From: Akinobu Mita Subject: [PATCH 1/3] lib/scatterlist: introduce sg_pcopy_from_buffer() and sg_pcopy_to_buffer() Date: Thu, 6 Jun 2013 21:52:56 +0900 Message-ID: <1370523178-5437-2-git-send-email-akinobu.mita@gmail.com> References: <1370523178-5437-1-git-send-email-akinobu.mita@gmail.com> Cc: Akinobu Mita , Tejun Heo , Imre Deak , Herbert Xu , "David S. Miller" , linux-crypto@vger.kernel.org, "James E.J. Bottomley" , Douglas Gilbert , linux-scsi@vger.kernel.org To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org Return-path: In-Reply-To: <1370523178-5437-1-git-send-email-akinobu.mita@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org 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 Cc: Tejun Heo Cc: Imre Deak Cc: Herbert Xu Cc: "David S. Miller" Cc: linux-crypto@vger.kernel.org Cc: "James E.J. Bottomley" Cc: Douglas Gilbert Cc: linux-scsi@vger.kernel.org --- include/linux/scatterlist.h | 5 ++ lib/scatterlist.c | 109 ++++++++++++++++++++++++++++++++++++-------- 2 files changed, 94 insertions(+), 20 deletions(-) diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 5951e3f..f5dee42 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -241,6 +241,11 @@ 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 a1cf8ca..3b40b72 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -453,6 +453,47 @@ void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, } EXPORT_SYMBOL(sg_miter_start); +static bool sg_miter_get_next_page(struct sg_mapping_iter *miter) +{ + if (!miter->__remaining) { + struct scatterlist *sg; + unsigned long pgoffset; + + if (!__sg_page_iter_next(&miter->piter)) + return false; + + sg = miter->piter.sg; + pgoffset = miter->piter.sg_pgoffset; + + miter->__offset = pgoffset ? 0 : sg->offset; + miter->__remaining = sg->offset + sg->length - + (pgoffset << PAGE_SHIFT) - miter->__offset; + miter->__remaining = min_t(unsigned long, miter->__remaining, + PAGE_SIZE - miter->__offset); + } + + return true; +} + +static bool sg_miter_seek(struct sg_mapping_iter *miter, off_t offset) +{ + WARN_ON(miter->addr); + + 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 @@ -478,22 +519,9 @@ bool sg_miter_next(struct sg_mapping_iter *miter) * Get to the next page if necessary. * __remaining, __offset is adjusted by sg_miter_stop */ - if (!miter->__remaining) { - struct scatterlist *sg; - unsigned long pgoffset; - - if (!__sg_page_iter_next(&miter->piter)) - return false; - - sg = miter->piter.sg; - pgoffset = miter->piter.sg_pgoffset; + if (!sg_miter_get_next_page(miter)) + return false; - miter->__offset = pgoffset ? 0 : sg->offset; - miter->__remaining = sg->offset + sg->length - - (pgoffset << PAGE_SHIFT) - miter->__offset; - miter->__remaining = min_t(unsigned long, miter->__remaining, - PAGE_SIZE - miter->__offset); - } miter->page = sg_page_iter_page(&miter->piter); miter->consumed = miter->length = miter->__remaining; @@ -552,14 +580,16 @@ 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; @@ -573,6 +603,9 @@ static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, sg_miter_start(&miter, sgl, nents, sg_flags); + if (!sg_miter_seek(&miter, skip)) + return false; + local_irq_save(flags); while (sg_miter_next(&miter) && offset < buflen) { @@ -607,7 +640,7 @@ 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); @@ -624,6 +657,42 @@ 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