os/bluestore: fix writes that span existing shard boundaries #11451
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Signed-off-by: Sage Weil <sage@redhat.com>
ifed01
reviewed
Oct 13, 2016
| @@ -1675,6 +1676,7 @@ void BlueStore::ExtentMap::reshard(Onode *o, uint64_t min_alloc_size) | |||
| } | |||
| } | |||
| } | |||
| needs_reshard = false; | |||
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Put that at function entrance to cover returns from the mid of the func?
ifed01
reviewed
Oct 13, 2016
| if (shards.empty()) { | ||
| return false; | ||
| } | ||
| size_t s = seek_shard(offset); |
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handling for not found shard? Or assert(s>=0) if this is unexpected.
ifed01
reviewed
Oct 13, 2016
| @@ -2088,6 +2090,9 @@ BlueStore::Extent *BlueStore::ExtentMap::set_lextent( | |||
| b->ref_map.get(offset, length); | |||
| Extent *le = new Extent(logical_offset, offset, length, blob_depth, b); | |||
| extent_map.insert(*le); | |||
| if (spans_shard(offset, length)) { | |||
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replace with if( !needs_reshard && spans_shard....)?
|
LGTM except mentioned nits |
A new write may create a new lextent that spans an existing shard boundary. If that happens, set a flag so that we force a reshard when the onode is written. Signed-off-by: Sage Weil <sage@redhat.com>
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For now I take the simple strategy and force a reshard if we happen to write across a boundary. I susepct the optimal solution is a bit more nuanced. For example, big writes could be split, but small writes probably shouldn't be. Or, better yet, this sort of write could just move the shard boundary over, or otherwise trigger a partial reshard. I'm happy leaving that for future work, though!