| Message ID | 20210222102456.6692-1-lhenriques@suse.de |
|---|---|
| State | New |
| Headers | show |
| Series | [v8] vfs: fix copy_file_range regression in cross-fs copies | expand |
On Mon, Feb 22, 2021 at 12:23 PM Luis Henriques <lhenriques@suse.de> wrote: > > A regression has been reported by Nicolas Boichat, found while using the > copy_file_range syscall to copy a tracefs file. Before commit > 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the > kernel would return -EXDEV to userspace when trying to copy a file across > different filesystems. After this commit, the syscall doesn't fail anymore > and instead returns zero (zero bytes copied), as this file's content is > generated on-the-fly and thus reports a size of zero. > > This patch restores some cross-filesystem copy restrictions that existed > prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across > devices"). Filesystems are still allowed to fall-back to the VFS > generic_copy_file_range() implementation, but that has now to be done > explicitly. > > nfsd is also modified to fall-back into generic_copy_file_range() in case > vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV. > > Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") > Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/ > Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/ > Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/ > Reported-by: Nicolas Boichat <drinkcat@chromium.org> > Signed-off-by: Luis Henriques <lhenriques@suse.de> > --- Reviewed-by: Amir Goldstein <amir73il@gmail.com> Thanks, Amir.
On 2/22/21 2:24 AM, Luis Henriques wrote: > A regression has been reported by Nicolas Boichat, found while using the > copy_file_range syscall to copy a tracefs file. Before commit > 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the > kernel would return -EXDEV to userspace when trying to copy a file across > different filesystems. After this commit, the syscall doesn't fail anymore > and instead returns zero (zero bytes copied), as this file's content is > generated on-the-fly and thus reports a size of zero. > > This patch restores some cross-filesystem copy restrictions that existed > prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across > devices"). Filesystems are still allowed to fall-back to the VFS > generic_copy_file_range() implementation, but that has now to be done > explicitly. > > nfsd is also modified to fall-back into generic_copy_file_range() in case > vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV. > > Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") > Link: https://urldefense.com/v3/__https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/__;!!GqivPVa7Brio!P1UWThiSkxbjfjFQWNYJmCxGEkiLFyvHjH6cS-G1ZTt1z-TeqwGQgQmi49dC6w$ > Link: https://urldefense.com/v3/__https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx*BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/__;Kw!!GqivPVa7Brio!P1UWThiSkxbjfjFQWNYJmCxGEkiLFyvHjH6cS-G1ZTt1z-TeqwGQgQmgCmMHzA$ > Link: https://urldefense.com/v3/__https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/__;!!GqivPVa7Brio!P1UWThiSkxbjfjFQWNYJmCxGEkiLFyvHjH6cS-G1ZTt1z-TeqwGQgQmzqItkrQ$ > Reported-by: Nicolas Boichat <drinkcat@chromium.org> > Signed-off-by: Luis Henriques <lhenriques@suse.de> > --- > Changes since v7 > - set 'ret' to '-EOPNOTSUPP' before the clone 'if' statement so that the > error returned is always related to the 'copy' operation > Changes since v6 > - restored i_sb checks for the clone operation > Changes since v5 > - check if ->copy_file_range is NULL before calling it > Changes since v4 > - nfsd falls-back to generic_copy_file_range() only *if* it gets -EOPNOTSUPP > or -EXDEV. > Changes since v3 > - dropped the COPY_FILE_SPLICE flag > - kept the f_op's checks early in generic_copy_file_checks, implementing > Amir's suggestions > - modified nfsd to use generic_copy_file_range() > Changes since v2 > - do all the required checks earlier, in generic_copy_file_checks(), > adding new checks for ->remap_file_range > - new COPY_FILE_SPLICE flag > - don't remove filesystem's fallback to generic_copy_file_range() > - updated commit changelog (and subject) > Changes since v1 (after Amir review) > - restored do_copy_file_range() helper > - return -EOPNOTSUPP if fs doesn't implement CFR > - updated commit description > > fs/nfsd/vfs.c | 8 +++++++- > fs/read_write.c | 49 ++++++++++++++++++++++++------------------------- > 2 files changed, 31 insertions(+), 26 deletions(-) > > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c > index 04937e51de56..23dab0fa9087 100644 > --- a/fs/nfsd/vfs.c > +++ b/fs/nfsd/vfs.c > @@ -568,6 +568,7 @@ __be32 nfsd4_clone_file_range(struct nfsd_file *nf_src, u64 src_pos, > ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst, > u64 dst_pos, u64 count) > { > + ssize_t ret; > > /* > * Limit copy to 4MB to prevent indefinitely blocking an nfsd > @@ -578,7 +579,12 @@ ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst, > * limit like this and pipeline multiple COPY requests. > */ > count = min_t(u64, count, 1 << 22); > - return vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0); > + ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0); > + > + if (ret == -EOPNOTSUPP || ret == -EXDEV) > + ret = generic_copy_file_range(src, src_pos, dst, dst_pos, > + count, 0); > + return ret; > } > > __be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp, > diff --git a/fs/read_write.c b/fs/read_write.c > index 75f764b43418..5a26297fd410 100644 > --- a/fs/read_write.c > +++ b/fs/read_write.c > @@ -1388,28 +1388,6 @@ 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) > -{ > - /* > - * 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); > - > - return generic_copy_file_range(file_in, pos_in, file_out, pos_out, len, > - flags); > -} > - > /* > * Performs necessary checks before doing a file copy > * > @@ -1427,6 +1405,25 @@ static int generic_copy_file_checks(struct file *file_in, loff_t pos_in, > loff_t size_in; > int ret; > > + /* > + * 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) { > + if (file_in->f_op->copy_file_range != > + file_out->f_op->copy_file_range) > + return -EXDEV; > + } else if (file_in->f_op->remap_file_range) { > + if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb) > + return -EXDEV; I think this check is redundant, it's done in vfs_copy_file_range. If this check is removed then the else clause below should be removed also. Once this check and the else clause are removed then might as well move the the check of copy_file_range from here to vfs_copy_file_range. -Dai > + } else { > + return -EOPNOTSUPP; > + } > + > ret = generic_file_rw_checks(file_in, file_out); > if (ret) > return ret; > @@ -1495,6 +1492,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, > > file_start_write(file_out); > > + ret = -EOPNOTSUPP; > /* > * Try cloning first, this is supported by more file systems, and > * more efficient if both clone and copy are supported (e.g. NFS). > @@ -1513,9 +1511,10 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, > } > } > > - ret = do_copy_file_range(file_in, pos_in, file_out, pos_out, len, > - flags); > - WARN_ON_ONCE(ret == -EOPNOTSUPP); > + 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); > done: > if (ret > 0) { > fsnotify_access(file_in);
On Mon, Feb 22, 2021 at 5:25 AM Luis Henriques <lhenriques@suse.de> wrote: > > A regression has been reported by Nicolas Boichat, found while using the > copy_file_range syscall to copy a tracefs file. Before commit > 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the > kernel would return -EXDEV to userspace when trying to copy a file across > different filesystems. After this commit, the syscall doesn't fail anymore > and instead returns zero (zero bytes copied), as this file's content is > generated on-the-fly and thus reports a size of zero. > > This patch restores some cross-filesystem copy restrictions that existed > prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across > devices"). Filesystems are still allowed to fall-back to the VFS > generic_copy_file_range() implementation, but that has now to be done > explicitly. > > nfsd is also modified to fall-back into generic_copy_file_range() in case > vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV. > > Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") > Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/ > Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/ > Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/ > Reported-by: Nicolas Boichat <drinkcat@chromium.org> > Signed-off-by: Luis Henriques <lhenriques@suse.de> I tested v8 and I believe it works for NFS. > --- > Changes since v7 > - set 'ret' to '-EOPNOTSUPP' before the clone 'if' statement so that the > error returned is always related to the 'copy' operation > Changes since v6 > - restored i_sb checks for the clone operation > Changes since v5 > - check if ->copy_file_range is NULL before calling it > Changes since v4 > - nfsd falls-back to generic_copy_file_range() only *if* it gets -EOPNOTSUPP > or -EXDEV. > Changes since v3 > - dropped the COPY_FILE_SPLICE flag > - kept the f_op's checks early in generic_copy_file_checks, implementing > Amir's suggestions > - modified nfsd to use generic_copy_file_range() > Changes since v2 > - do all the required checks earlier, in generic_copy_file_checks(), > adding new checks for ->remap_file_range > - new COPY_FILE_SPLICE flag > - don't remove filesystem's fallback to generic_copy_file_range() > - updated commit changelog (and subject) > Changes since v1 (after Amir review) > - restored do_copy_file_range() helper > - return -EOPNOTSUPP if fs doesn't implement CFR > - updated commit description > > fs/nfsd/vfs.c | 8 +++++++- > fs/read_write.c | 49 ++++++++++++++++++++++++------------------------- > 2 files changed, 31 insertions(+), 26 deletions(-) > > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c > index 04937e51de56..23dab0fa9087 100644 > --- a/fs/nfsd/vfs.c > +++ b/fs/nfsd/vfs.c > @@ -568,6 +568,7 @@ __be32 nfsd4_clone_file_range(struct nfsd_file *nf_src, u64 src_pos, > ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst, > u64 dst_pos, u64 count) > { > + ssize_t ret; > > /* > * Limit copy to 4MB to prevent indefinitely blocking an nfsd > @@ -578,7 +579,12 @@ ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst, > * limit like this and pipeline multiple COPY requests. > */ > count = min_t(u64, count, 1 << 22); > - return vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0); > + ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0); > + > + if (ret == -EOPNOTSUPP || ret == -EXDEV) > + ret = generic_copy_file_range(src, src_pos, dst, dst_pos, > + count, 0); > + return ret; > } > > __be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp, > diff --git a/fs/read_write.c b/fs/read_write.c > index 75f764b43418..5a26297fd410 100644 > --- a/fs/read_write.c > +++ b/fs/read_write.c > @@ -1388,28 +1388,6 @@ 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) > -{ > - /* > - * 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); > - > - return generic_copy_file_range(file_in, pos_in, file_out, pos_out, len, > - flags); > -} > - > /* > * Performs necessary checks before doing a file copy > * > @@ -1427,6 +1405,25 @@ static int generic_copy_file_checks(struct file *file_in, loff_t pos_in, > loff_t size_in; > int ret; > > + /* > + * 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) { > + if (file_in->f_op->copy_file_range != > + file_out->f_op->copy_file_range) > + return -EXDEV; > + } else if (file_in->f_op->remap_file_range) { > + if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb) > + return -EXDEV; > + } else { > + return -EOPNOTSUPP; > + } > + > ret = generic_file_rw_checks(file_in, file_out); > if (ret) > return ret; > @@ -1495,6 +1492,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, > > file_start_write(file_out); > > + ret = -EOPNOTSUPP; > /* > * Try cloning first, this is supported by more file systems, and > * more efficient if both clone and copy are supported (e.g. NFS). > @@ -1513,9 +1511,10 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, > } > } > > - ret = do_copy_file_range(file_in, pos_in, file_out, pos_out, len, > - flags); > - WARN_ON_ONCE(ret == -EOPNOTSUPP); > + 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); > done: > if (ret > 0) { > fsnotify_access(file_in);
