* [Qemu-devel] [PATCH] block/iscsi: allow caching of the allocation map
@ 2016-05-17 13:59 Peter Lieven
2016-05-18 7:41 ` Fam Zheng
0 siblings, 1 reply; 3+ messages in thread
From: Peter Lieven @ 2016-05-17 13:59 UTC (permalink / raw)
To: qemu-devel; +Cc: ronniesahlberg, pbonzini, qemu-block, Peter Lieven
until now the allocation map was used only as a hint if a cluster
is allocated or not. If a block was not allocated (or Qemu had
no info about the allocation status) a get_block_status call was
issued to check the allocation status and possibly avoid
a subsequent read of unallocated sectors. If a block known to be
allocated the get_block_status call was omitted. In the other case
a get_block_status call was issued before every read to avoid
the necessity for a consistent allocation map. To avoid the
potential overhead of calling get_block_status for each and
every read request this took only place for the bigger requests.
This patch enhances this mechanism to cache the allocation
status and avoid calling get_block_status for blocks where
the allocation status has been queried before. This allows
for bypassing the read request even for smaller requests and
additionally omits calling get_block_status for known to be
unallocated blocks.
Signed-off-by: Peter Lieven <pl@kamp.de>
---
block/iscsi.c | 194 +++++++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 144 insertions(+), 50 deletions(-)
diff --git a/block/iscsi.c b/block/iscsi.c
index 10f3906..b25bebd 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -2,7 +2,7 @@
* QEMU Block driver for iSCSI images
*
* Copyright (c) 2010-2011 Ronnie Sahlberg <ronniesahlberg@gmail.com>
- * Copyright (c) 2012-2015 Peter Lieven <pl@kamp.de>
+ * Copyright (c) 2012-2016 Peter Lieven <pl@kamp.de>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
@@ -62,7 +62,9 @@ typedef struct IscsiLun {
struct scsi_inquiry_logical_block_provisioning lbp;
struct scsi_inquiry_block_limits bl;
unsigned char *zeroblock;
- unsigned long *allocationmap;
+ unsigned long *allocmap;
+ unsigned long *allocmap_valid;
+ long allocmap_size;
int cluster_sectors;
bool use_16_for_rw;
bool write_protected;
@@ -415,39 +417,127 @@ static bool is_request_lun_aligned(int64_t sector_num, int nb_sectors,
return 1;
}
-static unsigned long *iscsi_allocationmap_init(IscsiLun *iscsilun)
+static void iscsi_allocmap_free(IscsiLun *iscsilun)
{
- return bitmap_try_new(DIV_ROUND_UP(sector_lun2qemu(iscsilun->num_blocks,
- iscsilun),
- iscsilun->cluster_sectors));
+ g_free(iscsilun->allocmap);
+ g_free(iscsilun->allocmap_valid);
+ iscsilun->allocmap = NULL;
+ iscsilun->allocmap_valid = NULL;
}
-static void iscsi_allocationmap_set(IscsiLun *iscsilun, int64_t sector_num,
- int nb_sectors)
+
+static int iscsi_allocmap_init(IscsiLun *iscsilun, int open_flags)
{
- if (iscsilun->allocationmap == NULL) {
- return;
+ iscsilun->allocmap_size =
+ DIV_ROUND_UP(sector_lun2qemu(iscsilun->num_blocks, iscsilun),
+ iscsilun->cluster_sectors);
+
+ iscsilun->allocmap = bitmap_try_new(iscsilun->allocmap_size);
+ if (!iscsilun->allocmap) {
+ return -ENOMEM;
+ }
+
+ if (open_flags & BDRV_O_NOCACHE) {
+ return 0;
+ }
+
+ iscsilun->allocmap_valid = bitmap_try_new(iscsilun->allocmap_size);
+ if (!iscsilun->allocmap_valid) {
+ return -ENOMEM;
}
- bitmap_set(iscsilun->allocationmap,
- sector_num / iscsilun->cluster_sectors,
- DIV_ROUND_UP(nb_sectors, iscsilun->cluster_sectors));
+
+ return 0;
}
-static void iscsi_allocationmap_clear(IscsiLun *iscsilun, int64_t sector_num,
- int nb_sectors)
+static void
+iscsi_allocmap_update(IscsiLun *iscsilun, int64_t sector_num,
+ int nb_sectors, bool allocated, bool valid)
{
int64_t cluster_num, nb_clusters;
- if (iscsilun->allocationmap == NULL) {
+
+ if (iscsilun->allocmap == NULL) {
return;
}
cluster_num = DIV_ROUND_UP(sector_num, iscsilun->cluster_sectors);
nb_clusters = (sector_num + nb_sectors) / iscsilun->cluster_sectors
- cluster_num;
- if (nb_clusters > 0) {
- bitmap_clear(iscsilun->allocationmap, cluster_num, nb_clusters);
+ if (allocated) {
+ bitmap_set(iscsilun->allocmap,
+ sector_num / iscsilun->cluster_sectors,
+ DIV_ROUND_UP(nb_sectors, iscsilun->cluster_sectors));
+ } else if (nb_clusters > 0) {
+ bitmap_clear(iscsilun->allocmap, cluster_num, nb_clusters);
+ }
+
+ if (iscsilun->allocmap_valid == NULL) {
+ return;
+ }
+ if (valid) {
+ if (nb_clusters > 0) {
+ bitmap_set(iscsilun->allocmap_valid, cluster_num, nb_clusters);
+ }
+ } else {
+ bitmap_clear(iscsilun->allocmap_valid,
+ sector_num / iscsilun->cluster_sectors,
+ DIV_ROUND_UP(nb_sectors, iscsilun->cluster_sectors));
}
}
+static void
