block: remove artifical max_hw_sectors cap

Set max_sectors to the value the drivers provides as hardware limit by
default.  Linux had proper I/O throttling for a long time and doesn't
rely on a artifically small maximum I/O size anymore.  By not limiting
the I/O size by default we remove an annoying tuning step required for
most Linux installation.

Note that both the user, and if absolutely required the driver can still
impose a limit for FS requests below max_hw_sectors_kb.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

3 files changed, 2 insertions, 5 deletions

diff --git a/block/blk-settings.c b/block/blk-settings.c
index aa02247d227e..6ed2cbe5e8c9 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -257,9 +257,7 @@ void blk_limits_max_hw_sectors(struct queue_limits *limits, unsigned int max_hw_
                        __func__, max_hw_sectors);
         }
 
-        limits->max_hw_sectors = max_hw_sectors;
-        limits->max_sectors = min_t(unsigned int, max_hw_sectors,
-                                    BLK_DEF_MAX_SECTORS);
+        limits->max_sectors = limits->max_hw_sectors = max_hw_sectors;
 }
 EXPORT_SYMBOL(blk_limits_max_hw_sectors);
 
diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
index dd73e1ff1759..46c282fff104 100644
--- a/drivers/block/aoe/aoeblk.c
+++ b/drivers/block/aoe/aoeblk.c
@@ -395,7 +395,7 @@ aoeblk_gdalloc(void *vp)
         WARN_ON(d->flags & DEVFL_TKILL);
         WARN_ON(d->gd);
         WARN_ON(d->flags & DEVFL_UP);
-        blk_queue_max_hw_sectors(q, BLK_DEF_MAX_SECTORS);
+        blk_queue_max_hw_sectors(q, 1024);
         q->backing_dev_info.name = "aoe";
         q->backing_dev_info.ra_pages = READ_AHEAD / PAGE_CACHE_SIZE;
         d->bufpool = mp;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 0207a78a8d82..74d14dba6fb7 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1186,7 +1186,6 @@ extern int blk_verify_command(unsigned char *cmd, fmode_t has_write_perm);
 enum blk_default_limits {
         BLK_MAX_SEGMENTS        = 128,
         BLK_SAFE_MAX_SECTORS    = 255,
-        BLK_DEF_MAX_SECTORS     = 1024,
         BLK_MAX_SEGMENT_SIZE    = 65536,
         BLK_SEG_BOUNDARY_MASK   = 0xFFFFFFFFUL,
 };