Re: [win-pv-devel] [PATCH 8/8] Rework indirect context structure

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx [mailto:win-pv-devel-
> bounces@xxxxxxxxxxxxxxxxxxxx] On Behalf Of Owen Smith
> Sent: 27 October 2015 11:16
> To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Owen Smith
> Subject: [win-pv-devel] [PATCH 8/8] Rework indirect context structure
> 
> Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>

Acked-by: Paul Durrant <paul.durrant@xxxxxxxxxx>

> ---
>  src/xenvbd/blockring.c | 48 ++++++++++++++++-----------------
>  src/xenvbd/pdo.c       | 72 ++++++++++++++++++++++++++++++++----------
> --------
>  src/xenvbd/srbext.h    | 13 ++++++---
>  3 files changed, 79 insertions(+), 54 deletions(-)
> 
> diff --git a/src/xenvbd/blockring.c b/src/xenvbd/blockring.c
> index 28f1393..6ca9cb2 100644
> --- a/src/xenvbd/blockring.c
> +++ b/src/xenvbd/blockring.c
> @@ -152,9 +152,10 @@ __BlockRingInsert(
>      case BLKIF_OP_WRITE:
>          if (Request->NrSegments > BLKIF_MAX_SEGMENTS_PER_REQUEST) {
>              // Indirect
> -            ULONG                       PageIndex;
> -            ULONG                       SegmentIndex;
> -            PLIST_ENTRY                 Entry;
> +            ULONG                       PageIdx;
> +            ULONG                       SegIdx;
> +            PLIST_ENTRY                 PageEntry;
> +            PLIST_ENTRY                 SegEntry;
>              blkif_request_indirect_t*   req_indirect;
> 
>              req_indirect = (blkif_request_indirect_t*)req;
> @@ -165,29 +166,28 @@ __BlockRingInsert(
>              req_indirect->sector_number     = Request->FirstSector;
>              req_indirect->handle            = (USHORT)BlockRing->DeviceId;
> 
> -            for (PageIndex = 0, SegmentIndex = 0, Entry = Request-
> >Segments.Flink;
> -                    PageIndex < BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST &&
> -                    Entry != &Request->Segments;
> -                        Entry = Entry->Flink) {
> -                PBLKIF_SEGMENT  Indirect = Request->Pages[PageIndex];
> -                PXENVBD_SEGMENT Segment = CONTAINING_RECORD(Entry,
> XENVBD_SEGMENT, Entry);
> -
> -                Indirect[SegmentIndex].GrantRef = GranterReference(Granter,
> Segment->Grant);
> -                Indirect[SegmentIndex].First    = Segment->FirstSector;
> -                Indirect[SegmentIndex].Last     = Segment->LastSector;
> -
> -                ++SegmentIndex;
> -                if (SegmentIndex >= XENVBD_MAX_SEGMENTS_PER_PAGE) {
> -                    ++PageIndex;
> -                    SegmentIndex = 0;
> +            for (PageIdx = 0,
> +                 PageEntry = Request->Indirects.Flink,
> +                 SegEntry = Request->Segments.Flink;
> +                    PageIdx < BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST &&
> +                    PageEntry != &Request->Indirects &&
> +                    SegEntry != &Request->Segments;
> +                        ++PageIdx, PageEntry = PageEntry->Flink) {
> +                PXENVBD_INDIRECT Page = CONTAINING_RECORD(PageEntry,
> XENVBD_INDIRECT, Entry);
> +
> +                req_indirect->indirect_grefs[PageIdx] =
> GranterReference(Granter, Page->Grant);
> +
> +                for (SegIdx = 0;
> +                        SegIdx < XENVBD_MAX_SEGMENTS_PER_PAGE &&
> +                        SegEntry != &Request->Segments;
> +                            ++SegIdx, SegEntry = SegEntry->Flink) {
> +                    PXENVBD_SEGMENT Segment =