+iscsi_allocmap_set_allocated(IscsiLun *iscsilun, int64_t sector_num,
+ int nb_sectors)
+{
+ iscsi_allocmap_update(iscsilun, sector_num, nb_sectors, true, true);
+}
+
+static void
+iscsi_allocmap_set_unallocated(IscsiLun *iscsilun, int64_t sector_num,
+ int nb_sectors)
+{
+ iscsi_allocmap_update(iscsilun, sector_num, nb_sectors, false, true);
+}
+
+static void iscsi_allocmap_set_invalid(IscsiLun *iscsilun, int64_t sector_num,
+ int nb_sectors)
+{
+ iscsi_allocmap_update(iscsilun, sector_num, nb_sectors, false, false);
+}
+
+static void iscsi_allocmap_invalidate(IscsiLun *iscsilun)
+{
+ if (iscsilun->allocmap) {
+ bitmap_zero(iscsilun->allocmap, iscsilun->allocmap_size);
+ }
+ if (iscsilun->allocmap_valid) {
+ bitmap_zero(iscsilun->allocmap_valid, iscsilun->allocmap_size);
+ }
+}
+
+static inline bool
+iscsi_allocmap_is_allocated(IscsiLun *iscsilun, int64_t sector_num,
+ int nb_sectors)
+{
+ unsigned long size;
+ if (iscsilun->allocmap == NULL) {
+ return true;
+ }
+ size = DIV_ROUND_UP(sector_num + nb_sectors, iscsilun->cluster_sectors);
+ return !(find_next_bit(iscsilun->allocmap, size,
+ sector_num / iscsilun->cluster_sectors) == size);
+}
+
+static inline bool iscsi_allocmap_is_valid(IscsiLun *iscsilun,
+ int64_t sector_num, int nb_sectors)
+{
+ unsigned long size;
+ if (iscsilun->allocmap_valid == NULL) {
+ return false;
+ }
+ size = DIV_ROUND_UP(sector_num + nb_sectors, iscsilun->cluster_sectors);
+ return (find_next_zero_bit(iscsilun->allocmap_valid, size,
+ sector_num / iscsilun->cluster_sectors) == size);
+}
+
static int coroutine_fn
iscsi_co_writev_flags(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
QEMUIOVector *iov, int flags)
@@ -507,26 +597,16 @@ retry:
}
if (iTask.status != SCSI_STATUS_GOOD) {
+ iscsi_allocmap_set_invalid(iscsilun, sector_num, nb_sectors);
return iTask.err_code;
}
- iscsi_allocationmap_set(iscsilun, sector_num, nb_sectors);
+ iscsi_allocmap_set_allocated(iscsilun, sector_num, nb_sectors);
return 0;
}
-static bool iscsi_allocationmap_is_allocated(IscsiLun *iscsilun,
- int64_t sector_num, int nb_sectors)
-{
- unsigned long size;
- if (iscsilun->allocationmap == NULL) {
- return true;
- }
- size = DIV_ROUND_UP(sector_num + nb_sectors, iscsilun->cluster_sectors);
- return !(find_next_bit(iscsilun->allocationmap, size,
- sector_num / iscsilun->cluster_sectors) == size);
-}
static int64_t coroutine_fn iscsi_co_get_block_status(BlockDriverState *bs,
int64_t sector_num,
@@ -611,9 +691,9 @@ retry:
}
if (ret & BDRV_BLOCK_ZERO) {
- iscsi_allocationmap_clear(iscsilun, sector_num, *pnum);
+ iscsi_allocmap_set_unallocated(iscsilun, sector_num, *pnum);
} else {
- iscsi_allocationmap_set(iscsilun, sector_num, *pnum);
+ iscsi_allocmap_set_allocated(iscsilun, sector_num, *pnum);
}
if (*pnum > nb_sectors) {
@@ -629,7 +709,7 @@ out:
return ret;
}
-static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
+ static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
QEMUIOVector *iov)
{
@@ -648,16 +728,25 @@ static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
return -EINVAL;
}
- if (iscsilun->lbprz && nb_sectors >= ISCSI_CHECKALLOC_THRES &&
- !iscsi_allocationmap_is_allocated(iscsilun, sector_num, nb_sectors)) {
- int64_t ret;
+ if (iscsi_allocmap_is_valid(iscsilun, sector_num, nb_sectors) &&
+ !iscsi_allocmap_is_allocated(iscsilun, sector_num, nb_sectors)) {
+ qemu_iovec_memset(iov, 0, 0x00, iov->size);
+ return 0;
+ }
+
+ if (nb_sectors >= ISCSI_CHECKALLOC_THRES &&
+ !iscsi_allocmap_is_valid(iscsilun, sector_num, nb_sectors) &&
+ !iscsi_allocmap_is_allocated(iscsilun, sector_num, nb_sectors)) {
int pnum;
BlockDriverState *file;
- ret = iscsi_co_get_block_status(bs, sector_num, INT_MAX, &pnum, &file);
+ int64_t ret = iscsi_co_get_block_status(bs,
+ sector_num - sector_num % iscsilun->cluster_sectors,
+ INT_MAX, &pnum, &file);
if (ret < 0) {
return ret;
}
- if (ret & BDRV_BLOCK_ZERO && pnum >= nb_sectors) {
+ if (ret & BDRV_BLOCK_ZERO &&
+ pnum >= nb_sectors + sector_num % iscsilun->cluster_sectors) {
qemu_iovec_memset(iov, 0, 0x00, iov->size);
return 0;
}
@@ -892,7 +981,6 @@ static BlockAIOCB *iscsi_aio_ioctl(BlockDriverState *bs,
}
iscsi_set_events(iscsilun);
-
return &acb->common;
}
@@ -963,7 +1051,7 @@ retry:
return iTask.err_code;
}
- iscsi_allocationmap_clear(iscsilun, sector_num, nb_sectors);
+ iscsi_allocmap_set_invalid(iscsilun, sector_num, nb_sectors);
return 0;
}
@@ -1053,13 +1141,14 @@ retry:
}
if (iTask.status != SCSI_STATUS_GOOD) {
+ iscsi_allocmap_set_invalid(iscsilun, sector_num, nb_sectors);
return iTask.err_code;
}
if (flags & BDRV_REQ_MAY_UNMAP) {
