Implement fallocate(2)

Closes #225

PiperOrigin-RevId: 247508791
Change-Id: I04f47cf2770b30043e5a272aba4ba6e11d0476cc

1 files changed, 9 insertions, 1 deletions

diff --git a/pkg/sentry/fs/fsutil/host_mappable.go b/pkg/sentry/fs/fsutil/host_mappable.go
index 28686f3b3..ad0518b8f 100644
--- a/pkg/sentry/fs/fsutil/host_mappable.go
+++ b/pkg/sentry/fs/fsutil/host_mappable.go
@@ -149,7 +149,7 @@ func (h *HostMappable) Truncate(ctx context.Context, newSize int64) error {
 	}
 
 	// Invalidate COW mappings that may exist beyond the new size in case the file
-	// is being shrunk. Other mappinsg don't need to be invalidated because
+	// is being shrunk. Other mappings don't need to be invalidated because
 	// translate will just return identical mappings after invalidation anyway,
 	// and SIGBUS will be raised and handled when the mappings are touched.
 	//
@@ -167,6 +167,14 @@ func (h *HostMappable) Truncate(ctx context.Context, newSize int64) error {
 	return nil
 }
 
+// Allocate reserves space in the backing file.
+func (h *HostMappable) Allocate(ctx context.Context, offset int64, length int64) error {
+	h.truncateMu.RLock()
+	err := h.backingFile.Allocate(ctx, offset, length)
+	h.truncateMu.RUnlock()
+	return err
+}
+
 // Write writes to the file backing this mappable.
 func (h *HostMappable) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) {
 	h.truncateMu.RLock()