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.

2 files changed, 10 insertions, 2 deletions

diff --git a/sys/fs/portalfs/portal_vfsops.c b/sys/fs/portalfs/portal_vfsops.c
index 4e73131..bc71fa5 100644
--- a/sys/fs/portalfs/portal_vfsops.c
+++ b/sys/fs/portalfs/portal_vfsops.c
@@ -132,7 +132,8 @@ portal_mount(mp, path, data, ndp, td)
 	VTOPORTAL(rvp)->pt_size = 0;
 	VTOPORTAL(rvp)->pt_fileid = PORTAL_ROOTFILEID;
 	fmp->pm_root = rvp;
-	fmp->pm_server = fp; fp->f_count++;
+	fhold(fp);
+	fmp->pm_server = fp;
 
 	mp->mnt_flag |= MNT_LOCAL;
 	mp->mnt_data = (qaddr_t) fmp;
@@ -159,6 +160,7 @@ portal_unmount(mp, mntflags, td)
 	struct thread *td;
 {
 	int error, flags = 0;
+	struct socket *so;
 
 
 	if (mntflags & MNT_FORCE)
diff --git a/sys/fs/portalfs/portal_vnops.c b/sys/fs/portalfs/portal_vnops.c
index dd90516..e8feeb1 100644
--- a/sys/fs/portalfs/portal_vnops.c
+++ b/sys/fs/portalfs/portal_vnops.c
@@ -402,12 +402,18 @@ portal_open(ap)
 	 * Check that the mode the file is being opened for is a subset
 	 * of the mode of the existing descriptor.
 	 */
- 	fp = td->td_proc->p_fd->fd_ofiles[fd];
+	fp = ffind_hold(td, fd);
+	if (fp == NULL) {
+		error = EBADF;
+		goto bad;
+	}
 	if (((ap->a_mode & (FREAD|FWRITE)) | fp->f_flag) != fp->f_flag) {
+		fdrop(fp, td);
 		portal_closefd(td, fd);
 		error = EACCES;
 		goto bad;
 	}
+	fdrop(fp, td);
 
 	/*
 	 * Save the dup fd in the proc structure then return the