On Tue, Feb 23, 2021 at 08:00:54PM -0500, Olga Kornievskaia wrote: > On Mon, Feb 22, 2021 at 5:25 AM Luis Henriques <lhenriques@suse.de> wrote: > > > > A regression has been reported by Nicolas Boichat, found while using the > > copy_file_range syscall to copy a tracefs file. Before commit > > 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the > > kernel would return -EXDEV to userspace when trying to copy a file across > > different filesystems. After this commit, the syscall doesn't fail anymore > > and instead returns zero (zero bytes copied), as this file's content is > > generated on-the-fly and thus reports a size of zero. > > > > This patch restores some cross-filesystem copy restrictions that existed > > prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across > > devices"). Filesystems are still allowed to fall-back to the VFS > > generic_copy_file_range() implementation, but that has now to be done > > explicitly. > > > > nfsd is also modified to fall-back into generic_copy_file_range() in case > > vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV. > > > > Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") > > Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/ > > Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/ > > Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/ > > Reported-by: Nicolas Boichat <drinkcat@chromium.org> > > Signed-off-by: Luis Henriques <lhenriques@suse.de> > > I tested v8 and I believe it works for NFS. Thanks a lot for the testing. And to everyone else for reviews, feedback,... and patience. I'll now go look into the manpage and see what needs to be changed. Cheers, -- Luís
On Wed, Feb 24, 2021 at 6:22 PM Luis Henriques <lhenriques@suse.de> wrote: > > On Tue, Feb 23, 2021 at 08:00:54PM -0500, Olga Kornievskaia wrote: > > On Mon, Feb 22, 2021 at 5:25 AM Luis Henriques <lhenriques@suse.de> wrote: > > > > > > A regression has been reported by Nicolas Boichat, found while using the > > > copy_file_range syscall to copy a tracefs file. Before commit > > > 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the > > > kernel would return -EXDEV to userspace when trying to copy a file across > > > different filesystems. After this commit, the syscall doesn't fail anymore > > > and instead returns zero (zero bytes copied), as this file's content is > > > generated on-the-fly and thus reports a size of zero. > > > > > > This patch restores some cross-filesystem copy restrictions that existed > > > prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across > > > devices"). Filesystems are still allowed to fall-back to the VFS > > > generic_copy_file_range() implementation, but that has now to be done > > > explicitly. > > > > > > nfsd is also modified to fall-back into generic_copy_file_range() in case > > > vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV. > > > > > > Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") > > > Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/ > > > Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/ > > > Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/ > > > Reported-by: Nicolas Boichat <drinkcat@chromium.org> > > > Signed-off-by: Luis Henriques <lhenriques@suse.de> > > > > I tested v8 and I believe it works for NFS. > > Thanks a lot for the testing. And to everyone else for reviews, > feedback,... and patience. Thanks so much to you!!! Works here, you can add my Tested-by: Nicolas Boichat <drinkcat@chromium.org> > > I'll now go look into the manpage and see what needs to be changed. > > Cheers, > -- > Luís
On Wed, Feb 24, 2021 at 4:22 PM Luis Henriques <lhenriques@suse.de> wrote: > > Update man-page with recent changes to this syscall. > > Signed-off-by: Luis Henriques <lhenriques@suse.de> > --- > Hi! > > Here's a suggestion for fixing the manpage for copy_file_range(). Note that > I've assumed the fix will hit 5.12. > > man2/copy_file_range.2 | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2 > index 611a39b8026b..b0fd85e2631e 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 > +.B EOPNOTSUPP > +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. > @@ -187,7 +190,7 @@ refers to an active swap file. > .B EXDEV > 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 mounted filesystem (pre Linux 5.3 and post Linux 5.12). I think you need to drop the (Linux range) altogether. What's missing here is the NFS cross server copy use case. Maybe: ...are not on the same mounted filesystem and the source and target filesystems do not support cross-filesystem copy. You may refer the reader to VERSIONS section where it will say which filesystems support cross-fs copy as of kernel version XXX (i.e. cifs and nfs). > .SH VERSIONS > The > .BR copy_file_range () > @@ -202,6 +205,11 @@ 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. > +.PP > +After Linux 5.12, support for copies between different filesystems was dropped. > +However, individual filesystems may still provide > +.BR copy_file_range () > +implementations that allow copies across different devices. Again, this is not likely to stay uptodate for very long. The stable kernels are expected to apply your patch (because it fixes a regression) so this should be phrased differently. If it were me, I would provide all the details of the situation to Michael and ask him to write the best description for this section. Thanks, Amir.
On Wed, Feb 24, 2021 at 06:10:45PM +0200, Amir Goldstein wrote: > On Wed, Feb 24, 2021 at 4:22 PM Luis Henriques <lhenriques@suse.de> wrote: > > > > Update man-page with recent changes to this syscall. > > > > Signed-off-by: Luis Henriques <lhenriques@suse.de> > > --- > > Hi! > > > > Here's a suggestion for fixing the manpage for copy_file_range(). Note that > > I've assumed the fix will hit 5.12. > > > > man2/copy_file_range.2 | 10 +++++++++- > > 1 file changed, 9 insertions(+), 1 deletion(-) > > > > diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2 > > index 611a39b8026b..b0fd85e2631e 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 > > +.B EOPNOTSUPP > > +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. > > @@ -187,7 +190,7 @@ refers to an active swap file. > > .B EXDEV > > 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 mounted filesystem (pre Linux 5.3 and post Linux 5.12). > > I think you need to drop the (Linux range) altogether. > What's missing here is the NFS cross server copy use case. > Maybe: > > ...are not on the same mounted filesystem and the source and target filesystems > do not support cross-filesystem copy. > > You may refer the reader to VERSIONS section where it will say which > filesystems support cross-fs copy as of kernel version XXX (i.e. cifs and nfs). > > > .SH VERSIONS > > The > > .BR copy_file_range () > > @@ -202,6 +205,11 @@ 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. > > +.PP > > +After Linux 5.12, support for copies between different filesystems was dropped. > > +However, individual filesystems may still provide > > +.BR copy_file_range () > > +implementations that allow copies across different devices. > > Again, this is not likely to stay uptodate for very long. > The stable kernels are expected to apply your patch (because it fixes > a regression) > so this should be phrased differently. > If it were me, I would provide all the details of the situation to > Michael and ask him > to write the best description for this section. Thanks Amir. Yeah, it's tricky. Support was added and then dropped. Since stable kernels will be picking this patch, maybe the best thing to do is to no mention the generic cross-filesystem support at all...? Or simply say that 5.3 temporarily supported it but that support was later dropped. Michael (or Alejandro), would you be OK handling this yourself as Amir suggested? Cheers, -- Luís
Hello Luis, On 2/25/21 11:21 AM, Luis Henriques wrote: > On Wed, Feb 24, 2021 at 06:10:45PM +0200, Amir Goldstein wrote: >> If it were me, I would provide all the details of the situation to >> Michael and ask him >> to write the best description for this section. > > Thanks Amir. > > Yeah, it's tricky. Support was added and then dropped. Since stable > kernels will be picking this patch, maybe the best thing to do is to no > mention the generic cross-filesystem support at all...? Or simply say > that 5.3 temporarily supported it but that support was later dropped. > > Michael (or Alejandro), would you be OK handling this yourself as Amir > suggested? Could you please provide a more detailed history of what is to be documented? Thanks, Alex -- Alejandro Colomar Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/ http://www.alejandro-colomar.es/
On Fri, Feb 26, 2021 at 12:13 PM Alejandro Colomar (man-pages) <alx.manpages@gmail.com> wrote: > > Hello Luis, > > On 2/25/21 11:21 AM, Luis Henriques wrote: > > On Wed, Feb 24, 2021 at 06:10:45PM +0200, Amir Goldstein wrote: > >> If it were me, I would provide all the details of the situation to > >> Michael and ask him > >> to write the best description for this section. > > > > Thanks Amir. > > > > Yeah, it's tricky. Support was added and then dropped. Since stable > > kernels will be picking this patch, maybe the best thing to do is to no > > mention the generic cross-filesystem support at all...? Or simply say > > that 5.3 temporarily supported it but that support was later dropped. > > > > Michael (or Alejandro), would you be OK handling this yourself as Amir > > suggested? > > Could you please provide a more detailed history of what is to be > documented? > Is this detailed enough? ;-) https://lwn.net/Articles/846403/ Thanks, Amir.
