vfs: no fallback for ->copy_file_range

Now that we have generic_copy_file_range(), remove it as a fallback
case when offloads fail. This puts the responsibility for executing
fallbacks on the filesystems that implement ->copy_file_range and
allows us to add operational validity checks to
generic_copy_file_range().

Rework vfs_copy_file_range() to call a new do_copy_file_range()
helper to execute the copying callout, and move calls to
generic_file_copy_range() into filesystem methods where they
currently return failures.

[Amir] overlayfs is not responsible of executing the fallback.
It is the responsibility of the underlying filesystem.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

5 files changed, 73 insertions, 18 deletions

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 183c37c0a8fc..31d450536175 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1889,9 +1889,9 @@ static int is_file_size_ok(struct inode *src_inode, struct inode *dst_inode,
         return 0;
 }
 
-static ssize_t ceph_copy_file_range(struct file *src_file, loff_t src_off,
-                                    struct file *dst_file, loff_t dst_off,
-                                    size_t len, unsigned int flags)
+static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
+                                      struct file *dst_file, loff_t dst_off,
+                                      size_t len, unsigned int flags)
 {
         struct inode *src_inode = file_inode(src_file);
         struct inode *dst_inode = file_inode(dst_file);
@@ -2100,6 +2100,21 @@ out:
         return ret;
 }
 
+static ssize_t ceph_copy_file_range(struct file *src_file, loff_t src_off,
+                                    struct file *dst_file, loff_t dst_off,
+                                    size_t len, unsigned int flags)
+{
+        ssize_t ret;
+
+        ret = __ceph_copy_file_range(src_file, src_off, dst_file, dst_off,
+                                     len, flags);
+
+        if (ret == -EOPNOTSUPP)
+                ret = generic_copy_file_range(src_file, src_off, dst_file,
+                                              dst_off, len, flags);
+        return ret;
+}
+
 const struct file_operations ceph_file_fops = {
         .open = ceph_open,
         .release = ceph_release,
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index f5fcd6360056..c65823270313 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -1148,6 +1148,10 @@ static ssize_t cifs_copy_file_range(struct file *src_file, loff_t off,
         rc = cifs_file_copychunk_range(xid, src_file, off, dst_file, destoff,
                                         len, flags);
         free_xid(xid);
+
+        if (rc == -EOPNOTSUPP)
+                rc = generic_copy_file_range(src_file, off, dst_file,
+                                             destoff, len, flags);
         return rc;
 }
 
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index b8f9c83835d5..4c20bf61d9c3 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -3112,9 +3112,9 @@ out:
         return err;
 }
 
-static ssize_t fuse_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)
+static ssize_t __fuse_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)
 {
         struct fuse_file *ff_in = file_in->private_data;
         struct fuse_file *ff_out = file_out->private_data;
@@ -3194,6 +3194,21 @@ out:
         return err;
 }
 
+static ssize_t fuse_copy_file_range(struct file *src_file, loff_t src_off,
+                                    struct file *dst_file, loff_t dst_off,
+                                    size_t len, unsigned int flags)
+{
+        ssize_t ret;
+
+        ret = __fuse_copy_file_range(src_file, src_off, dst_file, dst_off,
+                                     len, flags);
+
+        if (ret == -EOPNOTSUPP)
+                ret = generic_copy_file_range(src_file, src_off, dst_file,
+                                              dst_off, len, flags);
+        return ret;
+}
+
 static const struct file_operations fuse_file_operations = {
         .llseek         = fuse_file_llseek,
         .read_iter      = fuse_file_read_iter,
diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index cf42a8b939e3..4842f3ab3161 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -129,9 +129,9 @@ nfs4_file_flush(struct file *file, fl_owner_t id)
 }
 
 #ifdef CONFIG_NFS_V4_2
-static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
-                                    struct file *file_out, loff_t pos_out,
-                                    size_t count, unsigned int flags)
+static ssize_t __nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
+                                      struct file *file_out, loff_t pos_out,
+                                      size_t count, unsigned int flags)
 {
         if (!nfs_server_capable(file_inode(file_out), NFS_CAP_COPY))
                 return -EOPNOTSUPP;
@@ -140,6 +140,20 @@ static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
         return nfs42_proc_copy(file_in, pos_in, file_out, pos_out, count);
 }
 
+static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
+                                    struct file *file_out, loff_t pos_out,
+                                    size_t count, unsigned int flags)
+{
+        ssize_t ret;
+
+        ret = __nfs4_copy_file_range(file_in, pos_in, file_out, pos_out, count,
+                                     flags);
+        if (ret == -EOPNOTSUPP)
+                ret = generic_copy_file_range(file_in, pos_in, file_out,
+                                              pos_out, count, flags);
+        return ret;
+}
+
 static loff_t nfs4_file_llseek(struct file *filep, loff_t offset, int whence)
 {
         loff_t ret;
diff --git a/fs/read_write.c b/fs/read_write.c
index 676b02fae589..b63dcb4e4fe9 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1595,6 +1595,19 @@ ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
 }
 EXPORT_SYMBOL(generic_copy_file_range);
 
+static ssize_t do_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)
+{
+        if (file_out->f_op->copy_file_range)
+                return file_out->f_op->copy_file_range(file_in, pos_in,
+                                                       file_out, pos_out,
+                                                       len, flags);
+
+        return generic_copy_file_range(file_in, pos_in, file_out, pos_out, len,
+                                       flags);
+}
+
 /*
  * copy_file_range() differs from regular file read and write in that it
  * specifically allows return partial success.  When it does so is up to
@@ -1655,15 +1668,9 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
                 }
         }
 
-        if (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);
-                if (ret != -EOPNOTSUPP)
-                        goto done;
-        }
-
-        ret = generic_copy_file_range(file_in, pos_in, file_out, pos_out, len,
-                                      flags);
+        ret = do_copy_file_range(file_in, pos_in, file_out, pos_out, len,
+                                flags);
+        WARN_ON_ONCE(ret == -EOPNOTSUPP);
 done:
         if (ret > 0) {
                 fsnotify_access(file_in);