- iscsi_allocationmap_clear(iscsilun, sector_num, nb_sectors);
+ iscsi_allocmap_set_invalid(iscsilun, sector_num, nb_sectors);
} else {
- iscsi_allocationmap_set(iscsilun, sector_num, nb_sectors);
+ iscsi_allocmap_set_allocated(iscsilun, sector_num, nb_sectors);
}
return 0;
@@ -1633,10 +1722,7 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags,
iscsilun->cluster_sectors = (iscsilun->bl.opt_unmap_gran *
iscsilun->block_size) >> BDRV_SECTOR_BITS;
if (iscsilun->lbprz) {
- iscsilun->allocationmap = iscsi_allocationmap_init(iscsilun);
- if (iscsilun->allocationmap == NULL) {
- ret = -ENOMEM;
- }
+ ret = iscsi_allocmap_init(iscsilun, bs->open_flags);
}
}
@@ -1673,7 +1759,7 @@ static void iscsi_close(BlockDriverState *bs)
}
iscsi_destroy_context(iscsi);
g_free(iscsilun->zeroblock);
- g_free(iscsilun->allocationmap);
+ iscsi_allocmap_free(iscsilun);
memset(iscsilun, 0, sizeof(IscsiLun));
}
@@ -1750,9 +1836,9 @@ static int iscsi_truncate(BlockDriverState *bs, int64_t offset)
return -EINVAL;
}
- if (iscsilun->allocationmap != NULL) {
- g_free(iscsilun->allocationmap);
- iscsilun->allocationmap = iscsi_allocationmap_init(iscsilun);
+ if (iscsilun->allocmap != NULL) {
+ iscsi_allocmap_free(iscsilun);
+ iscsi_allocmap_init(iscsilun, bs->open_flags);
}
return 0;
@@ -1812,6 +1898,13 @@ static int iscsi_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
return 0;
}
+static void iscsi_invalidate_cache(BlockDriverState *bs,
+ Error **errp)
+{
+ IscsiLun *iscsilun = bs->opaque;
+ iscsi_allocmap_invalidate(iscsilun);
+}
+
static QemuOptsList iscsi_create_opts = {
.name = "iscsi-create-opts",
.head = QTAILQ_HEAD_INITIALIZER(iscsi_create_opts.head),
@@ -1836,6 +1929,7 @@ static BlockDriver bdrv_iscsi = {
.bdrv_create = iscsi_create,
.create_opts = &iscsi_create_opts,
.bdrv_reopen_prepare = iscsi_reopen_prepare,
+ .bdrv_invalidate_cache = iscsi_invalidate_cache,
.bdrv_getlength = iscsi_getlength,
.bdrv_get_info = iscsi_get_info,
--
1.9.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [PATCH] block/iscsi: allow caching of the allocation map
2016-05-17 13:59 [Qemu-devel] [PATCH] block/iscsi: allow caching of the allocation map Peter Lieven
@ 2016-05-18 7:41 ` Fam Zheng
2016-05-19 6:20 ` Peter Lieven
0 siblings, 1 reply; 3+ messages in thread
From: Fam Zheng @ 2016-05-18 7:41 UTC (permalink / raw)
To: Peter Lieven; +Cc: qemu-devel, pbonzini, qemu-block, ronniesahlberg
On Tue, 05/17 15:59, Peter Lieven wrote:
> until now the allocation map was used only as a hint if a cluster
> is allocated or not. If a block was not allocated (or Qemu had
> no info about the allocation status) a get_block_status call was
> issued to check the allocation status and possibly avoid
> a subsequent read of unallocated sectors. If a block known to be
> allocated the get_block_status call was omitted. In the other case
> a get_block_status call was issued before every read to avoid
> the necessity for a consistent allocation map. To avoid the
> potential overhead of calling get_block_status for each and
> every read request this took only place for the bigger requests.
>
> This patch enhances this mechanism to cache the allocation
> status and avoid calling get_block_status for blocks where
> the allocation status has been queried before. This allows
> for bypassing the read request even for smaller requests and
> additionally omits calling get_block_status for known to be
> unallocated blocks.
Looks good overall, I have some minor comments below, though.
>
> Signed-off-by: Peter Lieven <pl@kamp.de>
> ---
> block/iscsi.c | 194 +++++++++++++++++++++++++++++++++++++++++++---------------
> 1 file changed, 144 insertions(+), 50 deletions(-)
>
> diff --git a/block/iscsi.c b/block/iscsi.c
> index 10f3906..b25bebd 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -2,7 +2,7 @@
> * QEMU Block driver for iSCSI images
> *
> * Copyright (c) 2010-2011 Ronnie Sahlberg <ronniesahlberg@gmail.com>
> - * Copyright (c) 2012-2015 Peter Lieven <pl@kamp.de>
> + * Copyright (c) 2012-2016 Peter Lieven <pl@kamp.de>
> *
> * Permission is hereby granted, free of charge, to any person obtaining a copy
> * of this software and associated documentation files (the "Software"), to deal
> @@ -62,7 +62,9 @@ typedef struct IscsiLun {
> struct scsi_inquiry_logical_block_provisioning lbp;
> struct scsi_inquiry_block_limits bl;
> unsigned char *zeroblock;
> - unsigned long *allocationmap;
> + unsigned long *allocmap;
> + unsigned long *allocmap_valid;
> + long allocmap_size;
Could you add some comments about the relation between these three fields and
their respective semantics?