Hello Amir, On 2/26/21 11:34 AM, Amir Goldstein wrote: > Is this detailed enough? ;-) > > https://lwn.net/Articles/846403/ I'm sorry I can't read it yet: [ Subscription required The page you have tried to view (How useful should copy_file_range() be?) is currently available to LWN subscribers only. Reader subscriptions are a necessary way to fund the continued existence of LWN and the quality of its content. [...] (Alternatively, this item will become freely available on March 4, 2021) ] However, the 4th of March is close enough, i guess. Thanks, Alex -- Alejandro Colomar Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/ http://www.alejandro-colomar.es/
On Fri, 2021-02-26 at 12:15 +0100, Alejandro Colomar (man-pages) wrote: > Hello Amir, > > On 2/26/21 11:34 AM, Amir Goldstein wrote: > > Is this detailed enough? ;-) > > > > https://lwn.net/Articles/846403/ > > I'm sorry I can't read it yet: > > [ > Subscription required > The page you have tried to view (How useful should copy_file_range() > be?) is currently available to LWN subscribers only. Reader > subscriptions are a necessary way to fund the continued existence of LWN > and the quality of its content. > [...] > (Alternatively, this item will become freely available on March 4, 2021) > ] > Here's a link that should work. I'm probably breaking the rules a bit as a subscriber, but hopefully Jon won't mind too much. FWIW, I've found it to be worthwhile to subscribe to LWN if you're doing a lot of kernel development: https://lwn.net/SubscriberLink/846403/0fd639403e629cab/ Cheers, -- Jeff Layton <jlayton@kernel.org>
Hello Jeff, On 2/26/21 2:59 PM, Jeff Layton wrote: > Here's a link that should work. I'm probably breaking the rules a bit as > a subscriber, but hopefully Jon won't mind too much. FWIW, I've found it > to be worthwhile to subscribe to LWN if you're doing a lot of kernel > development: > > https://lwn.net/SubscriberLink/846403/0fd639403e629cab/ Thanks! (I already received the link privately some minutes before from various people.) It seems that he considers it fair use :) [[ Where is it appropriate to post a subscriber link? Almost anywhere. Private mail, messages to project mailing lists, and blog entries are all appropriate. As long as people do not use subscriber links as a way to defeat our attempts to gain subscribers, we are happy to see them shared. ]] <https://lwn.net/op/FAQ.lwn#site> Cheers, Alex -- Alejandro Colomar Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/ http://www.alejandro-colomar.es/
Hello Amir, Luis, On 2/24/21 5:10 PM, Amir Goldstein wrote: > On Wed, Feb 24, 2021 at 4:22 PM Luis Henriques <lhenriques@suse.de> wrote: >> >> Update man-page with recent changes to this syscall. >> >> Signed-off-by: Luis Henriques <lhenriques@suse.de> >> --- >> Hi! >> >> Here's a suggestion for fixing the manpage for copy_file_range(). Note that >> I've assumed the fix will hit 5.12. >> >> man2/copy_file_range.2 | 10 +++++++++- >> 1 file changed, 9 insertions(+), 1 deletion(-) >> >> diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2 >> index 611a39b8026b..b0fd85e2631e 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 >> +.B EOPNOTSUPP I'll add the kernel version here: .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. >> @@ -187,7 +190,7 @@ refers to an active swap file. >> .B EXDEV >> 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 mounted filesystem (pre Linux 5.3 and post Linux 5.12). I'm not sure that 'mounted' adds any value here. Would you remove the word here? It reads as if two separate devices with the same filesystem type would still give this error. Per the LWN.net article Amir shared, this is permitted ("When called from user space, copy_file_range() will only try to copy a file across filesystems if the two are of the same type"). This behavior was slightly different before 5.3 AFAICR (was it?) ("until then, copy_file_range() refused to copy between files that were not located on the same filesystem."). If that's the case, I'd specify the difference, or more probably split the error into two, one before 5.3, and one since 5.12. > > I think you need to drop the (Linux range) altogether. I'll keep the range. Users of 5.3..5.11 might be surprised if the filesystems are different and they don't get an error, I think. I reworded it to follow other pages conventions: .BR EXDEV " (before Linux 5.3; or since Linux 5.12)" which renders as: EXDEV (before Linux 5.3; or since Linux 5.12) The files referred to by fd_in and fd_out are not on the same mounted filesystem. > What's missing here is the NFS cross server copy use case. > Maybe: > > ...are not on the same mounted filesystem and the source and target filesystems > do not support cross-filesystem copy. Yes. Again, this wasn't true before 5.3, right? > > You may refer the reader to VERSIONS section where it will say which > filesystems support cross-fs copy as of kernel version XXX (i.e. cifs and nfs). > >> .SH VERSIONS >> The >> .BR copy_file_range () >> @@ -202,6 +205,11 @@ 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. >> +.PP >> +After Linux 5.12, support for copies between different filesystems was dropped. >> +However, individual filesystems may still provide >> +.BR copy_file_range () >> +implementations that allow copies across different devices. > > Again, this is not likely to stay uptodate for very long. > The stable kernels are expected to apply your patch (because it fixes > a regression) > so this should be phrased differently. > If it were me, I would provide all the details of the situation to > Michael and ask him > to write the best description for this section. I'll look into more detail at this part in a later review. On 2/26/21 11:34 AM, Amir Goldstein wrote: > Is this detailed enough? ;-) > > https://lwn.net/Articles/846403/ Yes, it is! Thanks, Alex -- Alejandro Colomar Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/ http://www.alejandro-colomar.es/
On Sat, Feb 27, 2021 at 12:19 AM Alejandro Colomar (man-pages) <alx.manpages@gmail.com> wrote: > > Hello Amir, Luis, > > On 2/24/21 5:10 PM, Amir Goldstein wrote: > > On Wed, Feb 24, 2021 at 4:22 PM Luis Henriques <lhenriques@suse.de> wrote: > >> > >> Update man-page with recent changes to this syscall. > >> > >> Signed-off-by: Luis Henriques <lhenriques@suse.de> > >> --- > >> Hi! > >> > >> Here's a suggestion for fixing the manpage for copy_file_range(). Note that > >> I've assumed the fix will hit 5.12. > >> > >> man2/copy_file_range.2 | 10 +++++++++- > >> 1 file changed, 9 insertions(+), 1 deletion(-) > >> > >> diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2 > >> index 611a39b8026b..b0fd85e2631e 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 > >> +.B EOPNOTSUPP > > I'll add the kernel version here: > > .BR EOPNOTSUPP " (since Linux 5.12)" Error could be returned prior to 5.3 and would be probably returned by future stable kernels 5.3..5.12 too > > >> +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. > >> @@ -187,7 +190,7 @@ refers to an active swap file. > >> .B EXDEV > >> 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 mounted filesystem (pre Linux 5.3 and post Linux 5.12). > > I'm not sure that 'mounted' adds any value here. Would you remove the > word here? See rename(2). 'mounted' in this context is explained there. HOWEVER, it does not fit here. copy_file_range() IS allowed between two mounts of the same filesystem instance. To make things more complicated, it appears that cross mount clone is not allowed via FICLONE/FICLONERANGE ioctl, so ioctl_ficlonerange(2) man page also uses the 'mounted filesystem' terminology for EXDEV As things stand now, because of the fallback to clone logic, copy_file_range() provides a way for users to clone across different mounts of the same filesystem instance, which they cannot do with the FICLONE ioctl. Fun :) BTW, I don't know if preventing cross mount clone was done intentionally, but as I wrote in a comment in the code once: /* * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on * the same mount. Practically, they only need to be on the same file * system. */ > > It reads as if two separate devices with the same filesystem type would > still give this error. > > Per the LWN.net article Amir shared, this is permitted ("When called > from user space, copy_file_range() will only try to copy a file across > filesystems if the two are of the same type"). > > This behavior was slightly different before 5.3 AFAICR (was it?) ("until > then, copy_file_range() refused to copy between files that were not > located on the same filesystem."). If that's the case, I'd specify the > difference, or more probably split the error into two, one before 5.3, > and one since 5.12. > True. > > > > I think you need to drop the (Linux range) altogether. > > I'll keep the range. Users of 5.3..5.11 might be surprised if the > filesystems are different and they don't get an error, I think. > > I reworded it to follow other pages conventions: > > .BR EXDEV " (before Linux 5.3; or since Linux 5.12)" > > which renders as: > > EXDEV (before Linux 5.3; or since Linux 5.12) > The files referred to by fd_in and fd_out are not on > the same mounted filesystem. > drop 'mounted' > > > What's missing here is the NFS cross server copy use case. > > Maybe: > > > > ...are not on the same mounted filesystem and the source and target filesystems > > do not support cross-filesystem copy. > > Yes. > > Again, this wasn't true before 5.3, right? > Right. Actually, v5.3 provides the vfs capabilities for filesystems to support cross fs copy. I am not sure if NFS already implements cross fs copy in v5.3 and not sure about cifs. Need to get input from nfs/cis developers or dig in the release notes for server-side copy. > > > > You may refer the reader to VERSIONS section where it will say which > > filesystems support cross-fs copy as of kernel version XXX (i.e. cifs and nfs). > > > >> .SH VERSIONS > >> The > >> .BR copy_file_range () > >> @@ -202,6 +205,11 @@ 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. > >> +.PP > >> +After Linux 5.12, support for copies between different filesystems was dropped. > >> +However, individual filesystems may still provide > >> +.BR copy_file_range () > >> +implementations that allow copies across different devices. > > > > Again, this is not likely to stay uptodate for very long. > > The stable kernels are expected to apply your patch (because it fixes > > a regression) > > so this should be phrased differently. > > If it were me, I would provide all the details of the situation to > > Michael and ask him > > to write the best description for this section. > > I'll look into more detail at this part in a later review. > > > On 2/26/21 11:34 AM, Amir Goldstein wrote: > > Is this detailed enough? ;-) > > > > https://lwn.net/Articles/846403/ > > Yes, it is! > Thanks to LWN :) Thanks, Amir.
