QUERY · ISSUE

stmhal: os.sync() [apparently] doesn't flush FatFS read buffers

openby pfalconopened 2015-11-05updated 2015-11-21

ports

My time to ask dumb questions. I created a new file on pyboard's internal flash over USB mass-storage . Expectedly, it didn't show up. I issued sync on Linux side, it didn't show up. I unmounted filesystem, and it still didn't show up. I issues os.sync() on pyboard, and it still didn't show up. I had to reboot pyboard to get hold of it. I'd say, unmounting mass-storage and os.sync() should be 100% enough.

CANDIDATE · PULL REQUEST

stmhal: Add os.invalidate which unmounts and remounts a filesystem.

closedby dhylandsopened 2015-11-06updated 2015-11-08

(no description)

Assessment

S Sonnet · medium

PR #1589 is a direct response to issue #1587. The issue reports that files written via USB mass storage don't appear in FatFS until reboot because os.sync() doesn't invalidate FatFS read buffers. The PR adds os.invalidate() which performs an unmount/remount to clear those buffers — exactly the operation described as needed in the issue. However, the PR does not fix os.sync() itself (the stated root cause), it adds a workaround function instead. If merged, os.invalidate() would resolve the practical workflow problem (avoid rebooting) but the underlying os.sync() deficiency remains unfixed. The PR status is not confirmed merged from the available data.

Suggested action

If PR #1589 was merged, close issue #1587 as resolved by that PR — os.invalidate() provides the needed cache-clearing capability. If the PR was not merged or was superseded, keep the issue open and link it to the PR for context. Note that the root cause (os.sync() not invalidating read buffers) is not addressed by the PR, so a follow-up fix to os.sync() may still be warranted.

stmhal: os.sync() [apparently] doesn't flush FatFS read buffers

stmhal: Add os.invalidate which unmounts and remounts a filesystem.

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