Files
seaweedFS/weed/mount/weedfs_forget.go
Chris Lu 9434d3733d mount: async flush on close() when writebackCache is enabled (#8727)
* mount: async flush on close() when writebackCache is enabled

When -writebackCache is enabled, defer data upload and metadata flush
from Flush() (triggered by close()) to a background goroutine in
Release(). This allows processes like rsync that write many small files
to proceed to the next file immediately instead of blocking on two
network round-trips (volume upload + filer metadata) per file.

Fixes #8718

* mount: add retry with backoff for async metadata flush

The metadata flush in completeAsyncFlush now retries up to 3 times
with exponential backoff (1s, 2s, 4s) on transient gRPC errors.
Since the chunk data is already safely on volume servers at this point,
only the filer metadata reference needs persisting — retrying is both
safe and effective.

Data flush (FlushData) is not retried externally because
UploadWithRetry already handles transient HTTP/gRPC errors internally;
if it still fails, the chunk memory has been freed.

* test: add integration tests for writebackCache async flush

Add comprehensive FUSE integration tests for the writebackCache
async flush feature (issue #8718):

- Basic operations: write/read, sequential files, large files, empty
  files, overwrites
- Fsync correctness: fsync forces synchronous flush even in writeback
  mode, immediate read-after-fsync
- Concurrent small files: multi-worker parallel writes (rsync-like
  workload), multi-directory, rapid create/close
- Data integrity: append after close, partial writes, file size
  correctness, binary data preservation
- Performance comparison: writeback vs synchronous flush throughput
- Stress test: 16 workers x 100 files with content verification
- Mixed concurrent operations: reads, writes, creates running together

Also fix pre-existing test infrastructure issues:
- Rename framework.go to framework_test.go (fixes Go package conflict)
- Fix undefined totalSize variable in concurrent_operations_test.go

* ci: update fuse-integration workflow to run full test suite

The workflow previously only ran placeholder tests (simple_test.go,
working_demo_test.go) in a temp directory due to a Go module conflict.
Now that framework.go is renamed to framework_test.go, the full test
suite compiles and runs correctly from test/fuse_integration/.

Changes:
- Run go test directly in test/fuse_integration/ (no temp dir copy)
- Install weed binary to /usr/local/bin for test framework discovery
- Configure /etc/fuse.conf with user_allow_other for FUSE mounts
- Install fuse3 for modern FUSE support
- Stream test output to log file for artifact upload

* mount: fix three P1 races in async flush

P1-1: Reopen overwrites data still flushing in background
ReleaseByHandle removes the old handle from fhMap before the deferred
flush finishes. A reopen of the same inode during that window would
build from stale filer metadata, overwriting the async flush.

Fix: Track in-flight async flushes per inode via pendingAsyncFlush map.
AcquireHandle now calls waitForPendingAsyncFlush(inode) to block until
any pending flush completes before reading filer metadata.

P1-2: Deferred flush races rename and unlink after close
completeAsyncFlush captured the path once at entry, but rename or
unlink after close() could cause metadata to be written under the
wrong name or recreate a deleted file.

Fix: Re-resolve path from inode via GetPath right before metadata
flush. GetPath returns the current path (reflecting renames) or
ENOENT (if unlinked), in which case we skip the metadata flush.

P1-3: SIGINT/SIGTERM bypasses the async-flush drain
grace.OnInterrupt runs hooks then calls os.Exit(0), so
WaitForAsyncFlush after server.Serve() never executes on signal.

Fix: Add WaitForAsyncFlush (with 10s timeout) to the WFS interrupt
handler, before cache cleanup. The timeout prevents hanging on Ctrl-C
when the filer is unreachable.

* mount: fix P1 races — draining handle stays in fhMap

P1-1: Reopen TOCTOU
The gap between ReleaseByHandle removing from fhMap and
submitAsyncFlush registering in pendingAsyncFlush allowed a
concurrent AcquireHandle to slip through with stale metadata.

Fix: Hold pendingAsyncFlushMu across both the counter decrement
(ReleaseByHandle) and the pending registration. The handle is
registered as pending before the lock is released, so
waitForPendingAsyncFlush always sees it.

P1-2: Rename/unlink can't find draining handle
ReleaseByHandle deleted from fhMap immediately. Rename's
FindFileHandle(inode) at line 251 could not find the handle to
update entry.Name. Unlink could not coordinate either.

