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* [PATCH v5] block/file-win32: add reopen handlers
@ 2021-08-25 17:36 Viktor Prutyanov
  2021-09-01 11:27 ` Hanna Reitz
  0 siblings, 1 reply; 2+ messages in thread
From: Viktor Prutyanov @ 2021-08-25 17:36 UTC (permalink / raw)
  To: philmd, kwolf, hreitz, sw, yan, qemu-block, qemu-devel
  Cc: Helge Konetzka, Viktor Prutyanov

Make 'qemu-img commit' work on Windows.

Command 'commit' requires reopening backing file in RW mode. So,
add reopen prepare/commit/abort handlers and change dwShareMode
for CreateFile call in order to allow further read/write reopening.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/418

Suggested-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Viktor Prutyanov <viktor.prutyanov@phystech.edu>
Tested-by: Helge Konetzka <hk@zapateado.de>
---
 v2:
    - fix indentation in raw_reopen_prepare
    - free rs if raw_reopen_prepare fails
 v3:
    - restore suggested-by field missed in v2
 v4:
    - add file type check
    - add comment about options
    - replace rs check with assert in raw_reopen_commit
 v5:
    - add CloseHandle at AIO attach fail

 block/file-win32.c | 101 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 100 insertions(+), 1 deletion(-)

diff --git a/block/file-win32.c b/block/file-win32.c
index 2642088bd6..b97c58d642 100644
--- a/block/file-win32.c
+++ b/block/file-win32.c
@@ -58,6 +58,10 @@ typedef struct BDRVRawState {
     QEMUWin32AIOState *aio;
 } BDRVRawState;
 
+typedef struct BDRVRawReopenState {
+    HANDLE hfile;
+} BDRVRawReopenState;
+
 /*
  * Read/writes the data to/from a given linear buffer.
  *
@@ -392,7 +396,7 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     s->hfile = CreateFile(filename, access_flags,
-                          FILE_SHARE_READ, NULL,
+                          FILE_SHARE_READ | FILE_SHARE_WRITE, NULL,
                           OPEN_EXISTING, overlapped, NULL);
     if (s->hfile == INVALID_HANDLE_VALUE) {
         int err = GetLastError();
@@ -634,6 +638,97 @@ static int coroutine_fn raw_co_create_opts(BlockDriver *drv,
     return raw_co_create(&options, errp);
 }
 
+static int raw_reopen_prepare(BDRVReopenState *state,
+                              BlockReopenQueue *queue, Error **errp)
+{
+    BDRVRawState *s = state->bs->opaque;
+    BDRVRawReopenState *rs;
+    int access_flags;
+    DWORD overlapped;
+    int ret = 0;
+
+    if (s->type != FTYPE_FILE) {
+        error_setg(errp, "Can only reopen files");
+        return -EINVAL;
+    }
+
+    rs = g_new0(BDRVRawReopenState, 1);
+
+    /*
+     * We do not support changing any options (only flags). By leaving
+     * all options in state->options, we tell the generic reopen code
+     * that we do not support changing any of them, so it will verify
+     * that their values did not change.
+     */
+
+    raw_parse_flags(state->flags, s->aio != NULL, &access_flags, &overlapped);
+    rs->hfile = CreateFile(state->bs->filename, access_flags,
+                           FILE_SHARE_READ | FILE_SHARE_WRITE, NULL,
+                           OPEN_EXISTING, overlapped, NULL);
+
+    if (rs->hfile == INVALID_HANDLE_VALUE) {
+        int err = GetLastError();
+
+        error_setg_win32(errp, err, "Could not reopen '%s'",
+                         state->bs->filename);
+        if (err == ERROR_ACCESS_DENIED) {
+            ret = -EACCES;
+        } else {
+            ret = -EINVAL;
+        }
+        goto fail;
+    }
+
+    if (s->aio) {
+        ret = win32_aio_attach(s->aio, rs->hfile);
+        if (ret < 0) {
+            error_setg_errno(errp, -ret, "Could not enable AIO");
+            CloseHandle(rs->hfile);
+            goto fail;
+        }
+    }
+
+    state->opaque = rs;
+
+    return 0;
+
+fail:
+    g_free(rs);
+    state->opaque = NULL;
+
+    return ret;
+}
+
+static void raw_reopen_commit(BDRVReopenState *state)
+{
+    BDRVRawState *s = state->bs->opaque;
+    BDRVRawReopenState *rs = state->opaque;
+
+    assert(rs != NULL);
+
+    CloseHandle(s->hfile);
+    s->hfile = rs->hfile;
+
+    g_free(rs);
+    state->opaque = NULL;
+}
+
+static void raw_reopen_abort(BDRVReopenState *state)
+{
+    BDRVRawReopenState *rs = state->opaque;
+
+    if (!rs) {
+        return;
+    }
+
+    if (rs->hfile != INVALID_HANDLE_VALUE) {
+        CloseHandle(rs->hfile);
+    }
+
+    g_free(rs);
+    state->opaque = NULL;
+}
+
 static QemuOptsList raw_create_opts = {
     .name = "raw-create-opts",
     .head = QTAILQ_HEAD_INITIALIZER(raw_create_opts.head),
@@ -659,6 +754,10 @@ BlockDriver bdrv_file = {
     .bdrv_co_create_opts = raw_co_create_opts,
     .bdrv_has_zero_init = bdrv_has_zero_init_1,
 
+    .bdrv_reopen_prepare = raw_reopen_prepare,
+    .bdrv_reopen_commit  = raw_reopen_commit,
+    .bdrv_reopen_abort   = raw_reopen_abort,
+
     .bdrv_aio_preadv    = raw_aio_preadv,
     .bdrv_aio_pwritev   = raw_aio_pwritev,
     .bdrv_aio_flush     = raw_aio_flush,
-- 
2.21.0



^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH v5] block/file-win32: add reopen handlers
  2021-08-25 17:36 [PATCH v5] block/file-win32: add reopen handlers Viktor Prutyanov
@ 2021-09-01 11:27 ` Hanna Reitz
  0 siblings, 0 replies; 2+ messages in thread
From: Hanna Reitz @ 2021-09-01 11:27 UTC (permalink / raw)
  To: Viktor Prutyanov, philmd, kwolf, sw, yan, qemu-block, qemu-devel
  Cc: Helge Konetzka

On 25.08.21 19:36, Viktor Prutyanov wrote:
> Make 'qemu-img commit' work on Windows.
>
> Command 'commit' requires reopening backing file in RW mode. So,
> add reopen prepare/commit/abort handlers and change dwShareMode
> for CreateFile call in order to allow further read/write reopening.
>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/418
>
> Suggested-by: Hanna Reitz <hreitz@redhat.com>
> Signed-off-by: Viktor Prutyanov <viktor.prutyanov@phystech.edu>
> Tested-by: Helge Konetzka <hk@zapateado.de>
> ---
>   v2:
>      - fix indentation in raw_reopen_prepare
>      - free rs if raw_reopen_prepare fails
>   v3:
>      - restore suggested-by field missed in v2
>   v4:
>      - add file type check
>      - add comment about options
>      - replace rs check with assert in raw_reopen_commit
>   v5:
>      - add CloseHandle at AIO attach fail
>
>   block/file-win32.c | 101 ++++++++++++++++++++++++++++++++++++++++++++-
>   1 file changed, 100 insertions(+), 1 deletion(-)

Thanks!  I’ve applied this patch to my block branch:

https://github.com/XanClic/qemu/commits/block

Hanna



^ permalink raw reply	[flat|nested] 2+ messages in thread

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