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[Qemu-block] [PATCH v2 06/17] iscsi: Advertise realistic limits to block
From: |
Eric Blake |
Subject: |
[Qemu-block] [PATCH v2 06/17] iscsi: Advertise realistic limits to block layer |
Date: |
Tue, 14 Jun 2016 15:30:28 -0600 |
The function sector_limits_lun2qemu() returns a value in units of
the block layer's 512-byte sector, and can be as large as
0x40000000, which is much larger than the block layer's inherent
limit of BDRV_REQUEST_MAX_SECTORS. The block layer already
handles '0' as a synonym to the inherent limit, and it is nicer
to return this value than it is to calculate an arbitrary
maximum, for two reasons: we want to ensure that the block layer
continues to special-case '0' as 'no limit beyond the inherent
limits'; and we want to be able to someday expand the block
layer to allow 64-bit limits, where auditing for uses of
BDRV_REQUEST_MAX_SECTORS will help us make sure we aren't
artificially constraining iscsi to old block layer limits.
Signed-off-by: Eric Blake <address@hidden>
---
v2: new patch
---
block/iscsi.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/block/iscsi.c b/block/iscsi.c
index 7e78ade..4290e41 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -1697,7 +1697,9 @@ static void iscsi_close(BlockDriverState *bs)
static int sector_limits_lun2qemu(int64_t sector, IscsiLun *iscsilun)
{
- return MIN(sector_lun2qemu(sector, iscsilun), INT_MAX / 2 + 1);
+ int limit = MIN(sector_lun2qemu(sector, iscsilun), INT_MAX / 2 + 1);
+
+ return limit < BDRV_REQUEST_MAX_SECTORS ? limit : 0;
}
static void iscsi_refresh_limits(BlockDriverState *bs, Error **errp)
--
2.5.5
- Re: [Qemu-block] [PATCH v2 03/17] block: Fix harmless off-by-one in bdrv_aligned_preadv(), (continued)
- [Qemu-block] [PATCH v2 05/17] nbd: Advertise realistic limits to block layer, Eric Blake, 2016/06/14
- [Qemu-block] [PATCH v2 11/17] raw-win32: Set request_alignment during .bdrv_refresh_limits(), Eric Blake, 2016/06/14
- [Qemu-block] [PATCH v2 12/17] block: Set request_alignment during .bdrv_refresh_limits(), Eric Blake, 2016/06/14
- [Qemu-block] [PATCH v2 06/17] iscsi: Advertise realistic limits to block layer,
Eric Blake <=
- [Qemu-block] [PATCH v2 15/17] block: Switch discard length bounds to byte-based, Eric Blake, 2016/06/14
- Re: [Qemu-block] [PATCH v2 15/17] block: Switch discard length bounds to byte-based, Kevin Wolf, 2016/06/21
- [Qemu-block] [PATCH v2 13/17] block: Set default request_alignment during bdrv_refresh_limits(), Eric Blake, 2016/06/14