From: Jeff Layton <jlayton@redhat.com>
Date: Mon, 26 Jul 2010 11:15:55 -0400
Subject: [fs] nfs: fix file create failure with HPUX client
Message-id: <1280142955-8734-1-git-send-email-jlayton@redhat.com>
Patchwork-id: 27091
O-Subject: [RHEL5.6 PATCH] BZ#605720: nfsd(v2/v3): fix the failure of creation
from HPUX client
Bugzilla: 605720
RH-Acked-by: Steve Dickson <SteveD@redhat.com>
From: wengang wang <wen.gang.wang@oracle.com>
I'm not aware of any customers having reported this problem, but Oracle
is apparently carrying a patch for OEL to fix this problem. The problem
is apparently that the HPUX NFS client sets the mode of the file oddly
on create. nfsd then attempts to do a follow on setattr to truncate the
file, but that fails on some filesystems because of the mode.
This patch fixes this by making the server skip the truncate if we're
setting the size to zero and it was just created by nfsd. I don't have a
client that behaves like this, but I've tested this patch from RHEL
clients and it seems to be OK.
The OEL patch for this seems to be based on an earlier version submitted
by Wengang, but this one more closely matches what finally went
upstream.
Original patch description follows:
-------------------------------[snip]----------------------------
sometimes HPUX nfs client sends a create request to linux nfs server(v2/v3).
the dump of the request is like:
obj_attributes
mode: value follows
set_it: value follows (1)
mode: 00
uid: no value
set_it: no value (0)
gid: value follows
set_it: value follows (1)
gid: 8030
size: value follows
set_it: value follows (1)
size: 0
atime: don't change
set_it: don't change (0)
mtime: don't change
set_it: don't change (0)
note that mode is 00(havs no rwx privilege even for the owner) and it requires
to set size to 0.
as current nfsd(v2/v3) implementation, the server does mainly 2 steps:
1) creates the file in mode specified by calling vfs_create().
2) sets attributes for the file by calling nfsd_setattr().
at step 2), it finally calls file system specific setattr() function which may
fail when checking permission because changing size needs WRITE privilege but
it has none since mode is 000.
for this case, a new file created, we may simply ignore the request of
setting size to 0, so that WRITE privilege is not needed and the open
succeeds.
Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
--
vfs.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 9f636e2..bc4c754 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1115,6 +1115,21 @@ nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp,
}
#endif /* CONFIG_NFSD_V3 */
+/* HPUX client sometimes creates a file in mode 000, and sets size to 0.
+ * setting size to 0 may fail for some specific file systems by the permission
+ * checking which requires WRITE permission but the mode is 000.
+ * we ignore the resizing(to 0) on the just new created file, since the size is
+ * 0 after file created.
+ *
+ * call this only after vfs_create() is called.
+ * */
+static void
+nfsd_check_ignore_resizing(struct iattr *iap)
+{
+ if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
+ iap->ia_valid &= ~ATTR_SIZE;
+}
+
/*
* Create a file (regular, directory, device, fifo); UNIX sockets
* not yet implemented.
@@ -1197,6 +1212,8 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
switch (type) {
case S_IFREG:
err = vfs_create(dirp, dchild, iap->ia_mode, NULL);
+ if (!err)
+ nfsd_check_ignore_resizing(iap);
break;
case S_IFDIR:
err = vfs_mkdir(dirp, dchild, iap->ia_mode);
@@ -1350,6 +1367,8 @@ nfsd_create_v3(struct svc_rqst *rqstp, struct svc_fh *fhp,
/* setattr will sync the child (or not) */
}
+ nfsd_check_ignore_resizing(iap);
+
if (createmode == NFS3_CREATE_EXCLUSIVE) {
/* Cram the verifier into atime/mtime */
iap->ia_valid = ATTR_MTIME|ATTR_ATIME
