On Mon, Mar 1, 2021 at 4:45 PM Alejandro Colomar <alx.manpages@xxxxxxxxx> 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 <lhenriques@xxxxxxx> > Reported-by: Amir Goldstein <amir73il@xxxxxxxxx> > Related: <https://lwn.net/Articles/846403/> > Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> > Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx> > Cc: Anna Schumaker <anna.schumaker@xxxxxxxxxx> > Cc: Jeff Layton <jlayton@xxxxxxxxxx> > Cc: Steve French <sfrench@xxxxxxxxx> > Cc: Miklos Szeredi <miklos@xxxxxxxxxx> > Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> > Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> > Cc: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx> > Cc: Dave Chinner <dchinner@xxxxxxxxxx> > Cc: Nicolas Boichat <drinkcat@xxxxxxxxxxxx> > Cc: Ian Lance Taylor <iant@xxxxxxxxxx> > Cc: Luis Lozano <llozano@xxxxxxxxxxxx> > Cc: Andreas Dilger <adilger@xxxxxxxxx> > Cc: Olga Kornievskaia <aglo@xxxxxxxxx> > Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx> > Cc: ceph-devel <ceph-devel@xxxxxxxxxxxxxxx> > Cc: linux-kernel <linux-kernel@xxxxxxxxxxxxxxx> > Cc: CIFS <linux-cifs@xxxxxxxxxxxxxxx> > Cc: samba-technical <samba-technical@xxxxxxxxxxxxxxx> > Cc: linux-fsdevel <linux-fsdevel@xxxxxxxxxxxxxxx> > Cc: Linux NFS Mailing List <linux-nfs@xxxxxxxxxxxxxxx> > Cc: Walter Harms <wharms@xxxxxx> > Signed-off-by: Alejandro Colomar <alx.manpages@xxxxxxxxx> > --- > > v3: > - Don't remove some important text. > - Reword BUGS. > > --- > Hi Amir, > > I covered your comments. I may need to add something else after your > discussion with Steve; please comment. > > I tried to reword BUGS so that it's as specific and understandable as I can. > If you still find it not good enough, please comment :) > > Thanks, > > Alex > > --- > man2/copy_file_range.2 | 26 ++++++++++++++++++++++---- > 1 file changed, 22 insertions(+), 4 deletions(-) > > diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2 > index 611a39b80..1c0df3f74 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 +210,10 @@ 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 5.12, > +cross-filesystem copies can be achieved > +when both filesystems are of the same type, > +and that filesystem implements support for it. Maybe refer to BUGS here for pre 5.12 behavior? > .SH CONFORMING TO > The > .BR copy_file_range () > @@ -226,6 +238,12 @@ 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 supported by the kernel, > +instead of being supported by individual filesystems. Not so clear/accurate IMO. Maybe: 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. Thanks, Amir.
