[v5,7/9] vfs: Remove copy_file_range mountpoint checks

Commit Message

Schumaker, Anna Sept. 30, 2015, 5:26 p.m. UTC

I still want to do an in-kernel copy even if the files are on different
mountpoints, and NFS has a "server to server" copy that expects two
files on different mountpoints.  Let's have individual filesystems
implement this check instead.

Signed-off-by: Anna Schumaker <[e-mail]>
Reviewed-by: David Sterba <[e-mail]>
---
 fs/read_write.c | 5 -----
 1 file changed, 5 deletions(-)

Comments

Christoph Hellwig Oct. 11, 2015, 2:23 p.m. UTC | #1

On Wed, Sep 30, 2015 at 01:26:51PM -0400, Anna Schumaker wrote:
> I still want to do an in-kernel copy even if the files are on different
> mountpoints, and NFS has a "server to server" copy that expects two
> files on different mountpoints.  Let's have individual filesystems
> implement this check instead.

NAK.  I thing this is a bad idea in general and will only be convinced
by a properly audited actual implementation.  And even then with a flag
where the file system specificly needs to opt into this behavior instead
of getting it by default.
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Schumaker, Anna Oct. 14, 2015, 5:41 p.m. UTC | #2

On 10/11/2015 10:23 AM, Christoph Hellwig wrote:
> On Wed, Sep 30, 2015 at 01:26:51PM -0400, Anna Schumaker wrote:
>> I still want to do an in-kernel copy even if the files are on different
>> mountpoints, and NFS has a "server to server" copy that expects two
>> files on different mountpoints.  Let's have individual filesystems
>> implement this check instead.
> 
> NAK.  I thing this is a bad idea in general and will only be convinced
> by a properly audited actual implementation.  And even then with a flag
> where the file system specificly needs to opt into this behavior instead
> of getting it by default.
> 

So I should drop this patch even with the pagecache copy?  Andy Adamson will have to add it in later as part of his server-to-server patches.

Anna
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Christoph Hellwig Oct. 14, 2015, 6:25 p.m. UTC | #3

On Wed, Oct 14, 2015 at 01:41:23PM -0400, Anna Schumaker wrote:
> > NAK.  I thing this is a bad idea in general and will only be convinced
> > by a properly audited actual implementation.  And even then with a flag
> > where the file system specificly needs to opt into this behavior instead
> > of getting it by default.
> > 
> 
> So I should drop this patch even with the pagecache copy?  Andy
> Adamson will have to add it in later as part of his server-to-server patches.

Yes.  Let him do the proof it works alright then.
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

diff --git a/fs/read_write.c b/fs/read_write.c
index 6f74f1f..ee9fa37 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1366,11 +1366,6 @@  ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 	    pos_in + len > i_size_read(inode_in))
 		return -EINVAL;
 
-	/* this could be relaxed once a method supports cross-fs copies */
-	if (inode_in->i_sb != inode_out->i_sb ||
-	    file_in->f_path.mnt != file_out->f_path.mnt)
-		return -EXDEV;
-
 	if (len == 0)
 		return 0;