From 8b9dfe9098d91e06a3dd6376624307fe5fa13be8 Mon Sep 17 00:00:00 2001 From: Peter Lieven Date: Sat, 14 Dec 2013 17:31:40 +0100 Subject: [PATCH 1/2] block/iscsi: use a bh to schedule co reentrance this fixes a potential segfault and performance regression. If the coroutine is reentered directly in the iscsi_co_generic_cb iscsi_process_{read,write} are interrupted and reentered any time later. One the one hand this could happen after an iscsi_close where the iscsi context is already gone (segfault). On the other hand this limits the number of processed callbacks in each aio_dispatch to one (potential performance regression). Cc: qemu-stable@nongnu.org Signed-off-by: Peter Lieven Signed-off-by: Paolo Bonzini --- block/iscsi.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/block/iscsi.c b/block/iscsi.c index fa69408df9..b0e6eea199 100644 --- a/block/iscsi.c +++ b/block/iscsi.c @@ -68,6 +68,7 @@ typedef struct IscsiTask { int do_retry; struct scsi_task *task; Coroutine *co; + QEMUBH *bh; } IscsiTask; typedef struct IscsiAIOCB { @@ -123,6 +124,13 @@ iscsi_schedule_bh(IscsiAIOCB *acb) qemu_bh_schedule(acb->bh); } +static void iscsi_co_generic_bh_cb(void *opaque) +{ + struct IscsiTask *iTask = opaque; + qemu_bh_delete(iTask->bh); + qemu_coroutine_enter(iTask->co, NULL); +} + static void iscsi_co_generic_cb(struct iscsi_context *iscsi, int status, void *command_data, void *opaque) @@ -147,7 +155,8 @@ iscsi_co_generic_cb(struct iscsi_context *iscsi, int status, out: if (iTask->co) { - qemu_coroutine_enter(iTask->co, NULL); + iTask->bh = qemu_bh_new(iscsi_co_generic_bh_cb, iTask); + qemu_bh_schedule(iTask->bh); } } From 8a1bd2973ed5f99a3c37c9afdff823c4a22152b1 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 20 Dec 2013 15:54:27 +0100 Subject: [PATCH 2/2] scsi-disk: add UNMAP limits to block limits VPD page Linux prefers WRITE SAME to UNMAP if the limits are zero, and WRITE SAME does not discard anything unless the device can guarantee that the resulting block is zero. Setting the maximum unmap block and descriptor counts to non-zero makes Linux choose UNMAP and fixes thin provisioning on glusterfs. While the maximum unmap block count can have some effect on performance, the (suggested) maximum number of descriptors is not particularly important so I didn't add a customization option. SCSI drivers are used to online firmware updates so I'm not yet adding versioning support for SCSI, but we're probably getting close to the point when it's worth thinking about it. Reported-by: Bharata B Rao Signed-off-by: Paolo Bonzini --- hw/scsi/scsi-disk.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c index 7653411097..bce617cb93 100644 --- a/hw/scsi/scsi-disk.c +++ b/hw/scsi/scsi-disk.c @@ -47,6 +47,7 @@ do { printf("scsi-disk: " fmt , ## __VA_ARGS__); } while (0) #define SCSI_MAX_MODE_LEN 256 #define DEFAULT_DISCARD_GRANULARITY 4096 +#define DEFAULT_MAX_UNMAP_SIZE (1 << 30) /* 1 GB */ typedef struct SCSIDiskState SCSIDiskState; @@ -74,6 +75,7 @@ struct SCSIDiskState bool media_event; bool eject_request; uint64_t wwn; + uint64_t max_unmap_size; QEMUBH *bh; char *version; char *serial; @@ -625,6 +627,8 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req, uint8_t *outbuf) s->qdev.conf.min_io_size / s->qdev.blocksize; unsigned int opt_io_size = s->qdev.conf.opt_io_size / s->qdev.blocksize; + unsigned int max_unmap_sectors = + s->max_unmap_size / s->qdev.blocksize; if (s->qdev.type == TYPE_ROM) { DPRINTF("Inquiry (EVPD[%02X] not supported for CDROM\n", @@ -647,6 +651,18 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req, uint8_t *outbuf) outbuf[14] = (opt_io_size >> 8) & 0xff; outbuf[15] = opt_io_size & 0xff; + /* max unmap LBA count, default is 1GB */ + outbuf[20] = (max_unmap_sectors >> 24) & 0xff; + outbuf[21] = (max_unmap_sectors >> 16) & 0xff; + outbuf[22] = (max_unmap_sectors >> 8) & 0xff; + outbuf[23] = max_unmap_sectors & 0xff; + + /* max unmap descriptors, 255 fit in 4 kb with an 8-byte header. */ + outbuf[24] = 0; + outbuf[25] = 0; + outbuf[26] = 0; + outbuf[27] = 255; + /* optimal unmap granularity */ outbuf[28] = (unmap_sectors >> 24) & 0xff; outbuf[29] = (unmap_sectors >> 16) & 0xff; @@ -2519,6 +2535,8 @@ static Property scsi_hd_properties[] = { DEFINE_PROP_BIT("dpofua", SCSIDiskState, features, SCSI_DISK_F_DPOFUA, false), DEFINE_PROP_HEX64("wwn", SCSIDiskState, wwn, 0), + DEFINE_PROP_UINT64("max_unmap_size", SCSIDiskState, max_unmap_size, + DEFAULT_MAX_UNMAP_SIZE), DEFINE_BLOCK_CHS_PROPERTIES(SCSIDiskState, qdev.conf), DEFINE_PROP_END_OF_LIST(), }; @@ -2628,6 +2646,8 @@ static Property scsi_disk_properties[] = { DEFINE_PROP_BIT("dpofua", SCSIDiskState, features, SCSI_DISK_F_DPOFUA, false), DEFINE_PROP_HEX64("wwn", SCSIDiskState, wwn, 0), + DEFINE_PROP_UINT64("max_unmap_size", SCSIDiskState, max_unmap_size, + DEFAULT_MAX_UNMAP_SIZE), DEFINE_PROP_END_OF_LIST(), };