vfs: fix copy_file_range() averts filesystem freeze protection

[sfrench/cifs-2.6.git] / fs / read_write.c

diff --git a/fs/read_write.c b/fs/read_write.c
index 328ce8cf9a85eef7057ffe0a35902a15c8af8486..24b9668d63770f6fc7e1e35772569da1aea915fd 100644 (file)
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -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) {