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Call fdnotifier.UpdateFD() from fsimpl/gofer.specialFileFD.

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The fdnotifier package provides an API to a thread that continually epolls
arbitrary host FDs. The set of events polled for each host FD is (intended to
be) all events for which a waiter.Entry has expressed interest, as returned by
waiter.Queue.Events() for the waiter.Queue registered to the given host FD.
When the set of events changes (due to a change in the set of registered
waiter.Entries), the mutator must call fdnotifier.UpdateFD() to recalculate the
new event set and propagate it to the epoll FD.

PiperOrigin-RevId: 319924719
This commit is contained in:
Jamie Liu
2020-07-06 22:55:48 -07:00
committed by gVisor bot
parent 937912a484
commit e227450dc1
1 changed files with 16 additions and 14 deletions
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pkg/sentry/fsimpl/gofer/special_file.go
+16 -14
View File
@@ -41,10 +41,10 @@ type specialFileFD struct {
// file offset is significant, i.e. a regular file. seekable is immutable.
seekable bool
// mayBlock is true if this file description represents a file for which
// queue may send I/O readiness events. mayBlock is immutable.
mayBlock bool
queue waiter.Queue
// haveQueue is true if this file description represents a file for which
// queue may send I/O readiness events. haveQueue is immutable.
haveQueue bool
queue waiter.Queue
// If seekable is true, off is the file offset. off is protected by mu.
mu sync.Mutex
@@ -54,14 +54,14 @@ type specialFileFD struct {
func newSpecialFileFD(h handle, mnt *vfs.Mount, d *dentry, locks *vfs.FileLocks, flags uint32) (*specialFileFD, error) {
ftype := d.fileType()
seekable := ftype == linux.S_IFREG
mayBlock := ftype == linux.S_IFIFO || ftype == linux.S_IFSOCK
haveQueue := (ftype == linux.S_IFIFO || ftype == linux.S_IFSOCK) && h.fd >= 0
fd := &specialFileFD{
handle: h,
seekable: seekable,
mayBlock: mayBlock,
handle: h,
seekable: seekable,
haveQueue: haveQueue,
}
fd.LockFD.Init(locks)
if mayBlock && h.fd >= 0 {
if haveQueue {
if err := fdnotifier.AddFD(h.fd, &fd.queue); err != nil {
return nil, err
}
@@ -70,7 +70,7 @@ func newSpecialFileFD(h handle, mnt *vfs.Mount, d *dentry, locks *vfs.FileLocks,
DenyPRead: !seekable,
DenyPWrite: !seekable,
}); err != nil {
if mayBlock && h.fd >= 0 {
if haveQueue {
fdnotifier.RemoveFD(h.fd)
}
return nil, err
@@ -80,7 +80,7 @@ func newSpecialFileFD(h handle, mnt *vfs.Mount, d *dentry, locks *vfs.FileLocks,
// Release implements vfs.FileDescriptionImpl.Release.
func (fd *specialFileFD) Release() {
if fd.mayBlock && fd.handle.fd >= 0 {
if fd.haveQueue {
fdnotifier.RemoveFD(fd.handle.fd)
}
fd.handle.close(context.Background())
@@ -100,7 +100,7 @@ func (fd *specialFileFD) OnClose(ctx context.Context) error {
// Readiness implements waiter.Waitable.Readiness.
func (fd *specialFileFD) Readiness(mask waiter.EventMask) waiter.EventMask {
if fd.mayBlock {
if fd.haveQueue {
return fdnotifier.NonBlockingPoll(fd.handle.fd, mask)
}
return fd.fileDescription.Readiness(mask)
@@ -108,8 +108,9 @@ func (fd *specialFileFD) Readiness(mask waiter.EventMask) waiter.EventMask {
// EventRegister implements waiter.Waitable.EventRegister.
func (fd *specialFileFD) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
if fd.mayBlock {
if fd.haveQueue {
fd.queue.EventRegister(e, mask)
fdnotifier.UpdateFD(fd.handle.fd)
return
}
fd.fileDescription.EventRegister(e, mask)
@@ -117,8 +118,9 @@ func (fd *specialFileFD) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
// EventUnregister implements waiter.Waitable.EventUnregister.
func (fd *specialFileFD) EventUnregister(e *waiter.Entry) {
if fd.mayBlock {
if fd.haveQueue {
fd.queue.EventUnregister(e)
fdnotifier.UpdateFD(fd.handle.fd)
return
}
fd.fileDescription.EventUnregister(e)