Hi Amir, On 2/27/21 6:41 AM, Amir Goldstein wrote: > On Sat, Feb 27, 2021 at 12:19 AM Alejandro Colomar (man-pages) >> On 2/24/21 5:10 PM, Amir Goldstein wrote: >>> On Wed, Feb 24, 2021 at 4:22 PM Luis Henriques <lhenriques@suse.de> wrote: >>>> .TP >>>> +.B EOPNOTSUPP >> >> I'll add the kernel version here: >> >> .BR EOPNOTSUPP " (since Linux 5.12)" > > Error could be returned prior to 5.3 and would be probably returned > by future stable kernels 5.3..5.12 too OK, I think I'll state <5.3 and >=5.12 for the moment, and if Greg adds that to stable 5.3..5.11 kernels, please update me. >>>> .B EXDEV >>>> 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 mounted filesystem (pre Linux 5.3 and post Linux 5.12). >> >> I'm not sure that 'mounted' adds any value here. Would you remove the >> word here? > > See rename(2). 'mounted' in this context is explained there. > HOWEVER, it does not fit here. > copy_file_range() IS allowed between two mounts of the same filesystem instance. Also allowed for <5.3 ? > > To make things more complicated, it appears that cross mount clone is not > allowed via FICLONE/FICLONERANGE ioctl, so ioctl_ficlonerange(2) man page > also uses the 'mounted filesystem' terminology for EXDEV > > As things stand now, because of the fallback to clone logic, > copy_file_range() provides a way for users to clone across different mounts > of the same filesystem instance, which they cannot do with the FICLONE ioctl. > > Fun :) > > BTW, I don't know if preventing cross mount clone was done intentionally, > but as I wrote in a comment in the code once: > > /* > * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on > * the same mount. Practically, they only need to be on the same file > * system. > */ :) > >> >> It reads as if two separate devices with the same filesystem type would >> still give this error. >> >> Per the LWN.net article Amir shared, this is permitted ("When called >> from user space, copy_file_range() will only try to copy a file across >> filesystems if the two are of the same type"). >> >> This behavior was slightly different before 5.3 AFAICR (was it?) ("until >> then, copy_file_range() refused to copy between files that were not >> located on the same filesystem."). If that's the case, I'd specify the >> difference, or more probably split the error into two, one before 5.3, >> and one since 5.12. >> > > True. > >>> >>> I think you need to drop the (Linux range) altogether. >> >> I'll keep the range. Users of 5.3..5.11 might be surprised if the >> filesystems are different and they don't get an error, I think. >> >> I reworded it to follow other pages conventions: >> >> .BR EXDEV " (before Linux 5.3; or since Linux 5.12)" >> >> which renders as: >> >> EXDEV (before Linux 5.3; or since Linux 5.12) >> The files referred to by fd_in and fd_out are not on >> the same mounted filesystem. >> > > drop 'mounted' Yes > >> >>> What's missing here is the NFS cross server copy use case. >>> Maybe: >>> >>> ...are not on the same mounted filesystem and the source and target filesystems >>> do not support cross-filesystem copy. >> >> Yes. >> >> Again, this wasn't true before 5.3, right? >> > > Right. > Actually, v5.3 provides the vfs capabilities for filesystems to support > cross fs copy. I am not sure if NFS already implements cross fs copy in > v5.3 and not sure about cifs. Need to get input from nfs/cis developers > or dig in the release notes for server-side copy. Okay > Thanks to LWN :) :) Thanks, Alex -- Alejandro Colomar Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/ http://www.alejandro-colomar.es/
On Sat, Feb 27, 2021 at 3:59 PM Alejandro Colomar <alx.manpages@gmail.com> wrote: > > Linux 5.12 fixes a regression. > > Cross-filesystem copies (introduced in 5.3) 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@suse.de> > Reported-by: Amir Goldstein <amir73il@gmail.com> > Related: <https://lwn.net/Articles/846403/> > Cc: Greg KH <gregkh@linuxfoundation.org> > Cc: Michael Kerrisk <mtk.manpages@gmail.com> > Cc: Anna Schumaker <anna.schumaker@netapp.com> > Cc: Jeff Layton <jlayton@kernel.org> > Cc: Steve French <sfrench@samba.org> > Cc: Miklos Szeredi <miklos@szeredi.hu> > Cc: Trond Myklebust <trond.myklebust@hammerspace.com> > Cc: Alexander Viro <viro@zeniv.linux.org.uk> > Cc: "Darrick J. Wong" <darrick.wong@oracle.com> > Cc: Dave Chinner <dchinner@redhat.com> > Cc: Nicolas Boichat <drinkcat@chromium.org> > Cc: Ian Lance Taylor <iant@google.com> > Cc: Luis Lozano <llozano@chromium.org> > Cc: Andreas Dilger <adilger@dilger.ca> > Cc: Olga Kornievskaia <aglo@umich.edu> > Cc: Christoph Hellwig <hch@infradead.org> > Cc: ceph-devel <ceph-devel@vger.kernel.org> > Cc: linux-kernel <linux-kernel@vger.kernel.org> > Cc: CIFS <linux-cifs@vger.kernel.org> > Cc: samba-technical <samba-technical@lists.samba.org> > Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org> > Cc: Linux NFS Mailing List <linux-nfs@vger.kernel.org> > Cc: Walter Harms <wharms@bfs.de> > Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com> > --- > > Hi all, > > Please check that this is correct. > I wrote it as I understood copy_file_range() from the LWN article, > and the conversation on this thread, > but maybe someone with more experience on this syscall find bugs in my patch. > > When kernels 5.3..5.11 fix this, some info could be compacted a bit more, > and maybe the BUGS section could be removed. > > Also, I'd like to know which filesystems support cross-fs, and since when. > > Amir, you said that it was only cifs and nfs (since when? 5.3? 5.12?). > > Also, I'm a bit surprised that <5.3 could fail with EOPNOTSUPP > and it wasn't documented. Is that for sure, Amir? No. You are right. EOPNOTSUPP is new. Kernel always fell back to sendfile(2) if the filesystem did not support copy_file_range(). > > Thanks, > > Alex > > --- > man2/copy_file_range.2 | 29 ++++++++++++++++++++--------- > 1 file changed, 20 insertions(+), 9 deletions(-) > > diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2 > index 611a39b80..93f54889d 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 " (before Linux 5.3; or since Linux 5.12)" > +The filesystem does not support this operation. > +.TP so not before 5.3 > .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 mounted filesystem (pre Linux 5.3). > +are not on the same filesystem. > +.TP > +.BR EXDEV " (or since Linux 5.12)" > +The files referred to by > +.IR fd_in " and " fd_out > +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. ok. > .SH VERSIONS > The > .BR copy_file_range () > @@ -195,13 +205,10 @@ system call first appeared in Linux 4.5, but glibc 2.27 provides a user-space > emulation when it is not available. > .\" https://sourceware.org/git/?p=glibc.git;a=commit;f=posix/unistd.h;h=bad7a0c81f501fbbcc79af9eaa4b8254441c4a1f > .PP > -A major rework of the kernel implementation occurred in 5.3. > -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 That information is useful. Why remove it? FYI, the LTP tests written to velidate the copy_file_range() API are not running on kernel < 5.3 at all. > -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. > .SH CONFORMING TO > The > .BR copy_file_range () > @@ -226,6 +233,10 @@ 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. I think it is a bit confusing to say "were supported", because how come support went away from kernel 5.12? maybe something along the lines that kernel implementation of copy was used if there was no filesystem support for the operation... > +However, on some virtual filesystems, the call failed to copy, > +eventhough it may have reported success. > .SH EXAMPLES > .EX > #define _GNU_SOURCE > -- > 2.30.1.721.g45526154a5 >
On Fri, Feb 26, 2021 at 11:43 PM Amir Goldstein <amir73il@gmail.com> wrote: > > On Sat, Feb 27, 2021 at 12:19 AM Alejandro Colomar (man-pages) > <alx.manpages@gmail.com> wrote: > > > > Hello Amir, Luis, > > > > On 2/24/21 5:10 PM, Amir Goldstein wrote: > > > On Wed, Feb 24, 2021 at 4:22 PM Luis Henriques <lhenriques@suse.de> wrote: > > >> > > >> Update man-page with recent changes to this syscall. > > >> > > >> Signed-off-by: Luis Henriques <lhenriques@suse.de> > > >> --- > > >> Hi! > > >> > > >> Here's a suggestion for fixing the manpage for copy_file_range(). Note that > > >> I've assumed the fix will hit 5.12. > > >> > > >> man2/copy_file_range.2 | 10 +++++++++- > > >> 1 file changed, 9 insertions(+), 1 deletion(-) > > >> > > >> diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2 > > >> index 611a39b8026b..b0fd85e2631e 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 > > >> +.B EOPNOTSUPP > > > > I'll add the kernel version here: > > > > .BR EOPNOTSUPP " (since Linux 5.12)" > > Error could be returned prior to 5.3 and would be probably returned > by future stable kernels 5.3..5.12 too > > > > > >> +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. > > >> @@ -187,7 +190,7 @@ refers to an active swap file. > > >> .B EXDEV > > >> 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 mounted filesystem (pre Linux 5.3 and post Linux 5.12). > > > > I'm not sure that 'mounted' adds any value here. Would you remove the > > word here? > > See rename(2). 'mounted' in this context is explained there. > HOWEVER, it does not fit here. > copy_file_range() IS allowed between two mounts of the same filesystem instance. > > To make things more complicated, it appears that cross mount clone is not > allowed via FICLONE/FICLONERANGE ioctl, so ioctl_ficlonerange(2) man page > also uses the 'mounted filesystem' terminology for EXDEV > > As things stand now, because of the fallback to clone logic, > copy_file_range() provides a way for users to clone across different mounts > of the same filesystem instance, which they cannot do with the FICLONE ioctl. > > Fun :) > > BTW, I don't know if preventing cross mount clone was done intentionally, > but as I wrote in a comment in the code once: > > /* > * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on > * the same mount. Practically, they only need to be on the same file > * system. > */ > > > > > It reads as if two separate devices with the same filesystem type would > > still give this error. > > > > Per the LWN.net article Amir shared, this is permitted ("When called > > from user space, copy_file_range() will only try to copy a file across > > filesystems if the two are of the same type"). > > > > This behavior was slightly different before 5.3 AFAICR (was it?) ("until > > then, copy_file_range() refused to copy between files that were not > > located on the same filesystem."). If that's the case, I'd specify the > > difference, or more probably split the error into two, one before 5.3, > > and one since 5.12. > > > > True. > > > > > > > I think you need to drop the (Linux range) altogether. > > > > I'll keep the range. Users of 5.3..5.11 might be surprised if the > > filesystems are different and they don't get an error, I think. > > > > I reworded it to follow other pages conventions: > > > > .BR EXDEV " (before Linux 5.3; or since Linux 5.12)" > > > > which renders as: > > > > EXDEV (before Linux 5.3; or since Linux 5.12) > > The files