diff options
| author | Max Reitz <mreitz@redhat.com> | 2017-11-23 03:08:17 +0100 |
|---|---|---|
| committer | Max Reitz <mreitz@redhat.com> | 2018-01-23 12:34:42 +0100 |
| commit | c9ceb3ec8a7e6dc4f74183ca7493895445b57845 (patch) | |
| tree | e8cc603dfe0c99b3a8077847d7639c1870b19320 /block | |
| parent | 3c363575dc5fe325a8b16b1a18e1fa48120df6b6 (diff) | |
qcow2: No persistent dirty bitmaps for compat=0.10
Persistent dirty bitmaps require a properly functioning
autoclear_features field, or we cannot track when an unsupporting
program might overwrite them. Therefore, we cannot support them for
compat=0.10 images.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20171123020832.8165-3-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/qcow2-bitmap.c | 10 | ||||
| -rw-r--r-- | block/qcow2.c | 14 |
2 files changed, 21 insertions, 3 deletions
diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c index f45e46cfbd..efa10c6663 100644 --- a/block/qcow2-bitmap.c +++ b/block/qcow2-bitmap.c @@ -1449,6 +1449,16 @@ bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs, bool found; Qcow2BitmapList *bm_list; + if (s->qcow_version < 3) { + /* Without autoclear_features, we would always have to assume + * that a program without persistent dirty bitmap support has + * accessed this qcow2 file when opening it, and would thus + * have to drop all dirty bitmaps (defeating their purpose). + */ + error_setg(errp, "Cannot store dirty bitmaps in qcow2 v2 files"); + goto fail; + } + if (check_constraints_on_bitmap(bs, name, granularity, errp) != 0) { goto fail; } diff --git a/block/qcow2.c b/block/qcow2.c index 4348b2c0c5..1f80961e1b 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -302,9 +302,17 @@ static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset, } if (!(s->autoclear_features & QCOW2_AUTOCLEAR_BITMAPS)) { - warn_report("a program lacking bitmap support " - "modified this file, so all bitmaps are now " - "considered inconsistent"); + if (s->qcow_version < 3) { + /* Let's be a bit more specific */ + warn_report("This qcow2 v2 image contains bitmaps, but " + "they may have been modified by a program " + "without persistent bitmap support; so now " + "they must all be considered inconsistent"); + } else { + warn_report("a program lacking bitmap support " + "modified this file, so all bitmaps are now " + "considered inconsistent"); + } error_printf("Some clusters may be leaked, " "run 'qemu-img check -r' on the image " "file to fix."); |