From: Akinobu Mita <akinobu.mita@gmail.com>
To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org
Cc: Akinobu Mita <akinobu.mita@gmail.com>, Tejun Heo <tj@kernel.org>,
Imre Deak <imre.deak@intel.com>,
Herbert Xu <herbert@gondor.hengli.com.au>,
"David S. Miller" <davem@davemloft.net>,
linux-crypto@vger.kernel.org,
"James E.J. Bottomley" <JBottomley@parallels.com>,
Douglas Gilbert <dgilbert@interlog.com>,
linux-scsi@vger.kernel.org
Subject: [PATCH v3 2/4] lib/scatterlist: introduce sg_pcopy_from_buffer() and sg_pcopy_to_buffer()
Date: Sun, 23 Jun 2013 21:37:39 +0900 [thread overview]
Message-ID: <1371991061-19437-3-git-send-email-akinobu.mita@gmail.com> (raw)
In-Reply-To: <1371991061-19437-1-git-send-email-akinobu.mita@gmail.com>
The only difference between sg_pcopy_{from,to}_buffer() and
sg_copy_{from,to}_buffer() is an additional argument that specifies
the number of bytes to skip the SG list before copying.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-crypto@vger.kernel.org
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: linux-scsi@vger.kernel.org
---
* Changes from v2
- Rename sg_miter_seek() to sg_miter_skip()
- Remove the restriction on when sg_miter_skip() can be called
include/linux/scatterlist.h | 5 +++
lib/scatterlist.c | 88 ++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 88 insertions(+), 5 deletions(-)
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 2680677..adae88f 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -244,6 +244,11 @@ size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
void *buf, size_t buflen);
+size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
+ void *buf, size_t buflen, off_t skip);
+size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
+ void *buf, size_t buflen, off_t skip);
+
/*
* 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 c35b929..129a82f 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -476,6 +476,43 @@ static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
}
/**
+ * sg_miter_skip - reposition mapping iterator
+ * @miter: sg mapping iter to be skipped
+ * @offset: number of bytes to plus the current location
+ *
+ * Description:
+ * Sets the offset of @miter to its current location plus @offset bytes.
+ * If mapping iterator @miter has been proceeded by sg_miter_next(), this
+ * stops @miter.
+ *
+ * Context:
+ * Don't care if @miter is stopped, or not proceeded yet.
+ * Otherwise, preemption disabled if the SG_MITER_ATOMIC is set.
+ *
+ * Returns:
+ * true if @miter contains the valid mapping. false if end of sg
+ * list is reached.
+ */
+static bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
+{
+ sg_miter_stop(miter);
+
+ while (offset) {
+ off_t consumed;
+
+ if (!sg_miter_get_next_page(miter))
+ return false;
+
+ consumed = min_t(off_t, offset, miter->__remaining);
+ miter->__offset += consumed;
+ miter->__remaining -= consumed;
+ offset -= consumed;
+ }
+
+ return true;
+}
+
+/**
* sg_miter_next - proceed mapping iterator to the next mapping
* @miter: sg mapping iter to proceed
*
@@ -561,14 +598,16 @@ EXPORT_SYMBOL(sg_miter_stop);
* @nents: Number of SG entries
* @buf: Where to copy from
* @buflen: The number of bytes to copy
- * @to_buffer: transfer direction (non zero == from an sg list to a
- * buffer, 0 == from a buffer to an sg list
+ * @skip: Number of bytes to skip before copying
+ * @to_buffer: transfer direction (true == from an sg list to a
+ * buffer, false == from a buffer to an sg list
*
* Returns the number of copied bytes.
*
**/
static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents,
- void *buf, size_t buflen, int to_buffer)
+ void *buf, size_t buflen, off_t skip,
+ bool to_buffer)
{
unsigned int offset = 0;
struct sg_mapping_iter miter;
@@ -582,6 +621,9 @@ static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents,
sg_miter_start(&miter, sgl, nents, sg_flags);
+ if (!sg_miter_skip(&miter, skip))
+ return false;
+
local_irq_save(flags);
while (sg_miter_next(&miter) && offset < buflen) {
@@ -616,7 +658,7 @@ static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents,
size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
void *buf, size_t buflen)
{
- return sg_copy_buffer(sgl, nents, buf, buflen, 0);
+ return sg_copy_buffer(sgl, nents, buf, buflen, 0, false);
}
EXPORT_SYMBOL(sg_copy_from_buffer);
@@ -633,6 +675,42 @@ EXPORT_SYMBOL(sg_copy_from_buffer);
size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
void *buf, size_t buflen)
{
- return sg_copy_buffer(sgl, nents, buf, buflen, 1);
+ return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
}
EXPORT_SYMBOL(sg_copy_to_buffer);
+
+/**
+ * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list
+ * @sgl: The SG list
+ * @nents: Number of SG entries
+ * @buf: Where to copy from
+ * @skip: Number of bytes to skip before copying
+ * @buflen: The number of bytes to copy
+ *
+ * Returns the number of copied bytes.
+ *
+ **/
+size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
+ void *buf, size_t buflen, off_t skip)
+{
+ return sg_copy_buffer(sgl, nents, buf, buflen, skip, false);
+}
+EXPORT_SYMBOL(sg_pcopy_from_buffer);
+
+/**
+ * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer
+ * @sgl: The SG list
+ * @nents: Number of SG entries
+ * @buf: Where to copy to
+ * @skip: Number of bytes to skip before copying
+ * @buflen: The number of bytes to copy
+ *
+ * Returns the number of copied bytes.
+ *
+ **/
+size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
+ void *buf, size_t buflen, off_t skip)
+{
+ return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
+}
+EXPORT_SYMBOL(sg_pcopy_to_buffer);
--
1.8.1.4
next prev parent reply other threads:[~2013-06-23 12:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-23 12:37 [PATCH v3 0/4] introduce sg_pcopy_from_buffer() and sg_pcopy_to_buffer() Akinobu Mita
2013-06-23 12:37 ` [PATCH v3 1/4] lib/scatterlist: factor out sg_miter_get_next_page() from sg_miter_next() Akinobu Mita
2013-06-23 12:37 ` Akinobu Mita [this message]
2013-06-24 23:27 ` [PATCH v3 2/4] lib/scatterlist: introduce sg_pcopy_from_buffer() and sg_pcopy_to_buffer() Tejun Heo
2013-06-23 12:37 ` [PATCH v3 3/4] crypto: talitos: use sg_pcopy_to_buffer() Akinobu Mita
2013-06-23 12:37 ` [PATCH v3 4/4] scsi_debug: fix do_device_access() with wrap around range Akinobu Mita
2013-06-24 23:34 ` Douglas Gilbert
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