* mount: add -asyncDio flag for async direct I/O
This adds support for async direct I/O via the -asyncDio flag.
Async DIO enables the FUSE_CAP_ASYNC_DIO capability, allowing the kernel
to perform direct I/O operations asynchronously. This improves concurrency
for applications that use O_DIRECT flag.
Benefits:
- Better concurrency for direct I/O operations
- Improved performance for applications using O_DIRECT
- Reduced blocking on I/O operations
Use cases:
- Database workloads that use direct I/O
- Applications that bypass page cache intentionally
- High-performance I/O scenarios
Implementation inspired by JuiceFS which enables this capability
for improved I/O performance.
Usage:
weed mount -filer=localhost:8888 -dir=/mnt/seaweedfs -asyncDio
* mount: add all remaining FUSE options (asyncDio, cacheSymlink, novncache)
This combines the remaining three FUSE mount options on top of the merged writebackCache PR:
1. asyncDio: Enable async direct I/O for better concurrency
2. cacheSymlink: Enable symlink caching to reduce metadata lookups
3. novncache: (macOS only) Disable vnode name caching to avoid stale data
All options use the function parameter 'option' instead of global 'mountOptions'.
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