> CONTAINING_RECORD(SegEntry, XENVBD_SEGMENT, Entry);
> +
> +                    Page->Page[SegIdx].GrantRef = GranterReference(Granter,
> Segment->Grant);
> +                    Page->Page[SegIdx].First    = Segment->FirstSector;
> +                    Page->Page[SegIdx].Last     = Segment->LastSector;
>                  }
>              }
> -            for (PageIndex = 0;
> -                    PageIndex < BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST &&
> -                    Request->Grants[PageIndex] != NULL;
> -                        ++PageIndex) {
> -                req_indirect->indirect_grefs[PageIndex] =
> GranterReference(Granter, Request->Grants[PageIndex]);
> -            }
>          } else {
>              // Direct
>              ULONG           Index;
> diff --git a/src/xenvbd/pdo.c b/src/xenvbd/pdo.c
> index e8d94cb..3c429b2 100644
> --- a/src/xenvbd/pdo.c
> +++ b/src/xenvbd/pdo.c
> @@ -567,20 +567,38 @@ PdoSectorSize(
>  }
> 
> 
> //=========================================================
> ====================
> -static PVOID
> +static PXENVBD_INDIRECT
>  PdoGetIndirect(
>      IN  PXENVBD_PDO             Pdo
>      )
>  {
> -    PVOID                       Indirect;
> +    PXENVBD_INDIRECT    Indirect;
> +    NTSTATUS            status;
> +    PXENVBD_GRANTER     Granter = FrontendGetGranter(Pdo->Frontend);
> 
>      Indirect = __LookasideAlloc(&Pdo->IndirectList);
>      if (Indirect == NULL)
>          goto fail1;
> 
> -    RtlZeroMemory(Indirect, PAGE_SIZE);
> +    RtlZeroMemory(Indirect, sizeof(XENVBD_INDIRECT));
> +
> +    Indirect->Page = __AllocPages(PAGE_SIZE, &Indirect->Mdl);
> +    if (Indirect->Page == NULL)
> +        goto fail2;
> +
> +    status = GranterGet(Granter,
> +                        MmGetMdlPfnArray(Indirect->Mdl)[0],
> +                        TRUE,
> +                        &Indirect->Grant);
> +    if (!NT_SUCCESS(status))
> +        goto fail3;
> +
>      return Indirect;
> 
> +fail3:
> +    __FreePages(Indirect->Page, Indirect->Mdl);
> +fail2:
> +    __LookasideFree(&Pdo->IndirectList, Indirect);
>  fail1:
>      return NULL;
>  }
> @@ -588,10 +606,17 @@ fail1:
>  static VOID
>  PdoPutIndirect(
>      IN  PXENVBD_PDO             Pdo,
> -    IN  PVOID                   Indirect
> +    IN  PXENVBD_INDIRECT        Indirect
>      )
>  {
> -    RtlZeroMemory(Indirect, PAGE_SIZE);
> +    PXENVBD_GRANTER Granter = FrontendGetGranter(Pdo->Frontend);
> +
> +    if (Indirect->Grant)
> +        GranterPut(Granter, Indirect->Grant);
> +    if (Indirect->Page)
> +        __FreePages(Indirect->Page, Indirect->Mdl);
> +
> +    RtlZeroMemory(Indirect, sizeof(XENVBD_INDIRECT));
>      __LookasideFree(&Pdo->IndirectList, Indirect);
>  }
> 
> @@ -648,6 +673,7 @@ PdoGetRequest(
>      RtlZeroMemory(Request, sizeof(XENVBD_REQUEST));
>      Request->Id = (ULONG)InterlockedIncrement((PLONG)&Pdo->NextTag);
>      InitializeListHead(&Request->Segments);
> +    InitializeListHead(&Request->Indirects);
> 
>      return Request;
> 
> @@ -661,11 +687,9 @@ PdoPutRequest(
>      IN  PXENVBD_REQUEST         Request
>      )
>  {
> -    ULONG           Index;
> -    PXENVBD_GRANTER Granter = FrontendGetGranter(Pdo->Frontend);
> +    PLIST_ENTRY     Entry;
> 
>      for (;;) {
> -        PLIST_ENTRY     Entry;
>          PXENVBD_SEGMENT Segment;
> 
>          Entry = RemoveHeadList(&Request->Segments);
> @@ -675,11 +699,14 @@ PdoPutRequest(
>          PdoPutSegment(Pdo, Segment);
>      }
> 
> -    for (Index = 0; Index < BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST;
