diff options
Diffstat (limited to 'qemu/block/dirty-bitmap.c')
| -rw-r--r-- | qemu/block/dirty-bitmap.c | 387 |
1 files changed, 387 insertions, 0 deletions
diff --git a/qemu/block/dirty-bitmap.c b/qemu/block/dirty-bitmap.c new file mode 100644 index 000000000..4902ca557 --- /dev/null +++ b/qemu/block/dirty-bitmap.c @@ -0,0 +1,387 @@ +/* + * Block Dirty Bitmap + * + * Copyright (c) 2016 Red Hat. Inc + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ +#include "qemu/osdep.h" +#include "qapi/error.h" +#include "qemu-common.h" +#include "trace.h" +#include "block/block_int.h" +#include "block/blockjob.h" + +/** + * A BdrvDirtyBitmap can be in three possible states: + * (1) successor is NULL and disabled is false: full r/w mode + * (2) successor is NULL and disabled is true: read only mode ("disabled") + * (3) successor is set: frozen mode. + * A frozen bitmap cannot be renamed, deleted, anonymized, cleared, set, + * or enabled. A frozen bitmap can only abdicate() or reclaim(). + */ +struct BdrvDirtyBitmap { + HBitmap *bitmap; /* Dirty sector bitmap implementation */ + BdrvDirtyBitmap *successor; /* Anonymous child; implies frozen status */ + char *name; /* Optional non-empty unique ID */ + int64_t size; /* Size of the bitmap (Number of sectors) */ + bool disabled; /* Bitmap is read-only */ + QLIST_ENTRY(BdrvDirtyBitmap) list; +}; + +BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs, const char *name) +{ + BdrvDirtyBitmap *bm; + + assert(name); + QLIST_FOREACH(bm, &bs->dirty_bitmaps, list) { + if (bm->name && !strcmp(name, bm->name)) { + return bm; + } + } + return NULL; +} + +void bdrv_dirty_bitmap_make_anon(BdrvDirtyBitmap *bitmap) +{ + assert(!bdrv_dirty_bitmap_frozen(bitmap)); + g_free(bitmap->name); + bitmap->name = NULL; +} + +BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs, + uint32_t granularity, + const char *name, + Error **errp) +{ + int64_t bitmap_size; + BdrvDirtyBitmap *bitmap; + uint32_t sector_granularity; + + assert((granularity & (granularity - 1)) == 0); + + if (name && bdrv_find_dirty_bitmap(bs, name)) { + error_setg(errp, "Bitmap already exists: %s", name); + return NULL; + } + sector_granularity = granularity >> BDRV_SECTOR_BITS; + assert(sector_granularity); + bitmap_size = bdrv_nb_sectors(bs); + if (bitmap_size < 0) { + error_setg_errno(errp, -bitmap_size, "could not get length of device"); + errno = -bitmap_size; + return NULL; + } + bitmap = g_new0(BdrvDirtyBitmap, 1); + bitmap->bitmap = hbitmap_alloc(bitmap_size, ctz32(sector_granularity)); + bitmap->size = bitmap_size; + bitmap->name = g_strdup(name); + bitmap->disabled = false; + QLIST_INSERT_HEAD(&bs->dirty_bitmaps, bitmap, list); + return bitmap; +} + +bool bdrv_dirty_bitmap_frozen(BdrvDirtyBitmap *bitmap) +{ + return bitmap->successor; +} + +bool bdrv_dirty_bitmap_enabled(BdrvDirtyBitmap *bitmap) +{ + return !