From mboxrd@z Thu Jan 1 00:00:00 1970 From: Petr Vorel Date: Wed, 24 Feb 2021 09:30:03 +0100 Subject: [LTP] [PATCH v4] vfs: fix copy_file_range regression in cross-fs copies In-Reply-To: References: <20210218143635.24916-1-lhenriques@suse.de> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ltp@lists.linux.it Hi Amir, > On Thu, Feb 18, 2021 at 4:35 PM 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. > Petr, > Please note that the check for verify_cross_fs_copy_support() in LTP > tests can no longer be used to determine if copy_file_range() is post v5.3. > You will need to fix the tests to expect cross-fs failures (this change of > behavior is supposed to be backported to stable kernels as well). > I guess the copy_file_range() tests will need to use min_kver. Thanks for info! I see, after "vfs: fix copy_file_range regression in cross-fs copies" and backported to 5.4.x, 5.10.x and 5.11.x we'll probably have to replace verify_cross_fs_copy_support() with .min_kver = "5.3". We have also tst_kvercmp2() in case original 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") was backported to any enterprise distro (and then this fix would follow). Kind regards, Petr > Thanks, > Amir.