referred to by fd_in and fd_out are not on > > the same mounted filesystem. > > > > drop 'mounted' > > > > > > What's missing here is the NFS cross server copy use case. > > > Maybe: At least for the SMB3 kernel server (ksmbd "cifsd") looks like they use splice. And for the user space CIFS/SMB3 server (like Samba) they have a configurable plug in library interface ("Samba VFS modules") that would allow you to implement cross filesystem copy optimally for your version of Linux and plug this into Samba with little work on your part. > > > > Again, this wasn't true before 5.3, right? > > > > Right. > Actually, v5.3 provides the vfs capabilities for filesystems to support > cross fs copy. I am not sure if NFS already implements cross fs copy in > v5.3 and not sure about cifs. Need to get input from nfs/cis developers > or dig in the release notes for server-side copy. The SMB3 protocol has multiple ways to do "server side copy" (copy offload to the server), some of which would apply to your example. The case of "reflink" in many cases would be most efficient, and is supported by the Linux client (see MS-SMB2 protocol specification section 3.3.5.15.18) but is supported by fewer server file systems, so probably more important to focus on the other mechanisms which are server side copy rather than clone. The most popular way, supported by most servers, is "CopyChunk" - 100s of millions of systems support this (if not more) - see MS-SMB2 protocol specification section 2.2.31.1 and 3.3.5.15.16 - there are various cases where two different SMB3 mounts on the same client could handle cross mount server side copy. There are other mechanisms supported by fewer servers SMB3 ODX/T10 style copy offload (Windows and some others see e.g. Gordon at Nexenta's presentation https://www.slideshare.net/gordonross/smb3-offload-data-transfer-odx) but still popular for virtualization workloads. For this it could be even more common for those to be different mounts on the client. The Linux client does not support the SMB3 ODX/T10 offload yet but it would be good to add support for it. There is a nice description of its additional benefits at https://docs.microsoft.com/en-us/windows-hardware/drivers/storage/offloaded-data-transfer But - yes SMB3 on Linux can have cross mount file copy today, which is far more efficient (having the server do the copy for us) rather than sending large reads/writes back and forth over the network from the client. In the future I am hoping that use case becomes even more common over SMB3 as cloud servers improve. > > > You may refer the reader to VERSIONS section where it will say which > > > filesystems support cross-fs copy as of kernel version XXX (i.e. cifs and nfs). > > > > > >> .SH VERSIONS > > >> The > > >> .BR copy_file_range () > > >> @@ -202,6 +205,11 @@ 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. > > >> +.PP > > >> +After Linux 5.12, support for copies between different filesystems was dropped. > > >> +However, individual filesystems may still provide > > >> +.BR copy_file_range () > > >> +implementations that allow copies across different devices. Yes - this could be very important, especially for cifs (smb3) going forward. -- Thanks, Steve
On Sun, Feb 28, 2021 at 1:08 AM Steve French <smfrench@gmail.com> wrote: > > On Fri, Feb 26, 2021 at 11:43 PM Amir Goldstein <amir73il@gmail.com> wrote: > > > > On Sat, Feb 27, 2021 at 12:19 AM Alejandro Colomar (man-pages) > > <alx.manpages@gmail.com> wrote: > > > > > > Hello Amir, Luis, > > > > > > On 2/24/21 5:10 PM, Amir Goldstein wrote: > > > > On Wed, Feb 24, 2021 at 4:22 PM Luis Henriques <lhenriques@suse.de> wrote: > > > >> > > > >> Update man-page with recent changes to this syscall. > > > >> > > > >> Signed-off-by: Luis Henriques <lhenriques@suse.de> > > > >> --- > > > >> Hi! > > > >> > > > >> Here's a suggestion for fixing the manpage for copy_file_range(). Note that > > > >> I've assumed the fix will hit 5.12. > > > >> > > > >> man2/copy_file_range.2 | 10 +++++++++- > > > >> 1 file changed, 9 insertions(+), 1 deletion(-) > > > >> > > > >> diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2 > > > >> index 611a39b8026b..b0fd85e2631e 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 > > > >> +.B EOPNOTSUPP > > > > > > I'll add the kernel version here: > > > > > > .BR EOPNOTSUPP " (since Linux 5.12)" > > > > Error could be returned prior to 5.3 and would be probably returned > > by future stable kernels 5.3..5.12 too > > > > > > > > >> +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. > > > >> @@ -187,7 +190,7 @@ refers to an active swap file. > > > >> .B EXDEV > > > >> 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 mounted filesystem (pre Linux 5.3 and post Linux 5.12). > > > > > > I'm not sure that 'mounted' adds any value here. Would you remove the > > > word here? > > > > See rename(2). 'mounted' in this context is explained there. > > HOWEVER, it does not fit here. > > copy_file_range() IS allowed between two mounts of the same filesystem instance. > > > > To make things more complicated, it appears that cross mount clone is not > > allowed via FICLONE/FICLONERANGE ioctl, so ioctl_ficlonerange(2) man page > > also uses the 'mounted filesystem' terminology for EXDEV > > > > As things stand now, because of the fallback to clone logic, > > copy_file_range() provides a way for users to clone across different mounts > > of the same filesystem instance, which they cannot do with the FICLONE ioctl. > > > > Fun :) > > > > BTW, I don't know if preventing cross mount clone was done intentionally, > > but as I wrote in a comment in the code once: > > > > /* > > * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on > > * the same mount. Practically, they only need to be on the same file > > * system. > > */ > > > > > > > > It reads as if two separate devices with the same filesystem type would > > > still give this error. > > > > > > Per the LWN.net article Amir shared, this is permitted ("When called > > > from user space, copy_file_range() will only try to copy a file across > > > filesystems if the two are of the same type"). > > > > > > This behavior was slightly different before 5.3 AFAICR (was it?) ("until > > > then, copy_file_range() refused to copy between files that were not > > > located on the same filesystem."). If that's the case, I'd specify the > > > difference, or more probably split the error into two, one before 5.3, > > > and one since 5.12. > > > > > > > True. > > > > > > > > > > I think you need to drop the (Linux range) altogether. > > > > > > I'll keep the range. Users of 5.3..5.11 might be surprised if the > > > filesystems are different and they don't get an error, I think. > > > > > > I reworded it to follow other pages conventions: > > > > > > .BR EXDEV " (before Linux 5.3; or since Linux 5.12)" > > > > > > which renders as: > > > > > > EXDEV (before Linux 5.3; or since Linux 5.12) > > > The files referred to by fd_in and fd_out are not on > > > the same mounted filesystem. > > > > > > > drop 'mounted' > > > > > > > > > What's missing here is the NFS cross server copy use case. > > > > Maybe: > > At least for the SMB3 kernel server (ksmbd "cifsd") looks like they use splice. > And for the user space CIFS/SMB3 server (like Samba) they have a configurable > plug in library interface ("Samba VFS modules") that would allow you > to implement > cross filesystem copy optimally for your version of Linux and plug > this into Samba > with little work on your part. > > > > > > > Again, this wasn't true before 5.3, right? > > > > > > > Right. > > Actually, v5.3 provides the vfs capabilities for filesystems to support > > cross fs copy. I am not sure if NFS already implements cross fs copy in > > v5.3 and not sure about cifs. Need to get input from nfs/cis developers > > or dig in the release notes for server-side copy. > > The SMB3 protocol has multiple ways to do "server side copy" (copy > offload to the server), some of which would apply to your example. > The case of "reflink" in many cases would be most efficient, and is supported > by the Linux client (see MS-SMB2 protocol specification section 3.3.5.15.18) but > is supported by fewer server file systems, so probably more important > to focus on > the other mechanisms which are server side copy rather than clone. The most > popular way, supported by most servers, is "CopyChunk" - 100s of > millions of systems > support this (if not more) - see MS-SMB2 protocol specification > section 2.2.31.1 and > 3.3.5.15.16 - there are various cases where two different SMB3 mounts > on the same > client could handle cross mount server side copy. > > There are other mechanisms supported by fewer servers SMB3 ODX/T10 style copy > offload (Windows and some others see e.g. Gordon at Nexenta's presentation > https://www.slideshare.net/gordonross/smb3-offload-data-transfer-odx) > but still popular for virtualization workloads. For this it could be > even more common > for those to be different mounts on the client. The Linux client does > not support > the SMB3 ODX/T10 offload yet but it would be good to add support for it. > There is a nice description of its additional benefits at > https://docs.microsoft.com/en-us/windows-hardware/drivers/storage/offloaded-data-transfer > > But - yes SMB3 on Linux can have cross mount file copy today, which is > far more efficient Can have? or does have? IIUC, server-side copy ability exists for "same cifs fs" for a long time and since v5.3, it is available for "same cifs connection", which is not exactly the same as "same cifs fs" but also not really different for most people. Can you elaborate about that? Just assume the server can do anything. What can the Linux client do since v5.3 or later? > (having the server do the copy for us) rather than sending large > reads/writes back and > forth over the network from the client. In the future I am hoping that use case > becomes even more common over SMB3 as cloud servers improve. > > > > > > You may refer the reader to VERSIONS section where it will say which > > > > filesystems support cross-fs copy as of kernel version XXX (i.e. cifs and nfs). > > > > > > > >> .SH VERSIONS > > > >> The > > > >> .BR copy_file_range () > > > >> @@ -202,6 +205,11 @@ 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. > > > >> +.PP > > > >> +After Linux 5.12, support for copies between different filesystems was dropped. > > > >> +However, individual filesystems may still provide > > > >> +.BR copy_file_range () > > > >> +implementations that allow copies across different devices. > > Yes - this could be very important, especially for cifs (smb3) going forward. > > > > -- > Thanks, > > Steve
