#include <linux/module.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
#include <scsi/sg.h> /* for struct sg_iovec */
#include "blk.h"
}
EXPORT_SYMBOL(blk_rq_unmap_user);
+struct blk_kern_sg_work {
+ atomic_t bios_inflight;
+ struct sg_table sg_table;
+ struct scatterlist *src_sgl;
+};
+
+static void blk_free_kern_sg_work(struct blk_kern_sg_work *bw)
+{
+ sg_free_table(&bw->sg_table);
+ kfree(bw);
+ return;
+}
+
+static void blk_bio_map_kern_endio(struct bio *bio, int err)
+{
+ struct blk_kern_sg_work *bw = bio->bi_private;
+
+ if (bw != NULL) {
+ /* Decrement the bios in processing and, if zero, free */
+ BUG_ON(atomic_read(&bw->bios_inflight) <= 0);
+ if (atomic_dec_and_test(&bw->bios_inflight)) {
+ if ((bio_data_dir(bio) == READ) && (err == 0)) {
+ unsigned long flags;
+
+ local_irq_save(flags); /* to protect KMs */
+ sg_copy(bw->src_sgl, bw->sg_table.sgl, 0, 0,
+ KM_BIO_DST_IRQ, KM_BIO_SRC_IRQ);
+ local_irq_restore(flags);
+ }
+ blk_free_kern_sg_work(bw);
+ }
+ }
+
+ bio_put(bio);
+ return;
+}
+
+static int blk_rq_copy_kern_sg(struct request *rq, struct scatterlist *sgl,
+ int nents, struct blk_kern_sg_work **pbw,
+ gfp_t gfp, gfp_t page_gfp)
+{
+ int res = 0, i;
+ struct scatterlist *sg;
+ struct scatterlist *new_sgl;
+ int new_sgl_nents;
+ size_t len = 0, to_copy;
+ struct blk_kern_sg_work *bw;
+
+ bw = kzalloc(sizeof(*bw), gfp);
+ if (bw == NULL)
+ goto out;
+
+ bw->src_sgl = sgl;
+
+ for_each_sg(sgl, sg, nents, i)
+ len += sg->length;
+ to_copy = len;
+
+ new_sgl_nents = PFN_UP(len);
+
+ res = sg_alloc_table(&bw->sg_table, new_sgl_nents, gfp);
+ if (res != 0)
+ goto out_free_bw;
+
+ new_sgl = bw->sg_table.sgl;
+
+ for_each_sg(new_sgl, sg, new_sgl_nents, i) {
+ struct page *pg;
+
+ pg = alloc_page(page_gfp);
+ if (pg == NULL)
+ goto err_free_new_sgl;
+
+ sg_assign_page(sg, pg);
+ sg->length = min_t(size_t, PAGE_SIZE, len);
+
+ len -= PAGE_SIZE;
+ }
+
+ if (rq_data_dir(rq) == WRITE) {
+ /*
+ * We need to limit amount of copied data to to_copy, because
+ * sgl might have the last element in sgl not marked as last in
+ * SG chaining.
+ */
+ sg_copy(new_sgl, sgl, 0, to_copy,
+ KM_USER0, KM_USER1);
+ }
+
+ *pbw = bw;
+ /*
+ * REQ_COPY_USER name is misleading. It should be something like
+ * REQ_HAS_TAIL_SPACE_FOR_PADDING.
+ */
+ rq->cmd_flags |= REQ_COPY_USER;
+
+out:
+ return res;
+
+err_free_new_sgl:
+ for_each_sg(new_sgl, sg, new_sgl_nents, i) {
+ struct page *pg = sg_page(sg);
+ if (pg == NULL)
+ break;
+ __free_page(pg);
+ }
+ sg_free_table(&bw->sg_table);
+
+out_free_bw:
+ kfree(bw);
+ res = -ENOMEM;
+ goto out;
+}
+
+static int __blk_rq_map_kern_sg(struct request *rq, struct scatterlist *sgl,
+ int nents, struct blk_kern_sg_work *bw, gfp_t gfp)
+{
+ int res;
+ struct request_queue *q = rq->q;
+ int rw = rq_data_dir(rq);
+ int max_nr_vecs, i;
+ size_t tot_len;
+ bool need_new_bio;
+ struct scatterlist *sg, *prev_sg = NULL;
+ struct bio *bio = NULL, *hbio = NULL, *tbio = NULL;
+ int bios;
+
+ if (unlikely((sgl == NULL) || (sgl->length == 0) || (nents <= 0))) {
+ WARN_ON(1);
+ res = -EINVAL;
+ goto out;
+ }
+
+ /*
+ * Let's keep each bio allocation inside a single page to decrease
+ * probability of failure.
+ */
+ max_nr_vecs = min_t(size_t,
+ ((PAGE_SIZE - sizeof(struct bio)) / sizeof(struct bio_vec)),
+ BIO_MAX_PAGES);
+
+ need_new_bio = true;
+ tot_len = 0;
+ bios = 0;
+ for_each_sg(sgl, sg, nents, i) {
+ struct page *page = sg_page(sg);
+ void *page_addr = page_address(page);
+ size_t len = sg->length, l;
+ size_t offset = sg->offset;
+
+ tot_len += len;
+ prev_sg = sg;
+
+ /*
+ * Each segment must be aligned on DMA boundary and
+ * not on stack. The last one may have unaligned
+ * length as long as the total length is aligned to
+ * DMA padding alignment.
