SMP Lock struct file, filedesc and the global file list.

Seigo Tanimura (tanimura) posted the initial delta.

I've polished it quite a bit reducing the need for locking and
adapting it for KSE.

Locks:

1 mutex in each filedesc
   protects all the fields.
   protects "struct file" initialization, while a struct file
     is being changed from &badfileops -> &pipeops or something
     the filedesc should be locked.

1 mutex in each struct file
   protects the refcount fields.
   doesn't protect anything else.
   the flags used for garbage collection have been moved to
     f_gcflag which was the FILLER short, this doesn't need
     locking because the garbage collection is a single threaded
     container.
  could likely be made to use a pool mutex.

1 sx lock for the global filelist.

struct file *	fhold(struct file *fp);
        /* increments reference count on a file */

struct file *	fhold_locked(struct file *fp);
        /* like fhold but expects file to locked */

struct file *	ffind_hold(struct thread *, int fd);
        /* finds the struct file in thread, adds one reference and
                returns it unlocked */

struct file *	ffind_lock(struct thread *, int fd);
        /* ffind_hold, but returns file locked */

I still have to smp-safe the fget cruft, I'll get to that asap.

1 files changed, 4 insertions, 0 deletions

diff --git a/sys/kern/vfs_acl.c b/sys/kern/vfs_acl.c
index b50c896..63be63d 100644
--- a/sys/kern/vfs_acl.c
+++ b/sys/kern/vfs_acl.c
@@ -703,6 +703,7 @@ __acl_get_fd(struct thread *td, struct __acl_get_fd_args *uap)
 	if (error == 0) {
 		error = vacl_get_acl(td, (struct vnode *)fp->f_data,
 			    SCARG(uap, type), SCARG(uap, aclp));
+		fdrop(fp, td);
 	}
 	mtx_unlock(&Giant);
 	return (error);
@@ -724,6 +725,7 @@ __acl_set_fd(struct thread *td, struct __acl_set_fd_args *uap)
 	if (error == 0) {
 		error = vacl_set_acl(td, (struct vnode *)fp->f_data,
 			    SCARG(uap, type), SCARG(uap, aclp));
+		fdrop(fp, td);
 	}
 	mtx_unlock(&Giant);
 	return (error);
@@ -767,6 +769,7 @@ __acl_delete_fd(struct thread *td, struct __acl_delete_fd_args *uap)
 	if (error == 0) {
 		error = vacl_delete(td, (struct vnode *)fp->f_data, 
 			    SCARG(uap, type));
+		fdrop(fp, td);
 	}
 	mtx_unlock(&Giant);
 	return (error);
@@ -811,6 +814,7 @@ __acl_aclcheck_fd(struct thread *td, struct __acl_aclcheck_fd_args *uap)
 	if (error == 0) {
 		error = vacl_aclcheck(td, (struct vnode *)fp->f_data,
 			    SCARG(uap, type), SCARG(uap, aclp));
+		fdrop(fp, td);
 	}
 	mtx_unlock(&Giant);
 	return (error);