path: root/fs/read_write.c
diff options
authorAmir Goldstein <amir73il@gmail.com>2019-06-05 08:04:50 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2019-06-09 10:06:20 -0700
commit5dae222a5ff0c269730393018a5539cc970a4726 (patch)
treee1e4e1634de00d8fb7668f575d7e25acace6518f /fs/read_write.c
parentxfs: use file_modified() helper (diff)
vfs: allow copy_file_range to copy across devices
We want to enable cross-filesystem copy_file_range functionality where possible, so push the "same superblock only" checks down to the individual filesystem callouts so they can make their own decisions about cross-superblock copy offload and fallack to generic_copy_file_range() for cross-superblock copy. [Amir] We do not call ->remap_file_range() in case the files are not on the same sb and do not call ->copy_file_range() in case the files do not belong to the same filesystem driver. This changes behavior of the copy_file_range(2) syscall, which will now allow cross filesystem in-kernel copy. CIFS already supports cross-superblock copy, between two shares to the same server. This functionality will now be available via the copy_file_range(2) syscall. Cc: Steve French <stfrench@microsoft.com> 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>
Diffstat (limited to 'fs/read_write.c')
1 files changed, 12 insertions, 6 deletions
diff --git a/fs/read_write.c b/fs/read_write.c
index cec7e7b1f693..1f5088dec566 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1599,7 +1599,16 @@ 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)
+ /*
+ * Although we now allow filesystems to handle cross sb copy, passing
+ * a file of the wrong filesystem type to filesystem driver can result
+ * in an attempt to dereference the wrong type of ->private_data, so
+ * avoid doing that until we really have a good reason. NFS defines
+ * several different file_system_type structures, but they all end up
+ * using the same ->copy_file_range() function pointer.
+ */
+ if (file_out->f_op->copy_file_range &&
+ file_out->f_op->copy_file_range == file_in->f_op->copy_file_range)
return file_out->f_op->copy_file_range(file_in, pos_in,
file_out, pos_out,
len, flags);
@@ -1622,10 +1631,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
if (flags != 0)
return -EINVAL;
- /* this could be relaxed once a method supports cross-fs copies */
- if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
- return -EXDEV;
ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len,
if (unlikely(ret))
@@ -1648,7 +1653,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
* 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->remap_file_range) {
+ if (file_in->f_op->remap_file_range &&
+ file_inode(file_in)->i_sb == file_inode(file_out)->i_sb) {
loff_t cloned;
cloned = file_in->f_op->remap_file_range(file_in, pos_in,