> ++Index) {
> -        if (Request->Grants[Index])
> -            GranterPut(Granter, Request->Grants[Index]);
> -        if (Request->Pages[Index])
> -            PdoPutIndirect(Pdo, Request->Pages[Index]);
> +    for (;;) {
> +        PXENVBD_INDIRECT    Indirect;
> +
> +        Entry = RemoveHeadList(&Request->Indirects);
> +        if (Entry == &Request->Indirects)
> +            break;
> +        Indirect = CONTAINING_RECORD(Entry, XENVBD_INDIRECT, Entry);
> +        PdoPutIndirect(Pdo, Indirect);
>      }
> 
>      RtlZeroMemory(Request, sizeof(XENVBD_REQUEST));
> @@ -1052,32 +1079,25 @@ PrepareBlkifIndirect(
>      IN  PXENVBD_REQUEST         Request
>      )
>  {
> -    NTSTATUS        status;
>      ULONG           Index;
>      ULONG           NrSegments = 0;
> -    PXENVBD_GRANTER Granter = FrontendGetGranter(Pdo->Frontend);
> 
>      for (Index = 0;
>              Index < BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST &&
>              NrSegments < Request->NrSegments;
>                  ++Index) {
> -        Request->Pages[Index] = PdoGetIndirect(Pdo);
> -        if (Request->Pages[Index] == NULL)
> -            goto fail1;
> +        PXENVBD_INDIRECT    Indirect;
> 
> -        status = GranterGet(Granter,
> -                            __Virt2Pfn(Request->Pages[Index]),
> -                            TRUE,
> -                            &Request->Grants[Index]);
> -        if (!NT_SUCCESS(status))
> -            goto fail2;
> +        Indirect = PdoGetIndirect(Pdo);
> +        if (Indirect == NULL)
> +            goto fail1;
> +        InsertTailList(&Request->Indirects, &Indirect->Entry);
> 
>          NrSegments += XENVBD_MAX_SEGMENTS_PER_PAGE;
>      }
> 
>      return TRUE;
> 
> -fail2:
>  fail1:
>      return FALSE;
>  }
> @@ -2583,7 +2603,7 @@ PdoCreate(
> 
>      __LookasideInit(&Pdo->RequestList, sizeof(XENVBD_REQUEST),
> REQUEST_POOL_TAG);
>      __LookasideInit(&Pdo->SegmentList, sizeof(XENVBD_SEGMENT),
> SEGMENT_POOL_TAG);
> -    __LookasideInit(&Pdo->IndirectList, PAGE_SIZE, INDIRECT_POOL_TAG);
> +    __LookasideInit(&Pdo->IndirectList, sizeof(XENVBD_INDIRECT),
> INDIRECT_POOL_TAG);
> 
>      Status = PdoD3ToD0(Pdo);
>      if (!NT_SUCCESS(Status))
> diff --git a/src/xenvbd/srbext.h b/src/xenvbd/srbext.h
> index 6550b72..6b41475 100644
> --- a/src/xenvbd/srbext.h
> +++ b/src/xenvbd/srbext.h
> @@ -48,6 +48,14 @@ typedef struct _BLKIF_SEGMENT {
> 
>  #define XENVBD_MAX_SEGMENTS_PER_PAGE    (PAGE_SIZE /
> sizeof(BLKIF_SEGMENT))
> 
> +// Internal indirect context
> +typedef struct _XENVBD_INDIRECT {
> +    LIST_ENTRY              Entry;
> +    PBLKIF_SEGMENT          Page;
> +    PVOID                   Grant;
> +    PMDL                    Mdl;
> +} XENVBD_INDIRECT, *PXENVBD_INDIRECT;
> +
>  // Internal segment context
>  typedef struct _XENVBD_SEGMENT {
>      LIST_ENTRY              Entry;
> @@ -74,10 +82,7 @@ typedef struct _XENVBD_REQUEST {
> 
>      ULONG64                 FirstSector;
>      ULONG64                 NrSectors;  // BLKIF_OP_DISCARD only
> -
> -    // BLKIF_OP_{READ/WRITE} with NrSegments > 11 only
> -    PVOID                   Pages[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
> -    PVOID                   Grants[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
> +    LIST_ENTRY              Indirects;  // BLKIF_OP_{READ/WRITE} with
> NrSegments > 11 only
>  } XENVBD_REQUEST, *PXENVBD_REQUEST;
> 
>  // SRBExtension - context for SRBs
> --
> 1.9.4.msysgit.1
> 
> 
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