Merge tag 'for-linus-20180727' of git://git.kernel.dk/linux-block

[sfrench/cifs-2.6.git] / block / bio.c

diff --git a/block/bio.c b/block/bio.c
index 67eff5eddc49190fe8be721edd7031e8b6284a1e..047c5dca6d90260f0a06f1a5d69b95d61a41460e 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -903,25 +903,27 @@ int bio_add_page(struct bio *bio, struct page *page,
 EXPORT_SYMBOL(bio_add_page);
 
 /**
- * bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio
+ * __bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio
  * @bio: bio to add pages to
  * @iter: iov iterator describing the region to be mapped
  *
- * Pins as many pages from *iter and appends them to @bio's bvec array. The
+ * Pins pages from *iter and appends them to @bio's bvec array. The
  * pages will have to be released using put_page() when done.
+ * For multi-segment *iter, this function only adds pages from the
+ * the next non-empty segment of the iov iterator.
  */
-int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
+static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 {
-       unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt;
+       unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt, idx;
        struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
        struct page **pages = (struct page **)bv;
-       size_t offset, diff;
+       size_t offset;
        ssize_t size;
 
        size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset);
        if (unlikely(size <= 0))
                return size ? size : -EFAULT;
-       nr_pages = (size + offset + PAGE_SIZE - 1) / PAGE_SIZE;
+       idx = nr_pages = (size + offset + PAGE_SIZE - 1) / PAGE_SIZE;
 
        /*
         * Deep magic below:  We need to walk the pinned pages backwards
@@ -934,21 +936,46 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
        bio->bi_iter.bi_size += size;
        bio->bi_vcnt += nr_pages;
 
-       diff = (nr_pages * PAGE_SIZE - offset) - size;
-       while (nr_pages--) {
-               bv[nr_pages].bv_page = pages[nr_pages];
-               bv[nr_pages].bv_len = PAGE_SIZE;
-               bv[nr_pages].bv_offset = 0;
+       while (idx--) {
+               bv[idx].bv_page = pages[idx];
+               bv[idx].bv_len = PAGE_SIZE;
+               bv[idx].bv_offset = 0;
        }
 
        bv[0].bv_offset += offset;
        bv[0].bv_len -= offset;
-       if (diff)
-               bv[bio->bi_vcnt - 1].bv_len -= diff;
+       bv[nr_pages - 1].bv_len -= nr_pages * PAGE_SIZE - offset - size;
 
        iov_iter_advance(iter, size);
        return 0;
 }
+
+/**
+ * bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio
+ * @bio: bio to add pages to
+ * @iter: iov iterator describing the region to be mapped
+ *
+ * Pins pages from *iter and appends them to @bio's bvec array. The
+ * pages will have to be released using put_page() when done.
+ * The function tries, but does not guarantee, to pin as many pages as
+ * fit into the bio, or are requested in *iter, whatever is smaller.
+ * If MM encounters an error pinning the requested pages, it stops.
+ * Error is returned only if 0 pages could be pinned.
+ */
+int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
+{
+       unsigned short orig_vcnt = bio->bi_vcnt;
+
+       do {
+               int ret = __bio_iov_iter_get_pages(bio, iter);
+
+               if (unlikely(ret))
+                       return bio->bi_vcnt > orig_vcnt ? 0 : ret;
+
+       } while (iov_iter_count(iter) && !bio_full(bio));
+
+       return 0;
+}
 EXPORT_SYMBOL_GPL(bio_iov_iter_get_pages);
 
 static void submit_bio_wait_endio(struct bio *bio)
@@ -1866,6 +1893,7 @@ struct bio *bio_split(struct bio *bio, int sectors,
                bio_integrity_trim(split);
 
        bio_advance(bio, split->bi_iter.bi_size);
+       bio->bi_iter.bi_done = 0;
 
        if (bio_flagged(bio, BIO_TRACE_COMPLETION))
                bio_set_flag(split, BIO_TRACE_COMPLETION);