From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37419) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dwVEC-00040d-NZ for qemu-devel@nongnu.org; Mon, 25 Sep 2017 11:23:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dwVE9-0006zu-Es for qemu-devel@nongnu.org; Mon, 25 Sep 2017 11:23:24 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:24585 helo=relay.sw.ru) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dwVE9-0006zB-29 for qemu-devel@nongnu.org; Mon, 25 Sep 2017 11:23:21 -0400 References: <20170925145526.32690-1-eblake@redhat.com> <20170925145526.32690-6-eblake@redhat.com> From: Vladimir Sementsov-Ogievskiy Message-ID: Date: Mon, 25 Sep 2017 18:23:14 +0300 MIME-Version: 1.0 In-Reply-To: <20170925145526.32690-6-eblake@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Subject: Re: [Qemu-devel] [PATCH v10 05/20] dirty-bitmap: Avoid size query failure during truncate List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake , qemu-devel@nongnu.org Cc: kwolf@redhat.com, jsnow@redhat.com, famz@redhat.com, qemu-block@nongnu.org, Max Reitz 25.09.2017 17:55, Eric Blake wrote: > We've previously fixed several places where we failed to account > for possible errors from bdrv_nb_sectors(). Fix another one by > making bdrv_dirty_bitmap_truncate() take the new size from the > caller instead of querying itself; then adjust the sole caller > bdrv_truncate() to pass the size just determined by a successful > resize, or to skip the bitmap resize on failure, thus avoiding nothing is skipped in this version > sizing the bitmaps to -1. This also fixes a bug where not all > failure paths in bdrv_truncate() would set errp. > > Note that bdrv_truncate() is still a bit awkward. We may want > to revisit it later and clean up things to better guarantee that > a resize attempt either fails cleanly up front, or cannot fail > after guest-visible changes have been made (if temporary changes > are made, then they need to be cleanly rolled back). But that > is a task for another day; for now, the goal is the bare minimum > fix to ensure that just bdrv_dirty_bitmap_truncate() cannot fail. > > Signed-off-by: Eric Blake Reviewed-by: Vladimir Sementsov-Ogievskiy > > --- > v10: always resize bitmap as before [John], enhance commit message to > point out errp bugfix [Vladimir] > v9: skip only bdrv_dirty_bitmap_truncate on error [Fam] > v8: retitle and rework to avoid possibility of secondary failure [John] > v7: new patch [Kevin] > --- > include/block/dirty-bitmap.h | 2 +- > block.c | 16 +++++++++++----- > block/dirty-bitmap.c | 6 +++--- > 3 files changed, 15 insertions(+), 9 deletions(-) > > diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h > index 8fd842eac9..7a27590047 100644 > --- a/include/block/dirty-bitmap.h > +++ b/include/block/dirty-bitmap.h > @@ -83,7 +83,7 @@ int64_t bdrv_dirty_iter_next(BdrvDirtyBitmapIter *iter); > void bdrv_set_dirty_iter(BdrvDirtyBitmapIter *hbi, int64_t sector_num); > int64_t bdrv_get_dirty_count(BdrvDirtyBitmap *bitmap); > int64_t bdrv_get_meta_dirty_count(BdrvDirtyBitmap *bitmap); > -void bdrv_dirty_bitmap_truncate(BlockDriverState *bs); > +void bdrv_dirty_bitmap_truncate(BlockDriverState *bs, int64_t bytes); > bool bdrv_dirty_bitmap_readonly(const BdrvDirtyBitmap *bitmap); > bool bdrv_has_readonly_bitmaps(BlockDriverState *bs); > bool bdrv_dirty_bitmap_get_autoload(const BdrvDirtyBitmap *bitmap); > diff --git a/block.c b/block.c > index 528cda7b2c..ef5af81f66 100644 > --- a/block.c > +++ b/block.c > @@ -3545,12 +3545,18 @@ int bdrv_truncate(BdrvChild *child, int64_t offset, PreallocMode prealloc, > assert(!(bs->open_flags & BDRV_O_INACTIVE)); > > ret = drv->bdrv_truncate(bs, offset, prealloc, errp); > - if (ret == 0) { > - ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS); > - bdrv_dirty_bitmap_truncate(bs); > - bdrv_parent_cb_resize(bs); > - atomic_inc(&bs->write_gen); > + if (ret < 0) { > + return ret; > } > + ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS); > + if (ret < 0) { > + error_setg_errno(errp, -ret, "Could not refresh total sector count"); > + } else { > + offset = bs->total_sectors * BDRV_SECTOR_SIZE; > + } > + bdrv_dirty_bitmap_truncate(bs, offset); > + bdrv_parent_cb_resize(bs); > + atomic_inc(&bs->write_gen); > return ret; > } > > diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c > index 42a55e4a4b..ee164fb518 100644 > --- a/block/dirty-bitmap.c > +++ b/block/dirty-bitmap.c > @@ -1,7 +1,7 @@ > /* > * Block Dirty Bitmap > * > - * Copyright (c) 2016 Red Hat. Inc > + * Copyright (c) 2016-2017 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 > @@ -302,10 +302,10 @@ BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs, > * Truncates _all_ bitmaps attached to a BDS. > * Called with BQL taken. > */ > -void bdrv_dirty_bitmap_truncate(BlockDriverState *bs) > +void bdrv_dirty_bitmap_truncate(BlockDriverState *bs, int64_t bytes) > { > BdrvDirtyBitmap *bitmap; > - uint64_t size = bdrv_nb_sectors(bs); > + int64_t size = DIV_ROUND_UP(bytes, BDRV_SECTOR_SIZE); > > bdrv_dirty_bitmaps_lock(bs); > QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) { -- Best regards, Vladimir