- Expand the scope of Giant some in mount(2) to protect the vfsp structure

  from going away.  mount(2) is now MPSAFE.
- Expand the scope of Giant some in unmount(2) to protect the mp structure
  (or rather, to handle concurrent unmount races) from going away.
  umount(2) is now MPSAFE, as well as linux_umount() and linux_oldumount().
- nmount(2) and linux_mount() were already MPSAFE.

5 files changed, 35 insertions, 24 deletions

diff --git a/sys/amd64/linux32/syscalls.master b/sys/amd64/linux32/syscalls.master
index a29068a..9af73d9 100644
--- a/sys/amd64/linux32/syscalls.master
+++ b/sys/amd64/linux32/syscalls.master
@@ -75,10 +75,10 @@
 19	AUE_LSEEK	MSTD	{ int linux_lseek(l_uint fdes, l_off_t off, \
 				    l_int whence); }
 20	AUE_GETPID	MSTD	{ int linux_getpid(void); }
-21	AUE_MOUNT	STD	{ int linux_mount(char *specialfile, \
+21	AUE_MOUNT	MSTD	{ int linux_mount(char *specialfile, \
 				    char *dir, char *filesystemtype, \
 				    l_ulong rwflag, void *data); }
-22	AUE_UMOUNT	STD	{ int linux_oldumount(char *path); }
+22	AUE_UMOUNT	MSTD	{ int linux_oldumount(char *path); }
 23	AUE_SETUID	MSTD	{ int linux_setuid16(l_uid16_t uid); }
 24	AUE_GETUID	MSTD	{ int linux_getuid16(void); }
 25	AUE_SETTIMEOFDAY	MSTD	{ int linux_stime(void); }
@@ -111,7 +111,7 @@
 49	AUE_GETEUID	MSTD	{ int linux_geteuid16(void); }
 50	AUE_GETEGID	MSTD	{ int linux_getegid16(void); }
 51	AUE_ACCT	MNOPROTO { int acct(char *path); }
-52	AUE_UMOUNT	STD	{ int linux_umount(char *path, l_int flags); }
+52	AUE_UMOUNT	MSTD	{ int linux_umount(char *path, l_int flags); }
 53	AUE_NULL	UNIMPL	lock
 54	AUE_IOCTL	STD	{ int linux_ioctl(l_uint fd, l_uint cmd, \
 				    uintptr_t arg); }
diff --git a/sys/compat/freebsd32/syscalls.master b/sys/compat/freebsd32/syscalls.master
index 7033e9b..a0ce10b 100644
--- a/sys/compat/freebsd32/syscalls.master
+++ b/sys/compat/freebsd32/syscalls.master
@@ -79,9 +79,9 @@
 				    int flags); }
 19	AUE_LSEEK	OBSOL	olseek
 20	AUE_GETPID	MNOPROTO { pid_t getpid(void); }
-21	AUE_MOUNT	NOPROTO { int mount(char *type, char *path, \
+21	AUE_MOUNT	MNOPROTO { int mount(char *type, char *path, \
 				    int flags, caddr_t data); }
-22	AUE_UMOUNT	NOPROTO { int unmount(char *path, int flags); }
+22	AUE_UMOUNT	MNOPROTO { int unmount(char *path, int flags); }
 23	AUE_SETUID	MNOPROTO { int setuid(uid_t uid); }
 24	AUE_GETUID	MNOPROTO { uid_t getuid(void); }
 25	AUE_GETEUID	MNOPROTO { uid_t geteuid(void); }
@@ -644,7 +644,7 @@
 375	AUE_NULL	UNIMPL	nfsclnt
 376	AUE_NULL	MNOPROTO	{ int eaccess(char *path, int flags); }
 377	AUE_NULL	UNIMPL	afs_syscall
-378	AUE_NULL	NOPROTO { int nmount(struct iovec *iovp, \
+378	AUE_NULL	MNOPROTO { int nmount(struct iovec *iovp, \
 				    unsigned int iovcnt, int flags); }
 379	AUE_NULL	MNOPROTO	{ int kse_exit(void); }
 380	AUE_NULL	MNOPROTO	{ int kse_wakeup(struct kse_mailbox *mbx); }
diff --git a/sys/i386/linux/syscalls.master b/sys/i386/linux/syscalls.master
index e5807f4..285cb66 100644
