vfs: cancel ongoing readahead requests after file is closed

[jiefenghuang]

close #132

[codecov]

Codecov Report

❌ Patch coverage is 58.53659% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 45.68%. Comparing base (bd39d9c) to head (d6cbb91).

Files with missing lines	Patch %	Lines
pkg/chunk/cached_store.go	50.00%	6 Missing and 3 partials ⚠️
cmd/debug.go	25.00%	3 Missing ⚠️
pkg/utils/utils.go	40.00%	3 Missing ⚠️
cmd/mount_unix.go	66.66%	1 Missing ⚠️
pkg/chunk/prefetch.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #6397       +/-   ##
===========================================
+ Coverage   22.30%   45.68%   +23.37%     
===========================================
  Files          30      166      +136     
  Lines       20432    50618    +30186     
===========================================
+ Hits         4558    23124    +18566     
- Misses      15363    24740     +9377     
- Partials      511     2754     +2243     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.