| Message ID | 1424473645-29161-19-git-send-email-jsnow@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 2015-02-20 at 18:07, John Snow wrote: > Signed-off-by: John Snow <jsnow@redhat.com> > --- > block.c | 20 ++++++++++++++++++++ > include/block/block.h | 1 + > include/qemu/hbitmap.h | 10 ++++++++++ > util/hbitmap.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 78 insertions(+) > > diff --git a/block.c b/block.c > index f3a6dd4..59a8ec9 100644 > --- a/block.c > +++ b/block.c > @@ -3514,6 +3514,7 @@ int bdrv_truncate(BlockDriverState *bs, int64_t offset) > ret = drv->bdrv_truncate(bs, offset); > if (ret == 0) { > ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS); > + bdrv_dirty_bitmap_truncate(bs); > if (bs->blk) { > blk_dev_resize_cb(bs->blk); > } > @@ -5524,6 +5525,25 @@ BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs, > return parent; > } > > +static void dirty_bitmap_truncate(BdrvDirtyBitmap *bitmap, uint64_t size) > +{ > + assert(!bdrv_dirty_bitmap_frozen(bitmap)); This assertion is valid because the only way to make a bitmap frozen is by starting a drive-backup block job on the BDS, and doing so blocks the HMP block_resize command (and I don't know other ways to invoke bdrv_truncate() online). (That means: It's fine. I just had to think about whether it is.) > + hbitmap_truncate(bitmap->bitmap, size); > +} > + > +void bdrv_dirty_bitmap_truncate(BlockDriverState *bs) > +{ > + BdrvDirtyBitmap *bitmap; > + uint64_t size = bdrv_nb_sectors(bs); > + > + QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) { > + if (bdrv_dirty_bitmap_frozen(bitmap)) { > + continue; > + } > + dirty_bitmap_truncate(bitmap, size); > + } > +} > + > void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap) > { > BdrvDirtyBitmap *bm, *next; > diff --git a/include/block/block.h b/include/block/block.h > index f6a50ae..aa6912d 100644 > --- a/include/block/block.h > +++ b/include/block/block.h > @@ -442,6 +442,7 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs, > uint32_t granularity, > const char *name, > Error **errp); > +void bdrv_dirty_bitmap_truncate(BlockDriverState *bs); > int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs, > BdrvDirtyBitmap *bitmap, > Error **errp); > diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h > index c19c1cb..a75157e 100644 > --- a/include/qemu/hbitmap.h > +++ b/include/qemu/hbitmap.h > @@ -65,6 +65,16 @@ struct HBitmapIter { > HBitmap *hbitmap_alloc(uint64_t size, int granularity); > > /** > + * hbitmap_truncate: > + * @hb: The bitmap to change the size of. > + * @size: The number of elements to change the bitmap to accommodate. > + * > + * truncate or grow an existing bitmap to accommodate a new number of elements. > + * This may invalidate existing HBitmapIterators. > + */ > +void hbitmap_truncate(HBitmap *hb, uint64_t size); > + > +/** > * hbitmap_merge: > * @a: The bitmap to store the result in. > * @b: The bitmap to merge into @a. > diff --git a/util/hbitmap.c b/util/hbitmap.c > index 962ff29..d17b850 100644 > --- a/util/hbitmap.c > +++ b/util/hbitmap.c > @@ -90,6 +90,9 @@ struct HBitmap { > * bitmap will still allocate HBITMAP_LEVELS arrays. > */ > unsigned long *levels[HBITMAP_LEVELS]; > + > + /* The length of each levels[] array. */ > + uint64_t sizes[HBITMAP_LEVELS]; > }; > > /* Advance hbi to the next nonzero word and return it. hbi->pos > @@ -384,6 +387,7 @@ HBitmap *hbitmap_alloc(uint64_t size, int granularity) > hb->granularity = granularity; > for (i = HBITMAP_LEVELS; i-- > 0; ) { > size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1); > + hb->sizes[i] = size; > hb->levels[i] = g_new0(unsigned long, size); > } > > @@ -396,6 +400,49 @@ HBitmap *hbitmap_alloc(uint64_t size, int granularity) > return hb; > } > > +void