The existing sg_zero_buffer() function is a bit restrictive.
For example protection information (PI) blocks are usually
initialized to 0xff bytes. As its name suggests sgl_memset()
is modelled on memset(). One difference is the type of the
val argument which is u8 rather than int.
Signed-off-by: Douglas Gilbert <dgilb...@interlog.com>
---
include/linux/scatterlist.h | 3 +++
lib/scatterlist.c | 39 +++++++++++++++++++++++++++++++++++--
2 files changed, 40 insertions(+), 2 deletions(-)
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index ae260dc5fedb..e50dc9a6d887 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -329,6 +329,9 @@ bool sgl_compare_sgl(struct scatterlist *x_sgl, unsigned
int x_nents, off_t x_sk
struct scatterlist *y_sgl, unsigned int y_nents, off_t
y_skip,
size_t n_bytes);
+void sgl_memset(struct scatterlist *sgl, unsigned int nents, off_t skip,
+ u8 val, size_t n_bytes);
+
/*
* Maximum number of entries that will be allocated in one piece, if
* a list larger than this is required then chaining will be utilized.
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 344725990b9d..3ca66f0c949f 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -1083,8 +1083,8 @@ EXPORT_SYMBOL(sgl_copy_sgl);
*
**/
bool sgl_compare_sgl(struct scatterlist *x_sgl, unsigned int x_nents, off_t
x_skip,
- struct scatterlist *y_sgl, unsigned int y_nents, off_t
y_skip,
- size_t n_bytes)
+ struct scatterlist *y_sgl, unsigned int y_nents, off_t
y_skip,
+ size_t n_bytes)
{
bool equ = true;
size_t x_off, y_off, len, x_len, y_len;
@@ -1140,3 +1140,38 @@ bool sgl_compare_sgl(struct scatterlist *x_sgl, unsigned
int x_nents, off_t x_sk
return equ;
}
EXPORT_SYMBOL(sgl_compare_sgl);
+
+/**
+ * sgl_memset - set byte 'val' n_bytes times on SG list
+ * @sgl: The SG list
+ * @nents: Number of SG entries in sgl
+ * @skip: Number of bytes to skip before starting
+ * @val: byte value to write to sgl
+ * @n_bytes: The number of bytes to modify
+ *
+ * Notes:
+ * Writes val n_bytes times or until sgl is exhausted.
+ *
+ **/
+void sgl_memset(struct scatterlist *sgl, unsigned int nents, off_t skip,
+ u8 val, size_t n_bytes)
+{
+ size_t offset = 0;
+ size_t len;
+ struct sg_mapping_iter miter;
+ unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG;
+
+ if (n_bytes == 0)
+ return;
+ sg_miter_start(&miter, sgl, nents, sg_flags);
+ if (!sg_miter_skip(&miter, skip))
+ goto fini;
+
+ while ((offset < n_bytes) && sg_miter_next(&miter)) {
+ len = min(miter.length, n_bytes - offset);
+ memset(miter.addr, val, len);
+ offset += len;
+ }
+fini:
+ sg_miter_stop(&miter);
+}
--
2.25.1
