| Message ID | 20170727154723.2208-4-jeffm@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2017年07月27日 23:47, jeffm@suse.com wrote: > From: Jeff Mahoney <jeffm@suse.com> > > When we are looking for extents in migrate_one_reserved_range, it's likely > that there will be multiple extents that fall into the 0-1MB range. > > If lookup_cache_extent is called with a range that covers multiple cache > entries, it will return the first entry it encounters while searching > from the top of the tree that happens to fall in that range. That > means that we can end up skipping regions within that range, resulting > in a file system image that can't be rolled back since it wasn't > all migrated properly. Thanks for catching this one. > > This is reproducible using convert-tests/008-readonly-image. There was > a range from 0-160kB, but the only entry that was returned began at > ~ 280kB. > > The fix is to use search_cache_extent to iterate through multiple regions > within that range > > Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: Qu Wenruo <quwenruo.btrfs@gmx.com> Thanks, Qu > --- > convert/main.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/convert/main.c b/convert/main.c > index 01657a6..24ed1de 100644 > --- a/convert/main.c > +++ b/convert/main.c > @@ -340,10 +340,12 @@ static int migrate_one_reserved_range(struct btrfs_trans_handle *trans, > * migrate ranges that covered by old fs data. > */ > while (cur_off < range_end(range)) { > - cache = lookup_cache_extent(used, cur_off, cur_len); > + cache = search_cache_extent(used, cur_off); > if (!cache) > break; > cur_off = max(cache->start, cur_off); > + if (cur_off >= range_end(range)) > + break; > cur_len = min(cache->start + cache->size, range_end(range)) - > cur_off; > BUG_ON(cur_len < root->sectorsize); > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/convert/main.c b/convert/main.c index 01657a6..24ed1de 100644 --- a/convert/main.c +++ b/convert/main.c @@ -340,10 +340,12 @@ static int migrate_one_reserved_range(struct btrfs_trans_handle *trans, * migrate ranges that covered by old fs data. */ while (cur_off < range_end(range)) { - cache = lookup_cache_extent(used, cur_off, cur_len); + cache = search_cache_extent(used, cur_off); if (!cache) break; cur_off = max(cache->start, cur_off); + if (cur_off >= range_end(range)) + break; cur_len = min(cache->start + cache->size, range_end(range)) - cur_off; BUG_ON(cur_len < root->sectorsize);