> int cluster_sectors;
> bool use_16_for_rw;
> bool write_protected;
> @@ -415,39 +417,127 @@ static bool is_request_lun_aligned(int64_t sector_num, int nb_sectors,
> return 1;
> }
>
> -static unsigned long *iscsi_allocationmap_init(IscsiLun *iscsilun)
> +static void iscsi_allocmap_free(IscsiLun *iscsilun)
> {
> - return bitmap_try_new(DIV_ROUND_UP(sector_lun2qemu(iscsilun->num_blocks,
> - iscsilun),
> - iscsilun->cluster_sectors));
> + g_free(iscsilun->allocmap);
> + g_free(iscsilun->allocmap_valid);
> + iscsilun->allocmap = NULL;
> + iscsilun->allocmap_valid = NULL;
> }
>
> -static void iscsi_allocationmap_set(IscsiLun *iscsilun, int64_t sector_num,
> - int nb_sectors)
> +
> +static int iscsi_allocmap_init(IscsiLun *iscsilun, int open_flags)
> {
> - if (iscsilun->allocationmap == NULL) {
> - return;
> + iscsilun->allocmap_size =
> + DIV_ROUND_UP(sector_lun2qemu(iscsilun->num_blocks, iscsilun),
> + iscsilun->cluster_sectors);
> +
> + iscsilun->allocmap = bitmap_try_new(iscsilun->allocmap_size);
> + if (!iscsilun->allocmap) {
> + return -ENOMEM;
> + }
> +
> + if (open_flags & BDRV_O_NOCACHE) {
> + return 0;
> + }
> +
> + iscsilun->allocmap_valid = bitmap_try_new(iscsilun->allocmap_size);
> + if (!iscsilun->allocmap_valid) {
Do you want to free iscsilun->allocmap? If you keep the two maps together...
> + return -ENOMEM;
> }
> - bitmap_set(iscsilun->allocationmap,
> - sector_num / iscsilun->cluster_sectors,
> - DIV_ROUND_UP(nb_sectors, iscsilun->cluster_sectors));
> +
> + return 0;
> }
>
> -static void iscsi_allocationmap_clear(IscsiLun *iscsilun, int64_t sector_num,
> - int nb_sectors)
> +static void
> +iscsi_allocmap_update(IscsiLun *iscsilun, int64_t sector_num,
> + int nb_sectors, bool allocated, bool valid)
^
Looks like the parameter list is not aligned.
> {
> int64_t cluster_num, nb_clusters;
> - if (iscsilun->allocationmap == NULL) {
> +
> + if (iscsilun->allocmap == NULL) {
> return;
> }
> cluster_num = DIV_ROUND_UP(sector_num, iscsilun->cluster_sectors);
> nb_clusters = (sector_num + nb_sectors) / iscsilun->cluster_sectors
> - cluster_num;
> - if (nb_clusters > 0) {
> - bitmap_clear(iscsilun->allocationmap, cluster_num, nb_clusters);
> + if (allocated) {
> + bitmap_set(iscsilun->allocmap,
> + sector_num / iscsilun->cluster_sectors,
> + DIV_ROUND_UP(nb_sectors, iscsilun->cluster_sectors));
> + } else if (nb_clusters > 0) {
> + bitmap_clear(iscsilun->allocmap, cluster_num, nb_clusters);
> + }
> +
> + if (iscsilun->allocmap_valid == NULL) {
> + return;
> + }
... there will be one less branch and code is simpler.
> + if (valid) {
> + if (nb_clusters > 0) {
> + bitmap_set(iscsilun->allocmap_valid, cluster_num, nb_clusters);
> + }
> + } else {
> + bitmap_clear(iscsilun->allocmap_valid,
> + sector_num / iscsilun->cluster_sectors,
> + DIV_ROUND_UP(nb_sectors, iscsilun->cluster_sectors));
> }
> }
>
> +static void
> +iscsi_allocmap_set_allocated(IscsiLun *iscsilun, int64_t sector_num,
> + int nb_sectors)
> +{
> + iscsi_allocmap_update(iscsilun, sector_num, nb_sectors, true, true);
> +}
> +
> +static void
> +iscsi_allocmap_set_unallocated(IscsiLun *iscsilun, int64_t sector_num,
> + int nb_sectors)
> +{
> + iscsi_allocmap_update(iscsilun, sector_num, nb_sectors, false, true);
> +}
> +
> +static void iscsi_allocmap_set_invalid(IscsiLun *iscsilun, int64_t sector_num,
> + int nb_sectors)
> +{
> + iscsi_allocmap_update(iscsilun, sector_num, nb_sectors, false, false);
> +}
> +
> +static void iscsi_allocmap_invalidate(IscsiLun *iscsilun)
> +{
> + if (iscsilun->allocmap) {
> + bitmap_zero(iscsilun->allocmap, iscsilun->allocmap_size);
> + }
> + if (iscsilun->allocmap_valid) {
> + bitmap_zero(iscsilun->allocmap_valid, iscsilun->allocmap_size);
> + }
> +}
> +
> +static inline bool
> +iscsi_allocmap_is_allocated(IscsiLun *iscsilun, int64_t sector_num,
> + int nb_sectors)
> +{
> + unsigned long size;
> + if (iscsilun->allocmap == NULL) {
> + return true;
> + }
> + size = DIV_ROUND_UP(sector_num + nb_sectors, iscsilun->cluster_sectors);
> + return !(find_next_bit(iscsilun->allocmap, size,
> + sector_num / iscsilun->cluster_sectors) == size);
> +}
> +
> +static inline bool iscsi_allocmap_is_valid(IscsiLun *iscsilun,
> + int64_t sector_num, int nb_sectors)
> +{
> + unsigned long size;
> + if (iscsilun->allocmap_valid == NULL) {
> + return false;
> + }
> + size = DIV_ROUND_UP(sector_num + nb_sectors, iscsilun->cluster_sectors);
> + return (find_next_zero_bit(iscsilun->allocmap_valid, size,
> + sector_num / iscsilun->cluster_sectors) == size);
> +}
> +
> static int coroutine_fn
> iscsi_co_writev_flags(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
> QEMUIOVector *iov, int flags)
> @@ -507,26 +597,16 @@ retry:
> }
>
> if (iTask.status != SCSI_STATUS_GOOD) {
> + iscsi_allocmap_set_invalid(iscsilun, sector_num, nb_sectors);
> return iTask.err_code;
> }
>
> - iscsi_allocationmap_set(iscsilun, sector_num, nb_sectors);
> + iscsi_allocmap_set_allocated(iscsilun, sector_num, nb_sectors);
>
> return 0;
> }
>
>
> -static bool iscsi_allocationmap_is_allocated(IscsiLun *iscsilun,
> - int64_t sector_num, int nb_sectors)
> -{
> - unsigned long size;
> - if (iscsilun->allocationmap == NULL) {
> - return true;
> - }
> - size = DIV_ROUND_UP(sector_num + nb_sectors, iscsilun->cluster_sectors);
> - return !(find_next_bit(iscsilun->allocationmap, size,
> - sector_num / iscsilun->cluster_sectors) == size);
> -}
>
> static int64_t coroutine_fn iscsi_co_get_block_status(BlockDriverState *bs,
> int64_t sector_num,
> @@ -611,9 +691,9 @@ retry:
> }
>
> if (ret & BDRV_BLOCK_ZERO) {
> - iscsi_allocationmap_clear(iscsilun, sector_num, *pnum);
> + iscsi_allocmap_set_unallocated(iscsilun, sector_num, *pnum);
> } else {
> - iscsi_allocationmap_set(iscsilun, sector_num, *pnum);
> + iscsi_allocmap_set_allocated(iscsilun, sector_num, *pnum);
> }
>
> if (*pnum > nb_sectors) {
> @@ -629,7 +709,7 @@ out:
> return ret;
> }
>
> -static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
> + static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
A superfluous leading whitespace?
