tools/virtiofsd/passthrough_ll.c | 16 ++++++++++------ 1 files changed, 10 insertions(+), 6 deletions(-)
cache=none means to bypass host cache. So we can't remove O_DIRECT flag in
unconditionally in update_open_flags();
Signed-off-by: Catherine Ho <catherine.hecx@gmail.com>
---
tools/virtiofsd/passthrough_ll.c | 16 ++++++++++------
1 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 4c35c95..889e144 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -1677,7 +1677,8 @@ static void lo_releasedir(fuse_req_t req, fuse_ino_t ino,
fuse_reply_err(req, 0);
}
-static void update_open_flags(int writeback, struct fuse_file_info *fi)
+static void update_open_flags(int writeback, int cache_mode,
+ struct fuse_file_info *fi)
{
/*
* With writeback cache, kernel may send read requests even
@@ -1702,10 +1703,13 @@ static void update_open_flags(int writeback, struct fuse_file_info *fi)
/*
* O_DIRECT in guest should not necessarily mean bypassing page
- * cache on host as well. If somebody needs that behavior, it
- * probably should be a configuration knob in daemon.
+ * cache on host as well. If cache=none, set the flag to O_DIRECT
*/
- fi->flags &= ~O_DIRECT;
+ if (cache_mode == CACHE_NONE) {
+ fi->flags |= O_DIRECT;
+ } else {
+ fi->flags &= ~O_DIRECT;
+ }
}
static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
@@ -1737,7 +1741,7 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
goto out;
}
- update_open_flags(lo->writeback, fi);
+ update_open_flags(lo->writeback, lo->cache, fi);
fd = openat(parent_inode->fd, name, (fi->flags | O_CREAT) & ~O_NOFOLLOW,
mode);
@@ -1947,7 +1951,7 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
fuse_log(FUSE_LOG_DEBUG, "lo_open(ino=%" PRIu64 ", flags=%d)\n", ino,
fi->flags);
- update_open_flags(lo->writeback, fi);
+ update_open_flags(lo->writeback, lo->cache, fi);
sprintf(buf, "%i", lo_fd(req, ino));
fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
--
1.7.1
cache=none means to bypass host cache. So we can't remove O_DIRECT flag in
unconditionally in update_open_flags();
Signed-off-by: Catherine Ho <catherine.hecx@gmail.com>
---
v2: Fix to keep flags unchanged if cache=none, otherwise changed the file
without O_DIRECT incorrectly.
tools/virtiofsd/passthrough_ll.c | 14 ++++++++------
1 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 4c35c95..59e64dd 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -1677,7 +1677,8 @@ static void lo_releasedir(fuse_req_t req, fuse_ino_t ino,
fuse_reply_err(req, 0);
}
-static void update_open_flags(int writeback, struct fuse_file_info *fi)
+static void update_open_flags(int writeback, int cache_mode,
+ struct fuse_file_info *fi)
{
/*
* With writeback cache, kernel may send read requests even
@@ -1702,10 +1703,11 @@ static void update_open_flags(int writeback, struct fuse_file_info *fi)
/*
* O_DIRECT in guest should not necessarily mean bypassing page
- * cache on host as well. If somebody needs that behavior, it
- * probably should be a configuration knob in daemon.
