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authorDimitris Aragiorgis <dimara@arrikto.com>2015-06-23 13:44:57 +0300
committerStefan Hajnoczi <stefanha@redhat.com>2015-06-23 15:08:52 +0100
commit1b6bc94d5d43ff3e39abadae19f2dbcb0954eb93 (patch)
tree11fe472b6b008b4a918d27b2067b2697e390c8cb /block
parentb192af8acc597a6e8068873434e56e0c7de1b7d3 (diff)
Fix migration in case of scsi-generic
During migration, QEMU uses fsync()/fdatasync() on the open file descriptor for read-write block devices to flush data just before stopping the VM. However, fsync() on a scsi-generic device returns -EINVAL which causes the migration to fail. This patch skips flushing data in case of an SG device, since submitting SCSI commands directly via an SG character device (e.g. /dev/sg0) bypasses the page cache completely, anyway. Note that fsync() not only flushes the page cache but also the disk cache. The scsi-generic device never sends flushes, and for migration it assumes that the same SCSI device is used by the destination host, so it does not issue any SCSI SYNCHRONIZE CACHE (10) command. Finally, remove the bdrv_is_sg() test from iscsi_co_flush() since this is now redundant (we flush the underlying protocol at the end of bdrv_co_flush() which, with this patch, we never reach). Signed-off-by: Dimitris Aragiorgis <dimara@arrikto.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 1435056300-14924-3-git-send-email-dimara@arrikto.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'block')
-rw-r--r--block/io.c3
-rw-r--r--block/iscsi.c4
2 files changed, 2 insertions, 5 deletions
diff --git a/block/io.c b/block/io.c
index 43f85ab452..e2959920b8 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2265,7 +2265,8 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
{
int ret;
- if (!bs || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
+ if (!bs || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs) ||
+ bdrv_is_sg(bs)) {
return 0;
}
diff --git a/block/iscsi.c b/block/iscsi.c
index aff8198d3f..49cee4dda9 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -628,10 +628,6 @@ static int coroutine_fn iscsi_co_flush(BlockDriverState *bs)
IscsiLun *iscsilun = bs->opaque;
struct IscsiTask iTask;
- if (bdrv_is_sg(bs)) {
- return 0;
- }
-
if (!iscsilun->force_next_flush) {
return 0;
}