littlefs: Fixed issue with cleanup in mount function on error #7851
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As a part of the v1.6 update, littlefs added proper handling for cleaning up memory in the case of an error during mount. This took care of a memory leak users were seeing. Ironically, it turns out the implementation and user patterns in mbed-os was _relying_ on this memory leak to avoid a double free in the same case of an error during mount. The issue was that a failed mount would leave the LittleFileSystem class in a state where it thought it was mounted, and later it would attempt to unmount the filesystem. With the previous memory leak this would be "ok", and the leaked memory would be freed. But with the fix in v1.6, no memory is leaked, and the incorrect free triggers a hard fault. Fixed to clean up state properly on failed mounts.
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Well that's a new one. |
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/morph build |
Build : SUCCESSBuild number : 2861 Triggering tests/morph test |
Exporter Build : SUCCESSBuild number : 2491 |
Test : SUCCESSBuild number : 2624 |
Exporter Build : FAILUREBuild number : 2504 |
| LFS_INFO("unmount -> %d", lfs_toerror(err)); | ||
| _mutex.unlock(); | ||
| return lfs_toerror(err); | ||
| if (err && !res) { |
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Just a nit: !res check is not really needed here Too late :-)
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Yeah, I just kept it for consistency. That way if any code is added between the declaration of res and this line, it won't break anything.
The compiler will optimize it out anyways.
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The compiler will optimize it out anyways.
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Description
As a part of the v1.6 update (#7713), littlefs added proper handling for cleaning up memory in the case of an error during mount (littlefs-project/littlefs#80). This took care of a memory leak users were seeing. Ironically, it turns out the implementation and user patterns in mbed-os was relying on this memory leak to avoid a double free in the same case of an error during mount.
The issue was that a failed mount would leave the LittleFileSystem class in a state where it thought it was mounted, and later it would attempt to unmount the filesystem. With the previous memory leak this would be "ok", and the leaked memory would be freed. But with the fix in v1.6, no memory is leaked, and the incorrect free triggers a hard fault.
Fixed to clean up state properly on failed mounts.
cc @juhoeskeli, @dannybenor, @deepikabhavnani, @ARMmbed/mbed-os-storage
Pull request type