On Sun, Feb 28, 2021 at 1:36 AM Amir Goldstein <amir73il@gmail.com> wrote: > > On Sun, Feb 28, 2021 at 1:08 AM Steve French <smfrench@gmail.com> wrote: > > > > On Fri, Feb 26, 2021 at 11:43 PM Amir Goldstein <amir73il@gmail.com> wrote: > > > > > > On Sat, Feb 27, 2021 at 12:19 AM Alejandro Colomar (man-pages) > > > <alx.manpages@gmail.com> wrote: > > > > > > > > Hello Amir, Luis, > > > > > > > > On 2/24/21 5:10 PM, Amir Goldstein wrote: > > > > > On Wed, Feb 24, 2021 at 4:22 PM Luis Henriques <lhenriques@suse.de> wrote: > > > > >> > > > > >> Update man-page with recent changes to this syscall. > > > > >> > > > > >> Signed-off-by: Luis Henriques <lhenriques@suse.de> > > > > >> --- > > > > >> Hi! > > > > >> > > > > >> Here's a suggestion for fixing the manpage for copy_file_range(). Note that > > > > >> I've assumed the fix will hit 5.12. > > > > >> > > > > >> man2/copy_file_range.2 | 10 +++++++++- > > > > >> 1 file changed, 9 insertions(+), 1 deletion(-) > > > > >> > > > > >> diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2 > > > > >> index 611a39b8026b..b0fd85e2631e 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 > > > > >> +.B EOPNOTSUPP > > > > > > > > I'll add the kernel version here: > > > > > > > > .BR EOPNOTSUPP " (since Linux 5.12)" > > > > > > Error could be returned prior to 5.3 and would be probably returned > > > by future stable kernels 5.3..5.12 too > > > > > > > > > > > >> +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. > > > > >> @@ -187,7 +190,7 @@ refers to an active swap file. > > > > >> .B EXDEV > > > > >> 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 mounted filesystem (pre Linux 5.3 and post Linux 5.12). > > > > > > > > I'm not sure that 'mounted' adds any value here. Would you remove the > > > > word here? > > > > > > See rename(2). 'mounted' in this context is explained there. > > > HOWEVER, it does not fit here. > > > copy_file_range() IS allowed between two mounts of the same filesystem instance. > > > > > > To make things more complicated, it appears that cross mount clone is not > > > allowed via FICLONE/FICLONERANGE ioctl, so ioctl_ficlonerange(2) man page > > > also uses the 'mounted filesystem' terminology for EXDEV > > > > > > As things stand now, because of the fallback to clone logic, > > > copy_file_range() provides a way for users to clone across different mounts > > > of the same filesystem instance, which they cannot do with the FICLONE ioctl. > > > > > > Fun :) > > > > > > BTW, I don't know if preventing cross mount clone was done intentionally, > > > but as I wrote in a comment in the code once: > > > > > > /* > > > * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on > > > * the same mount. Practically, they only need to be on the same file > > > * system. > > > */ > > > > > > > > > > > It reads as if two separate devices with the same filesystem type would > > > > still give this error. > > > > > > > > Per the LWN.net article Amir shared, this is permitted ("When called > > > > from user space, copy_file_range() will only try to copy a file across > > > > filesystems if the two are of the same type"). > > > > > > > > This behavior was slightly different before 5.3 AFAICR (was it?) ("until > > > > then, copy_file_range() refused to copy between files that were not > > > > located on the same filesystem."). If that's the case, I'd specify the > > > > difference, or more probably split the error into two, one before 5.3, > > > > and one since 5.12. > > > > > > > > > > True. > > > > > > > > > > > > > I think you need to drop the (Linux range) altogether. > > > > > > > > I'll keep the range. Users of 5.3..5.11 might be surprised if the > > > > filesystems are different and they don't get an error, I think. > > > > > > > > I reworded it to follow other pages conventions: > > > > > > > > .BR EXDEV " (before Linux 5.3; or since Linux 5.12)" > > > > > > > > which renders as: > > > > > > > > EXDEV (before Linux 5.3; or since Linux 5.12) > > > > The files referred to by fd_in and fd_out are not on > > > > the same mounted filesystem. > > > > > > > > > > drop 'mounted' > > > > > > > > > > > > What's missing here is the NFS cross server copy use case. > > > > > Maybe: > > > > At least for the SMB3 kernel server (ksmbd "cifsd") looks like they use splice. > > And for the user space CIFS/SMB3 server (like Samba) they have a configurable > > plug in library interface ("Samba VFS modules") that would allow you > > to implement > > cross filesystem copy optimally for your version of Linux and plug > > this into Samba > > with little work on your part. > > > > > > > > > > Again, this wasn't true before 5.3, right? > > > > > > > > > > Right. > > > Actually, v5.3 provides the vfs capabilities for filesystems to support > > > cross fs copy. I am not sure if NFS already implements cross fs copy in > > > v5.3 and not sure about cifs. Need to get input from nfs/cis developers > > > or dig in the release notes for server-side copy. > > > > The SMB3 protocol has multiple ways to do "server side copy" (copy > > offload to the server), some of which would apply to your example. > > The case of "reflink" in many cases would be most efficient, and is supported > > by the Linux client (see MS-SMB2 protocol specification section 3.3.5.15.18) but > > is supported by fewer server file systems, so probably more important > > to focus on > > the other mechanisms which are server side copy rather than clone. The most > > popular way, supported by most servers, is "CopyChunk" - 100s of > > millions of systems > > support this (if not more) - see MS-SMB2 protocol specification > > section 2.2.31.1 and > > 3.3.5.15.16 - there are various cases where two different SMB3 mounts > > on the same > > client could handle cross mount server side copy. > > > > There are other mechanisms supported by fewer servers SMB3 ODX/T10 style copy > > offload (Windows and some others see e.g. Gordon at Nexenta's presentation > > https://www.slideshare.net/gordonross/smb3-offload-data-transfer-odx) > > but still popular for virtualization workloads. For this it could be > > even more common > > for those to be different mounts on the client. The Linux client does > > not support > > the SMB3 ODX/T10 offload yet but it would be good to add support for it. > > There is a nice description of its additional benefits at > > https://docs.microsoft.com/en-us/windows-hardware/drivers/storage/offloaded-data-transfer > > > > But - yes SMB3 on Linux can have cross mount file copy today, which is > > far more efficient > > Can have? or does have? > IIUC, server-side copy ability exists for "same cifs fs" for a long time and > since v5.3, it is available for "same cifs connection", which is not exactly > the same as "same cifs fs" but also not really different for most people. > Can you elaborate about that? > Just assume the server can do anything. What can the Linux client do > since v5.3 or later? Inside the SMB3 client (cifs.ko) we check that the file handles provided are for the same authenticated user to the same server, so e.g. you could mount //server/share on /mnt1 and //server/anothershare on /mnt2 and do a copy_file_range from /mnt1/file1 to /mnt2/file2 even though these are different mounts. The cifs client should allow additional cases of cross mount copy, but at least this helps for various common scenarios and is very widely supported on most servers as well. -- Thanks, Steve
On Mon, Mar 1, 2021 at 12:25 AM Steve French <smfrench@gmail.com> wrote: > > On Sun, Feb 28, 2021 at 1:36 AM Amir Goldstein <amir73il@gmail.com> wrote: > > > > On Sun, Feb 28, 2021 at 1:08 AM Steve French <smfrench@gmail.com> wrote: > > > > > > On Fri, Feb 26, 2021 at 11:43 PM Amir Goldstein <amir73il@gmail.com> wrote: > > > > > > > > On Sat, Feb 27, 2021 at 12:19 AM Alejandro Colomar (man-pages) > > > > <alx.manpages@gmail.com> wrote: > > > > > > > > > > Hello Amir, Luis, > > > > > > > > > > On 2/24/21 5:10 PM, Amir Goldstein wrote: > > > > > > On Wed, Feb 24, 2021 at 4:22 PM Luis Henriques <lhenriques@suse.de> wrote: > > > > > >> > > > > > >> Update man-page with recent changes to this syscall. > > > > > >> > > > > > >> Signed-off-by: Luis Henriques <lhenriques@suse.de> > > > > > >> --- > > > > > >> Hi! > > > > > >> > > > > > >> Here's a suggestion for fixing the manpage for copy_file_range(). Note that > > > > > >> I've assumed the fix will hit 5.12. > > > > > >> > > > > > >> man2/copy_file_range.2 | 10 +++++++++- > > > > > >> 1 file changed, 9 insertions(+), 1 deletion(-) > > > > > >> > > > > > >> diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2 > > > > > >> index 611a39b8026b..b0fd85e2631e 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 > > > > > >> +.B EOPNOTSUPP > > > > > > > > > > I'll add the kernel version here: > > > > > > > > > > .BR EOPNOTSUPP " (since Linux 5.12)" > > > > > > > > Error could be returned prior to 5.3 and would be probably returned > > > > by future stable kernels 5.3..5.12 too > > > > > > > > > > > > > > >> +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. > > > > > >> @@ -187,7 +190,7 @@ refers to an active swap file. > > > > > >> .B EXDEV > > > > > >> 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 mounted filesystem (pre Linux 5.3 and post Linux 5.12). > > > > > > > > > > I'm not sure that 'mounted' adds any value here. Would you remove the > > > > > word here? > > > > > > > > See rename(2). 'mounted' in this context is explained there. > > > > HOWEVER, it does not fit here. > > > > copy_file_range() IS allowed between two mounts of the same filesystem instance. > > > > > > > > To make things more complicated, it appears that cross mount clone is not > > > > allowed via FICLONE/FICLONERANGE ioctl, so ioctl_ficlonerange(2) man page > > > > also uses the 'mounted filesystem' terminology for EXDEV > > > > > > > > As things stand now, because of the fallback to clone logic, > > > > copy_file_range() provides a way for users to clone across different mounts > > > > of the same filesystem instance, which they cannot do with the FICLONE ioctl. > > > > > > > > Fun :) > > > > > > > > BTW, I don't know if preventing cross mount clone was done intentionally, > > > > but as I wrote in a comment in the code once: > > > > > > > > /* > > > > * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on > > > > * the same mount. Practically, they only need to be on the same file > > > > * system. > > > > */ > > > > > > > > > > > > > > It reads as if two separate devices with the same filesystem type would > > > > > still give this error. > > > > > > > > > > Per the LWN.net article Amir shared, this is permitted ("When called > > > > > from user space, copy_file_range() will only try to copy a file across > > > > > filesystems if the two are of the same type"). > > > > > > > > > > This behavior was slightly different before 5.3 AFAICR (was it?) ("until > > > > > then, copy_file_range() refused to copy between files that were not > > > > > located on the same filesystem."). If that's the case, I'd specify the > > > > > difference, or more probably split the error into two, one before 5.3, > > > > > and one since 5.12. > > > > > > > > > > > > > True. > > > > > > > > > > > > > > > > I think you need to drop the (Linux range) altogether. > > > > > > > > > > I'll keep the range. Users of 5.3..5.11 might be surprised if the > > > > > filesystems are different and they don't get an error, I think. > > > > > > > > > > I reworded it to follow other pages conventions: > > > > > > > > > > .BR EXDEV " (before Linux 5.3; or since Linux 