> int64_t sector_num, int nb_sectors,
> QEMUIOVector *iov)
> {
> @@ -648,16 +728,25 @@ static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
> return -EINVAL;
> }
>
> - if (iscsilun->lbprz && nb_sectors >= ISCSI_CHECKALLOC_THRES &&
> - !iscsi_allocationmap_is_allocated(iscsilun, sector_num, nb_sectors)) {
> - int64_t ret;
> + if (iscsi_allocmap_is_valid(iscsilun, sector_num, nb_sectors) &&
> + !iscsi_allocmap_is_allocated(iscsilun, sector_num, nb_sectors)) {
> + qemu_iovec_memset(iov, 0, 0x00, iov->size);
> + return 0;
> + }
> +
> + if (nb_sectors >= ISCSI_CHECKALLOC_THRES &&
> + !iscsi_allocmap_is_valid(iscsilun, sector_num, nb_sectors) &&
> + !iscsi_allocmap_is_allocated(iscsilun, sector_num, nb_sectors)) {
> int pnum;
> BlockDriverState *file;
> - ret = iscsi_co_get_block_status(bs, sector_num, INT_MAX, &pnum, &file);
> + int64_t ret = iscsi_co_get_block_status(bs,
> + sector_num - sector_num % iscsilun->cluster_sectors,
> + INT_MAX, &pnum, &file);
> if (ret < 0) {
> return ret;
> }
> - if (ret & BDRV_BLOCK_ZERO && pnum >= nb_sectors) {
> + if (ret & BDRV_BLOCK_ZERO &&
> + pnum >= nb_sectors + sector_num % iscsilun->cluster_sectors) {
> qemu_iovec_memset(iov, 0, 0x00, iov->size);
> return 0;
> }
> @@ -892,7 +981,6 @@ static BlockAIOCB *iscsi_aio_ioctl(BlockDriverState *bs,
> }
>
> iscsi_set_events(iscsilun);
> -
Superfluous whitespace change.
> return &acb->common;
> }
>
> @@ -963,7 +1051,7 @@ retry:
> return iTask.err_code;
> }
>
> - iscsi_allocationmap_clear(iscsilun, sector_num, nb_sectors);
> + iscsi_allocmap_set_invalid(iscsilun, sector_num, nb_sectors);
>
> return 0;
> }
> @@ -1053,13 +1141,14 @@ retry:
> }
>
> if (iTask.status != SCSI_STATUS_GOOD) {
> + iscsi_allocmap_set_invalid(iscsilun, sector_num, nb_sectors);
> return iTask.err_code;
> }
>
> if (flags & BDRV_REQ_MAY_UNMAP) {
> - iscsi_allocationmap_clear(iscsilun, sector_num, nb_sectors);
> + iscsi_allocmap_set_invalid(iscsilun, sector_num, nb_sectors);
> } else {
> - iscsi_allocationmap_set(iscsilun, sector_num, nb_sectors);
> + iscsi_allocmap_set_allocated(iscsilun, sector_num, nb_sectors);
> }
>
> return 0;
> @@ -1633,10 +1722,7 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags,
> iscsilun->cluster_sectors = (iscsilun->bl.opt_unmap_gran *
> iscsilun->block_size) >> BDRV_SECTOR_BITS;
> if (iscsilun->lbprz) {
> - iscsilun->allocationmap = iscsi_allocationmap_init(iscsilun);
> - if (iscsilun->allocationmap == NULL) {
> - ret = -ENOMEM;
> - }
> + ret = iscsi_allocmap_init(iscsilun, bs->open_flags);
> }
> }
>
> @@ -1673,7 +1759,7 @@ static void iscsi_close(BlockDriverState *bs)
> }
> iscsi_destroy_context(iscsi);
> g_free(iscsilun->zeroblock);
> - g_free(iscsilun->allocationmap);
> + iscsi_allocmap_free(iscsilun);
> memset(iscsilun, 0, sizeof(IscsiLun));
> }
>
> @@ -1750,9 +1836,9 @@ static int iscsi_truncate(BlockDriverState *bs, int64_t offset)
> return -EINVAL;
> }
>
> - if (iscsilun->allocationmap != NULL) {
> - g_free(iscsilun->allocationmap);
> - iscsilun->allocationmap = iscsi_allocationmap_init(iscsilun);
> + if (iscsilun->allocmap != NULL) {
> + iscsi_allocmap_free(iscsilun);
> + iscsi_allocmap_init(iscsilun, bs->open_flags);
Need to handle the return value here?
