Looks good, thanks for your persistance--applied to
git://linux-nfs.org/~bfields/linux.git for-2.6.30
--b.
On Tue, Feb 10, 2009 at 11:27:51AM +0800, wengang wang wrote:
> 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
> fails when checking permission because changing size needs WRITE privilege but
> it has no since mode is 000.
>
> for this case, a new file created, we may simply ignore the request of setting
> size to 0. so that the WRITE privilege is not needed and finally success.
>
> the patch is based on 2.6.27.10.
> this is the 3rd edition of the patch. comparing with the 1st edition, it moves
> common code and comment to function nfsd_check_ignore_resizing().
> nfsd_create() and nfsd_create_v3() calls this function instead of embedding the
> code and comment directly.
>
> Signed-off-by: Wengang Wang <wen.gang.wang@xxxxxxxxxx>
> --
> vfs.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
> diff -up ./fs/nfsd/vfs.c.orig ./fs/nfsd/vfs.c
> --- ./fs/nfsd/vfs.c.orig 2009-02-10 09:59:07.000000000 +0800
> +++ ./fs/nfsd/vfs.c 2009-02-10 10:07:31.000000000 +0800
> @@ -1173,6 +1173,21 @@ nfsd_create_setattr(struct svc_rqst *rqs
> return 0;
> }
>
> +/* 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.
> @@ -1268,6 +1283,8 @@ nfsd_create(struct svc_rqst *rqstp, stru
> switch (type) {
> case S_IFREG:
> host_err = vfs_create(dirp, dchild, iap->ia_mode, NULL);
> + if (!host_err)
> + nfsd_check_ignore_resizing(iap);
> break;
> case S_IFDIR:
> host_err = vfs_mkdir(dirp, dchild, iap->ia_mode);
> @@ -1421,6 +1438,8 @@ nfsd_create_v3(struct svc_rqst *rqstp, s
> /* 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
> --
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