fastpath: Only allow IO to approved file types and file systems#238
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kurtmcmillan merged 28 commits intoApr 1, 2026
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Pull request overview
Updates the fastpath backend’s eligibility logic to only select fastpath I/O for regular files on ext4 (data=ordered) or xfs by default, with an environment-variable override to permit other filesystems.
Changes:
- Add
HIPFILE_UNSUPPORTED_FILESYSTEMSenvironment plumbing viaEnvironmentandConfiguration. - Update
Fastpath::score()to require a regular file and a supported filesystem (unless overridden). - Extend unit tests to cover the new configuration flag and fastpath filesystem/type gating behavior.
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| File | Description |
|---|---|
src/amd_detail/backend/fastpath.cpp |
Enforces regular-file + supported-filesystem constraints in fastpath scoring. |
src/amd_detail/environment.h |
Adds the new env var constant and accessor declaration. |
src/amd_detail/environment.cpp |
Implements Environment::unsupported_filesystems() via existing bool parser. |
src/amd_detail/configuration.h |
Adds Configuration::unsupportedFilesystems() API. |
src/amd_detail/configuration.cpp |
Reads/caches HIPFILE_UNSUPPORTED_FILESYSTEMS into configuration. |
test/amd_detail/mconfiguration.h |
Extends configuration mock with unsupportedFilesystems(). |
test/amd_detail/configuration.cpp |
Adds tests verifying env var parsing/default behavior for unsupported filesystems flag. |
test/amd_detail/fastpath.cpp |
Updates/extends fastpath tests for mount info + regular file checks and override behavior. |
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The necessary data from the statx struct is now cached in File.
The mount information the fastpath needs can now be obtained from File::onXfs() and File::onExt4Ordered().
At one time this was used to determine if O_DIRECT was set on File's file descriptor. File now holds buffered (~O_DIRECT) and unbuffered (O_DIRECT) file descriptors. Clients can use the file descriptor that best suits their purpose.
…::score expectations This will reduce the blast radius of the following changes.
This will be used by the to determine if IO to unsupported file systems should be permitted to use the fastpath backend.
… checks in Fastpath::score If HIPFILE_UNSUPPORTED_FILE_SYSTEMS=true, Fastpath::score will accept IO to regular files on any filesystem.
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Motivation
Currently, hipFile has only been tested with block devices and regular files on ext4(ordered) or xfs file systems. This change updates
Fastpath::score()to accept IO operations that target block devices or files backed by ext4(ordered) or xfs.Technical Details
When a file is registered, hipFile will cache file type and mount information.
Fastpath::score()will use the cached information to determine if it will accept an IO.If
HIPFILE_UNSUPPORTED_FILE_SYSTEMS=trueis set in the environment, thenFastpath::scorewill allow IO to regular files on unsupported filesystems.AIHIPFILE-114