Fix: When asyncFlushPending is true, ReleaseByHandle/ReleaseByInode
leave the handle in fhMap (counter=0 but maps intact). The handle
stays visible to FindFileHandle so rename can update entry.Name.
completeAsyncFlush re-resolves the path from the inode (GetPath)
right before metadata flush for correctness after rename/unlink.
After drain, RemoveFileHandle cleans up the maps.

Double-return prevention: ReleaseByHandle/ReleaseByInode return nil
if counter is already <= 0, so Forget after Release doesn't start a
second drain goroutine.

P1-3: SIGINT deletes swap files under running goroutines
After the 10s timeout, os.RemoveAll deleted the write cache dir
(containing swap files) while FlushData goroutines were still
reading from them.

Fix: Increase timeout to 30s. If timeout expires, skip write cache
dir removal so in-flight goroutines can finish reading swap files.
The OS (or next mount) cleans them up. Read cache is always removed.

* mount: never skip metadata flush when Forget drops inode mapping

Forget removes the inode→path mapping when the kernel's lookup count
reaches zero, but this does NOT mean the file was unlinked — it only
means the kernel evicted its cache entry.  completeAsyncFlush was
treating GetPath failure as "file unlinked" and skipping the metadata
flush, which orphaned the just-uploaded chunks for live files.

Fix: Save dir and name at doFlush defer time.  In completeAsyncFlush,
try GetPath first to pick up renames; if the mapping is gone, fall
back to the saved dir/name.  Always attempt the metadata flush — the
filer is the authority on whether the file exists, not the local
inode cache.

* mount: distinguish Forget from Unlink in async flush path fallback

The saved-path fallback (from the previous fix) always flushed
metadata when GetPath failed, which recreated files that were
explicitly unlinked after close().  The same stale fallback could
recreate the pre-rename path if Forget dropped the inode mapping
after a rename.

Root cause: GetPath failure has two meanings:
  1. Forget — kernel evicted the cache entry (file still exists)
  2. Unlink — file was explicitly deleted (should not recreate)

Fix (three coordinated changes):

Unlink (weedfs_file_mkrm.go): Before RemovePath, look up the inode
and find any draining handle via FindFileHandle.  Set fh.isDeleted =
true so the async flush knows the file was explicitly removed.

Rename (weedfs_rename.go): When renaming a file with a draining
handle, update asyncFlushDir/asyncFlushName to the post-rename
location.  This keeps the saved-path fallback current so Forget
after rename doesn't flush to the old (pre-rename) path.

completeAsyncFlush (weedfs_async_flush.go): Check fh.isDeleted
first — if true, skip metadata flush (file was unlinked, chunks
become orphans for volume.fsck).  Otherwise, try GetPath for the
current path (renames); fall back to saved path if Forget dropped
the mapping (file is live, just evicted from kernel cache).

* test/ci: address PR review nitpicks

concurrent_operations_test.go:
- Restore precise totalSize assertion instead of info.Size() > 0

writeback_cache_test.go:
- Check rand.Read errors in all 3 locations (lines 310, 512, 757)
- Check os.MkdirAll error in stress test (line 752)
- Remove dead verifyErrors variable (line 332)
- Replace both time.Sleep(5s) with polling via waitForFileContent
  to avoid flaky tests under CI load (lines 638, 700)

fuse-integration.yml:
- Add set -o pipefail so go test failures propagate through tee

* ci: fix fuse3/fuse package conflict on ubuntu-22.04 runner

fuse3 is pre-installed on ubuntu-22.04 runners and conflicts with
the legacy fuse package. Only install libfuse3-dev for the headers.

* mount/page_writer: remove debug println statements

Remove leftover debug println("read new data1/2") from
ReadDataAt in MemChunk and SwapFileChunk.

* test: fix findWeedBinary matching source directory instead of binary

findWeedBinary() matched ../../weed (the source directory) via
os.Stat before checking PATH, then tried to exec a directory
which fails with "permission denied" on the CI runner.

Fix: Check PATH first (reliable in CI where the binary is installed
to /usr/local/bin). For relative paths, verify the candidate is a
regular file (!info.IsDir()). Add ../../weed/weed as a candidate
for in-tree builds.

