Re: [PATCH v8] vfs: fix copy_file_range regression in cross-fs copies
From: Luis Henriques
Date: Wed Feb 24 2021 - 05:24:46 EST
On Tue, Feb 23, 2021 at 08:00:54PM -0500, Olga Kornievskaia wrote:
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On Mon, Feb 22, 2021 at 5:25 AM Luis Henriques <lhenriques@xxxxxxx> wrote:
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> A regression has been reported by Nicolas Boichat, found while using the
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> copy_file_range syscall to copy a tracefs file. Before commit
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> 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the
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> kernel would return -EXDEV to userspace when trying to copy a file across
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> different filesystems. After this commit, the syscall doesn't fail anymore
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> and instead returns zero (zero bytes copied), as this file's content is
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> generated on-the-fly and thus reports a size of zero.
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> This patch restores some cross-filesystem copy restrictions that existed
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> prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across
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> devices"). Filesystems are still allowed to fall-back to the VFS
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> generic_copy_file_range() implementation, but that has now to be done
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> explicitly.
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> nfsd is also modified to fall-back into generic_copy_file_range() in case
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> vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV.
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> Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices")
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> Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@xxxxxxxxxxxx/
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> Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@xxxxxxxxxxxxxx/
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> Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/
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> Reported-by: Nicolas Boichat <drinkcat@xxxxxxxxxxxx>
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> Signed-off-by: Luis Henriques <lhenriques@xxxxxxx>
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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