| Message ID | 1463739037-10514-1-git-send-email-pl@kamp.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 05/20 12:10, 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 to me apart from several wording fixes below. Reviewed-by: Fam Zheng <famz@redhat.com> > > Signed-off-by: Peter Lieven <pl@kamp.de> > --- > v1->v2: - add more comments [Fam] > - free allocmap if allocation of allocmap_valid fails [Fam] > - fix indent and whitespace errors [Fam] > - account for cache mode changes on reopen > block/iscsi.c | 228 ++++++++++++++++++++++++++++++++++++++++++++------------- > 1 file changed, 179 insertions(+), 49 deletions(-) > > diff --git a/block/iscsi.c b/block/iscsi.c > index 10f3906..e62a9ee 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 +62,22 @@ typedef struct IscsiLun { > struct scsi_inquiry_logical_block_provisioning lbp; > struct scsi_inquiry_block_limits bl; > unsigned char *zeroblock; > - unsigned long *allocationmap; > +/* The allocationmap tracks which clusters (pages) on the iSCSI target are s/allocationmap/allocmap/ to match the post-patch field name? > + * 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 s/Qemus/QEMU's/ > + * allocated or not. In case Qemus has no valid information about a page the s/Qemus/QEMU/ > + * 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. */ s/its/it's/ ? The indentation is a few columes off. > + unsigned long *allocmap; > + unsigned long *allocmap_valid; > + long allocmap_size; > int cluster_sectors; > bool use_16_for_rw; > bool write_protected; > @@ -415,37 +430,132 @@ 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; > + iscsi_allocmap_free(iscsilun); > + > + 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) { > + /* in case that cache.direct = on all allocmap entries are > + * threated as invalid to force a relookup of the block s/threated/treated > + * status on every read request */ > + return 0; > + } > + > + iscsilun->allocmap_valid = bitmap_try_new(iscsilun->allocmap_size); > + if (!iscsilun->allocmap_valid) { > + /* if we are under memory pressure free the allocmap as well */ > + iscsi_allocmap_free(iscsilun); > + 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 > @@ -507,26 +617,16 @@ 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 +711,9 @@ 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) { > @@ -648,16 +748,32 @@ 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 cache.direct is off and we have a valid entry in our allocation map > + * we can skip checking the block status and directly return zeroes if > + * the request falls within an unallocated area */ > + 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); > + /* check the block status from the beginning of the cluster > + * containing the start sector */ > + 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 the whole request falls into an unallocated area we can avoid > + * to read and directly return zeroes instead */ > + if (ret & BDRV_BLOCK_ZERO && > + pnum >= nb_sectors + sector_num % iscsilun->cluster_sectors) { > qemu_iovec_memset(iov, 0, 0x00, iov->size); > return 0; > } > @@ -963,7 +1079,7 @@ 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 +1169,14 @@ 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 +1750,7 @@ 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 +1787,7 @@ 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)); > } > > @@ -1731,6 +1845,14 @@ static int iscsi_reopen_prepare(BDRVReopenState *state, > return 0; > } > > +static void iscsi_reopen_commit(BDRVReopenState *reopen_state) > +{ > + IscsiLun *iscsilun = reopen_state->bs->opaque; > + > + /* the cache.direct status might have changed */ > + iscsi_allocmap_init(iscsilun, reopen_state->flags); > +} > + > static int iscsi_truncate(BlockDriverState *bs, int64_t offset) > { > IscsiLun *iscsilun = bs->opaque; > @@ -1750,9 +1872,8 @@ 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_init(iscsilun, bs->open_flags); > } > > return 0; > @@ -1812,6 +1933,13 @@ 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), > @@ -1835,7 +1963,9 @@ static BlockDriver bdrv_iscsi = { > .bdrv_close = iscsi_close, > .bdrv_create = iscsi_create, > .create_opts = &iscsi_create_opts, > - .bdrv_reopen_prepare = iscsi_reopen_prepare, > + .bdrv_reopen_prepare = iscsi_reopen_prepare, > + .bdrv_reopen_commit = iscsi_reopen_commit, > + .bdrv_invalidate_cache = iscsi_invalidate_cache, > > .bdrv_getlength = iscsi_getlength, > .bdrv_get_info = iscsi_get_info, > -- > 1.7.9.5 >
diff --git a/block/iscsi.c b/block/iscsi.c index 10f3906..e62a9ee 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 +62,22 @@ typedef struct IscsiLun { struct scsi_inquiry_logical_block_provisioning lbp; struct scsi_inquiry_block_limits bl; unsigned char *zeroblock; - unsigned long *allocationmap; +/* The allocationmap 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. */ + unsigned long *allocmap; + unsigned long *allocmap_valid; + long allocmap_size; int cluster_sectors; bool use_16_for_rw; bool write_protected; @@ -415,37 +430,132 @@ 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; + iscsi_allocmap_free(iscsilun); + + 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) { + /* in case that cache.direct = on all allocmap entries are + * threated as invalid to force a relookup of the block + * status on every read request */ + return 0; + } + + iscsilun->allocmap_valid = bitmap_try_new(iscsilun->allocmap_size); + if (!iscsilun->allocmap_valid) { + /* if we are under memory pressure free the allocmap as well */ + iscsi_allocmap_free(iscsilun); + 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 @@ -507,26 +617,16 @@ 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 +711,9 @@ 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) { @@ -648,16 +748,32 @@ 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 cache.direct is off and we have a valid entry in our allocation map + * we can skip checking the block status and directly return zeroes if + * the request falls within an unallocated area */ + 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); + /* check the block status from the beginning of the cluster + * containing the start sector */ + 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 the whole request falls into an unallocated area we can avoid + * to read and directly return zeroes instead */ + if (ret & BDRV_BLOCK_ZERO && + pnum >= nb_sectors + sector_num % iscsilun->cluster_sectors) { qemu_iovec_memset(iov, 0, 0x00, iov->size); return 0; } @@ -963,7 +1079,7 @@ 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 +1169,14 @@ 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 +1750,7 @@ 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 +1787,7 @@ 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)); } @@ -1731,6 +1845,14 @@ static int iscsi_reopen_prepare(BDRVReopenState *state, return 0; } +static void iscsi_reopen_commit(BDRVReopenState *reopen_state) +{ + IscsiLun *iscsilun = reopen_state->bs->opaque; + + /* the cache.direct status might have changed */ + iscsi_allocmap_init(iscsilun, reopen_state->flags); +} + static int iscsi_truncate(BlockDriverState *bs, int64_t offset) { IscsiLun *iscsilun = bs->opaque; @@ -1750,9 +1872,8 @@ 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_init(iscsilun, bs->open_flags); } return 0; @@ -1812,6 +1933,13 @@ 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), @@ -1835,7 +1963,9 @@ static BlockDriver bdrv_iscsi = { .bdrv_close = iscsi_close, .bdrv_create = iscsi_create, .create_opts = &iscsi_create_opts, - .bdrv_reopen_prepare = iscsi_reopen_prepare, + .bdrv_reopen_prepare = iscsi_reopen_prepare, + .bdrv_reopen_commit = iscsi_reopen_commit, + .bdrv_invalidate_cache = iscsi_invalidate_cache, .bdrv_getlength = iscsi_getlength, .bdrv_get_info = iscsi_get_info,
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> --- v1->v2: - add more comments [Fam] - free allocmap if allocation of allocmap_valid fails [Fam] - fix indent and whitespace errors [Fam] - account for cache mode changes on reopen block/iscsi.c | 228 ++++++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 179 insertions(+), 49 deletions(-)