From 74da6b943565c451d275de1b0253546c5e729d20 Mon Sep 17 00:00:00 2001 From: John Snow Date: Tue, 12 Mar 2019 12:05:49 -0400 Subject: [PATCH] block/dirty-bitmaps: implement inconsistent bit Set the inconsistent bit on load instead of rejecting such bitmaps. There is no way to un-set it; the only option is to delete the bitmap. Obvervations: - bitmap loading does not need to update the header for in_use bitmaps. - inconsistent bitmaps don't need to have their data loaded; they're glorified corruption sentinels. - bitmap saving does not need to save inconsistent bitmaps back to disk. - bitmap reopening DOES need to drop the readonly flag from inconsistent bitmaps to allow reopening of qcow2 files with non-qemu-owned bitmaps being eventually flushed back to disk. Signed-off-by: John Snow Reviewed-by: Eric Blake Message-id: 20190301191545.8728-8-jsnow@redhat.com Signed-off-by: John Snow --- block/qcow2-bitmap.c | 105 ++++++++++++++++++++++--------------------- 1 file changed, 54 insertions(+), 51 deletions(-) diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c index 9d968bdcda..2c3e0886cf 100644 --- a/block/qcow2-bitmap.c +++ b/block/qcow2-bitmap.c @@ -343,11 +343,17 @@ static BdrvDirtyBitmap *load_bitmap(BlockDriverState *bs, uint32_t granularity; BdrvDirtyBitmap *bitmap = NULL; - if (bm->flags & BME_FLAG_IN_USE) { - error_setg(errp, "Bitmap '%s' is in use", bm->name); + granularity = 1U << bm->granularity_bits; + bitmap = bdrv_create_dirty_bitmap(bs, granularity, bm->name, errp); + if (bitmap == NULL) { goto fail; } + if (bm->flags & BME_FLAG_IN_USE) { + /* Data is unusable, skip loading it */ + return bitmap; + } + ret = bitmap_table_load(bs, &bm->table, &bitmap_table); if (ret < 0) { error_setg_errno(errp, -ret, @@ -356,12 +362,6 @@ static BdrvDirtyBitmap *load_bitmap(BlockDriverState *bs, goto fail; } - granularity = 1U << bm->granularity_bits; - bitmap = bdrv_create_dirty_bitmap(bs, granularity, bm->name, errp); - if (bitmap == NULL) { - goto fail; - } - ret = load_bitmap_data(bs, bitmap_table, bm->table.size, bitmap); if (ret < 0) { error_setg_errno(errp, -ret, "Could not read bitmap '%s' from image", @@ -950,6 +950,7 @@ bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, Error **errp) Qcow2Bitmap *bm; GSList *created_dirty_bitmaps = NULL; bool header_updated = false; + bool needs_update = false; if (s->nb_bitmaps == 0) { /* No bitmaps - nothing to do */ @@ -963,35 +964,39 @@ bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, Error **errp) } QSIMPLEQ_FOREACH(bm, bm_list, entry) { - if (!(bm->flags & BME_FLAG_IN_USE)) { - BdrvDirtyBitmap *bitmap = load_bitmap(bs, bm, errp); - if (bitmap == NULL) { - goto fail; - } - - if (!(bm->flags & BME_FLAG_AUTO)) { - bdrv_disable_dirty_bitmap(bitmap); - } - bdrv_dirty_bitmap_set_persistance(bitmap, true); - bm->flags |= BME_FLAG_IN_USE; - created_dirty_bitmaps = - g_slist_append(created_dirty_bitmaps, bitmap); + BdrvDirtyBitmap *bitmap = load_bitmap(bs, bm, errp); + if (bitmap == NULL) { + goto fail; } + + bdrv_dirty_bitmap_set_persistance(bitmap, true); + if (bm->flags & BME_FLAG_IN_USE) { + bdrv_dirty_bitmap_set_inconsistent(bitmap); + } else { + /* NB: updated flags only get written if can_write(bs) is true. */ + bm->flags |= BME_FLAG_IN_USE; + needs_update = true; + } + if (!(bm->flags & BME_FLAG_AUTO)) { + bdrv_disable_dirty_bitmap(bitmap); + } + created_dirty_bitmaps = + g_slist_append(created_dirty_bitmaps, bitmap); } - if (created_dirty_bitmaps != NULL) { - if (can_write(bs)) { - /* in_use flags must be updated */ - int ret = update_ext_header_and_dir_in_place(bs, bm_list); - if (ret < 0) { - error_setg_errno(errp, -ret, "Can't update bitmap directory"); - goto fail; - } - header_updated = true; - } else { - g_slist_foreach(created_dirty_bitmaps, set_readonly_helper, - (gpointer)true); + if (needs_update && can_write(bs)) { + /* in_use flags must be updated */ + int ret = update_ext_header_and_dir_in_place(bs, bm_list); + if (ret < 0) { + error_setg_errno(errp, -ret, "Can't update bitmap directory"); + goto fail; } + header_updated = true; + } + + if (!can_write(bs)) { + g_slist_foreach(created_dirty_bitmaps, set_readonly_helper, + (gpointer)true); } g_slist_free(created_dirty_bitmaps); @@ -1113,23 +1118,21 @@ int qcow2_reopen_bitmaps_rw_hint(BlockDriverState *bs, bool *header_updated, } QSIMPLEQ_FOREACH(bm, bm_list, entry) { - if (!(bm->flags & BME_FLAG_IN_USE)) { - BdrvDirtyBitmap *bitmap = bdrv_find_dirty_bitmap(bs, bm->name); - if (bitmap == NULL) { - continue; - } - - if (!bdrv_dirty_bitmap_readonly(bitmap)) { - error_setg(errp, "Bitmap %s is not readonly but not marked" - "'IN_USE' in the image. Something went wrong," - "all the bitmaps may be corrupted", bm->name); - ret = -EINVAL; - goto out; - } - - bm->flags |= BME_FLAG_IN_USE; - ro_dirty_bitmaps = g_slist_append(ro_dirty_bitmaps, bitmap); + BdrvDirtyBitmap *bitmap = bdrv_find_dirty_bitmap(bs, bm->name); + if (bitmap == NULL) { + continue; } + + if (!bdrv_dirty_bitmap_readonly(bitmap)) { + error_setg(errp, "Bitmap %s was loaded prior to rw-reopen, but was " + "not marked as readonly. This is a bug, something went " + "wrong. All of the bitmaps may be corrupted", bm->name); + ret = -EINVAL; + goto out; + } + + bm->flags |= BME_FLAG_IN_USE; + ro_dirty_bitmaps = g_slist_append(ro_dirty_bitmaps, bitmap); } if (ro_dirty_bitmaps != NULL) { @@ -1425,8 +1428,8 @@ void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp) Qcow2Bitmap *bm; if (!bdrv_dirty_bitmap_get_persistance(bitmap) || - bdrv_dirty_bitmap_readonly(bitmap)) - { + bdrv_dirty_bitmap_readonly(bitmap) || + bdrv_dirty_bitmap_inconsistent(bitmap)) { continue; }