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blockdev: enable discard by default

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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>
This commit is contained in:
Paolo Bonzini 2013-02-08 14:06:14 +01:00 committed by Kevin Wolf
parent ded9d2d5e2
commit 215e47b9ea
3 changed files with 15 additions and 5 deletions
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2
hw/block-common.h
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@ -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), \

5
hw/ide/qdev.c
View File

@ -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;
}

7
hw/scsi-disk.c
View File

@ -45,6 +45,8 @@ do { printf("scsi-disk: " fmt , ## __VA_ARGS__); } while (0)
#define SCSI_MAX_INQUIRY_LEN 256
#define SCSI_MAX_MODE_LEN 256
#define DEFAULT_DISCARD_GRANULARITY 4096
typedef struct SCSIDiskState SCSIDiskState;
typedef struct SCSIDiskReq {
@ -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());
}