Cache mounts on the host

[msau42]

Is this a BUG REPORT or FEATURE REQUEST?:
/kind feature
/sig storage

What happened:
In #48402 a new mount check was added to handle the case of bind mounts on directories (and not actual mount points). The new check has to iterate through all the mounts on the system, which could be time-consuming if there are many mounts. It may be worth looking into caching the mounts to optimize this check.

[msau42]

cc @kubernetes/sig-storage-feature-requests

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[msau42]

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More areas of the code are using the fully iterative mount check, so this will become more important as we start to scale the number of mounts allowed on a single system.

[cofyc]

hi, @msau42 I'm going to work on this.

[msau42]

/assign @cofyc

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[krmayankk]

@msau42 @cofyc in my thinking , its premature to do caching until we have some numbers to say its hurting. What is the number of mount points typically beyond which this starts hurting