+ */
+ if (i == nents - 1)
+ l = 0;
+ else
+ l = len;
+ if (((sg->offset | l) & queue_dma_alignment(q)) ||
+ (page_addr && object_is_on_stack(page_addr + sg->offset))) {
+ res = -EINVAL;
+ goto out_free_bios;
+ }
+
+ while (len > 0) {
+ size_t bytes;
+ int rc;
+
+ if (need_new_bio) {
+ bio = bio_kmalloc(gfp, max_nr_vecs);
+ if (bio == NULL) {
+ res = -ENOMEM;
+ goto out_free_bios;
+ }
+
+ if (rw == WRITE)
+ bio->bi_rw |= REQ_WRITE;
+
+ bios++;
+ bio->bi_private = bw;
+ bio->bi_end_io = blk_bio_map_kern_endio;
+
+ if (hbio == NULL)
+ hbio = tbio = bio;
+ else
+ tbio = tbio->bi_next = bio;
+ }
+
+ bytes = min_t(size_t, len, PAGE_SIZE - offset);
+
+ rc = bio_add_pc_page(q, bio, page, bytes, offset);
+ if (rc < bytes) {
+ if (unlikely(need_new_bio || (rc < 0))) {
+ if (rc < 0)
+ res = rc;
+ else
+ res = -EIO;
+ goto out_free_bios;
+ } else {
+ need_new_bio = true;
+ len -= rc;
+ offset += rc;
+ continue;
+ }
+ }
+
+ need_new_bio = false;
+ offset = 0;
+ len -= bytes;
+ page = nth_page(page, 1);
+ }
+ }
+
+ if (hbio == NULL) {
+ res = -EINVAL;
+ goto out_free_bios;
+ }
+
+ /* Total length must be aligned on DMA padding alignment */
+ if ((tot_len & q->dma_pad_mask) &&
+ !(rq->cmd_flags & REQ_COPY_USER)) {
+ res = -EINVAL;
+ goto out_free_bios;
+ }
+
+ if (bw != NULL)
+ atomic_set(&bw->bios_inflight, bios);
+
+ while (hbio != NULL) {
+ bio = hbio;
+ hbio = hbio->bi_next;
+ bio->bi_next = NULL;
+
+ blk_queue_bounce(q, &bio);
+
+ res = blk_rq_append_bio(q, rq, bio);
+ if (unlikely(res != 0)) {
+ bio->bi_next = hbio;
+ hbio = bio;
+ /* We can have one or more bios bounced */
+ goto out_unmap_bios;
+ }
+ }
+
+ res = 0;
+
+ rq->buffer = NULL;
+out:
+ return res;
+
+out_unmap_bios:
+ blk_rq_unmap_kern_sg(rq, res);
+
+out_free_bios:
+ while (hbio != NULL) {
+ bio = hbio;
+ hbio = hbio->bi_next;
+ bio_put(bio);
+ }
+ goto out;
+}
+
+/**
+ * blk_rq_map_kern_sg - map kernel data to a request, for REQ_TYPE_BLOCK_PC
+ * @rq: request to fill
+ * @sgl: area to map
+ * @nents: number of elements in @sgl
+ * @gfp: memory allocation flags
+ *
+ * Description:
+ * Data will be mapped directly if possible. Otherwise a bounce
+ * buffer will be used.
+ */
+int blk_rq_map_kern_sg(struct request *rq, struct scatterlist *sgl,
+ int nents, gfp_t gfp)
+{
+ int res;
+
+ res = __blk_rq_map_kern_sg(rq, sgl, nents, NULL, gfp);
+ if (unlikely(res != 0)) {
+ struct blk_kern_sg_work *bw = NULL;
+
+ res = blk_rq_copy_kern_sg(rq, sgl, nents, &bw,
+ gfp, rq->q->bounce_gfp | gfp);
+ if (unlikely(res != 0))
+ goto out;
+
+ res = __blk_rq_map_kern_sg(rq, bw->sg_table.sgl,
+ bw->sg_table.nents, bw, gfp);
+ if (res != 0) {
+ blk_free_kern_sg_work(bw);
+ goto out;
+ }
+ }
+
+ rq->buffer = NULL;
+
+out:
+ return res;
+}
+EXPORT_SYMBOL(blk_rq_map_kern_sg);
+
+/**
+ * blk_rq_unmap_kern_sg - unmap a request with kernel sg
+ * @rq: request to unmap
+ * @err: non-zero error code
+ *
+ * Description:
+ * Unmap a rq previously mapped by blk_rq_map_kern_sg(). Must be called
+ * only in case of an error!
+ */
+void blk_rq_unmap_kern_sg(struct request *rq, int err)
+{
+ struct bio *bio = rq->bio;
+
+ while (bio) {
+ struct bio *b = bio;
+ bio = bio->bi_next;
+ b->bi_end_io(b, err);
+ }
+ rq->bio = NULL;
+
+ return;
+}
+EXPORT_SYMBOL(blk_rq_unmap_kern_sg);
+
/**
* blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
* @q: request queue where request should be inserted
projects / mv-sheeva.git / blobdiff