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>

diff --git a/block/blk-settings.c b/block/blk-settings.c
index aa02247..6ed2cbe 100644 (file)
--- 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 dd73e1f..46c282f 100644 (file)
--- 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 0207a78..74d14db 100644 (file)
--- 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,
 };