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[v2,14/16] block: raw-win32 driver reopen support

Message ID 32a171a78d9832961307119937486b9fd5bd141d.1347548248.git.jcody@redhat.com
State New
Headers show

Commit Message

Jeff Cody Sept. 13, 2012, 3:49 p.m. UTC
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 <jcody@redhat.com>
---
 block/raw-posix.c |   1 -
 block/raw-win32.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 104 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/block/raw-posix.c b/block/raw-posix.c
index 2407eeb..d0a931a 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -141,7 +141,6 @@  typedef struct BDRVRawState {
 } BDRVRawState;
 
 typedef struct BDRVRawReopenState {
-    BDRVReopenState reopen_state;
     int fd;
     int open_flags;
 #ifdef CONFIG_LINUX_AIO
diff --git a/block/raw-win32.c b/block/raw-win32.c
index 78c8306..cfa5def 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 +122,102 @@  static int raw_open(BlockDriverState *bs, const char *filename, int flags)
     return 0;
 }
 
+static int raw_reopen_prepare(BDRVReopenState *state, 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);
+            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",
+                          state->bs->filename);
+                ret = -1;
+            } else{
+                /* since we had to close the original, go ahead and
+                 * re-assign here */
+                s->hfile = raw_s->hfile;
+                raw_s->hfile = INVALID_HANDLE_VALUE;
+            }
+        }
+    }
+
+    return ret;
+}
+
+
+static void raw_reopen_commit(BDRVReopenState *state)
+{
+    BDRVRawReopenState *raw_s = state->opaque;
+    BDRVRawState *s = state->bs->opaque;
+
+    if (raw_s->hfile != INVALID_HANDLE_VALUE) {
+        CloseHandle(s->hfile);
+        s->hfile = raw_s->hfile;
+    }
+
+    g_free(state->opaque);
+    state->opaque = NULL;
+}
+
+
+static void raw_reopen_abort(BDRVReopenState *state)
+{
+    BDRVRawReopenState *raw_s = state->opaque;
+
+     /* nothing to do if NULL, we didn't get far enough */
+    if (raw_s == NULL) {
+        return;
+    }
+
+    if (raw_s->hfile != INVALID_HANDLE_VALUE) {
+        CloseHandle(raw_s->hfile);
+    }
+    g_free(state->opaque);
+    state->opaque = NULL;
+}
+
 static int raw_read(BlockDriverState *bs, int64_t sector_num,
                     uint8_t *buf, int nb_sectors)
 {
@@ -287,6 +388,9 @@  static BlockDriver bdrv_file = {
     .protocol_name	= "file",
     .instance_size	= sizeof(BDRVRawState),
     .bdrv_file_open	= raw_open,
+    .bdrv_reopen_prepare = raw_reopen_prepare,
+    .bdrv_reopen_commit = raw_reopen_commit,
+    .bdrv_reopen_abort = raw_reopen_abort,
     .bdrv_close		= raw_close,
     .bdrv_create	= raw_create,