> }
>
> return 0;
Thanks,
Fam
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [PATCH] block/iscsi: allow caching of the allocation map
2016-05-18 7:41 ` Fam Zheng
@ 2016-05-19 6:20 ` Peter Lieven
0 siblings, 0 replies; 3+ messages in thread
From: Peter Lieven @ 2016-05-19 6:20 UTC (permalink / raw)
To: Fam Zheng; +Cc: qemu-devel, pbonzini, qemu-block, ronniesahlberg
Am 18.05.2016 um 09:41 schrieb Fam Zheng:
> On Tue, 05/17 15:59, Peter Lieven wrote:
>> until now the allocation map was used only as a hint if a cluster
>> is allocated or not. If a block was not allocated (or Qemu had
>> no info about the allocation status) a get_block_status call was
>> issued to check the allocation status and possibly avoid
>> a subsequent read of unallocated sectors. If a block known to be
>> allocated the get_block_status call was omitted. In the other case
>> a get_block_status call was issued before every read to avoid
>> the necessity for a consistent allocation map. To avoid the
>> potential overhead of calling get_block_status for each and
>> every read request this took only place for the bigger requests.
>>
>> This patch enhances this mechanism to cache the allocation
>> status and avoid calling get_block_status for blocks where
>> the allocation status has been queried before. This allows
>> for bypassing the read request even for smaller requests and
>> additionally omits calling get_block_status for known to be
>> unallocated blocks.
> Looks good overall, I have some minor comments below, though.
>
>> Signed-off-by: Peter Lieven <pl@kamp.de>
>> ---
>> block/iscsi.c | 194 +++++++++++++++++++++++++++++++++++++++++++---------------
>> 1 file changed, 144 insertions(+), 50 deletions(-)
>>
>> diff --git a/block/iscsi.c b/block/iscsi.c
>> index 10f3906..b25bebd 100644
>> --- a/block/iscsi.c
>> +++ b/block/iscsi.c
>> @@ -2,7 +2,7 @@
>> * QEMU Block driver for iSCSI images
>> *
>> * Copyright (c) 2010-2011 Ronnie Sahlberg <ronniesahlberg@gmail.com>
>> - * Copyright (c) 2012-2015 Peter Lieven <pl@kamp.de>
>> + * Copyright (c) 2012-2016 Peter Lieven <pl@kamp.de>
>> *
>> * Permission is hereby granted, free of charge, to any person obtaining a copy
>> * of this software and associated documentation files (the "Software"), to deal
>> @@ -62,7 +62,9 @@ typedef struct IscsiLun {
>> struct scsi_inquiry_logical_block_provisioning lbp;
>> struct scsi_inquiry_block_limits bl;
>> unsigned char *zeroblock;
>> - unsigned long *allocationmap;
>> + unsigned long *allocmap;
>> + unsigned long *allocmap_valid;
>> + long allocmap_size;
> Could you add some comments about the relation between these three fields and
> their respective semantics?
Sure.
Are you happy with this comment?
*/ The allocation map tracks which clusters (pages) on the iSCSI target are
* allocated and which are not. In case a target returns zeros for unallocated
* pages (iscsilun->lprz) we can directly return zeros instead of reading zeros over
* the wire if a read request falls within an unallocated block. As there are 3 possible
* states we need 2 bitmaps to track. allocmap_valid keeps track if Qemus
* information about a page is valid. allocmap tracks if a page is allocated or
* not. In case Qemus has no valid information about a page the corresponding
* allocmap entry should be switched to unallocated as well to force a new lookup of
* the allocation status as lookups are generally skipped if a page is suspect
* to be allocated. If a iSCSI target is opened with cache.direct = on the allocmap_valid
* does not exist turning all cached information invalid so that a fresh lookup
* is made for any page even if allocmap entry returns its unallocated. */
>
>> int cluster_sectors;
>> bool use_16_for_rw;
>> bool write_protected;
>> @@ -415,39 +417,127 @@ static bool is_request_lun_aligned(int64_t sector_num, int nb_sectors,
>> return 1;
>> }
>>
>> -static unsigned long *iscsi_allocationmap_init(IscsiLun *iscsilun)
>> +static void iscsi_allocmap_free(IscsiLun *iscsilun)
>> {
>> - return bitmap_try_new(DIV_ROUND_UP(sector_lun2qemu(iscsilun->num_blocks,
>> - iscsilun),
>> - iscsilun->cluster_sectors));
>> + g_free(iscsilun->allocmap);
>> + g_free(iscsilun->allocmap_valid);
>> + iscsilun->allocmap = NULL;
>> + iscsilun->allocmap_valid = NULL;
>> }
>>
>> -static void iscsi_allocationmap_set(IscsiLun *iscsilun, int64_t sector_num,
>> - int nb_sectors)
>> +
>> +static int iscsi_allocmap_init(IscsiLun *iscsilun, int open_flags)
>> {
>> - if (iscsilun->allocationmap == NULL) {
>> - return;
>> + iscsilun->allocmap_size =
>> + DIV_ROUND_UP(sector_lun2qemu(iscsilun->num_blocks, iscsilun),
>> + iscsilun->cluster_sectors);
>> +
>> + iscsilun->allocmap = bitmap_try_new(iscsilun->allocmap_size);
>> + if (!iscsilun->allocmap) {
>> + return -ENOMEM;
>> + }
>> +
>> + if (open_flags & BDRV_O_NOCACHE) {
>> + return 0;
>> + }
>> +
>> + iscsilun->allocmap_valid = bitmap_try_new(iscsilun->allocmap_size);
>> + if (!iscsilun->allocmap_valid) {
> Do you want to free iscsilun->allocmap? If you keep the two maps together...
It does still work without the allocmap_valid, but it might be a good idea
to free that memory if we are under memory pressure.
