From d19c6b36ffe09cec7ce7ac6a3e979bfe923ebba9 Mon Sep 17 00:00:00 2001 From: John Snow Date: Mon, 11 Mar 2019 21:51:46 +0300 Subject: [PATCH] block/qcow2-bitmap: Allow resizes with persistent bitmaps Since we now load all bitmaps into memory anyway, we can just truncate them in-memory and then flush them back to disk. Just in case, we will still check and enforce that this shortcut is valid -- i.e. that any bitmap described on-disk is indeed in-memory and can be modified. If there are any inconsistent bitmaps, we refuse to allow the truncate as we do not actually load these bitmaps into memory, and it isn't safe or reasonable to attempt to truncate corrupted data. Signed-off-by: John Snow Signed-off-by: Vladimir Sementsov-Ogievskiy Message-id: 20190311185147.52309-4-vsementsov@virtuozzo.com [vsementsov: drop bitmap flushing, fix block comments style] Signed-off-by: John Snow --- block/qcow2-bitmap.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ block/qcow2.c | 4 +--- block/qcow2.h | 1 + 3 files changed, 48 insertions(+), 3 deletions(-) diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c index 92cef1cfd4..e53a1609d7 100644 --- a/block/qcow2-bitmap.c +++ b/block/qcow2-bitmap.c @@ -1175,6 +1175,52 @@ int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp) return qcow2_reopen_bitmaps_rw_hint(bs, NULL, errp); } +/* Checks to see if it's safe to resize bitmaps */ +int qcow2_truncate_bitmaps_check(BlockDriverState *bs, Error **errp) +{ + BDRVQcow2State *s = bs->opaque; + Qcow2BitmapList *bm_list; + Qcow2Bitmap *bm; + int ret = 0; + + if (s->nb_bitmaps == 0) { + return 0; + } + + bm_list = bitmap_list_load(bs, s->bitmap_directory_offset, + s->bitmap_directory_size, errp); + if (bm_list == NULL) { + return -EINVAL; + } + + QSIMPLEQ_FOREACH(bm, bm_list, entry) { + BdrvDirtyBitmap *bitmap = bdrv_find_dirty_bitmap(bs, bm->name); + if (bitmap == NULL) { + /* + * We rely on all bitmaps being in-memory to be able to resize them, + * Otherwise, we'd need to resize them on disk explicitly + */ + error_setg(errp, "Cannot resize qcow2 with persistent bitmaps that " + "were not loaded into memory"); + ret = -ENOTSUP; + goto out; + } + + /* + * The checks against readonly and busy are redundant, but certainly + * do no harm. checks against inconsistent are crucial: + */ + if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_DEFAULT, errp)) { + ret = -ENOTSUP; + goto out; + } + } + +out: + bitmap_list_free(bm_list); + return ret; +} + /* store_bitmap_data() * Store bitmap to image, filling bitmap table accordingly. */ diff --git a/block/qcow2.c b/block/qcow2.c index c4dd876fb4..d48e2e56f7 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -3646,9 +3646,7 @@ static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset, } /* cannot proceed if image has bitmaps */ - if (s->nb_bitmaps) { - /* TODO: resize bitmaps in the image */ - error_setg(errp, "Can't resize an image which has bitmaps"); + if (qcow2_truncate_bitmaps_check(bs, errp)) { ret = -ENOTSUP; goto fail; } diff --git a/block/qcow2.h b/block/qcow2.h index de2a3bdfc5..fdee297f33 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -723,6 +723,7 @@ Qcow2BitmapInfoList *qcow2_get_bitmap_info_list(BlockDriverState *bs, int qcow2_reopen_bitmaps_rw_hint(BlockDriverState *bs, bool *header_updated, Error **errp); int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp); +int qcow2_truncate_bitmaps_check(BlockDriverState *bs, Error **errp); void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp); int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp); bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs, -- 2.11.4.GIT