X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=lib%2Fscatterlist.c;h=0d475d8167bfd7f4f9909424ea29a72653b581fe;hb=55f9321a024a2d03f71a23b74003792692ca1a38;hp=b80c21100d783ceeee87fa828600d90b322120ab;hpb=b1adaf65ba0398c9a1adc8f3a274533165a4df61;p=safe%2Fjmp%2Flinux-2.6 diff --git a/lib/scatterlist.c b/lib/scatterlist.c index b80c211..0d475d8 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -295,6 +295,124 @@ int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) EXPORT_SYMBOL(sg_alloc_table); /** + * sg_miter_start - start mapping iteration over a sg list + * @miter: sg mapping iter to be started + * @sgl: sg list to iterate over + * @nents: number of sg entries + * + * Description: + * Starts mapping iterator @miter. + * + * Context: + * Don't care. + */ +void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, + unsigned int nents, unsigned int flags) +{ + memset(miter, 0, sizeof(struct sg_mapping_iter)); + + miter->__sg = sgl; + miter->__nents = nents; + miter->__offset = 0; + WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG))); + miter->__flags = flags; +} +EXPORT_SYMBOL(sg_miter_start); + +/** + * sg_miter_next - proceed mapping iterator to the next mapping + * @miter: sg mapping iter to proceed + * + * Description: + * Proceeds @miter@ to the next mapping. @miter@ should have been + * started using sg_miter_start(). On successful return, + * @miter@->page, @miter@->addr and @miter@->length point to the + * current mapping. + * + * Context: + * IRQ disabled if SG_MITER_ATOMIC. IRQ must stay disabled till + * @miter@ is stopped. May sleep if !SG_MITER_ATOMIC. + * + * Returns: + * true if @miter contains the next mapping. false if end of sg + * list is reached. + */ +bool sg_miter_next(struct sg_mapping_iter *miter) +{ + unsigned int off, len; + + /* check for end and drop resources from the last iteration */ + if (!miter->__nents) + return false; + + sg_miter_stop(miter); + + /* get to the next sg if necessary. __offset is adjusted by stop */ + while (miter->__offset == miter->__sg->length) { + if (--miter->__nents) { + miter->__sg = sg_next(miter->__sg); + miter->__offset = 0; + } else + return false; + } + + /* map the next page */ + off = miter->__sg->offset + miter->__offset; + len = miter->__sg->length - miter->__offset; + + miter->page = nth_page(sg_page(miter->__sg), off >> PAGE_SHIFT); + off &= ~PAGE_MASK; + miter->length = min_t(unsigned int, len, PAGE_SIZE - off); + miter->consumed = miter->length; + + if (miter->__flags & SG_MITER_ATOMIC) + miter->addr = kmap_atomic(miter->page, KM_BIO_SRC_IRQ) + off; + else + miter->addr = kmap(miter->page) + off; + + return true; +} +EXPORT_SYMBOL(sg_miter_next); + +/** + * sg_miter_stop - stop mapping iteration + * @miter: sg mapping iter to be stopped + * + * Description: + * Stops mapping iterator @miter. @miter should have been started + * started using sg_miter_start(). A stopped iteration can be + * resumed by calling sg_miter_next() on it. This is useful when + * resources (kmap) need to be released during iteration. + * + * Context: + * IRQ disabled if the SG_MITER_ATOMIC is set. Don't care otherwise. + */ +void sg_miter_stop(struct sg_mapping_iter *miter) +{ + WARN_ON(miter->consumed > miter->length); + + /* drop resources from the last iteration */ + if (miter->addr) { + miter->__offset += miter->consumed; + + if (miter->__flags & SG_MITER_TO_SG) + flush_kernel_dcache_page(miter->page); + + if (miter->__flags & SG_MITER_ATOMIC) { + WARN_ON(!irqs_disabled()); + kunmap_atomic(miter->addr, KM_BIO_SRC_IRQ); + } else + kunmap(miter->page); + + miter->page = NULL; + miter->addr = NULL; + miter->length = 0; + miter->consumed = 0; + } +} +EXPORT_SYMBOL(sg_miter_stop); + +/** * sg_copy_buffer - Copy data between a linear buffer and an SG list * @sgl: The SG list * @nents: Number of SG entries @@ -309,56 +427,37 @@ EXPORT_SYMBOL(sg_alloc_table); static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, size_t buflen, int to_buffer) { - struct scatterlist *sg; - size_t buf_off = 0; - int i; - - WARN_ON(!irqs_disabled()); - - for_each_sg(sgl, sg, nents, i) { - struct page *page; - int n = 0; - unsigned int sg_off = sg->offset; - unsigned int sg_copy = sg->length; - - if (sg_copy > buflen) - sg_copy = buflen; - buflen -= sg_copy; - - while (sg_copy > 0) { - unsigned int page_copy; - void *p; - - page_copy = PAGE_SIZE - sg_off; - if (page_copy > sg_copy) - page_copy = sg_copy; - - page = nth_page(sg_page(sg), n); - p = kmap_atomic(page, KM_BIO_SRC_IRQ); - - if (to_buffer) - memcpy(buf + buf_off, p + sg_off, page_copy); - else { - memcpy(p + sg_off, buf + buf_off, page_copy); - flush_kernel_dcache_page(page); - } - - kunmap_atomic(p, KM_BIO_SRC_IRQ); - - buf_off += page_copy; - sg_off += page_copy; - if (sg_off == PAGE_SIZE) { - sg_off = 0; - n++; - } - sg_copy -= page_copy; - } + unsigned int offset = 0; + struct sg_mapping_iter miter; + unsigned long flags; + unsigned int sg_flags = SG_MITER_ATOMIC; + + if (to_buffer) + sg_flags |= SG_MITER_FROM_SG; + else + sg_flags |= SG_MITER_TO_SG; + + sg_miter_start(&miter, sgl, nents, sg_flags); - if (!buflen) - break; + local_irq_save(flags); + + while (sg_miter_next(&miter) && offset < buflen) { + unsigned int len; + + len = min(miter.length, buflen - offset); + + if (to_buffer) + memcpy(buf + offset, miter.addr, len); + else + memcpy(miter.addr, buf + offset, len); + + offset += len; } - return buf_off; + sg_miter_stop(&miter); + + local_irq_restore(flags); + return offset; } /**