[Qemu-devel] [PATCH 2/5] block/vpc: simplify vpc_read

[Peter Lieven <pl@kamp.de>]

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 block/vpc.c |  116 +++++++++++++++++++++++++++--------------------------------
 1 file changed, 52 insertions(+), 64 deletions(-)

diff --git a/block/vpc.c b/block/vpc.c
index 326c2bb..4e5ba85 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -497,40 +497,70 @@ static int vpc_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
     return 0;
 }
 
-static int vpc_read(BlockDriverState *bs, int64_t sector_num,
-                    uint8_t *buf, int nb_sectors)
+static int64_t coroutine_fn vpc_co_get_block_status(BlockDriverState *bs,
+        int64_t sector_num, int nb_sectors, int *pnum)
 {
     BDRVVPCState *s = bs->opaque;
-    int ret;
-    int64_t offset;
-    int64_t sectors, sectors_per_block;
-    VHDFooter *footer = (VHDFooter *) s->footer_buf;
+    VHDFooter *footer = (VHDFooter*) s->footer_buf;
+    int64_t start, offset;
+    bool allocated;
+    int n;
 
     if (be32_to_cpu(footer->type) == VHD_FIXED) {
-        return bdrv_read(bs->file, sector_num, buf, nb_sectors);
+        *pnum = nb_sectors;
+        return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID | BDRV_BLOCK_DATA |
+               (sector_num << BDRV_SECTOR_BITS);
     }
-    while (nb_sectors > 0) {
-        offset = get_sector_offset(bs, sector_num, 0);
 
-        sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
-        sectors = sectors_per_block - (sector_num % sectors_per_block);
-        if (sectors > nb_sectors) {
-            sectors = nb_sectors;
+    offset = get_sector_offset(bs, sector_num, 0);
+    start = offset;
+    allocated = (offset != -1);
+    *pnum = 0;
+
+    do {
+        /* All sectors in a block are contiguous (without using the bitmap) */
+        n = ROUND_UP(sector_num + 1, s->block_size / BDRV_SECTOR_SIZE)
+          - sector_num;
+        n = MIN(n, nb_sectors);
+
+        *pnum += n;
+        sector_num += n;
+        nb_sectors -= n;
+
+        if (allocated) {
+            return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
         }
+        if (nb_sectors == 0) {
+            break;
+        }
+        offset = get_sector_offset(bs, sector_num, 0);
+    } while (offset == -1);
 
-        if (offset == -1) {
-            memset(buf, 0, sectors * BDRV_SECTOR_SIZE);
-        } else {
-            ret = bdrv_pread(bs->file, offset, buf,
-                sectors * BDRV_SECTOR_SIZE);
-            if (ret != sectors * BDRV_SECTOR_SIZE) {
+    return 0;
+}
+
+static int vpc_read(BlockDriverState *bs, int64_t sector_num,
+                    uint8_t *buf, int nb_sectors)
+{
+    int ret, n;
+    int64_t ret2;
+
+    while (nb_sectors > 0) {
+        ret2 = vpc_co_get_block_status(bs, sector_num, nb_sectors, &n);
+        
+        if (ret2 & BDRV_BLOCK_OFFSET_VALID) {
+            ret = bdrv_pread(bs->file, ret2 & BDRV_SECTOR_MASK, buf,
+                             n * BDRV_SECTOR_SIZE);
+            if (ret != n * BDRV_SECTOR_SIZE) {
                 return -1;
             }
+        } else {
+            memset(buf, 0x00, n * BDRV_SECTOR_SIZE);
         }
 
-        nb_sectors -= sectors;
-        sector_num += sectors;
-        buf += sectors * BDRV_SECTOR_SIZE;
+        sector_num += n;
+        nb_sectors -= n;
+        buf += n * BDRV_SECTOR_SIZE;
     }
     return 0;
 }
@@ -597,48 +627,6 @@ static coroutine_fn int vpc_co_write(BlockDriverState *bs, int64_t sector_num,
     return ret;
 }
 
-static int64_t coroutine_fn vpc_co_get_block_status(BlockDriverState *bs,
-        int64_t sector_num, int nb_sectors, int *pnum)
-{
-    BDRVVPCState *s = bs->opaque;
-    VHDFooter *footer = (VHDFooter*) s->footer_buf;
-    int64_t start, offset;
-    bool allocated;
-    int n;
-
-    if (be32_to_cpu(footer->type) == VHD_FIXED) {
-        *pnum = nb_sectors;
-        return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID | BDRV_BLOCK_DATA |
-               (sector_num << BDRV_SECTOR_BITS);
-    }
-
-    offset = get_sector_offset(bs, sector_num, 0);
-    start = offset;
-    allocated = (offset != -1);
-    *pnum = 0;
-
-    do {
-        /* All sectors in a block are contiguous (without using the bitmap) */
-        n = ROUND_UP(sector_num + 1, s->block_size / BDRV_SECTOR_SIZE)
-          - sector_num;
-        n = MIN(n, nb_sectors);
-
-        *pnum += n;
-        sector_num += n;
-        nb_sectors -= n;
-
-        if (allocated) {
-            return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
-        }
-        if (nb_sectors == 0) {
-            break;
-        }
-        offset = get_sector_offset(bs, sector_num, 0);
-    } while (offset == -1);
-
-    return 0;
-}
-
 /*
  * Calculates the number of cylinders, heads and sectors per cylinder
  * based on a given number of sectors. This is the algorithm described
-- 
1.7.9.5