* test: fix framework — dynamic ports, output capture, data dirs

The integration test framework was failing in CI because:

1. All tests used hardcoded ports (19333/18080/18888), so sequential
   tests could conflict when prior processes hadn't fully released
   their ports yet.

2. Data subdirectories (data/master, data/volume) were not created
   before starting processes.

3. Master was started with -peers=none which is not a valid address.

4. Process stdout/stderr was not captured, making failures opaque
   ("service not ready within timeout" with no diagnostics).

5. The unmount fallback used 'umount' instead of 'fusermount -u'.

6. The mount used -cacheSizeMB (nonexistent) instead of
   -cacheCapacityMB and was missing -allowOthers=false for
   unprivileged CI runners.

Fixes:
- Dynamic port allocation via freePort() (net.Listen ":0")
- Explicit gRPC ports via -port.grpc to avoid default port conflicts
- Create data/master and data/volume directories in Setup()
- Remove invalid -peers=none and -raftBootstrap flags
- Capture process output to logDir/*.log via startProcess() helper
- dumpLog() prints tail of log file on service startup failure
- Use fusermount3/fusermount -u for unmount
- Fix mount flag names (-cacheCapacityMB, -allowOthers=false)

* test: remove explicit -port.grpc flags from test framework

SeaweedFS convention: gRPC port = HTTP port + 10000.  Volume and
filer discover the master gRPC port by this convention.  Setting
explicit -port.grpc on master/volume/filer broke inter-service
communication because the volume server computed master gRPC as
HTTP+10000 but the actual gRPC was on a different port.

Remove all -port.grpc flags and let the default convention work.
Dynamic HTTP ports already ensure uniqueness; the derived gRPC
ports (HTTP+10000) will also be unique.

---------

Co-authored-by: Copilot <copilot@github.com>
2026-03-22 15:24:08 -07:00

76 lines
2.5 KiB
Go

package mount
import (
"context"
"github.com/seaweedfs/seaweedfs/weed/util"
)
// Forget is called when the kernel discards entries from its
// dentry cache. This happens on unmount, and when the kernel
// is short on memory. Since it is not guaranteed to occur at
// any moment, and since there is no return value, Forget
// should not do I/O, as there is no channel to report back
// I/O errors.
// from https://github.com/libfuse/libfuse/blob/master/include/fuse_lowlevel.h
/**
* Forget about an inode
*
* This function is called when the kernel removes an inode
* from its internal caches.
*
* The inode's lookup count increases by one for every call to
* fuse_reply_entry and fuse_reply_create. The nlookup parameter
* indicates by how much the lookup count should be decreased.
*
* Inodes with a non-zero lookup count may receive request from
* the kernel even after calls to unlink, rmdir or (when
* overwriting an existing file) rename. Filesystems must handle
* such requests properly and it is recommended to defer removal
* of the inode until the lookup count reaches zero. Calls to
* unlink, rmdir or rename will be followed closely by forget
* unless the file or directory is open, in which case the
* kernel issues forget only after the release or releasedir
* calls.
*
* Note that if a file system will be exported over NFS the
* inodes lifetime must extend even beyond forget. See the
* generation field in struct fuse_entry_param above.
*
* On unmount the lookup count for all inodes implicitly drops
* to zero. It is not guaranteed that the file system will
* receive corresponding forget messages for the affected
* inodes.
*
* Valid replies:
* fuse_reply_none
*
* @param req request handle
* @param ino the inode number
* @param nlookup the number of lookups to forget
*/
/*
https://libfuse.github.io/doxygen/include_2fuse__lowlevel_8h.html
int fuse_reply_entry ( fuse_req_t req,
const struct fuse_entry_param * e
)
Reply with a directory entry
Possible requests: lookup, mknod, mkdir, symlink, link
Side effects: increments the lookup count on success
*/
func (wfs *WFS) Forget(nodeid, nlookup uint64) {
wfs.inodeToPath.Forget(nodeid, nlookup, func(dir util.FullPath) {
wfs.metaCache.DeleteFolderChildren(context.Background(), dir)
})
// ReleaseByInode returns nil if the handle is already draining (counter
// was already <= 0 from a prior Release). Only non-async handles that
// reach counter 0 here need cleanup.
if fhToRelease := wfs.fhMap.ReleaseByInode(nodeid); fhToRelease != nil {
fhToRelease.ReleaseHandle()
}
}