+ * cache on host as well. If cache=none, keep the flag unchanged
*/
- fi->flags &= ~O_DIRECT;
+ if (cache_mode != CACHE_NONE) {
+ fi->flags &= ~O_DIRECT;
+ }
}
static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
@@ -1737,7 +1739,7 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
goto out;
}
- update_open_flags(lo->writeback, fi);
+ update_open_flags(lo->writeback, lo->cache, fi);
fd = openat(parent_inode->fd, name, (fi->flags | O_CREAT) & ~O_NOFOLLOW,
mode);
@@ -1947,7 +1949,7 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
fuse_log(FUSE_LOG_DEBUG, "lo_open(ino=%" PRIu64 ", flags=%d)\n", ino,
fi->flags);
- update_open_flags(lo->writeback, fi);
+ update_open_flags(lo->writeback, lo->cache, fi);
sprintf(buf, "%i", lo_fd(req, ino));
fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
--
1.7.1
Ping :) --- B.R. Catherine On Sat, 11 Apr 2020 at 16:41, Catherine Ho <catherine.hecx@gmail.com> wrote: > > cache=none means to bypass host cache. So we can't remove O_DIRECT flag in > unconditionally in update_open_flags(); > > Signed-off-by: Catherine Ho <catherine.hecx@gmail.com> > --- > v2: Fix to keep flags unchanged if cache=none, otherwise changed the file > without O_DIRECT incorrectly. > tools/virtiofsd/passthrough_ll.c | 14 ++++++++------ > 1 files changed, 8 insertions(+), 6 deletions(-) > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > index 4c35c95..59e64dd 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -1677,7 +1677,8 @@ static void lo_releasedir(fuse_req_t req, fuse_ino_t ino, > fuse_reply_err(req, 0); > } > > -static void update_open_flags(int writeback, struct fuse_file_info *fi) > +static void update_open_flags(int writeback, int cache_mode, > + struct fuse_file_info *fi) > { > /* > * With writeback cache, kernel may send read requests even > @@ -1702,10 +1703,11 @@ static void update_open_flags(int writeback, struct fuse_file_info *fi) > > /* > * O_DIRECT in guest should not necessarily mean bypassing page > - * cache on host as well. If somebody needs that behavior, it > - * probably should be a configuration knob in daemon. > + * cache on host as well. If cache=none, keep the flag unchanged > */ > - fi->flags &= ~O_DIRECT; > + if (cache_mode != CACHE_NONE) { > + fi->flags &= ~O_DIRECT; > + } > } > > static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name, > @@ -1737,7 +1739,7 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name, > goto out; > } > > - update_open_flags(lo->writeback, fi); > + update_open_flags(lo->writeback, lo->cache, fi); > > fd = openat(parent_inode->fd, name, (fi->flags | O_CREAT) & ~O_NOFOLLOW, > mode); > @@ -1947,7 +1949,7 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi) > fuse_log(FUSE_LOG_DEBUG, "lo_open(ino=%" PRIu64 ", flags=%d)\n", ino, > fi->flags); > > - update_open_flags(lo->writeback, fi); > + update_open_flags(lo->writeback, lo->cache, fi); > > sprintf(buf, "%i", lo_fd(req, ino)); > fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW); > -- > 1.7.1 >
On Sat, Apr 11, 2020 at 04:35:44AM -0400, Catherine Ho wrote: > @@ -1702,10 +1703,11 @@ static void update_open_flags(int writeback, struct fuse_file_info *fi) > > /* > * O_DIRECT in guest should not necessarily mean bypassing page > - * cache on host as well. If somebody needs that behavior, it > - * probably should be a configuration knob in daemon. > + * cache on host as well. If cache=none, keep the flag unchanged > */ > - fi->flags &= ~O_DIRECT; > + if (cache_mode != CACHE_NONE) { > + fi->flags &= ~O_DIRECT; > + } > } > Thanks for the patch! I have CCed the virtio-fs mailing list so more people see it. Please add a new command-line option to control O_DIRECT behavior. There are two cases: 1. O_DIRECT bypasses the guest page cache but not the host page cache. This makes sense when the DAX feature is enabled. 2. O_DIRECT bypasses both the guest and host page cache. This make sense for non-DAX and for I/O performance benchmarking. Today only #1 is supported. Your patch makes the behavior dependent on the cache mode option, but the cache mode doesn't necessarily determine how O_DIRECT should be handled. For example, in the DAX case the guest page cache is bypassed and cache=none can be used, but we do want to use the host page cache. You can add a new option so that O_DIRECT handling is configurable for all cases. Stefan
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