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-rw-r--r--internal/contentenc/offsets.go1
-rw-r--r--internal/fusefrontend/file.go48
-rw-r--r--internal/fusefrontend/file_holes.go4
-rw-r--r--tests/matrix/matrix_test.go27
4 files changed, 52 insertions, 28 deletions
diff --git a/internal/contentenc/offsets.go b/internal/contentenc/offsets.go
index da0551a..256ea26 100644
--- a/internal/contentenc/offsets.go
+++ b/internal/contentenc/offsets.go
@@ -66,6 +66,7 @@ func (be *ContentEnc) PlainSizeToCipherSize(plainSize uint64) uint64 {
}
// Split a plaintext byte range into (possibly partial) blocks
+// Returns an empty slice if length == 0.
func (be *ContentEnc) ExplodePlainRange(offset uint64, length uint64) []intraBlock {
var blocks []intraBlock
var nextBlock intraBlock
diff --git a/internal/fusefrontend/file.go b/internal/fusefrontend/file.go
index 513dbbf..8f13553 100644
--- a/internal/fusefrontend/file.go
+++ b/internal/fusefrontend/file.go
@@ -217,6 +217,8 @@ const FALLOC_FL_KEEP_SIZE = 0x01
//
// Called by Write() for normal writing,
// and by Truncate() to rewrite the last file block.
+//
+// Empty writes do nothing and are allowed.
func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
// Read header from disk, create a new one if the file is empty
@@ -282,6 +284,8 @@ func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
}
// Write - FUSE call
+//
+// If the write creates a hole, pads the file to the next block boundary.
func (f *file) Write(data []byte, off int64) (uint32, fuse.Status) {
f.fdLock.RLock()
defer f.fdLock.RUnlock()
@@ -362,7 +366,6 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
wlock.lock(f.ino)
defer wlock.unlock(f.ino)
var err error
-
// Common case first: Truncate to zero
if newSize == 0 {
err = syscall.Ftruncate(int(f.fd.Fd()), 0)
@@ -374,7 +377,6 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
f.header = nil
return fuse.OK
}
-
// We need the old file size to determine if we are growing or shrinking
// the file
fi, err := f.fd.Stat()
@@ -388,12 +390,10 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
newB := float32(newSize) / float32(f.contentEnc.PlainBS())
tlog.Debug.Printf("ino%d: FUSE Truncate from %.2f to %.2f blocks (%d to %d bytes)", f.ino, oldB, newB, oldSize, newSize)
}
-
// File size stays the same - nothing to do
if newSize == oldSize {
return fuse.OK
}
-
// File grows
if newSize > oldSize {
// File was empty, create new header
@@ -405,30 +405,22 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
}
// New blocks to add
addBlocks := f.contentEnc.ExplodePlainRange(oldSize, newSize-oldSize)
- for _, b := range addBlocks {
- // First and last block may be partial and must be actually written
- if b.IsPartial() {
- off, _ := b.PlaintextRange()
- off += b.Skip
- _, status := f.doWrite(make([]byte, b.Length), int64(off))
- if status != fuse.OK {
- return status
- }
- } else {
- // Complete all-zero blocks can stay all-zero because we do file
- // hole passthrough.
- // TODO We are growing the file block-by-block which is pretty
- // inefficient. We could coalesce all the grows into a single
- // Ftruncate.
