diff options
| author | Jiachen Zhang <zhangjiachen.jaycee@bytedance.com> | 2020-08-24 18:59:57 +0800 |
|---|---|---|
| committer | Dr. David Alan Gilbert <dgilbert@redhat.com> | 2020-09-25 12:45:58 +0100 |
| commit | e12a0edafeb5019aac74114b62a4703f79c5c693 (patch) | |
| tree | badeaa53bb34f24540bf03dc00e536483eaa61f1 /tools/virtiofsd/helper.c | |
| parent | 04d325e86f79bd61f8fd50d45ff795aca0dd3404 (diff) | |
virtiofsd: Add -o allow_direct_io|no_allow_direct_io options
Due to the commit 65da4539803373ec4eec97ffc49ee90083e56efd, 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>
Diffstat (limited to 'tools/virtiofsd/helper.c')
| -rw-r--r-- | tools/virtiofsd/helper.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/tools/virtiofsd/helper.c b/tools/virtiofsd/helper.c index 7bc5d7dc5a..85770d63f1 100644 --- a/tools/virtiofsd/helper.c +++ b/tools/virtiofsd/helper.c @@ -178,6 +178,10 @@ void fuse_cmdline_help(void) " (0 leaves rlimit unchanged)\n" " default: min(1000000, fs.file-max - 16384)\n" " if the current rlimit is lower\n" + " -o allow_direct_io|no_allow_direct_io\n" + " retain/discard O_DIRECT flags passed down\n" + " to virtiofsd from guest applications.\n" + " default: no_allow_direct_io\n" ); } |