[Do not review] Sync/flush changes for buffered writes

[ashmeenkaur]

Description

This PR includes changes to

• integrate buffered write handler with sync/flush file flow.
• Fall back to temp file flow in case of out of order writes.
• Finalize the object in case of error during write.

Some refactoring is done to reuse the code.

Note: Flush empty file changes required precondition to be propagated to gcs request and will be taken up in the follow up PR. Unit tests are not added for it.

Link to the issue in case of a bug fix.

NA

Testing details

1. Manual - NA
2. Unit tests - Added
3. Integration tests - NA

[codecov]

Codecov Report

Attention: Patch coverage is 93.61702% with 3 lines in your changes missing coverage. Please review.

Project coverage is 76.62%. Comparing base (2838d80) to head (4a9d15c).

Files with missing lines	Patch %	Lines
internal/fs/inode/file.go	93.61%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2778      +/-   ##
==========================================
+ Coverage   76.51%   76.62%   +0.10%     
==========================================
  Files         116      116              
  Lines       16065    16106      +41     
==========================================
+ Hits        12292    12341      +49     
+ Misses       3257     3251       -6     
+ Partials      516      514       -2     

Flag	Coverage Δ
unittests	76.62% <93.61%> (+0.10%)	⬆️

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[vadlakondaswetha]

we shouldn't flush on sync call.
from LLD:

Sync() can be called multiple times during the lifetime of the file write. Once the resumable upload is finalized we will not be able to append anymore data to it. But the intention of sync() call from the application side, is to persist all the data to the backend device. So we will block the syncFile() call and upload all pending buffers to GCS and free up the free buffers. We will not finalize the upload.

[bhawesh-khandelwal]

Hey, I wanted to follow this. Is it possible to get access to the LLD?