- off, length := b.CiphertextRange()
- err = syscall.Ftruncate(int(f.fd.Fd()), int64(off+length))
- if err != nil {
- tlog.Warn.Printf("grow Ftruncate returned error: %v", err)
- return fuse.ToStatus(err)
- }
+ if len(addBlocks) >= 2 {
+ f.zeroPad(oldSize)
+ }
+ lastBlock := addBlocks[len(addBlocks)-1]
+ if lastBlock.IsPartial() {
+ off, _ := lastBlock.PlaintextRange()
+ _, status := f.doWrite(make([]byte, lastBlock.Length), int64(off+lastBlock.Skip))
+ return status
+ } else {
+ off, length := lastBlock.CiphertextRange()
+ err = syscall.Ftruncate(f.intFd(), int64(off+length))
+ if err != nil {
+ tlog.Warn.Printf("Truncate: grow Ftruncate returned error: %v", err)
}
+ return fuse.ToStatus(err)
}
- return fuse.OK
} else {
// File shrinks
blockNo := f.contentEnc.PlainOffToBlockNo(newSize)
@@ -440,14 +432,14 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
var status fuse.Status
data, status = f.doRead(plainOff, lastBlockLen)
if status != fuse.OK {
- tlog.Warn.Printf("shrink doRead returned error: %v", err)
+ tlog.Warn.Printf("Truncate: shrink doRead returned error: %v", err)
return status
}
}
// Truncate down to the last complete block
err = syscall.Ftruncate(int(f.fd.Fd()), int64(cipherOff))
if err != nil {
- tlog.Warn.Printf("shrink Ftruncate returned error: %v", err)
+ tlog.Warn.Printf("Truncate: shrink Ftruncate returned error: %v", err)
return fuse.ToStatus(err)
}
// Append partial block
diff --git a/internal/fusefrontend/file_holes.go b/internal/fusefrontend/file_holes.go
index 46a5865..1d9a5fb 100644
--- a/internal/fusefrontend/file_holes.go
+++ b/internal/fusefrontend/file_holes.go
@@ -22,6 +22,10 @@ func (f *file) createsHole(plainSize uint64, off int64) bool {
func (f *file) zeroPad(plainSize uint64) fuse.Status {
lastBlockLen := plainSize % f.contentEnc.PlainBS()
missing := f.contentEnc.PlainBS() - lastBlockLen
+ if missing == 0 {
+ // Already block-aligned
+ return fuse.OK
+ }
pad := make([]byte, missing)
tlog.Debug.Printf("zeroPad: Writing %d bytes\n", missing)
_, status := f.doWrite(pad, int64(plainSize))
diff --git a/tests/matrix/matrix_test.go b/tests/matrix/matrix_test.go
index eb49d59..d59a677 100644
--- a/tests/matrix/matrix_test.go
+++ b/tests/matrix/matrix_test.go
@@ -113,6 +113,8 @@ func TestWrite100x100(t *testing.T) {
}
}
+// Hint for calculating reference md5sums:
+// dd if=/dev/zero count=1 bs=XYZ | md5sum
func TestTruncate(t *testing.T) {
fn := test_helpers.DefaultPlainDir + "/truncate"
file, err := os.Create(fn)
@@ -143,6 +145,31 @@ func TestTruncate(t *testing.T) {
if test_helpers.Md5fn(fn) != "620f0b67a91f7f74151bc5be745b7110" {
t.Errorf("wrong content")
}
+ // Truncate to zero
+ file.Truncate(0)
+ test_helpers.VerifySize(t, fn, 0)
+ // Grow to 10MB (creates file holes)
+ var sz int
+ sz = 10 * 1024 * 1024
+ file.Truncate(int64(sz))
+ test_helpers.VerifySize(t, fn, sz)
+ if test_helpers.Md5fn(fn) != "f1c9645dbc14efddc7d8a322685f26eb" {
+ t.Errorf("wrong content")
+ }
+ // Grow to 10MB + 100B (partial block on the end)
+ sz = 10*1024*1024 + 100
+ file.Truncate(int64(sz))
+ test_helpers.VerifySize(t, fn, sz)
+ if test_helpers.Md5fn(fn) != "c23ea79b857b91a7ff07c6ecf185f1ca" {
+ t.Errorf("wrong content")
+ }
+ // Grow to 20MB (creates file holes, partial block on the front)
+ sz = 20 * 1024 * 1024
+ file.Truncate(int64(sz))
+ test_helpers.VerifySize(t, fn, sz)
+ if test_helpers.Md5fn(fn) != "8f4e33f3dc3e414ff94e5fb6905cba8c" {
+ t.Errorf("wrong content")
+ }
}
func TestAppend(t *testing.T) {
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-27 06:54:16 +0000