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[virtio-9p] Ignore O_DIRECT hint from client. 

The O_DIRECT flag imposes alignment restrictions on the length and address
of userspace buffers and the file offset of I/Os.

While VirtFS/9P has plans to implement O_DIRECT behavior on the server,
for now we will stick to a behavior like NFS by bypassing the page cache
only on the client. Server may still cache the I/O.

Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
This commit is contained in:
Venkateswararao Jujjuri (JV) 2010-09-19 10:47:11 -07:00 committed by Anthony Liguori
parent df0973a465
commit 0f8151cb75
1 changed files with 5 additions and 0 deletions
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5
hw/virtio-9p.c
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@ -1704,6 +1704,8 @@ static void v9fs_open_post_lstat(V9fsState *s, V9fsOpenState *vs, int err)
if (s->proto_version == V9FS_PROTO_2000L) {
flags = vs->mode;
flags &= ~(O_NOCTTY | O_ASYNC | O_CREAT);
/* Ignore direct disk access hint until the server supports it. */
flags &= ~O_DIRECT;
} else {
flags = omode_to_uflags(vs->mode);
}
@ -1826,6 +1828,9 @@ static void v9fs_lcreate(V9fsState *s, V9fsPDU *pdu)
v9fs_string_sprintf(&vs->fullname, "%s/%s", vs->fidp->path.data,
vs->name.data);
/* Ignore direct disk access hint until the server supports it. */
flags &= ~O_DIRECT;
vs->fidp->fs.fd = v9fs_do_open2(s, vs->fullname.data, vs->fidp->uid,
gid, flags, mode);
v9fs_lcreate_post_do_open2(s, vs, err);