5.12)" > > > > > > > > > > which renders as: > > > > > > > > > > EXDEV (before Linux 5.3; or since Linux 5.12) > > > > > The files referred to by fd_in and fd_out are not on > > > > > the same mounted filesystem. > > > > > > > > > > > > > drop 'mounted' > > > > > > > > > > > > > > > What's missing here is the NFS cross server copy use case. > > > > > > Maybe: > > > > > > At least for the SMB3 kernel server (ksmbd "cifsd") looks like they use splice. > > > And for the user space CIFS/SMB3 server (like Samba) they have a configurable > > > plug in library interface ("Samba VFS modules") that would allow you > > > to implement > > > cross filesystem copy optimally for your version of Linux and plug > > > this into Samba > > > with little work on your part. > > > > > > > > > > > > > Again, this wasn't true before 5.3, right? > > > > > > > > > > > > > Right. > > > > Actually, v5.3 provides the vfs capabilities for filesystems to support > > > > cross fs copy. I am not sure if NFS already implements cross fs copy in > > > > v5.3 and not sure about cifs. Need to get input from nfs/cis developers > > > > or dig in the release notes for server-side copy. > > > > > > The SMB3 protocol has multiple ways to do "server side copy" (copy > > > offload to the server), some of which would apply to your example. > > > The case of "reflink" in many cases would be most efficient, and is supported > > > by the Linux client (see MS-SMB2 protocol specification section 3.3.5.15.18) but > > > is supported by fewer server file systems, so probably more important > > > to focus on > > > the other mechanisms which are server side copy rather than clone. The most > > > popular way, supported by most servers, is "CopyChunk" - 100s of > > > millions of systems > > > support this (if not more) - see MS-SMB2 protocol specification > > > section 2.2.31.1 and > > > 3.3.5.15.16 - there are various cases where two different SMB3 mounts > > > on the same > > > client could handle cross mount server side copy. > > > > > > There are other mechanisms supported by fewer servers SMB3 ODX/T10 style copy > > > offload (Windows and some others see e.g. Gordon at Nexenta's presentation > > > https://www.slideshare.net/gordonross/smb3-offload-data-transfer-odx) > > > but still popular for virtualization workloads. For this it could be > > > even more common > > > for those to be different mounts on the client. The Linux client does > > > not support > > > the SMB3 ODX/T10 offload yet but it would be good to add support for it. > > > There is a nice description of its additional benefits at > > > https://docs.microsoft.com/en-us/windows-hardware/drivers/storage/offloaded-data-transfer > > > > > > But - yes SMB3 on Linux can have cross mount file copy today, which is > > > far more efficient > > > > Can have? or does have? > > IIUC, server-side copy ability exists for "same cifs fs" for a long time and > > since v5.3, it is available for "same cifs connection", which is not exactly > > the same as "same cifs fs" but also not really different for most people. > > Can you elaborate about that? > > Just assume the server can do anything. What can the Linux client do > > since v5.3 or later? > > Inside the SMB3 client (cifs.ko) we check that the file handles provided > are for the same authenticated user to the same server, so > e.g. you could mount //server/share on /mnt1 and //server/anothershare on /mnt2 > and do a copy_file_range from /mnt1/file1 to /mnt2/file2 even though these are > different mounts. The cifs client should allow additional cases of cross mount > copy, but at least this helps for various common scenarios and is very widely > supported on most servers as well. > Got it. Thanks for clarifying. So it appears that both cifs and nfs support cross-fs copy since v5.3 and many other fs that support clone, started supporting cross-mnt (same fs) copy (implemented as clone) since v5.3 and still do to this day. Alejandro, just to be clear, none of these changes are in v5.12 yet, so please hold on to your patch for now. Thanks, Amir.
On Wed, Feb 24, 2021 at 6:44 PM Nicolas Boichat <drinkcat@chromium.org> wrote: > > On Wed, Feb 24, 2021 at 6:22 PM Luis Henriques <lhenriques@suse.de> wrote: > > > > On Tue, Feb 23, 2021 at 08:00:54PM -0500, Olga Kornievskaia wrote: > > > On Mon, Feb 22, 2021 at 5:25 AM Luis Henriques <lhenriques@suse.de> wrote: > > > > > > > > A regression has been reported by Nicolas Boichat, found while using the > > > > copy_file_range syscall to copy a tracefs file. Before commit > > > > 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the > > > > kernel would return -EXDEV to userspace when trying to copy a file across > > > > different filesystems. After this commit, the syscall doesn't fail anymore > > > > and instead returns zero (zero bytes copied), as this file's content is > > > > generated on-the-fly and thus reports a size of zero. > > > > > > > > This patch restores some cross-filesystem copy restrictions that existed > > > > prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across > > > > devices"). Filesystems are still allowed to fall-back to the VFS > > > > generic_copy_file_range() implementation, but that has now to be done > > > > explicitly. > > > > > > > > nfsd is also modified to fall-back into generic_copy_file_range() in case > > > > vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV. > > > > > > > > Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") > > > > Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/ > > > > Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/ > > > > Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/ > > > > Reported-by: Nicolas Boichat <drinkcat@chromium.org> > > > > Signed-off-by: Luis Henriques <lhenriques@suse.de> > > > > > > I tested v8 and I believe it works for NFS. > > > > Thanks a lot for the testing. And to everyone else for reviews, > > feedback,... and patience. > > Thanks so much to you!!! > > Works here, you can add my > Tested-by: Nicolas Boichat <drinkcat@chromium.org> What happened to this patch? It does not seem to have been picked up yet? Any reason why? > > > > I'll now go look into the manpage and see what needs to be changed. > > > > Cheers, > > -- > > Luís
Nicolas Boichat <drinkcat@chromium.org> writes: > On Wed, Feb 24, 2021 at 6:44 PM Nicolas Boichat <drinkcat@chromium.org> wrote: >> >> On Wed, Feb 24, 2021 at 6:22 PM Luis Henriques <lhenriques@suse.de> wrote: >> > >> > On Tue, Feb 23, 2021 at 08:00:54PM -0500, Olga Kornievskaia wrote: >> > > On Mon, Feb 22, 2021 at 5:25 AM Luis Henriques <lhenriques@suse.de> wrote: >> > > > >> > > > A regression has been reported by Nicolas Boichat, found while using the >> > > > copy_file_range syscall to copy a tracefs file. Before commit >> > > > 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the >> > > > kernel would return -EXDEV to userspace when trying to copy a file across >> > > > different filesystems. After this commit, the syscall doesn't fail anymore >> > > > and instead returns zero (zero bytes copied), as this file's content is >> > > > generated on-the-fly and thus reports a size of zero. >> > > > >> > > > This patch restores some cross-filesystem copy restrictions that existed >> > > > prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across >> > > > devices"). Filesystems are still allowed to fall-back to the VFS >> > > > generic_copy_file_range() implementation, but that has now to be done >> > > > explicitly. >> > > > >> > > > nfsd is also modified to fall-back into generic_copy_file_range() in case >> > > > vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV. >> > > > >> > > > Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") >> > > > Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/ >> > > > Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/ >> > > > Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/ >> > > > Reported-by: Nicolas Boichat <drinkcat@chromium.org> >> > > > Signed-off-by: Luis Henriques <lhenriques@suse.de> >> > > >> > > I tested v8 and I believe it works for NFS. >> > >> > Thanks a lot for the testing. And to everyone else for reviews, >> > feedback,... and patience. >> >> Thanks so much to you!!! >> >> Works here, you can add my >> Tested-by: Nicolas Boichat <drinkcat@chromium.org> > > What happened to this patch? It does not seem to have been picked up > yet? Any reason why? Hmm... good question. I'm not actually sure who would be picking it. Al, maybe...? Cheers, -- Luis > >> > >> > I'll now go look into the manpage and see what needs to be changed. >> > >> > Cheers, >> > -- >> > Luís
On Fri, Apr 9, 2021 at 4:39 PM Luis Henriques <lhenriques@suse.de> wrote: > > Nicolas Boichat <drinkcat@chromium.org> writes: > > > On Wed, Feb 24, 2021 at 6:44 PM Nicolas Boichat <drinkcat@chromium.org> wrote: > >> > >> On Wed, Feb 24, 2021 at 6:22 PM Luis Henriques <lhenriques@suse.de> wrote: > >> > > >> > On Tue, Feb 23, 2021 at 08:00:54PM -0500, Olga Kornievskaia wrote: > >> > > On Mon, Feb 22, 2021 at 5:25 AM Luis Henriques <lhenriques@suse.de> wrote: > >> > > > > >> > > > A regression has been reported by Nicolas Boichat, found while using the > >> > > > copy_file_range syscall to copy a tracefs file. Before commit > >> > > > 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the > >> > > > kernel would return -EXDEV to userspace when trying to copy a file across > >> > > > different filesystems. After this commit, the syscall doesn't fail anymore > >> > > > and instead returns zero (zero bytes copied), as this file's content is > >> > > > generated on-the-fly and thus reports a size of zero. > >> > > > > >> > > > This patch restores some cross-filesystem copy restrictions that existed > >> > > > prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across > >> > > > devices"). Filesystems are still allowed to fall-back to the VFS > >> > > > generic_copy_file_range() implementation, but that has now to be done > >> > > > explicitly. > >> > > > > >> > > > nfsd is also modified to fall-back into generic_copy_file_range() in case > >> > > > vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV. > >> > > > > >> > > > Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") > >> > > > Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/ > >> > > > Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/ > >> > > > Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/ > >> > > > Reported-by: Nicolas Boichat <drinkcat@chromium.org> > >> > > > Signed-off-by: Luis Henriques <lhenriques@suse.de> > >> > > > >> > > I tested v8 and I believe it works for NFS. > >> > > >> > Thanks a lot for the testing. And to everyone else for reviews, > >> > feedback,... and patience. > >> > >> Thanks so much to you!!! > >> > >> Works here, you can add my > >> Tested-by: Nicolas Boichat <drinkcat@chromium.org> > > > > What happened to this patch? It does not seem to have been picked up > > yet? Any reason why? > > Hmm... good question. I'm not actually sure who would be picking it. Al, > maybe...? > Darrick, Would you mind taking this through your tree in case Al doesn't pick it up? Thanks, Amir.
