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authorPaolo Bonzini <pbonzini@redhat.com>2013-02-08 14:06:14 +0100
committerKevin Wolf <kwolf@redhat.com>2013-02-22 21:29:44 +0100
commit215e47b9ea2cd7926333b7dc683024aa00e0c386 (patch)
treed1ae0848fbdfc0ef88ac9d87abc23171fde3d6cb
parentded9d2d5e247dc4d141c01bc8dc99d6ec832f9e8 (diff)
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blockdev: enable discard by default
Because discard is now a host parameter, we can always fake it as enabled in the guest. This is an extension of the current choice to ignore "not supported" errors from the host when discard_granularity is set to nonzero. The default granularity is set to the logical block size or 4k, whichever is largest, because cluster sizes below 4k are rarely used and 4K is a typical block size for files. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r--hw/block-common.h2
-rw-r--r--hw/ide/qdev.c5
-rw-r--r--hw/scsi-disk.c13
3 files changed, 15 insertions, 5 deletions
diff --git a/hw/block-common.h b/hw/block-common.h
index bb808f7f56..dd115320c9 100644
--- a/hw/block-common.h
+++ b/hw/block-common.h
@@ -50,7 +50,7 @@ static inline unsigned int get_physical_block_exp(BlockConf *conf)
DEFINE_PROP_UINT32("opt_io_size", _state, _conf.opt_io_size, 0), \
DEFINE_PROP_INT32("bootindex", _state, _conf.bootindex, -1), \
DEFINE_PROP_UINT32("discard_granularity", _state, \
- _conf.discard_granularity, 0)
+ _conf.discard_granularity, -1)
#define DEFINE_BLOCK_CHS_PROPERTIES(_state, _conf) \
DEFINE_PROP_UINT32("cyls", _state, _conf.cyls, 0), \
diff --git a/hw/ide/qdev.c b/hw/ide/qdev.c
index c436b38bcb..fd06da7003 100644
--- a/hw/ide/qdev.c
+++ b/hw/ide/qdev.c
@@ -143,7 +143,10 @@ static int ide_dev_initfn(IDEDevice *dev, IDEDriveKind kind)
IDEBus *bus = DO_UPCAST(IDEBus, qbus, dev->qdev.parent_bus);
IDEState *s = bus->ifs + dev->unit;
- if (dev->conf.discard_granularity && dev->conf.discard_granularity != 512) {
+ if (dev->conf.discard_granularity == -1) {
+ dev->conf.discard_granularity = 512;
+ } else if (dev->conf.discard_granularity &&
+ dev->conf.discard_granularity != 512) {
error_report("discard_granularity must be 512 for ide");
return -1;
}
diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
index 28e75bbf5b..d41158693e 100644
--- a/hw/scsi-disk.c
+++ b/hw/scsi-disk.c
@@ -41,9 +41,11 @@ do { printf("scsi-disk: " fmt , ## __VA_ARGS__); } while (0)
#include <scsi/sg.h>
#endif
-#define SCSI_DMA_BUF_SIZE 131072
-#define SCSI_MAX_INQUIRY_LEN 256
-#define SCSI_MAX_MODE_LEN 256
+#define SCSI_DMA_BUF_SIZE 131072
+#define SCSI_MAX_INQUIRY_LEN 256
+#define SCSI_MAX_MODE_LEN 256
+
+#define DEFAULT_DISCARD_GRANULARITY 4096
typedef struct SCSIDiskState SCSIDiskState;
@@ -2059,6 +2061,11 @@ static int scsi_initfn(SCSIDevice *dev)
return -1;
}
+ if (s->qdev.conf.discard_granularity == -1) {
+ s->qdev.conf.discard_granularity =
+ MAX(s->qdev.conf.logical_block_size, DEFAULT_DISCARD_GRANULARITY);
+ }
+
if (!s->version) {
s->version = g_strdup(qemu_get_version());
}