range().

To preserve behavior of nfsd and ksmbd server-side-copy, the fallback to
generic_copy_file_range() was added in nfsd and ksmbd code, but that
call is missing sb_start_write(), fsnotify hooks and more.

Ideally, nfsd and ksmbd would pass a flag to vfs_copy_file_range() that
will take care of the fallback, but that code would be subtle and we got
vfs_copy_file_range() logic wrong too many times already.

Instead, add a flag to explicitly request vfs_copy_file_range() to
perform only generic_copy_file_range() and let nfsd and ksmbd use this
flag only in the fallback path.

This choise keeps the logic changes to minimum in the non-nfsd/ksmbd code
paths to reduce the risk of further regressions.

Fixes: 868f9f2f ("vfs: fix copy_file_range() regression in cross-fs copies")
Tested-by: default avatarNamjae Jeon <linkinjeon@kernel.org>
Tested-by: default avatarLuis Henriques <lhenriques@suse.de>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 406c706c

fs/ksmbd/vfs.c

+3 −3
Original line number Diff line number Diff line
@@ -1794,9 +1794,9 @@ int ksmbd_vfs_copy_file_ranges(struct ksmbd_work *work, 
		ret = vfs_copy_file_range(src_fp->filp, src_off,

					  dst_fp->filp, dst_off, len, 0);

		if (ret == -EOPNOTSUPP || ret == -EXDEV)

			ret = generic_copy_file_range(src_fp->filp, src_off,

						      dst_fp->filp, dst_off,

						      len, 0);

			ret = vfs_copy_file_range(src_fp->filp, src_off,

						  dst_fp->filp, dst_off, len,

						  COPY_FILE_SPLICE);

		if (ret < 0)

			return ret;

fs/nfsd/vfs.c

+2 −2
Original line number Diff line number Diff line
@@ -596,8 +596,8 @@ ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst, 
	ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);



	if (ret == -EOPNOTSUPP || ret == -EXDEV)

		ret = generic_copy_file_range(src, src_pos, dst, dst_pos,

					      count, 0);

		ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count,

					  COPY_FILE_SPLICE);

	return ret;

}

fs/read_write.c

+15 −4
Original line number Diff line number Diff line
@@ -1388,6 +1388,8 @@ ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in, 
				struct file *file_out, loff_t pos_out,

				size_t len, unsigned int flags)

{

	lockdep_assert(sb_write_started(file_inode(file_out)->i_sb));



	return do_splice_direct(file_in, &pos_in, file_out, &pos_out,

				len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);

}
@@ -1424,7 +1426,9 @@ static int generic_copy_file_checks(struct file *file_in, loff_t pos_in, 
	 * and several different sets of file_operations, but they all end up

	 * using the same ->copy_file_range() function pointer.

	 */

	if (file_out->f_op->copy_file_range) {

	if (flags & COPY_FILE_SPLICE) {

		/* cross sb splice is allowed */

	} else if (file_out->f_op->copy_file_range) {

		if (file_in->f_op->copy_file_range !=

		    file_out->f_op->copy_file_range)

			return -EXDEV;
@@ -1474,8 +1478,9 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, 
			    size_t len, unsigned int flags)

{

	ssize_t ret;

	bool splice = flags & COPY_FILE_SPLICE;



	if (flags != 0)

	if (flags & ~COPY_FILE_SPLICE)

		return -EINVAL;



	ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len,
@@ -1501,14 +1506,14 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, 
	 * same sb using clone, but for filesystems where both clone and copy

	 * are supported (e.g. nfs,cifs), we only call the copy method.

	 */

	if (file_out->f_op->copy_file_range) {

	if (!splice && file_out->f_op->copy_file_range) {

		ret = file_out->f_op->copy_file_range(file_in, pos_in,

						      file_out, pos_out,

						      len, flags);

		goto done;

	}



	if (file_in->f_op->remap_file_range &&

	if (!splice && file_in->f_op->remap_file_range &&

	    file_inode(file_in)->i_sb == file_inode(file_out)->i_sb) {

		ret = file_in->f_op->remap_file_range(file_in, pos_in,

				file_out, pos_out,
@@ -1528,6 +1533,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, 
	 * consistent story about which filesystems support copy_file_range()

	 * and which filesystems do not, that will allow userspace tools to

	 * make consistent desicions w.r.t using copy_file_range().

	 *

	 * We also get here if caller (e.g. nfsd) requested COPY_FILE_SPLICE.

	 */

	ret = generic_copy_file_range(file_in, pos_in, file_out, pos_out, len,

				      flags);
@@ -1582,6 +1589,10 @@ SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user *, off_in, 
		pos_out = f_out.file->f_pos;

	}



	ret = -EINVAL;

	if (flags != 0)

		goto out;



	ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len,

				  flags);

	if (ret > 0) {

include/linux/fs.h

+8 −0
Original line number Diff line number Diff line
@@ -2089,6 +2089,14 @@ struct dir_context { 
 */

#define REMAP_FILE_ADVISORY		(REMAP_FILE_CAN_SHORTEN)



/*

 * These flags control the behavior of vfs_copy_file_range().

 * They are not available to the user via syscall.

 *

 * COPY_FILE_SPLICE: call splice direct instead of fs clone/copy ops

 */

#define COPY_FILE_SPLICE		(1 << 0)



struct iov_iter;

struct io_uring_cmd;