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[Qemu-devel] [PATCH v2 6/9] block: vhdx - update log guid in header, and


From: Jeff Cody
Subject: [Qemu-devel] [PATCH v2 6/9] block: vhdx - update log guid in header, and first write tracker
Date: Wed, 31 Jul 2013 23:23:51 -0400

Allow tracking of first file write in the VHDX image, as well as
the ability to update the GUID in the header.  This is in preparation
for log support.

Signed-off-by: Jeff Cody <address@hidden>
---
 block/vhdx.c | 28 +++++++++++++++++++++++-----
 block/vhdx.h |  7 +++++--
 2 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/block/vhdx.c b/block/vhdx.c
index 9802b74..0de4d6f 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -233,7 +233,8 @@ static int vhdx_probe(const uint8_t *buf, int buf_size, 
const char *filename)
  *
  *  - non-current header is updated with largest sequence number
  */
-static int vhdx_update_header(BlockDriverState *bs, BDRVVHDXState *s, bool rw)
+static int vhdx_update_header(BlockDriverState *bs, BDRVVHDXState *s, bool rw,
+                              MSGUID *log_guid)
 {
     int ret = 0;
     int hdr_idx = 0;
@@ -266,6 +267,11 @@ static int vhdx_update_header(BlockDriverState *bs, 
BDRVVHDXState *s, bool rw)
         vhdx_guid_generate(&inactive_header->data_write_guid);
     }
 
+    /* update the log guid if present */
+    if (log_guid) {
+        memcpy(&inactive_header->log_guid, log_guid, sizeof(MSGUID));
+    }
+
     /* the header checksum is not over just the packed size of VHDXHeader,
      * but rather over the entire 'reserved' range for the header, which is
      * 4KB (VHDX_HEADER_SIZE). */
@@ -293,15 +299,16 @@ exit:
  * The VHDX spec calls for header updates to be performed twice, so that both
  * the current and non-current header have valid info
  */
-static int vhdx_update_headers(BlockDriverState *bs, BDRVVHDXState *s, bool rw)
+int vhdx_update_headers(BlockDriverState *bs, BDRVVHDXState *s, bool rw,
+                        MSGUID *log_guid)
 {
     int ret;
 
-    ret = vhdx_update_header(bs, s, rw);
+    ret = vhdx_update_header(bs, s, rw, log_guid);
     if (ret < 0) {
         return ret;
     }
-    ret = vhdx_update_header(bs, s, rw);
+    ret = vhdx_update_header(bs, s, rw, log_guid);
     return ret;
 }
 
@@ -781,6 +788,7 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, 
int flags)
 
 
     s->bat = NULL;
+    s->first_visible_write = true;
 
     qemu_co_mutex_init(&s->lock);
 
@@ -861,7 +869,7 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, 
int flags)
     }
 
     if (flags & BDRV_O_RDWR) {
-        vhdx_update_headers(bs, s, false);
+        vhdx_update_headers(bs, s, false, NULL);
     }
 
     /* TODO: differencing files, write */
@@ -998,6 +1006,16 @@ exit:
 
 
 
+/* Per the spec, on the first write of guest-visible data to the file the
+ * data write guid must be updated in the header */
+void vhdx_user_visible_write(BlockDriverState *bs, BDRVVHDXState *s)
+{
+    if (s->first_visible_write) {
+        s->first_visible_write = false;
+        vhdx_update_headers(bs, s, true, NULL);
+    }
+}
+
 static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t 
sector_num,
                                       int nb_sectors, QEMUIOVector *qiov)
 {
diff --git a/block/vhdx.h b/block/vhdx.h
index 5e0a1d3..cb3ce0e 100644
--- a/block/vhdx.h
+++ b/block/vhdx.h
@@ -366,6 +366,7 @@ typedef struct BDRVVHDXState {
     VHDXBatEntry *bat;
     uint64_t bat_offset;
 
+    bool first_visible_write;
     MSGUID session_guid;
 
     VHDXLogEntries log;
@@ -377,6 +378,9 @@ typedef struct BDRVVHDXState {
 
 void vhdx_guid_generate(MSGUID *guid);
 
+int vhdx_update_headers(BlockDriverState *bs, BDRVVHDXState *s, bool rw,
+                        MSGUID *log_guid);
+
 uint32_t vhdx_update_checksum(uint8_t *buf, size_t size, int crc_offset);
 uint32_t vhdx_checksum_calc(uint32_t crc, uint8_t *buf, size_t size,
                             int crc_offset);
@@ -406,8 +410,7 @@ void vhdx_log_data_le_export(VHDXLogDataSector *d);
 void vhdx_log_entry_hdr_le_import(VHDXLogEntryHeader *hdr);
 void vhdx_log_entry_hdr_le_export(VHDXLogEntryHeader *hdr);
 
-
-
+void vhdx_user_visible_write(BlockDriverState *bs, BDRVVHDXState *s);
 
 
 
-- 
1.8.1.4




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