On Fri, Apr 9, 2021 at 9:50 PM Amir Goldstein <amir73il@gmail.com> wrote: > > On Fri, Apr 9, 2021 at 4:39 PM Luis Henriques <lhenriques@suse.de> wrote: > > > > Nicolas Boichat <drinkcat@chromium.org> writes: > > > > > On Wed, Feb 24, 2021 at 6:44 PM Nicolas Boichat <drinkcat@chromium.org> wrote: > > >> > > >> On Wed, Feb 24, 2021 at 6:22 PM Luis Henriques <lhenriques@suse.de> wrote: > > >> > > > >> > On Tue, Feb 23, 2021 at 08:00:54PM -0500, Olga Kornievskaia wrote: > > >> > > On Mon, Feb 22, 2021 at 5:25 AM Luis Henriques <lhenriques@suse.de> wrote: > > >> > > > > > >> > > > A regression has been reported by Nicolas Boichat, found while using the > > >> > > > copy_file_range syscall to copy a tracefs file. Before commit > > >> > > > 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the > > >> > > > kernel would return -EXDEV to userspace when trying to copy a file across > > >> > > > different filesystems. After this commit, the syscall doesn't fail anymore > > >> > > > and instead returns zero (zero bytes copied), as this file's content is > > >> > > > generated on-the-fly and thus reports a size of zero. > > >> > > > > > >> > > > This patch restores some cross-filesystem copy restrictions that existed > > >> > > > prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across > > >> > > > devices"). Filesystems are still allowed to fall-back to the VFS > > >> > > > generic_copy_file_range() implementation, but that has now to be done > > >> > > > explicitly. > > >> > > > > > >> > > > nfsd is also modified to fall-back into generic_copy_file_range() in case > > >> > > > vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV. > > >> > > > > > >> > > > Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") > > >> > > > Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/ > > >> > > > Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/ > > >> > > > Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/ > > >> > > > Reported-by: Nicolas Boichat <drinkcat@chromium.org> > > >> > > > Signed-off-by: Luis Henriques <lhenriques@suse.de> > > >> > > > > >> > > I tested v8 and I believe it works for NFS. > > >> > > > >> > Thanks a lot for the testing. And to everyone else for reviews, > > >> > feedback,... and patience. > > >> > > >> Thanks so much to you!!! > > >> > > >> Works here, you can add my > > >> Tested-by: Nicolas Boichat <drinkcat@chromium.org> > > > > > > What happened to this patch? It does not seem to have been picked up > > > yet? Any reason why? > > > > Hmm... good question. I'm not actually sure who would be picking it. Al, > > maybe...? > > > > Darrick, > > Would you mind taking this through your tree in case Al doesn't pick it up? Err, sorry for yet another ping... but it would be good to move forward with those patches ,-P Thanks! > Thanks, > Amir.
Nicolas Boichat <drinkcat@chromium.org> writes: > On Fri, Apr 9, 2021 at 9:50 PM Amir Goldstein <amir73il@gmail.com> wrote: >> >> On Fri, Apr 9, 2021 at 4:39 PM Luis Henriques <lhenriques@suse.de> wrote: >> > >> > Nicolas Boichat <drinkcat@chromium.org> writes: >> > >> > > On Wed, Feb 24, 2021 at 6:44 PM Nicolas Boichat <drinkcat@chromium.org> wrote: >> > >> >> > >> On Wed, Feb 24, 2021 at 6:22 PM Luis Henriques <lhenriques@suse.de> wrote: >> > >> > >> > >> > On Tue, Feb 23, 2021 at 08:00:54PM -0500, Olga Kornievskaia wrote: >> > >> > > On Mon, Feb 22, 2021 at 5:25 AM Luis Henriques <lhenriques@suse.de> wrote: >> > >> > > > >> > >> > > > A regression has been reported by Nicolas Boichat, found while using the >> > >> > > > copy_file_range syscall to copy a tracefs file. Before commit >> > >> > > > 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the >> > >> > > > kernel would return -EXDEV to userspace when trying to copy a file across >> > >> > > > different filesystems. After this commit, the syscall doesn't fail anymore >> > >> > > > and instead returns zero (zero bytes copied), as this file's content is >> > >> > > > generated on-the-fly and thus reports a size of zero. >> > >> > > > >> > >> > > > This patch restores some cross-filesystem copy restrictions that existed >> > >> > > > prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across >> > >> > > > devices"). Filesystems are still allowed to fall-back to the VFS >> > >> > > > generic_copy_file_range() implementation, but that has now to be done >> > >> > > > explicitly. >> > >> > > > >> > >> > > > nfsd is also modified to fall-back into generic_copy_file_range() in case >> > >> > > > vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV. >> > >> > > > >> > >> > > > Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") >> > >> > > > Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/ >> > >> > > > Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/ >> > >> > > > Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/ >> > >> > > > Reported-by: Nicolas Boichat <drinkcat@chromium.org> >> > >> > > > Signed-off-by: Luis Henriques <lhenriques@suse.de> >> > >> > > >> > >> > > I tested v8 and I believe it works for NFS. >> > >> > >> > >> > Thanks a lot for the testing. And to everyone else for reviews, >> > >> > feedback,... and patience. >> > >> >> > >> Thanks so much to you!!! >> > >> >> > >> Works here, you can add my >> > >> Tested-by: Nicolas Boichat <drinkcat@chromium.org> >> > > >> > > What happened to this patch? It does not seem to have been picked up >> > > yet? Any reason why? >> > >> > Hmm... good question. I'm not actually sure who would be picking it. Al, >> > maybe...? >> > >> >> Darrick, >> >> Would you mind taking this through your tree in case Al doesn't pick it up? > > Err, sorry for yet another ping... but it would be good to move > forward with those patches ,-P Yeah, I'm not sure what else to do, or who else to bug regarding this :-/ Cheers, -- Luis
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 04937e51de56..23dab0fa9087 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -568,6 +568,7 @@ __be32 nfsd4_clone_file_range(struct nfsd_file *nf_src, u64 src_pos, ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst, u64 dst_pos, u64 count) { + ssize_t ret; /* * Limit copy to 4MB to prevent indefinitely blocking an nfsd @@ -578,7 +579,12 @@ ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst, * limit like this and pipeline multiple COPY requests. */ count = min_t(u64, count, 1 << 22); - return vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0); + ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0); + + if (ret == -EOPNOTSUPP || ret == -EXDEV) + ret = generic_copy_file_range(src, src_pos, dst, dst_pos, + count, 0); + return ret; } __be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp, diff --git a/fs/read_write.c b/fs/read_write.c index 75f764b43418..5a26297fd410 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -1388,28 +1388,6 @@ 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) -{ - /* - * 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); - - return generic_copy_file_range(file_in, pos_in, file_out, pos_out, len, - flags); -} - /* * Performs necessary checks before doing a file copy * @@ -1427,6 +1405,25 @@ static int generic_copy_file_checks(struct file *file_in, loff_t pos_in, loff_t size_in; int ret; + /* + * 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) { + if (file_in->f_op->copy_file_range != + file_out->f_op->copy_file_range) + return -EXDEV; + } else if (file_in->f_op->remap_file_range) { + if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb) + return -EXDEV; + } else { + return -EOPNOTSUPP; + } + ret = generic_file_rw_checks(file_in, file_out); if (ret) return ret; @@ -1495,6 +1492,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, file_start_write(file_out); + ret = -EOPNOTSUPP; /* * Try cloning first, this is supported by more file systems, and * more efficient if both clone and copy are supported (e.g. NFS). @@ -1513,9 +1511,10 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, } } - ret = do_copy_file_range(file_in, pos_in, file_out, pos_out, len, - flags); - WARN_ON_ONCE(ret == -EOPNOTSUPP); + 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); done: if (ret > 0) { fsnotify_access(file_in);
A regression has been reported by Nicolas Boichat, found while using the copy_file_range syscall to copy a tracefs file. Before commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the kernel would return -EXDEV to userspace when trying to copy a file across different filesystems. After this commit, the syscall doesn't fail anymore and instead returns zero (zero bytes copied), as this file's content is generated on-the-fly and thus reports a size of zero. This patch restores some cross-filesystem copy restrictions that existed prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices"). Filesystems are still allowed to fall-back to the VFS generic_copy_file_range() implementation, but that has now to be done explicitly. nfsd is also modified to fall-back into generic_copy_file_range() in case vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV. Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/ Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/ Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/ Reported-by: Nicolas Boichat <drinkcat@chromium.org> Signed-off-by: Luis Henriques <lhenriques@suse.de> --- Changes since v7 - set 'ret' to '-EOPNOTSUPP' before the clone 'if' statement so that the error returned is always related to the 'copy' operation Changes since v6 - restored i_sb checks for the clone operation Changes since v5 - check if ->copy_file_range is NULL before calling it Changes since v4 - nfsd falls-back to generic_copy_file_range() only *if* it gets -EOPNOTSUPP or -EXDEV. Changes since v3 - dropped the COPY_FILE_SPLICE flag - kept the f_op's checks early in generic_copy_file_checks, implementing Amir's suggestions - modified nfsd to use generic_copy_file_range() Changes since v2 - do all the required checks earlier, in generic_copy_file_checks(), adding new checks for ->remap_file_range - new COPY_FILE_SPLICE flag - don't remove filesystem's fallback to generic_copy_file_range() - updated commit changelog (and subject) Changes since v1 (after Amir review) - restored do_copy_file_range() helper - return -EOPNOTSUPP if fs doesn't implement CFR - updated commit description fs/nfsd/vfs.c | 8 +++++++- fs/read_write.c | 49 ++++++++++++++++++++++++------------------------- 2 files changed, 31 insertions(+), 26 deletions(-)