millions of hex 80 0_0000 omap keys in single index shard for single bucket

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I am using ceph 17.2.6 on Rocky 8.
I have a system that started giving me large omap object warnings.

I tracked this down to a specific index shard for a single s3 bucket.

rados -p <indexpool> listomapkeys .dir.<zoneid>.bucketid.nn.shardid
shows over 3 million keys for that shard. There are only about 2
million objects in the entire bucket according to a listing of the bucket
and radosgw-admin bucket stats --bucket bucketname. No other shard
has anywhere near this many index objects. Perhaps it should be noted that this
shard is the highest numbered shard for this bucket. For a bucket with
16 shards, this is shard 15.

If I look at the list of omapkeys generated, there are *many*
beginning with "<80>0_0000", almost the entire set of the three + million
keys in the shard. These are index objects in the so-called 'ugly' namespace. The rest ofthey omapkeys appear to be normal.

The 0_0000 after the <80> indicates some sort of 'bucket log index' according to src/cls/rgw/ 
However, using some sed magic previously discussed here, I ran:

rados -p <indexpool> getomapval .dir.<zoneid>.bucketid.nn.shardid --omap-key-file /tmp/key.txt

Where /tmp/key.txt contains only the funny <80>0_0000 key name without a newline

The output of this shows, in a hex dump, the object name to which the index
refers, which was at one time a valid object.

However, that object no longer exists in the bucket, and based on expiration policy, was
previously deleted. Let's say, in the hex dump, that the object was:


The prefix foo/bar/baz/ used to have 32 objects, say foo/bar/baz/{object1.bin, object2.bin, ... }
An s3api listing shows that those objects no longer exist (and that is OK, as they  were previously deleted).
BUT, now, there is a weirdo object left in the bucket:

foo/bar/baz/ <- with the slash at the end, and it is an object not a PRE (fix).

All objects under foo/ have a 3 day lifecycle expiration. If I wait(at most) 3 days, the weirdo object with '/'
at the end will be deleted, or I can delete it manually using aws s3api. But either way, the log index
objects, <80>0_0000.... remain.

The bucket in question is heavily used. But with over 3 million of these <80>0_0000 objects (and growing)
in a single shard, I am currently at a loss as to what to do or how to stop this from occuring.
I've poked around at a few other buckets, and I found a few others that have this problem, but not enoughto cause a large omap warning. (A few hundred <80>0_000.... index objects in a shard), no where near enoughto cause the large omap warning that led me to this post.

Any ideas?

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