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| author | Chuck Lever <chuck.lever@oracle.com> | 2026-04-27 16:50:47 +0300 |
|---|---|---|
| committer | Chuck Lever <cel@kernel.org> | 2026-06-09 23:32:59 +0300 |
| commit | e9be933959b581effd426f93b86654f5fbf0c574 (patch) | |
| tree | 08f08c29cf8327b7d0bf2a6f8857d906d79b46ac /include | |
| parent | f8b942fc380c3b38b8a0e2d97f020b162fa3f3ae (diff) | |
| download | linux-e9be933959b581effd426f93b86654f5fbf0c574.tar.xz | |
SUNRPC: Add helpers to convert xdr_buf byte ranges to scatterlists
The crypto/krb5 library accepts data in scatterlist form, but
the GSS-API layer presents RPC payloads as struct xdr_buf.
Bridge that gap with a pair of helper functions:
xdr_buf_to_sg() - populate a caller-supplied scatterlist
array from a byte range
xdr_buf_to_sg_alloc() - populate a caller-supplied inline
scatterlist, chaining to a heap-
allocated overflow for large payloads
The inline array (typically stack-allocated at eight entries)
covers the common case of small RPCs with no heap allocation
on the encrypt/decrypt path. Only buffers spanning many pages
incur a kmalloc for the chained extension.
The segment-walking logic follows the same head, page array,
tail traversal as xdr_process_buf(), but populates a
scatterlist directly rather than invoking a per-segment
callback. sg_next() traversal makes the walker safe for
chained scatterlists. Once subsequent patches reroute all
per-message crypto operations through crypto/krb5,
xdr_process_buf() loses its last callers and is removed.
Assisted-by: Claude:claude-opus-4-6
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Anna Schumaker <anna.schumaker@hammerspace.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/sunrpc/xdr.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h index b639a6fafcbc..f82446993fde 100644 --- a/include/linux/sunrpc/xdr.h +++ b/include/linux/sunrpc/xdr.h @@ -140,6 +140,21 @@ int xdr_alloc_bvec(struct xdr_buf *buf, gfp_t gfp); void xdr_free_bvec(struct xdr_buf *buf); unsigned int xdr_buf_to_bvec(struct bio_vec *bvec, unsigned int bvec_size, const struct xdr_buf *xdr); +int xdr_buf_to_sg(const struct xdr_buf *buf, unsigned int offset, + unsigned int len, struct scatterlist *sg, unsigned int nsg); +int xdr_buf_to_sg_alloc(const struct xdr_buf *buf, unsigned int offset, + unsigned int len, struct scatterlist *sg_head, + unsigned int sg_head_nents, + struct scatterlist **sg_overflow, gfp_t gfp); + +/* + * Inline scatterlist entries for xdr_buf_to_sg_alloc(). Sized to cover the + * head kvec, tail kvec, and a few page fragments without any heap allocation. + */ +enum { + XDR_BUF_TO_SG_NENTS = 8, +}; + static inline __be32 *xdr_encode_array(__be32 *p, const void *s, unsigned int len) { |