hbitmap_truncate(HBitmap *hb, uint64_t size) > +{ > + bool truncate; > + unsigned i; > + uint64_t num_elements = size; > + > + /* Size comes in as logical elements, adjust for granularity. */ > + size = (size + (1ULL << hb->granularity) - 1) >> hb->granularity; > + assert(size <= ((uint64_t)1 << HBITMAP_LOG_MAX_SIZE)); > + truncate = size < hb->size; > + > + if (size == hb->size) { > + /* A hard day's work */ > + return; > + } > + > + hb->size = size; > + for (i = HBITMAP_LEVELS; i-- > 0; ) { By now I've heard that this is a relatively wide-spread pattern; but I still don't like it because I find it pretty hard to figure out that it does what it's supposed to if you've never seen it before (and with "by now I've heard" I mean that I read some blog post where someone mentioned that he didn't like it). At least it's not "i --> 0", so I guess I should be fine with it. (and with "by now" I mean that I'm the one responsible for it not being "-->" in hbitmap_merge()) > + size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1); > + if (hb->sizes[i] == size) { > + continue; > + } > + hb->sizes[i] = size; > + hb->levels[i] = g_realloc_n(hb->levels[i], size, sizeof(unsigned long)); How about initializing the new memory in case of truncate == false? I'm not sure whether to initialize it to 0 or 1, though. Probably 0. > + } > + assert(size == 1); > + > + /* Clear out any "extra space" we may have that the user didn't request: > + * It may have garbage data in it, now. */ > + if (truncate) { > + /* Due to granularity fuzziness, we may accidentally reset some of > + * the last bits that are actually valid. So, record the current value, > + * reset the "dead range," then re-set the one sector we care about. */ > + bool status = hbitmap_get(hb, num_elements - 1); > + uint64_t fix_count = (hb->size << hb->granularity) - num_elements; > + hbitmap_reset(hb, num_elements, fix_count); This can fail an assertion (or at least I believe it's this function, it may be the hbitmap_set() below, too (but status should be false, so I don't think that)): ./qemu-img create -f raw test.img 64M; echo "{'execute':'qmp_capabilities'}{'execute':'block-dirty-bitmap-add','arguments':{'node':'drv','name':'foo'}}{'execute':'human-monitor-command','arguments':{'command-line':'block_resize drv 32M'}}" | x86_64-softmmu/qemu-system-x86_64 -drive if=none,id=drv,file=test.img,format=raw -qmp stdio -machine accel=qtest -nodefaults -display none Formatting 'test.img', fmt=raw size=67108864 {"QMP": {"version": {"qemu": {"micro": 50, "minor": 2, "major": 2}, "package": ""}, "capabilities": []}} {"return": {}} {"return": {}} qemu-system-x86_64: util/hbitmap.c:149: hbitmap_iter_init: Assertion `pos < hb->size' failed. It's probably because fix_count == 0 and therefore num_elements is not an index into the bitmap (which hbitmap_reset() and subsequently hb_count_between() don't take into account). Max > + if (status) { > + hbitmap_set(hb, num_elements - 1, 1); > + } > + } > +} > + > + > /** > * Given HBitmaps A and B, let A := A (BITOR) B. > * Bitmap B will not be modified.
On 02/23/2015 12:03 PM, Max Reitz wrote: > On 2015-02-20 at 18:07, John Snow wrote: >> Signed-off-by: John Snow <jsnow@redhat.com> >> --- >> block.c | 20 ++++++++++++++++++++ >> include/block/block.h | 1 + >> include/qemu/hbitmap.h | 10 ++++++++++ >> util/hbitmap.c | 47 >> +++++++++++++++++++++++++++++++++++++++++++++++ >> 4 files changed, 78 insertions(+) >> >> diff --git a/block.c b/block.c >> index f3a6dd4..59a8ec9 100644 >> --- a/block.c >> +++ b/block.c >> @@ -3514,6 +3514,7 @@ int bdrv_truncate(BlockDriverState *bs, int64_t >> offset) >> ret = drv->bdrv_truncate(bs, offset); >> if (ret == 0) { >> ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS); >> + bdrv_dirty_bitmap_truncate(bs); >> if (bs->blk) { >> blk_dev_resize_cb(bs->blk); >> } >> @@ -5524,6 +5525,25 @@ BdrvDirtyBitmap >> *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs, >> return parent; >> } >> +static void dirty_bitmap_truncate(BdrvDirtyBitmap *bitmap, uint64_t >> size) >> +{ >> + assert(!bdrv_dirty_bitmap_frozen(bitmap)); > > This assertion is valid because the only way to make a bitmap frozen is > by starting a drive-backup block job on the BDS, and doing so blocks the > HMP block_resize command (and I don't know other ways to invoke > bdrv_truncate() online). > > (That means: It's fine. I just had to think about whether it is.) > >> + hbitmap_truncate(bitmap->bitmap, size); >> +} >> + >> +void bdrv_dirty_bitmap_truncate(BlockDriverState *bs) >> +{ >> + BdrvDirtyBitmap *bitmap; >> + uint64_t size = bdrv_nb_sectors(bs); >> + >> + QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) { >> + if (bdrv_dirty_bitmap_frozen(bitmap)) { >> + continue; >> + } >> + dirty_bitmap_truncate(bitmap, size); >> + } >> +} >> + >> void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap >> *bitmap) >> { >> BdrvDirtyBitmap *bm, *next; >> diff --git a/include/block/block.h b/include/block/block.h >> index f6a50ae..aa6912d 100644 >> --- a/include/block/block.h >> +++ b/include/block/block.h >> @@ -442,6 +442,7 @@ BdrvDirtyBitmap >> *bdrv_create_dirty_bitmap(BlockDriverState *bs, >> uint32_t granularity, >> const char *name, >> Error **errp); >> +void bdrv_dirty_bitmap_truncate(BlockDriverState *bs); >> int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs, >> BdrvDirtyBitmap *bitmap, >> Error **errp); >> diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h >> index c19c1cb..a75157e 100644 >> --- a/include/qemu/hbitmap.h >> +++ b/include/qemu/hbitmap.h >> @@ -65,6 +65,16 @@ struct HBitmapIter { >> HBitmap *hbitmap_alloc(uint64_t size, int granularity); >> /** >> + * hbitmap_truncate: >> + * @hb: The bitmap to change the size of. >> + * @size: The number of elements to change the bitmap to accommodate. >> + * >> + * truncate or grow an existing bitmap to accommodate a new number of >> elements. >> + * This may invalidate existing HBitmapIterators. >> + */ >> +void hbitmap_truncate(HBitmap *hb, uint64_t size); >> + >> +/** >> * hbitmap_merge: >> * @a: The bitmap to store the result in. >> * @b: The bitmap to merge into @a. >> diff --git a/util/hbitmap.c b/util/hbitmap.c >> index 962ff29..d17b850 100644 >> --- a/util/hbitmap.c >> +++ b/util/hbitmap.c >> @@ -90,6 +90,9 @@ struct HBitmap { >> * bitmap will still allocate HBITMAP_LEVELS arrays. >> */ >> unsigned long *levels[HBITMAP_LEVELS]; >> + >> + /* The length of each levels[] array. */ >> + uint64_t sizes[HBITMAP_LEVELS]; >> }; >> /* Advance hbi to the next nonzero word and return it. hbi->pos >> @@ -384,6 +387,7 @@ HBitmap *hbitmap_alloc(uint64_t size, int >> granularity) >> hb->granularity = granularity; >> for (i = HBITMAP_LEVELS; i-- > 0; ) { >> size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1); >> + hb->sizes[i] = size; >> hb->levels[i] = g_new0(unsigned long, size); >> } >> @@ -396,6 +400,49 @@ HBitmap *hbitmap_alloc(uint64_t size, int >> granularity) >> return hb; >> } >> +void hbitmap_truncate(HBitmap *hb, uint64_t size) >> +{ >> + bool truncate; >> + unsigned i; >> + uint64_t num_elements = size; >> + >> + /* Size comes in as logical elements, adjust for granularity. */ >> + size = (size + (1ULL << hb->granularity) - 1) >> hb->granularity; >> + assert(size <= ((uint64_t)1 << HBITMAP_LOG_MAX_SIZE)); >> + truncate = size < hb->size; >> + >> + if (size == hb->size) { >> + /* A hard day's work */ >> + return; >> + } >> + >> + hb->size = size; >> + for (i = HBITMAP_LEVELS; i-- > 0; ) { > > By now I've heard that this is a relatively