>
>> + return -ENOMEM;
>> }
>> - bitmap_set(iscsilun->allocationmap,
>> - sector_num / iscsilun->cluster_sectors,
>> - DIV_ROUND_UP(nb_sectors, iscsilun->cluster_sectors));
>> +
>> + return 0;
>> }
>>
>> -static void iscsi_allocationmap_clear(IscsiLun *iscsilun, int64_t sector_num,
>> - int nb_sectors)
>> +static void
>> +iscsi_allocmap_update(IscsiLun *iscsilun, int64_t sector_num,
>> + int nb_sectors, bool allocated, bool valid)
> ^
> Looks like the parameter list is not aligned.
>
>> {
>> int64_t cluster_num, nb_clusters;
>> - if (iscsilun->allocationmap == NULL) {
>> +
>> + if (iscsilun->allocmap == NULL) {
>> return;
>> }
>> cluster_num = DIV_ROUND_UP(sector_num, iscsilun->cluster_sectors);
>> nb_clusters = (sector_num + nb_sectors) / iscsilun->cluster_sectors
>> - cluster_num;
>> - if (nb_clusters > 0) {
>> - bitmap_clear(iscsilun->allocationmap, cluster_num, nb_clusters);
>> + if (allocated) {
>> + bitmap_set(iscsilun->allocmap,
>> + sector_num / iscsilun->cluster_sectors,
>> + DIV_ROUND_UP(nb_sectors, iscsilun->cluster_sectors));
>> + } else if (nb_clusters > 0) {
>> + bitmap_clear(iscsilun->allocmap, cluster_num, nb_clusters);
>> + }
>> +
>> + if (iscsilun->allocmap_valid == NULL) {
>> + return;
>> + }
> ... there will be one less branch and code is simpler.
I have to keep this one. Its valid to have no allocmap_valid bitmap. Thats
the case when cache.direct is on. In this case the map is always invalid
which returns to the old allocmap behaviour.
>
>> + if (valid) {
>> + if (nb_clusters > 0) {
>> + bitmap_set(iscsilun->allocmap_valid, cluster_num, nb_clusters);
>> + }
>> + } else {
>> + bitmap_clear(iscsilun->allocmap_valid,
>> + sector_num / iscsilun->cluster_sectors,
>> + DIV_ROUND_UP(nb_sectors, iscsilun->cluster_sectors));
>> }
>> }
>>
>> +static void
>> +iscsi_allocmap_set_allocated(IscsiLun *iscsilun, int64_t sector_num,
>> + int nb_sectors)
>> +{
>> + iscsi_allocmap_update(iscsilun, sector_num, nb_sectors, true, true);
>> +}
>> +
>> +static void
>> +iscsi_allocmap_set_unallocated(IscsiLun *iscsilun, int64_t sector_num,
>> + int nb_sectors)
>> +{
>> + iscsi_allocmap_update(iscsilun, sector_num, nb_sectors, false, true);
>> +}
>> +
>> +static void iscsi_allocmap_set_invalid(IscsiLun *iscsilun, int64_t sector_num,
>> + int nb_sectors)
>> +{
>> + iscsi_allocmap_update(iscsilun, sector_num, nb_sectors, false, false);
>> +}
>> +
>> +static void iscsi_allocmap_invalidate(IscsiLun *iscsilun)
>> +{
>> + if (iscsilun->allocmap) {
>> + bitmap_zero(iscsilun->allocmap, iscsilun->allocmap_size);
>> + }
>> + if (iscsilun->allocmap_valid) {
>> + bitmap_zero(iscsilun->allocmap_valid, iscsilun->allocmap_size);
>> + }
>> +}
>> +
>> +static inline bool
>> +iscsi_allocmap_is_allocated(IscsiLun *iscsilun, int64_t sector_num,
>> + int nb_sectors)
>> +{
>> + unsigned long size;
>> + if (iscsilun->allocmap == NULL) {
>> + return true;
>> + }
>> + size = DIV_ROUND_UP(sector_num + nb_sectors, iscsilun->cluster_sectors);
>> + return !(find_next_bit(iscsilun->allocmap, size,
>> + sector_num / iscsilun->cluster_sectors) == size);
>> +}
>> +
>> +static inline bool iscsi_allocmap_is_valid(IscsiLun *iscsilun,
>> + int64_t sector_num, int nb_sectors)
>> +{
>> + unsigned long size;
>> + if (iscsilun->allocmap_valid == NULL) {
>> + return false;
>> + }
>> + size = DIV_ROUND_UP(sector_num + nb_sectors, iscsilun->cluster_sectors);
>> + return (find_next_zero_bit(iscsilun->allocmap_valid, size,
>> + sector_num / iscsilun->cluster_sectors) == size);
>> +}
>> +
>> static int coroutine_fn
>> iscsi_co_writev_flags(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
>> QEMUIOVector *iov, int flags)
>> @@ -507,26 +597,16 @@ retry:
>> }
>>
>> if (iTask.status != SCSI_STATUS_GOOD) {
>> + iscsi_allocmap_set_invalid(iscsilun, sector_num, nb_sectors);
>> return iTask.err_code;
>> }
>>
>> - iscsi_allocationmap_set(iscsilun, sector_num, nb_sectors);
>> + iscsi_allocmap_set_allocated(iscsilun, sector_num, nb_sectors);
>>
>> return 0;
>> }
>>
>>
>> -static bool iscsi_allocationmap_is_allocated(IscsiLun *iscsilun,
>> - int64_t sector_num, int nb_sectors)
>> -{
>> - unsigned long size;
>> - if (iscsilun->allocationmap == NULL) {
>> - return true;
>> - }
>> - size = DIV_ROUND_UP(sector_num + nb_sectors, iscsilun->cluster_sectors);
>> - return !(find_next_bit(iscsilun->allocationmap, size,
>> - sector_num / iscsilun->cluster_sectors) == size);
>> -}
>>
>> static int64_t coroutine_fn iscsi_co_get_block_status(BlockDriverState *bs,
>> int64_t sector_num,
>> @@ -611,9 +691,9 @@ retry:
>> }
>>
>> if (ret & BDRV_BLOCK_ZERO) {
>> - iscsi_allocationmap_clear(iscsilun, sector_num, *pnum);
>> + iscsi_allocmap_set_unallocated(iscsilun, sector_num, *pnum);
>> } else {
>> - iscsi_allocationmap_set(iscsilun, sector_num, *pnum);
>> + iscsi_allocmap_set_allocated(iscsilun, sector_num, *pnum);
>> }
>>
>> if (*pnum > nb_sectors) {
>> @@ -629,7 +709,7 @@ out:
>> return ret;
>> }
>>
>> -static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
>> + static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
> A superfluous leading whitespace?
