On Thu, Mar 04, 2021 at 10:38:07AM +0100, Alejandro Colomar wrote: > Linux 5.12 fixes a regression. > > Cross-filesystem (introduced in 5.3) copies were buggy. > > Move the statements documenting cross-fs to BUGS. > Kernels 5.3..5.11 should be patched soon. > > State version information for some errors related to this. > > Reported-by: Luis Henriques <[email protected]> > Reported-by: Amir Goldstein <[email protected]> > Related: <https://lwn.net/Articles/846403/> > Cc: Greg KH <[email protected]> > Cc: Michael Kerrisk <[email protected]> > Cc: Anna Schumaker <[email protected]> > Cc: Jeff Layton <[email protected]> > Cc: Steve French <[email protected]> > Cc: Miklos Szeredi <[email protected]> > Cc: Trond Myklebust <[email protected]> > Cc: Alexander Viro <[email protected]> > Cc: "Darrick J. Wong" <[email protected]> > Cc: Dave Chinner <[email protected]> > Cc: Nicolas Boichat <[email protected]> > Cc: Ian Lance Taylor <[email protected]> > Cc: Luis Lozano <[email protected]> > Cc: Andreas Dilger <[email protected]> > Cc: Olga Kornievskaia <[email protected]> > Cc: Christoph Hellwig <[email protected]> > Cc: ceph-devel <[email protected]> > Cc: linux-kernel <[email protected]> > Cc: CIFS <[email protected]> > Cc: samba-technical <[email protected]> > Cc: linux-fsdevel <[email protected]> > Cc: Linux NFS Mailing List <[email protected]> > Cc: Walter Harms <[email protected]> > Signed-off-by: Alejandro Colomar <[email protected]> > --- > > v3: > - Don't remove some important text. > - Reword BUGS. > v4: > - Reword. > - Link to BUGS. > > Thanks, Amir, for all the help and better wordings. > > Cheers, > > Alex > > --- > man2/copy_file_range.2 | 27 +++++++++++++++++++++++---- > 1 file changed, 23 insertions(+), 4 deletions(-) > > diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2 > index 611a39b80..f58bfea8f 100644 > --- a/man2/copy_file_range.2 > +++ b/man2/copy_file_range.2 > @@ -169,6 +169,9 @@ Out of memory. > .B ENOSPC > There is not enough space on the target filesystem to complete the copy. > .TP > +.BR EOPNOTSUPP " (since Linux 5.12)" > +The filesystem does not support this operation. > +.TP > .B EOVERFLOW > The requested source or destination range is too large to represent in the > specified data types. > @@ -184,10 +187,17 @@ or > .I fd_out > refers to an active swap file. > .TP > -.B EXDEV > +.BR EXDEV " (before Linux 5.3)" > +The files referred to by > +.IR fd_in " and " fd_out > +are not on the same filesystem. > +.TP > +.BR EXDEV " (since Linux 5.12)" > The files referred to by > .IR fd_in " and " fd_out > -are not on the same mounted filesystem (pre Linux 5.3). > +are not on the same filesystem, > +and the source and target filesystems are not of the same type, > +or do not support cross-filesystem copy. > .SH VERSIONS > The > .BR copy_file_range () > @@ -200,8 +210,11 @@ Areas of the API that weren't clearly defined were > clarified and the API bounds > are much more strictly checked than on earlier kernels. > Applications should target the behaviour and requirements of 5.3 kernels. > .PP > -First support for cross-filesystem copies was introduced in Linux 5.3. > -Older kernels will return -EXDEV when cross-filesystem copies are attempted. > +Since Linux 5.12, > +cross-filesystem copies can be achieved > +when both filesystems are of the same type, > +and that filesystem implements support for it. > +See BUGS for behavior prior to 5.12. > .SH CONFORMING TO > The > .BR copy_file_range () > @@ -226,6 +239,12 @@ gives filesystems an opportunity to implement "copy > acceleration" techniques, > such as the use of reflinks (i.e., two or more inodes that share > pointers to the same copy-on-write disk blocks) > or server-side-copy (in the case of NFS). > +.SH BUGS > +In Linux kernels 5.3 to 5.11, > +cross-filesystem copies were implemented by the kernel, > +if the operation was not supported by individual filesystems. > +However, on some virtual filesystems, > +the call failed to copy, while still reporting success.
...success, or merely a short copy? (The rest looks reasonable (at least by c_f_r standards) to me.) --D > .SH EXAMPLES > .EX > #define _GNU_SOURCE > -- > 2.30.1.721.g45526154a5 >