wide-spread pattern; but I > still don't like it because I find it pretty hard to figure out that it > does what it's supposed to if you've never seen it before (and with "by > now I've heard" I mean that I read some blog post where someone > mentioned that he didn't like it). > > At least it's not "i --> 0", so I guess I should be fine with it. > > (and with "by now" I mean that I'm the one responsible for it not being > "-->" in hbitmap_merge()) > A copy-paste loop from hbitmap_alloc is why this pattern keeps emerging. It's not necessarily how I'd do it, either. >> + size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1); >> + if (hb->sizes[i] == size) { >> + continue; >> + } >> + hb->sizes[i] = size; >> + hb->levels[i] = g_realloc_n(hb->levels[i], size, >> sizeof(unsigned long)); > > How about initializing the new memory in case of truncate == false? I'm > not sure whether to initialize it to 0 or 1, though. Probably 0. > Good call; I had actually thought that g_realloc did initialize the memory, but looking at the docs again: nope. >> + } >> + assert(size == 1); >> + >> + /* Clear out any "extra space" we may have that the user didn't >> request: >> + * It may have garbage data in it, now. */ >> + if (truncate) { >> + /* Due to granularity fuzziness, we may accidentally reset >> some of >> + * the last bits that are actually valid. So, record the >> current value, >> + * reset the "dead range," then re-set the one sector we care >> about. */ >> + bool status = hbitmap_get(hb, num_elements - 1); >> + uint64_t fix_count = (hb->size << hb->granularity) - >> num_elements; >> + hbitmap_reset(hb, num_elements, fix_count); > > This can fail an assertion (or at least I believe it's this function, it > may be the hbitmap_set() below, too (but status should be false, so I > don't think that)): > > ./qemu-img create -f raw test.img 64M; echo > "{'execute':'qmp_capabilities'}{'execute':'block-dirty-bitmap-add','arguments':{'node':'drv','name':'foo'}}{'execute':'human-monitor-command','arguments':{'command-line':'block_resize > drv 32M'}}" | x86_64-softmmu/qemu-system-x86_64 -drive > if=none,id=drv,file=test.img,format=raw -qmp stdio -machine accel=qtest > -nodefaults -display none > Formatting 'test.img', fmt=raw size=67108864 > {"QMP": {"version": {"qemu": {"micro": 50, "minor": 2, "major": 2}, > "package": ""}, "capabilities": []}} > {"return": {}} > {"return": {}} > qemu-system-x86_64: util/hbitmap.c:149: hbitmap_iter_init: Assertion > `pos < hb->size' failed. > > It's probably because fix_count == 0 and therefore num_elements is not > an index into the bitmap (which hbitmap_reset() and subsequently > hb_count_between() don't take into account). > > Max > Ah, indeed. If you hit a perfect even multiple where there are no bits at all to clean, you wind up with a one-past-the-end, even though the operation should be a no-op. >> + if (status) { >> + hbitmap_set(hb, num_elements - 1, 1); >> + } >> + } >> +} >> + >> + >> /** >> * Given HBitmaps A and B, let A := A (BITOR) B. >> * Bitmap B will not be modified. >
diff --git a/block.c b/block.c index f3a6dd4..59a8ec9 100644 --- a/block.c +++ b/block.c @@ -3514,6 +3514,7 @@ int bdrv_truncate(BlockDriverState *bs, int64_t offset) ret = drv->bdrv_truncate(bs, offset); if (ret == 0) { ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS); + bdrv_dirty_bitmap_truncate(bs); if (bs->blk) { blk_dev_resize_cb(bs->blk); } @@ -5524,6 +5525,25 @@ BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs, return parent; } +static void dirty_bitmap_truncate(BdrvDirtyBitmap *bitmap, uint64_t size) +{ + assert(!bdrv_dirty_bitmap_frozen(bitmap)); + hbitmap_truncate(bitmap->bitmap, size); +} + +void bdrv_dirty_bitmap_truncate(BlockDriverState *bs) +{ + BdrvDirtyBitmap *bitmap; + uint64_t size = bdrv_nb_sectors(bs); + + QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) { + if (bdrv_dirty_bitmap_frozen(bitmap)) { + continue; + } + dirty_bitmap_truncate(bitmap, size); + } +} + void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap) { BdrvDirtyBitmap *bm, *next; diff --git a/include/block/block.h b/include/block/block.h index f6a50ae..aa6912d 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -442,6 +442,7 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs, uint32_t granularity, const char *name, Error **errp); +void bdrv_dirty_bitmap_truncate(BlockDriverState *bs); int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs, BdrvDirtyBitmap *bitmap, Error **errp); diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h index c19c1cb..a75157e 100644 --- a/include/qemu/hbitmap.h +++ b/include/qemu/hbitmap.h @@ -65,6 +65,16 @@ struct HBitmapIter { HBitmap *hbitmap_alloc(uint64_t size, int granularity); /** + * hbitmap_truncate: + * @hb: The bitmap to change the size of. + * @size: The number of elements to change the bitmap to accommodate. + * + * truncate or grow an existing bitmap to accommodate a new number of elements. + * This may invalidate existing HBitmapIterators. + */ +void hbitmap_truncate(HBitmap *hb, uint64_t size); + +/** * hbitmap_merge: * @a: The bitmap to store the result in. * @b: The bitmap to merge into @a. diff --git a/util/hbitmap.c b/util/hbitmap.c index 962ff29..d17b850 100644 --- a/util/hbitmap.c +++ b/util/hbitmap.c @@ -90,6 +90,9 @@ struct HBitmap { * bitmap will still allocate HBITMAP_LEVELS arrays. */ unsigned long *levels[HBITMAP_LEVELS]; + + /* The length of each levels[] array. */ + uint64_t sizes[HBITMAP_LEVELS]; }; /* Advance hbi to the next nonzero word and return it. hbi->pos @@ -384,6 +387,7 @@ HBitmap *hbitmap_alloc(uint64_t size, int granularity) hb->granularity = granularity; for (i = HBITMAP_LEVELS; i-- > 0; ) { size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1); + hb->sizes[i] = size; hb->levels[i] = g_new0(unsigned long, size); } @@ -396,6 +400,49 @@ HBitmap *hbitmap_alloc(uint64_t size, int granularity) return hb; } +void hbitmap_truncate(HBitmap *hb, uint64_t size) +{ + bool truncate; + unsigned i; + uint64_t num_elements = size; + + /* Size comes in as logical elements, adjust for granularity. */ + size = (size + (1ULL << hb->granularity) - 1) >> hb->granularity; + assert(size <= ((uint64_t)1 << HBITMAP_LOG_MAX_SIZE)); + truncate = size < hb->size; + + if (size == hb->size) { + /* A hard day's work */ + return; + } + + hb->size = size; + for (i = HBITMAP_LEVELS; i-- > 0; ) { + size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1); + if (hb->sizes[i] == size) { + continue; + } + hb->sizes[i] = size; + hb->levels[i] = g_realloc_n(hb->levels[i], size, sizeof(unsigned long)); + } + assert(size == 1); + + /* Clear out any "extra space" we may have that the user didn't request: + * It may have garbage data in it, now. */ + if (truncate) { + /* Due to granularity fuzziness, we may accidentally reset some of + * the last bits that are actually valid. So, record the current value, + * reset the "dead range," then re-set the one sector we care about. */ + bool status = hbitmap_get(hb, num_elements - 1); + uint64_t fix_count = (hb->size << hb->granularity) - num_elements; + hbitmap_reset(hb, num_elements, fix_count); + if (status) { + hbitmap_set(hb, num_elements - 1, 1); + } + } +} + + /** * Given HBitmaps A and B, let A := A (BITOR) B. * Bitmap B will not be modified.
Signed-off-by: John Snow <jsnow@redhat.com> --- block.c | 20 ++++++++++++++++++++ include/block/block.h | 1 + include/qemu/hbitmap.h | 10 ++++++++++ util/hbitmap.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 78 insertions(+)