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[Qemu-devel] [PATCH -V4 26/26] virtio-9p: Change handling of flags in op
From: |
Venkateswararao Jujjuri (JV) |
Subject: |
[Qemu-devel] [PATCH -V4 26/26] virtio-9p: Change handling of flags in open() path for 9P2000.L |
Date: |
Sun, 29 Aug 2010 12:02:52 -0700 |
From: Sripathi Kodi <address@hidden>
This patch applies on top of 9P2000.L patches that we have on the list.
I took a look at how 9P server is handling open() flags in 9P2000.L path.
I think we can do away with the valid_flags() function and simplify the
code. The reasoning is as follows:
O_NOCTTY: (If the file is a terminal, don't make it the controlling
terminal of the process even though the process does not have a controlling
terminal) By the time the control reaches 9P client it is clear that what
we have is not a terminal device. Hence it does not matter what we do with
this flag. In any case 9P server can filter this flag out before making the
syscall.
O_NONBLOCK: (Don't block if i) Can't read/write to the file ii) Can't get
locks) This has an impact on FIFOs, but also on file locks. Hence we can
pass it down to the system call.
O_ASYNC: From the manpage:
O_ASYNC
Enable signal-driven I/O: generate a signal (SIGIO by default, but
this can be changed via fcntl(2)) when input or output becomes pos-
sible on this file descriptor. This feature is only available for
terminals, pseudo-terminals, sockets, and (since Linux 2.6) pipes
and FIFOs. See fcntl(2) for further details.
Again, this does not make any impact on regular files handled by 9P. Also,
we don't want 9P server to receive SIGIO. Hence I think 9P server can
filter this flag out before making the syscall.
O_CLOEXEC: This flag makes sense only on the client. If guest user space
sets this flag the guest VFS will take care of calling close() on the fd if
an exec() happens. Hence 9P client need not be bothered with this flag.
Also I think QEMU will not do an exec, but if it does, it makes sense to
close these fds. Hence we can pass this flag down to the syscall.
O_CREAT: Since we are in open() path it means we have confirmed that the file
exists. Hence there is no need to pass O_CREAT flag down to the system. In fact
on some versions of glibc this causes problems, because we pass O_CREAT flag,
but don't have permission bits. Hence we can just mask this flag out.
So in summary:
Mask out:
O_NOCTTY
O_ASYNC
O_CREAT
Pass-through:
O_NONBLOCK
O_CLOEXEC
Signed-off-by: Sripathi Kodi <address@hidden>
Signed-off-by: Venkateswararao Jujjuri <address@hidden>
---
hw/virtio-9p.c | 14 +-------------
1 files changed, 1 insertions(+), 13 deletions(-)
diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
index b6cbbbb..5347961 100644
--- a/hw/virtio-9p.c
+++ b/hw/virtio-9p.c
@@ -1672,15 +1672,6 @@ out:
qemu_free(vs);
}
-static inline int valid_flags(int flag)
-{
- if (flag & O_NOCTTY || flag & O_NONBLOCK || flag & O_ASYNC ||
- flag & O_CLOEXEC)
- return 0;
- else
- return 1;
-}
-
static void v9fs_open_post_lstat(V9fsState *s, V9fsOpenState *vs, int err)
{
int flags;
@@ -1697,11 +1688,8 @@ static void v9fs_open_post_lstat(V9fsState *s,
V9fsOpenState *vs, int err)
v9fs_open_post_opendir(s, vs, err);
} else {
if (s->proto_version == V9FS_PROTO_2000L) {
- if (!valid_flags(vs->mode)) {
- err = -EINVAL;
- goto out;
- }
flags = vs->mode;
+ flags &= ~(O_NOCTTY | O_ASYNC | O_CREAT);
} else {
flags = omode_to_uflags(vs->mode);
}
--
1.6.5.2
- [Qemu-devel] [PATCH -V4 16/26] [virtio-9p] qemu: virtio-9p: Implement LOPEN, (continued)
- [Qemu-devel] [PATCH -V4 16/26] [virtio-9p] qemu: virtio-9p: Implement LOPEN, Venkateswararao Jujjuri (JV), 2010/08/29
- [Qemu-devel] [PATCH -V4 14/26] qemu: virtio-9p: Implement TMKDIR, Venkateswararao Jujjuri (JV), 2010/08/29
- [Qemu-devel] [PATCH -V4 18/26] virtio-9p: Implement TXATTRWALK, Venkateswararao Jujjuri (JV), 2010/08/29
- [Qemu-devel] [PATCH -V4 17/26] virtio-9p: Add fidtype so that we can do type specific operation, Venkateswararao Jujjuri (JV), 2010/08/29
- [Qemu-devel] [PATCH -V4 19/26] virtio-9p: Implement TXATTRCREATE, Venkateswararao Jujjuri (JV), 2010/08/29
- [Qemu-devel] [PATCH -V4 20/26] virtio-9p: Hide user.virtfs xattr in case of mapped security., Venkateswararao Jujjuri (JV), 2010/08/29
- [Qemu-devel] [PATCH -V4 22/26] virtio-9p: Use lchown which won't follow symlink, Venkateswararao Jujjuri (JV), 2010/08/29
- [Qemu-devel] [PATCH -V4 25/26] [virtio-9p] This patch implements TLERROR/RLERROR on the qemu 9P server., Venkateswararao Jujjuri (JV), 2010/08/29
- [Qemu-devel] [PATCH -V4 24/26] [virtio-9p] Remove all instances of unnecessary dotu variable., Venkateswararao Jujjuri (JV), 2010/08/29
- [Qemu-devel] [PATCH -V4 23/26] virtio-9p: Fix the memset usage, Venkateswararao Jujjuri (JV), 2010/08/29
- [Qemu-devel] [PATCH -V4 26/26] virtio-9p: Change handling of flags in open() path for 9P2000.L,
Venkateswararao Jujjuri (JV) <=
- [Qemu-devel] [PATCH -V4 21/26] virtio-9p: Add SM_NONE security model, Venkateswararao Jujjuri (JV), 2010/08/29
- [Qemu-devel] [PATCH -V4 04/26] [V4] virtio-9p: readdir implementation for 9p2000.L, Venkateswararao Jujjuri (JV), 2010/08/29
- [Qemu-devel] [PATCH -V4 03/26] virtio-9p: Return correct error from v9fs_remove, Venkateswararao Jujjuri (JV), 2010/08/29