diff options
| author | Eric Blake <eblake@redhat.com> | 2016-06-23 16:37:10 -0600 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2016-07-05 16:46:25 +0200 |
| commit | f9e95af0a6be281f56ecc8413ea4a3ac3545ce17 (patch) | |
| tree | d9bcbcb304a8a3f43e57aecb3051d11579a45d9e | |
| parent | 202204717a7e73971cccebd38c5d8ac4b0bfcef8 (diff) | |
iscsi: Advertise realistic limits to block layer
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 <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
| -rw-r--r-- | block/iscsi.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/block/iscsi.c b/block/iscsi.c index 9bb5ff6216..c5dedb3407 100644 --- a/block/iscsi.c +++ b/block/iscsi.c @@ -1698,7 +1698,9 @@ 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) |