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QEMU main repository: Please see https://www.qemu.org/docs/master/devel/submitting-a-patch.html for how to submit changes to QEMU. Pull Requests are ignored. Please only use release tarballs from the QEMU website. http://www.qemu.org

emulation kvm qemu virtualization

Tree: aa087962d7

History

Jiachen Zhang e12a0edafe virtiofsd: Add -o allow_direct_io\|no_allow_direct_io options Due to the commit `65da453980`, the O_DIRECT open flag of guest applications will be discarded by virtiofsd. While this behavior makes it consistent with the virtio-9p scheme when guest applications use direct I/O, we no longer have any chance to bypass the host page cache. Therefore, we add a flag 'allow_direct_io' to lo_data. If '-o no_allow_direct_io' option is added, or none of '-o allow_direct_io' or '-o no_allow_direct_io' is added, the 'allow_direct_io' will be set to 0, and virtiofsd discards O_DIRECT as before. If '-o allow_direct_io' is added to the starting command-line, 'allow_direct_io' will be set to 1, so that the O_DIRECT flags will be retained and host page cache can be bypassed. Signed-off-by: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-Id: <20200824105957.61265-1-zhangjiachen.jaycee@bytedance.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>	6 years ago
..
virtiofsd	virtiofsd: Add -o allow_direct_io\|no_allow_direct_io options	6 years ago
meson.build	tools/virtiofsd: convert to Meson	6 years ago

Jiachen Zhang e12a0edafe virtiofsd: Add -o allow_direct_io|no_allow_direct_io options

Due to the commit 65da453980, the O_DIRECT
open flag of guest applications will be discarded by virtiofsd. While
this behavior makes it consistent with the virtio-9p scheme when guest
applications use direct I/O, we no longer have any chance to bypass the
host page cache.

Therefore, we add a flag 'allow_direct_io' to lo_data. If '-o
 no_allow_direct_io' option is added, or none of '-o allow_direct_io' or
 '-o no_allow_direct_io' is added, the 'allow_direct_io' will be set to
 0, and virtiofsd discards O_DIRECT as before. If '-o allow_direct_io'
is added to the starting command-line, 'allow_direct_io' will be set to
1, so that the O_DIRECT flags will be retained and host page cache can
be bypassed.

Signed-off-by: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200824105957.61265-1-zhangjiachen.jaycee@bytedance.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

6 years ago

virtiofsd virtiofsd: Add -o allow_direct_io|no_allow_direct_io options 6 years ago

meson.build tools/virtiofsd: convert to Meson 6 years ago