>
>> int64_t sector_num, int nb_sectors,
>> QEMUIOVector *iov)
>> {
>> @@ -648,16 +728,25 @@ static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
>> return -EINVAL;
>> }
>>
>> - if (iscsilun->lbprz && nb_sectors >= ISCSI_CHECKALLOC_THRES &&
>> - !iscsi_allocationmap_is_allocated(iscsilun, sector_num, nb_sectors)) {
>> - int64_t ret;
>> + if (iscsi_allocmap_is_valid(iscsilun, sector_num, nb_sectors) &&
>> + !iscsi_allocmap_is_allocated(iscsilun, sector_num, nb_sectors)) {
>> + qemu_iovec_memset(iov, 0, 0x00, iov->size);
>> + return 0;
>> + }
>> +
>> + if (nb_sectors >= ISCSI_CHECKALLOC_THRES &&
>> + !iscsi_allocmap_is_valid(iscsilun, sector_num, nb_sectors) &&
>> + !iscsi_allocmap_is_allocated(iscsilun, sector_num, nb_sectors)) {
>> int pnum;
>> BlockDriverState *file;
>> - ret = iscsi_co_get_block_status(bs, sector_num, INT_MAX, &pnum, &file);
>> + int64_t ret = iscsi_co_get_block_status(bs,
>> + sector_num - sector_num % iscsilun->cluster_sectors,
>> + INT_MAX, &pnum, &file);
>> if (ret < 0) {
>> return ret;
>> }
>> - if (ret & BDRV_BLOCK_ZERO && pnum >= nb_sectors) {
>> + if (ret & BDRV_BLOCK_ZERO &&
>> + pnum >= nb_sectors + sector_num % iscsilun->cluster_sectors) {
>> qemu_iovec_memset(iov, 0, 0x00, iov->size);
>> return 0;
>> }
>> @@ -892,7 +981,6 @@ static BlockAIOCB *iscsi_aio_ioctl(BlockDriverState *bs,
>> }
>>
>> iscsi_set_events(iscsilun);
>> -
> Superfluous whitespace change.
>
>> return &acb->common;
>> }
>>
>> @@ -963,7 +1051,7 @@ retry:
>> return iTask.err_code;
>> }
>>
>> - iscsi_allocationmap_clear(iscsilun, sector_num, nb_sectors);
>> + iscsi_allocmap_set_invalid(iscsilun, sector_num, nb_sectors);
>>
>> return 0;
>> }
>> @@ -1053,13 +1141,14 @@ retry:
>> }
>>
>> if (iTask.status != SCSI_STATUS_GOOD) {
>> + iscsi_allocmap_set_invalid(iscsilun, sector_num, nb_sectors);
>> return iTask.err_code;
>> }
>>
>> if (flags & BDRV_REQ_MAY_UNMAP) {
>> - iscsi_allocationmap_clear(iscsilun, sector_num, nb_sectors);
>> + iscsi_allocmap_set_invalid(iscsilun, sector_num, nb_sectors);
>> } else {
>> - iscsi_allocationmap_set(iscsilun, sector_num, nb_sectors);
>> + iscsi_allocmap_set_allocated(iscsilun, sector_num, nb_sectors);
>> }
>>
>> return 0;
>> @@ -1633,10 +1722,7 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags,
>> iscsilun->cluster_sectors = (iscsilun->bl.opt_unmap_gran *
>> iscsilun->block_size) >> BDRV_SECTOR_BITS;
>> if (iscsilun->lbprz) {
>> - iscsilun->allocationmap = iscsi_allocationmap_init(iscsilun);
>> - if (iscsilun->allocationmap == NULL) {
>> - ret = -ENOMEM;
>> - }
>> + ret = iscsi_allocmap_init(iscsilun, bs->open_flags);
>> }
>> }
>>
>> @@ -1673,7 +1759,7 @@ static void iscsi_close(BlockDriverState *bs)
>> }
>> iscsi_destroy_context(iscsi);
>> g_free(iscsilun->zeroblock);
>> - g_free(iscsilun->allocationmap);
>> + iscsi_allocmap_free(iscsilun);
>> memset(iscsilun, 0, sizeof(IscsiLun));
>> }
>>
>> @@ -1750,9 +1836,9 @@ static int iscsi_truncate(BlockDriverState *bs, int64_t offset)
>> return -EINVAL;
>> }
>>
>> - if (iscsilun->allocationmap != NULL) {
>> - g_free(iscsilun->allocationmap);
>> - iscsilun->allocationmap = iscsi_allocationmap_init(iscsilun);
>> + if (iscsilun->allocmap != NULL) {
>> + iscsi_allocmap_free(iscsilun);
>> + iscsi_allocmap_init(iscsilun, bs->open_flags);
> Need to handle the return value here?
I think when originally implementing this we decide that a truncate should not fail
if the allocmap can't be resized. The feature is just disabled in this case.
Thinking about Jeffs comment on my NFS patch I also need to free allocmap_valid
if we change from cache.direct = off -> on.
Thanks for reviewing,
Peter
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-05-17 13:59 [Qemu-devel] [PATCH] block/iscsi: allow caching of the allocation map Peter Lieven
2016-05-18 7:41 ` Fam Zheng
2016-05-19 6:20 ` Peter Lieven
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