(bitmap->disabled || bitmap->successor); +} + +DirtyBitmapStatus bdrv_dirty_bitmap_status(BdrvDirtyBitmap *bitmap) +{ + if (bdrv_dirty_bitmap_frozen(bitmap)) { + return DIRTY_BITMAP_STATUS_FROZEN; + } else if (!bdrv_dirty_bitmap_enabled(bitmap)) { + return DIRTY_BITMAP_STATUS_DISABLED; + } else { + return DIRTY_BITMAP_STATUS_ACTIVE; + } +} + +/** + * Create a successor bitmap destined to replace this bitmap after an operation. + * Requires that the bitmap is not frozen and has no successor. + */ +int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs, + BdrvDirtyBitmap *bitmap, Error **errp) +{ + uint64_t granularity; + BdrvDirtyBitmap *child; + + if (bdrv_dirty_bitmap_frozen(bitmap)) { + error_setg(errp, "Cannot create a successor for a bitmap that is " + "currently frozen"); + return -1; + } + assert(!bitmap->successor); + + /* Create an anonymous successor */ + granularity = bdrv_dirty_bitmap_granularity(bitmap); + child = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp); + if (!child) { + return -1; + } + + /* Successor will be on or off based on our current state. */ + child->disabled = bitmap->disabled; + + /* Install the successor and freeze the parent */ + bitmap->successor = child; + return 0; +} + +/** + * For a bitmap with a successor, yield our name to the successor, + * delete the old bitmap, and return a handle to the new bitmap. + */ +BdrvDirtyBitmap *bdrv_dirty_bitmap_abdicate(BlockDriverState *bs, + BdrvDirtyBitmap *bitmap, + Error **errp) +{ + char *name; + BdrvDirtyBitmap *successor = bitmap->successor; + + if (successor == NULL) { + error_setg(errp, "Cannot relinquish control if " + "there's no successor present"); + return NULL; + } + + name = bitmap->name; + bitmap->name = NULL; + successor->name = name; + bitmap->successor = NULL; + bdrv_release_dirty_bitmap(bs, bitmap); + + return successor; +} + +/** + * In cases of failure where we can no longer safely delete the parent, + * we may wish to re-join the parent and child/successor. + * The merged parent will be un-frozen, but not explicitly re-enabled. + */ +BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs, + BdrvDirtyBitmap *parent, + Error **errp) +{ + BdrvDirtyBitmap *successor = parent->successor; + + if (!successor) { + error_setg(errp, "Cannot reclaim a successor when none is present"); + return NULL; + } + + if (!hbitmap_merge(parent->bitmap, successor->bitmap)) { + error_setg(errp, "Merging of parent and successor bitmap failed"); + return NULL; + } + bdrv_release_dirty_bitmap(bs, successor); + parent->successor = NULL; + + return parent; +} + +/** + * Truncates _all_ bitmaps attached to a BDS. + */ +void bdrv_dirty_bitmap_truncate(BlockDriverState *bs) +{ + BdrvDirtyBitmap *bitmap; + uint64_t size = bdrv_nb_sectors(bs); + + QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) { + assert(!bdrv_dirty_bitmap_frozen(bitmap)); + hbitmap_truncate(bitmap->bitmap, size); + bitmap->size = size; + } +} + +static void bdrv_do_release_matching_dirty_bitmap(BlockDriverState *bs, + BdrvDirtyBitmap *bitmap, + bool only_named) +{ + BdrvDirtyBitmap *bm, *next; + QLIST_FOREACH_SAFE(bm, &bs->dirty_bitmaps, list, next) { + if ((!bitmap || bm == bitmap) && (!only_named || bm->name)) { + assert(!bdrv_dirty_bitmap_frozen(bm)); + QLIST_REMOVE(bm, list); + hbitmap_free(bm->bitmap); + g_free(bm->name); + g_free(bm); + + if (bitmap) { + return; + } + } + } +} + +void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap) +{ + bdrv_do_release_matching_dirty_bitmap(bs, bitmap, false); +} + +/** + * Release all named dirty bitmaps attached to a BDS (for use in bdrv_close()). + * There must not be any frozen bitmaps attached. + */ +void bdrv_release_named_dirty_bitmaps(BlockDriverState *bs) +{ + bdrv_do_release_matching_dirty_bitmap(bs, NULL, true); +} + +void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap) +{ + assert(!bdrv_dirty_bitmap_frozen(bitmap)); + bitmap->disabled = true; +} + +void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap) +{ + assert(!bdrv_dirty_bitmap_frozen(bitmap)); + bitmap->disabled = false; +} + +BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs) +{ + BdrvDirtyBitmap *bm; + BlockDirtyInfoList *list = NULL; + BlockDirtyInfoList **plist = &list; + + QLIST_FOREACH(bm, &bs->dirty_bitmaps, list) { + BlockDirtyInfo *info = g_new0(BlockDirtyInfo, 1); + BlockDirtyInfoList *entry = g_new0(BlockDirtyInfoList, 1); + info->count = bdrv_get_dirty_count(bm); + info->granularity = bdrv_dirty_bitmap_granularity(bm); + info->has_name = !!bm->name; + info->name = g_strdup(bm->name); + info->status = bdrv_dirty_bitmap_status(bm); + entry->value = info; + *plist = entry; + plist = &entry->next; + } + + return list; +} + +int bdrv_get_dirty(BlockDriverState *bs, BdrvDirtyBitmap *bitmap, + int64_t sector) +{ + if (bitmap) { + return hbitmap_get(bitmap->bitmap, sector); + } else { + return 0; + } +} + +/** + * Chooses a default granularity based on the existing cluster size, + * but clamped between [4K, 64K]. Defaults to 64K in the case that there + * is no cluster size information available. + */ +uint32_t bdrv_get_default_bitmap_granularity(BlockDriverState *bs) +{ + BlockDriverInfo bdi; + uint32_t granularity; + + if (bdrv_get_info(bs, &bdi) >= 0 && bdi.cluster_size > 0) { + granularity = MAX(4096, bdi.cluster_size); + granularity = MIN(65536, granularity); + } else { + granularity = 65536; + } + + return granularity; +} + +uint32_t bdrv_dirty_bitmap_granularity(BdrvDirtyBitmap *bitmap) +{ + return BDRV_SECTOR_SIZE << hbitmap_granularity(bitmap->bitmap); +} + +void bdrv_dirty_iter_init(BdrvDirtyBitmap *bitmap, HBitmapIter *hbi) +{ + hbitmap_iter_init(hbi, bitmap->bitmap, 0); +} + +void bdrv_set_dirty_bitmap(BdrvDirtyBitmap *bitmap, + int64_t cur_sector, int nr_sectors) +{ + assert(bdrv_dirty_bitmap_enabled(bitmap)); + hbitmap_set(bitmap->bitmap, cur_sector, nr_sectors); +} + +void bdrv_reset_dirty_bitmap(BdrvDirtyBitmap *bitmap, + int64_t cur_sector, int nr_sectors) +{ + assert(bdrv_dirty_bitmap_enabled(bitmap)); + hbitmap_reset(bitmap->bitmap, cur_sector, nr_sectors); +} + +void bdrv_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap, HBitmap **out) +{ + assert(bdrv_dirty_bitmap_enabled(bitmap)); + if (!out) { + hbitmap_reset_all(bitmap->bitmap); + } else { + HBitmap *backup = bitmap->bitmap; + bitmap->bitmap = hbitmap_alloc(bitmap->size, + hbitmap_granularity(backup)); + *out = backup; + } +} + +void bdrv_undo_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap, HBitmap *in) +{ + HBitmap *tmp = bitmap->bitmap; + assert(bdrv_dirty_bitmap_enabled(bitmap)); + bitmap->bitmap = in; + hbitmap_free(tmp); +} + +void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector, + int nr_sectors) +{ + BdrvDirtyBitmap *bitmap; + QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) { + if (!bdrv_dirty_bitmap_enabled(bitmap)) { + continue; + } + hbitmap_set(bitmap->bitmap, cur_sector, nr_sectors); + } +} + +/** + * Advance an HBitmapIter to an arbitrary offset. + */ +void bdrv_set_dirty_iter(HBitmapIter *hbi, int64_t offset) +{ + assert(hbi->hb); + hbitmap_iter_init(hbi, hbi->hb, offset); +} + +int64_t bdrv_get_dirty_count(BdrvDirtyBitmap *bitmap) +{ + return hbitmap_count(bitmap->bitmap); +} |