[Qemu-devel] [PATCH stable-0.15 26/36] qcow: Fix bdrv_write_compressed error handling

["Andreas Färber" <afaerber@suse.de>]

From: Kevin Wolf <kwolf@redhat.com>

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 64ebe71aa0e498d24e8c02b133192142fce3a0d0)

Signed-off-by: Bruce Rogers <brogers@suse.com>
[AF: backported]
Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 block/qcow.c |   30 +++++++++++++++++++-----------
 1 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/block/qcow.c b/block/qcow.c
index 227b104..115b820 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -926,8 +926,6 @@ static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
         return -EINVAL;
 
     out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
-    if (!out_buf)
-        return -1;
 
     /* best compression, small window, no zlib header */
     memset(&strm, 0, sizeof(strm));
@@ -935,8 +933,8 @@ static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
                        Z_DEFLATED, -12,
                        9, Z_DEFAULT_STRATEGY);
     if (ret != 0) {
-        qemu_free(out_buf);
-        return -1;
+        ret = -EINVAL;
+        goto fail;
     }
 
     strm.avail_in = s->cluster_size;
@@ -946,9 +944,9 @@ static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
 
     ret = deflate(&strm, Z_FINISH);
     if (ret != Z_STREAM_END && ret != Z_OK) {
-        qemu_free(out_buf);
         deflateEnd(&strm);
-        return -1;
+        ret = -EINVAL;
+        goto fail;
     }
     out_len = strm.next_out - out_buf;
 
@@ -956,19 +954,29 @@ static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
 
     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
         /* could not compress: write normal cluster */
-        bdrv_write(bs, sector_num, buf, s->cluster_sectors);
+        ret = bdrv_write(bs, sector_num, buf, s->cluster_sectors);
+        if (ret < 0) {
+            goto fail;
+        }
     } else {
         cluster_offset = get_cluster_offset(bs, sector_num << 9, 2,
                                             out_len, 0, 0);
+        if (cluster_offset == 0) {
+            ret = -EIO;
+            goto fail;
+        }
+
         cluster_offset &= s->cluster_offset_mask;
-        if (bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len) != out_len) {
-            qemu_free(out_buf);
-            return -1;
+        ret = bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len);
+        if (ret < 0) {
+            goto fail;
         }
     }
 
+    ret = 0;
+fail:
     qemu_free(out_buf);
-    return 0;
+    return ret;
 }
 
 static int qcow_flush(BlockDriverState *bs)
-- 
1.7.7