[Qemu-devel] [PATCH v6 08/11] dump: Add APIs to operate DataCache

[Qiao Nuohan]

DataCache is used to store data temporarily, then the data will be written to
vmcore. These functions will be called later when writing data of page to
vmcore.

Signed-off-by: Qiao Nuohan <address@hidden>
---
 dump.c                |   52 +++++++++++++++++++++++++++++++++++++++++++++++++
 include/sysemu/dump.h |    9 ++++++++
 2 files changed, 61 insertions(+), 0 deletions(-)

diff --git a/dump.c b/dump.c
index 1fae152..b4c40f2 100644
--- a/dump.c
+++ b/dump.c
@@ -1088,6 +1088,58 @@ out:
     return ret;
 }
 
+static void prepare_data_cache(DataCache *data_cache, DumpState *s)
+{
+    data_cache->fd = s->fd;
+    data_cache->data_size = 0;
+    data_cache->buf_size = BUFSIZE_DATA_CACHE;
+    data_cache->buf = g_malloc0(BUFSIZE_DATA_CACHE);
+}
+
+static int write_cache(DataCache *dc, bool flag_flatten, void *buf, size_t 
size)
+{
+    /*
+     * check if the space is enough to cache data, if not, write the cached
+     * data to dc->fd and reset the buf
+     */
+    if (dc->data_size + size > dc->buf_size) {
+        if (write_buffer(dc->fd, flag_flatten, dc->offset, dc->buf,
+                         dc->data_size) < 0) {
+            return -1;
+        }
+
+        dc->offset += dc->data_size;
+        dc->data_size = 0;
+    }
+
+    memcpy(dc->buf + dc->data_size, buf, size);
+    dc->data_size += size;
+
+    return 0;
+}
+
+/* write the remaining data in dc->buf to dc->fd */
+static int sync_data_cache(DataCache *dc, bool flag_flatten)
+{
+    if (dc->data_size == 0) {
+        return 0;
+    }
+
+    if (write_buffer(dc->fd, flag_flatten, dc->offset, dc->buf,
+                     dc->data_size) < 0) {
+        return -1;
+    }
+
+    dc->offset += dc->data_size;
+
+    return 0;
+}
+
+static void free_data_cache(DataCache *data_cache)
+{
+    g_free(data_cache->buf);
+}
+
 static ram_addr_t get_start_block(DumpState *s)
 {
     GuestPhysBlock *block;
diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
index b5eaf8d..ab44af8 100644
--- a/include/sysemu/dump.h
+++ b/include/sysemu/dump.h
@@ -36,6 +36,7 @@
 #define BUFSIZE_BITMAP              (PAGE_SIZE)
 #define PFN_BUFBITMAP               (CHAR_BIT * BUFSIZE_BITMAP)
 #define ARCH_PFN_OFFSET             (0)
+#define BUFSIZE_DATA_CACHE          (PAGE_SIZE * 4)
 
 #define paddr_to_pfn(X, page_shift) \
     (((unsigned long long)(X) >> (page_shift)) - ARCH_PFN_OFFSET)
@@ -140,6 +141,14 @@ typedef struct QEMU_PACKED KdumpSubHeader64 {
     uint64_t max_mapnr_64;          /* header_version 6 and later */
 } KdumpSubHeader64;
 
+typedef struct DataCache {
+    int fd;             /* fd of the file where to write the cached data */
+    char *buf;          /* buffer for cached data */
+    size_t buf_size;    /* size of the buf */
+    size_t data_size;   /* size of cached data in buf */
+    off_t offset;       /* offset of the file */
+} DataCache;
+
 struct GuestPhysBlockList; /* memory_mapping.h */
 int cpu_get_dump_info(ArchDumpInfo *info,
                       const struct GuestPhysBlockList *guest_phys_blocks);
-- 
1.7.1