Remove map from fd_map, change to fd_table.

This renames FDMap to FDTable and drops the kernel.FD type, which had an entire
package to itself and didn't serve much use (it was freely cast between types,
and served as more of an annoyance than providing any protection.)

Based on BenchmarkFDLookupAndDecRef-12, we can expect 5-10 ns per lookup
operation, and 10-15 ns per concurrent lookup operation of savings.

This also fixes two tangential usage issues with the FDMap. Namely, non-atomic
use of NewFDFrom and associated calls to Remove (that are both racy and fail to
drop the reference on the underlying file.)

PiperOrigin-RevId: 256285890

1 files changed, 12 insertions, 13 deletions

diff --git a/pkg/sentry/syscalls/linux/sys_splice.go b/pkg/sentry/syscalls/linux/sys_splice.go
index b6517313f..a7c98efcb 100644
--- a/pkg/sentry/syscalls/linux/sys_splice.go
+++ b/pkg/sentry/syscalls/linux/sys_splice.go
@@ -19,7 +19,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
-	"gvisor.dev/gvisor/pkg/sentry/kernel/kdefs"
 	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
@@ -81,8 +80,8 @@ func doSplice(t *kernel.Task, outFile, inFile *fs.File, opts fs.SpliceOpts, nonB
 
 // Sendfile implements linux system call sendfile(2).
 func Sendfile(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
-	outFD := kdefs.FD(args[0].Int())
-	inFD := kdefs.FD(args[1].Int())
+	outFD := args[0].Int()
+	inFD := args[1].Int()
 	offsetAddr := args[2].Pointer()
 	count := int64(args[3].SizeT())
 
@@ -92,13 +91,13 @@ func Sendfile(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
 	}
 
 	// Get files.
-	outFile := t.FDMap().GetFile(outFD)
+	outFile := t.GetFile(outFD)
 	if outFile == nil {
 		return 0, nil, syserror.EBADF
 	}
 	defer outFile.DecRef()
 
-	inFile := t.FDMap().GetFile(inFD)
+	inFile := t.GetFile(inFD)
 	if inFile == nil {
 		return 0, nil, syserror.EBADF
 	}
@@ -163,9 +162,9 @@ func Sendfile(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
 
 // Splice implements splice(2).
 func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
-	inFD := kdefs.FD(args[0].Int())
+	inFD := args[0].Int()
 	inOffset := args[1].Pointer()
-	outFD := kdefs.FD(args[2].Int())
+	outFD := args[2].Int()
 	outOffset := args[3].Pointer()
 	count := int64(args[4].SizeT())
 	flags := args[5].Int()
@@ -182,13 +181,13 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
 	nonBlocking := (flags & linux.SPLICE_F_NONBLOCK) != 0
 
 	// Get files.
-	outFile := t.FDMap().GetFile(outFD)
+	outFile := t.GetFile(outFD)
 	if outFile == nil {
 		return 0, nil, syserror.EBADF
 	}
 	defer outFile.DecRef()
 
-	inFile := t.FDMap().GetFile(inFD)
+	inFile := t.GetFile(inFD)
 	if inFile == nil {
 		return 0, nil, syserror.EBADF
 	}
@@ -251,8 +250,8 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
 
 // Tee imlements tee(2).
 func Tee(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
-	inFD := kdefs.FD(args[0].Int())
-	outFD := kdefs.FD(args[1].Int())
+	inFD := args[0].Int()
+	outFD := args[1].Int()
 	count := int64(args[2].SizeT())
 	flags := args[3].Int()
 
@@ -265,13 +264,13 @@ func Tee(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallCo
 	nonBlocking := (flags & linux.SPLICE_F_NONBLOCK) != 0
 
 	// Get files.
-	outFile := t.FDMap().GetFile(outFD)
+	outFile := t.GetFile(outFD)
 	if outFile == nil {
 		return 0, nil, syserror.EBADF
 	}
 	defer outFile.DecRef()
 
-	inFile := t.FDMap().GetFile(inFD)
+	inFile := t.GetFile(inFD)
 	if inFile == nil {
 		return 0, nil, syserror.EBADF
 	}