[SCSI] seperate max_sectors from max_hw_sectors

- export __blk_put_request and blk_execute_rq_nowait
needed for async REQ_BLOCK_PC requests
- seperate max_hw_sectors and max_sectors for block/scsi_ioctl.c and
SG_IO bio.c helpers per Jens's last comments. Since block/scsi_ioctl.c SG_IO was
already testing against max_sectors and SCSI-ml was setting max_sectors and
max_hw_sectors to the same value this does not change any scsi SG_IO behavior. It only
prepares ll_rw_blk.c, scsi_ioctl.c and bio.c for when SCSI-ml begins to set
a valid max_hw_sectors for all LLDs. Today if a LLD does not set it
SCSI-ml sets it to a safe default and some LLDs set it to a artificial low
value to overcome memory and feedback issues.

Note: Since we now cap max_sectors to BLK_DEF_MAX_SECTORS, which is 1024,
drivers that used to call blk_queue_max_sectors with a large value of
max_sectors will now see the fs requests capped to BLK_DEF_MAX_SECTORS.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 11 insertions, 9 deletions

diff --git a/fs/bio.c b/fs/bio.c
index 4d21ee3873ec..38d3e8023a07 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -313,7 +313,8 @@ int bio_get_nr_vecs(struct block_device *bdev)
 }
 
 static int __bio_add_page(request_queue_t *q, struct bio *bio, struct page
-                          *page, unsigned int len, unsigned int offset)
+                          *page, unsigned int len, unsigned int offset,
+                          unsigned short max_sectors)
 {
         int retried_segments = 0;
         struct bio_vec *bvec;
@@ -327,7 +328,7 @@ static int __bio_add_page(request_queue_t *q, struct bio *bio, struct page
         if (bio->bi_vcnt >= bio->bi_max_vecs)
                 return 0;
 
-        if (((bio->bi_size + len) >> 9) > q->max_sectors)
+        if (((bio->bi_size + len) >> 9) > max_sectors)
                 return 0;
 
         /*
@@ -401,7 +402,7 @@ static int __bio_add_page(request_queue_t *q, struct bio *bio, struct page
 int bio_add_pc_page(request_queue_t *q, struct bio *bio, struct page *page,
                     unsigned int len, unsigned int offset)
 {
-        return __bio_add_page(q, bio, page, len, offset);
+        return __bio_add_page(q, bio, page, len, offset, q->max_hw_sectors);
 }
 
 /**
@@ -420,8 +421,8 @@ int bio_add_pc_page(request_queue_t *q, struct bio *bio, struct page *page,
 int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
                  unsigned int offset)
 {
-        return __bio_add_page(bdev_get_queue(bio->bi_bdev), bio, page,
-                              len, offset);
+        struct request_queue *q = bdev_get_queue(bio->bi_bdev);
+        return __bio_add_page(q, bio, page, len, offset, q->max_sectors);
 }
 
 struct bio_map_data {
@@ -533,7 +534,7 @@ struct bio *bio_copy_user(request_queue_t *q, unsigned long uaddr,
                         break;
                 }
 
-                if (__bio_add_page(q, bio, page, bytes, 0) < bytes) {
+                if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes) {
                         ret = -EINVAL;
                         break;
                 }
@@ -647,7 +648,8 @@ static struct bio *__bio_map_user_iov(request_queue_t *q,
                         /*
                          * sorry...
                          */
-                        if (__bio_add_page(q, bio, pages[j], bytes, offset) < bytes)
+                        if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
+                                            bytes)
                                 break;
 
                         len -= bytes;
@@ -820,8 +822,8 @@ static struct bio *__bio_map_kern(request_queue_t *q, void *data,
                 if (bytes > len)
                         bytes = len;
 
-                if (__bio_add_page(q, bio, virt_to_page(data), bytes,
-                                   offset) < bytes)
+                if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
+                                    offset) < bytes)
                         break;
 
                 data += bytes;