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Re: [Qemu-devel] [PATCH v4 15/19] block: raw-win32 driver reopen support
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH v4 15/19] block: raw-win32 driver reopen support |
Date: |
Fri, 21 Sep 2012 10:33:39 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 |
Am 20.09.2012 21:13, schrieb Jeff Cody:
> This is the support for reopen, for win32. Note that there is a key
> difference in the win32 reopen, namely that it is not guaranteed safe
> like all the other drivers. Attempts are made to reopen the file, or
> open the file in a new handle prior to closing the old handle. However,
> this is not always feasible, and there are times when we must close the
> existing file and then open the new file, breaking the transactional nature
> of the reopen.
>
> Signed-off-by: Jeff Cody <address@hidden>
> ---
> block/raw-win32.c | 105
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 105 insertions(+)
I can't really review win32 code, but two comments anyway:
> diff --git a/block/raw-win32.c b/block/raw-win32.c
> index 78c8306..8a698d3 100644
> --- a/block/raw-win32.c
> +++ b/block/raw-win32.c
> @@ -31,6 +31,7 @@
> #define FTYPE_FILE 0
> #define FTYPE_CD 1
> #define FTYPE_HARDDISK 2
> +#define WINDOWS_VISTA 6
>
> typedef struct BDRVRawState {
> HANDLE hfile;
> @@ -38,6 +39,10 @@ typedef struct BDRVRawState {
> char drive_path[16]; /* format: "d:\" */
> } BDRVRawState;
>
> +typedef struct BDRVRawReopenState {
> + HANDLE hfile;
> +} BDRVRawReopenState;
> +
> int qemu_ftruncate64(int fd, int64_t length)
> {
> LARGE_INTEGER li;
> @@ -117,6 +122,103 @@ static int raw_open(BlockDriverState *bs, const char
> *filename, int flags)
> return 0;
> }
>
> +static int raw_reopen_prepare(BDRVReopenState *state,
> + BlockReopenQueue *queue, Error **errp)
> +{
> + BDRVRawState *s;
> + BDRVRawReopenState *raw_s;
> + int ret = 0;
> + int access_flags;
> + DWORD overlapped;
> + OSVERSIONINFO osvi;
> +
> + assert(state != NULL);
> + assert(state->bs != NULL);
> +
> + s = state->bs->opaque;
> +
> + state->opaque = g_malloc0(sizeof(BDRVRawReopenState));
> + raw_s = state->opaque;
> +
> + raw_parse_flags(state->flags, &access_flags, &overlapped);
> +
> + ZeroMemory(&osvi, sizeof(OSVERSIONINFO));
> + osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
> +
> + GetVersionEx(&osvi);
> + raw_s->hfile = INVALID_HANDLE_VALUE;
> +
> + if (osvi.dwMajorVersion >= WINDOWS_VISTA) {
> + raw_s->hfile = ReOpenFile(s->hfile, access_flags, FILE_SHARE_READ,
> + overlapped);
> + }
> +
> + /* could not reopen the file handle, so fall back to opening
> + * new file (CreateFile) */
> + if (raw_s->hfile == INVALID_HANDLE_VALUE) {
> + raw_s->hfile = CreateFile(state->bs->filename, access_flags,
> + FILE_SHARE_READ, NULL, OPEN_EXISTING,
> + overlapped, NULL);
> + if (raw_s->hfile == INVALID_HANDLE_VALUE) {
> + /* this could happen because the access_flags requested are
> + * incompatible with the existing share mode of s->hfile,
> + * so our only option now is to close s->hfile, and try again.
> + * This could end badly */
> + CloseHandle(s->hfile);
How common is this case?
We do have another option, namely not reopen at all and return an error.
Of course, this only makes sense if it doesn't mean that we almost never
succeed.
> + s->hfile = INVALID_HANDLE_VALUE;
> + raw_s->hfile = CreateFile(state->bs->filename, access_flags,
> + FILE_SHARE_READ, NULL, OPEN_EXISTING,
> + overlapped, NULL);
> + if (raw_s->hfile == INVALID_HANDLE_VALUE) {
> + /* Unrecoverable error */
> + error_set(errp, ERROR_CLASS_GENERIC_ERROR,
> + "Fatal error reopening %s file; file closed and
> cannot be opened\n",
This line is longer than 80 characters.
Kevin
- [Qemu-devel] [PATCH v4 07/19] block: use BDRV_O_NOCACHE instead of s->aligned_buf in raw-posix.c, (continued)
- [Qemu-devel] [PATCH v4 07/19] block: use BDRV_O_NOCACHE instead of s->aligned_buf in raw-posix.c, Jeff Cody, 2012/09/20
- [Qemu-devel] [PATCH v4 05/19] block: move open flag parsing in raw block drivers to helper functions, Jeff Cody, 2012/09/20
- [Qemu-devel] [PATCH v4 09/19] block: raw-posix image file reopen, Jeff Cody, 2012/09/20
- [Qemu-devel] [PATCH v4 08/19] block: purge s->aligned_buf and s->aligned_buf_size from raw-posix.c, Jeff Cody, 2012/09/20
- [Qemu-devel] [PATCH v4 12/19] block: qcow2 image file reopen, Jeff Cody, 2012/09/20
- [Qemu-devel] [PATCH v4 19/19] block: remove keep_read_only flag from BlockDriverState struct, Jeff Cody, 2012/09/20
- [Qemu-devel] [PATCH v4 10/19] block: raw image file reopen, Jeff Cody, 2012/09/20
- [Qemu-devel] [PATCH v4 17/19] block: vpc image file reopen, Jeff Cody, 2012/09/20
- [Qemu-devel] [PATCH v4 18/19] block: convert bdrv_commit() to use bdrv_reopen(), Jeff Cody, 2012/09/20
- [Qemu-devel] [PATCH v4 15/19] block: raw-win32 driver reopen support, Jeff Cody, 2012/09/20
- Re: [Qemu-devel] [PATCH v4 15/19] block: raw-win32 driver reopen support,
Kevin Wolf <=
[Qemu-devel] [PATCH v4 16/19] block: vdi image file reopen, Jeff Cody, 2012/09/20
[Qemu-devel] [PATCH v4 11/19] block: qed image file reopen, Jeff Cody, 2012/09/20
[Qemu-devel] [PATCH v4 13/19] block: qcow image file reopen, Jeff Cody, 2012/09/20
[Qemu-devel] [PATCH v4 14/19] block: vmdk image file reopen, Jeff Cody, 2012/09/20
Re: [Qemu-devel] [PATCH v4 00/19] block: bdrv_reopen() patches, Kevin Wolf, 2012/09/21