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[Qemu-devel] [PATCH 2/2] iscsi: add intelligent has_zero_init check
From: |
Peter Lieven |
Subject: |
[Qemu-devel] [PATCH 2/2] iscsi: add intelligent has_zero_init check |
Date: |
Thu, 20 Jun 2013 20:08:46 +0200 |
iscsi targets are not created by bdrv_create and thus we cannot
blindly assume that a target is empty. to avoid writing and allocating
blocks of zeroes we now check if all blocks of an existing target
are unallocated and return 1 for bdrv_has_zero_init if the
target is completely unalloacted and unallocated blocks read
as zeroes.
Signed-off-by: Peter Lieven <address@hidden>
---
block/iscsi.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)
diff --git a/block/iscsi.c b/block/iscsi.c
index e6b966d..fe41d9a 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -50,6 +50,7 @@ typedef struct IscsiLun {
int events;
QEMUTimer *nop_timer;
uint8_t lbpme;
+ uint8_t lbprz;
} IscsiLun;
typedef struct IscsiAIOCB {
@@ -1004,6 +1005,7 @@ static int iscsi_readcapacity_sync(IscsiLun *iscsilun)
iscsilun->block_size = rc16->block_length;
iscsilun->num_blocks = rc16->returned_lba + 1;
iscsilun->lbpme = rc16->lbpme;
+ iscsilun->lbprz = rc16->lbprz;
}
}
break;
@@ -1249,7 +1251,28 @@ static int iscsi_truncate(BlockDriverState *bs, int64_t
offset)
static int iscsi_has_zero_init(BlockDriverState *bs)
{
- return 0;
+ IscsiLun *iscsilun = bs->opaque;
+ uint64_t lba;
+ int n, ret, nb_sectors;
+
+ if (iscsilun->lbprz == 0) {
+ return 0;
+ }
+
+ for (lba = 0; lba < iscsilun->num_blocks; lba += 1 << 26) {
+ nb_sectors = 1 << 26;
+ if (lba + nb_sectors > iscsilun->num_blocks) {
+ nb_sectors = iscsilun->num_blocks - lba;
+ }
+ nb_sectors *= (iscsilun->block_size / BDRV_SECTOR_SIZE);
+ n = 0;
+ ret = iscsi_co_is_allocated(bs, lba, nb_sectors, &n);
+ if (ret || n != nb_sectors) {
+ return 0;
+ }
+ }
+
+ return 1;
}
static int iscsi_create(const char *filename, QEMUOptionParameter *options)
--
1.7.9.5