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authorChuck Lever <chuck.lever@oracle.com>2018-03-27 10:54:21 -0400
committerJ. Bruce Fields <bfields@redhat.com>2018-04-03 15:08:16 -0400
commit38a70315599dedacd9ff3bd1016f9048c9d0ad12 (patch)
tree047a3d88ea7e400827c806be98c8a22c35428db8 /net/sunrpc
parent8154ef2776aa512a3eaa0e7db030dc4803354d61 (diff)
downloadlinux-38a70315599dedacd9ff3bd1016f9048c9d0ad12.tar.bz2
NFSD: Clean up legacy NFS SYMLINK argument XDR decoders
Move common code in NFSD's legacy SYMLINK decoders into a helper. The immediate benefits include: - one fewer data copies on transports that support DDP - consistent error checking across all versions - reduction of code duplication - support for both legal forms of SYMLINK requests on RDMA transports for all versions of NFS (in particular, NFSv2, for completeness) In the long term, this helper is an appropriate spot to perform a per-transport call-out to fill the pathname argument using, say, RDMA Reads. Filling the pathname in the proc function also means that eventually the incoming filehandle can be interpreted so that filesystem- specific memory can be allocated as a sink for the pathname argument, rather than using anonymous pages. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'net/sunrpc')
-rw-r--r--net/sunrpc/svc.c67
1 files changed, 67 insertions, 0 deletions
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index a155e2de19aa..30a4226baf03 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -1575,3 +1575,70 @@ unsigned int svc_fill_write_vector(struct svc_rqst *rqstp, struct kvec *first,
return i;
}
EXPORT_SYMBOL_GPL(svc_fill_write_vector);
+
+/**
+ * svc_fill_symlink_pathname - Construct pathname argument for VFS symlink call
+ * @rqstp: svc_rqst to operate on
+ * @first: buffer containing first section of pathname
+ * @total: total length of the pathname argument
+ *
+ * Returns pointer to a NUL-terminated string, or an ERR_PTR. The buffer is
+ * released automatically when @rqstp is recycled.
+ */
+char *svc_fill_symlink_pathname(struct svc_rqst *rqstp, struct kvec *first,
+ size_t total)
+{
+ struct xdr_buf *arg = &rqstp->rq_arg;
+ struct page **pages;
+ char *result;
+
+ /* VFS API demands a NUL-terminated pathname. This function
+ * uses a page from @rqstp as the pathname buffer, to enable
+ * direct placement. Thus the total buffer size is PAGE_SIZE.
+ * Space in this buffer for NUL-termination requires that we
+ * cap the size of the returned symlink pathname just a
+ * little early.
+ */
+ if (total > PAGE_SIZE - 1)
+ return ERR_PTR(-ENAMETOOLONG);
+
+ /* Some types of transport can present the pathname entirely
+ * in rq_arg.pages. If not, then copy the pathname into one
+ * page.
+ */
+ pages = arg->pages;
+ WARN_ON_ONCE(arg->page_base != 0);
+ if (first->iov_base == 0) {
+ result = page_address(*pages);
+ result[total] = '\0';
+ } else {
+ size_t len, remaining;
+ char *dst;
+
+ result = page_address(*(rqstp->rq_next_page++));
+ dst = result;
+ remaining = total;
+
+ len = min_t(size_t, total, first->iov_len);
+ memcpy(dst, first->iov_base, len);
+ dst += len;
+ remaining -= len;
+
+ /* No more than one page left */
+ if (remaining) {
+ len = min_t(size_t, remaining, PAGE_SIZE);
+ memcpy(dst, page_address(*pages), len);
+ dst += len;
+ }
+
+ *dst = '\0';
+ }
+
+ /* Sanity check: we don't allow the pathname argument to
+ * contain a NUL byte.
+ */
+ if (strlen(result) != total)
+ return ERR_PTR(-EINVAL);
+ return result;
+}
+EXPORT_SYMBOL_GPL(svc_fill_symlink_pathname);