iblock: fix handling of large requests

Requesting to many bvecs upsets bio_alloc_bioset, so limit the number we ask
for to the amount it can handle.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index d43d5eb5ed20..8572eae62da7 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -488,6 +488,13 @@ iblock_get_bio(struct se_task *task, sector_t lba, u32 sg_num)
         struct iblock_req *ib_req = IBLOCK_REQ(task);
         struct bio *bio;
 
+        /*
+         * Only allocate as many vector entries as the bio code allows us to,
+         * we'll loop later on until we have handled the whole request.
+         */
+        if (sg_num > BIO_MAX_PAGES)
+                sg_num = BIO_MAX_PAGES;
+
         bio = bio_alloc_bioset(GFP_NOIO, sg_num, ib_dev->ibd_bio_set);
         if (!bio) {
                 pr_err("Unable to allocate memory for bio\n");