[Qemu-devel] [PATCH] block/raw-posix: use seek_hole ahead of fiemap

[Tony Breeds]

The command
  qemu-img convert -O raw inputimage.qcow2 outputimage.raw

intermittently creates corrupted output images, when the input image is not yet 
fully synchronized to disk.  This patch preferese the use of seek_hole checks 
to determine if the sector is present in the disk image.

While we're there modify try_fiemap() to set FIEMAP_FLAG_SYNC.

Reported-By: Michael Steffens <address@hidden>
CC: Pádraig Brady <address@hidden>
Signed-off-by: Tony Breeds <address@hidden>
---
 block/raw-posix.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/block/raw-posix.c b/block/raw-posix.c
index a253697..b438c54 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1472,7 +1472,7 @@ static int64_t try_fiemap(BlockDriverState *bs, off_t 
start, off_t *data,
 
     f.fm.fm_start = start;
     f.fm.fm_length = (int64_t)nb_sectors * BDRV_SECTOR_SIZE;
-    f.fm.fm_flags = 0;
+    f.fm.fm_flags = FIEMAP_FLAG_SYNC;
     f.fm.fm_extent_count = 1;
     f.fm.fm_reserved = 0;
     if (ioctl(s->fd, FS_IOC_FIEMAP, &f) == -1) {
@@ -1561,9 +1561,9 @@ static int64_t coroutine_fn 
raw_co_get_block_status(BlockDriverState *bs,
 
     start = sector_num * BDRV_SECTOR_SIZE;
 
-    ret = try_fiemap(bs, start, &data, &hole, nb_sectors, pnum);
+    ret = try_seek_hole(bs, start, &data, &hole, pnum);
     if (ret < 0) {
-        ret = try_seek_hole(bs, start, &data, &hole, pnum);
+        ret = try_fiemap(bs, start, &data, &hole, nb_sectors, pnum);
         if (ret < 0) {
             /* Assume everything is allocated. */
             data = 0;
-- 
1.9.3