[PATCH v3 3/6] SUNRPC: Introduce xdr_buf_trim_head()
From: Anna Schumaker <anna@kernel.org>
Date: 2022-07-15 18:44:42
Subsystem:
kernel nfsd, sunrpc, and lockd servers, networking [general], nfs, sunrpc, and lockd clients, the rest · Maintainers:
Chuck Lever, Jeff Layton, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Trond Myklebust, Anna Schumaker, Linus Torvalds
From: Anna Schumaker <redacted> The READ_PLUS operation uses a 32-bit length field for encoding a DATA segment, but 64-bit length field for encoding a HOLE segment. When setting up our reply buffer, we need to reserve enough space to encode a HOLE before reading the file data and use this function if the first segment turns out to be DATA. Signed-off-by: Anna Schumaker <redacted> --- include/linux/sunrpc/xdr.h | 1 + net/sunrpc/xdr.c | 17 +++++++++++++++++ 2 files changed, 18 insertions(+)
diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index e26047d474b2..bdaf048edde0 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h@@ -191,6 +191,7 @@ xdr_adjust_iovec(struct kvec *iov, __be32 *p) extern void xdr_shift_buf(struct xdr_buf *, size_t); extern void xdr_buf_from_iov(const struct kvec *, struct xdr_buf *); extern int xdr_buf_subsegment(const struct xdr_buf *, struct xdr_buf *, unsigned int, unsigned int); +extern void xdr_buf_trim_head(struct xdr_buf *, unsigned int); extern void xdr_buf_trim(struct xdr_buf *, unsigned int); extern int read_bytes_from_xdr_buf(const struct xdr_buf *, unsigned int, void *, unsigned int); extern int write_bytes_to_xdr_buf(const struct xdr_buf *, unsigned int, void *, unsigned int);
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 63d9cdc989da..37956a274f81 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c@@ -1739,6 +1739,23 @@ unsigned int xdr_stream_move_subsegment(struct xdr_stream *xdr, unsigned int off } EXPORT_SYMBOL_GPL(xdr_stream_move_subsegment); +/** + * xdr_buf_trim_head - lop at most "len" bytes off the end of "buf"->head + * @buf: buf to be trimmed + * @len: number of bytes to reduce "buf"->head by + * + * Trim an xdr_buf->head by the given number of bytes by fixing up the lengths. + * Note that it's possible that we'll trim less than that amount if the + * xdr_buf->head is too small. + */ +void xdr_buf_trim_head(struct xdr_buf *buf, unsigned int len) +{ + size_t trim = min_t(size_t, buf->head[0].iov_len, len); + buf->head[0].iov_len -= trim; + buf->len -= trim; +} +EXPORT_SYMBOL_GPL(xdr_buf_trim_head); + /** * xdr_buf_trim - lop at most "len" bytes off the end of "buf" * @buf: buf to be trimmed
--
2.37.1