--- a/sys/i386/linux/syscalls.master
+++ b/sys/i386/linux/syscalls.master
@@ -74,10 +74,10 @@
 19	AUE_LSEEK	MSTD	{ int linux_lseek(l_uint fdes, l_off_t off, \
 				    l_int whence); }
 20	AUE_GETPID	MSTD	{ int linux_getpid(void); }
-21	AUE_MOUNT	STD	{ int linux_mount(char *specialfile, \
+21	AUE_MOUNT	MSTD	{ int linux_mount(char *specialfile, \
 				    char *dir, char *filesystemtype, \
 				    l_ulong rwflag, void *data); }
-22	AUE_UMOUNT	STD	{ int linux_oldumount(char *path); }
+22	AUE_UMOUNT	MSTD	{ int linux_oldumount(char *path); }
 23	AUE_SETUID	MSTD	{ int linux_setuid16(l_uid16_t uid); }
 24	AUE_GETUID	MSTD	{ int linux_getuid16(void); }
 25	AUE_SETTIMEOFDAY	MSTD	{ int linux_stime(void); }
@@ -111,7 +111,7 @@
 49	AUE_GETEUID	MSTD	{ int linux_geteuid16(void); }
 50	AUE_GETEGID	MSTD	{ int linux_getegid16(void); }
 51	AUE_ACCT	MNOPROTO { int acct(char *path); }
-52	AUE_UMOUNT	STD	{ int linux_umount(char *path, l_int flags); }
+52	AUE_UMOUNT	MSTD	{ int linux_umount(char *path, l_int flags); }
 53	AUE_NULL	UNIMPL	lock
 54	AUE_IOCTL	STD	{ int linux_ioctl(l_uint fd, l_uint cmd, \
 				    l_ulong arg); }
diff --git a/sys/kern/syscalls.master b/sys/kern/syscalls.master
index c29cd2e..1209e13 100644
--- a/sys/kern/syscalls.master
+++ b/sys/kern/syscalls.master
@@ -82,10 +82,10 @@
 19	AUE_LSEEK	MCOMPAT	{ long lseek(int fd, long offset, \
 				    int whence); }
 20	AUE_GETPID	MSTD	{ pid_t getpid(void); }
-21	AUE_MOUNT	STD	{ int mount(char *type, char *path, \
+21	AUE_MOUNT	MSTD	{ int mount(char *type, char *path, \
 				    int flags, caddr_t data); }
 ; XXX `path' should have type `const char *' but we're not ready for that.
-22	AUE_UMOUNT	STD	{ int unmount(char *path, int flags); }
+22	AUE_UMOUNT	MSTD	{ int unmount(char *path, int flags); }
 23	AUE_SETUID	MSTD	{ int setuid(uid_t uid); }
 24	AUE_GETUID	MSTD	{ uid_t getuid(void); }
 25	AUE_GETEUID	MSTD	{ uid_t geteuid(void); }
@@ -662,7 +662,7 @@
 375	AUE_NULL	NOIMPL	{ int nfsclnt(int flag, caddr_t argp); }
 376	AUE_EACCESS	MSTD	{ int eaccess(char *path, int flags); }
 377	AUE_NULL	UNIMPL	afs_syscall
-378	AUE_NMOUNT	STD	{ int nmount(struct iovec *iovp, \
+378	AUE_NMOUNT	MSTD	{ int nmount(struct iovec *iovp, \
 				    unsigned int iovcnt, int flags); }
 379	AUE_NULL	MSTD	{ int kse_exit(void); }
 380	AUE_NULL	MSTD	{ int kse_wakeup(struct kse_mailbox *mbx); }
diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
index 66a2fea..cd725ba 100644
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -744,19 +744,23 @@ mount(td, uap)
 
 	fstype = malloc(MFSNAMELEN, M_TEMP, M_WAITOK);
 	error = copyinstr(uap->type, fstype, MFSNAMELEN, NULL);
-	if (!error) {
-		AUDIT_ARG(text, fstype);
-		mtx_lock(&Giant);	/* XXX ? */
-		vfsp = vfs_byname_kld(fstype, td, &error);
-		mtx_unlock(&Giant);
+	if (error) {
+		free(fstype, M_TEMP);
+		return (error);
 	}
+
+	AUDIT_ARG(text, fstype);
+	mtx_lock(&Giant);
+	vfsp = vfs_byname_kld(fstype, td, &error);
 	free(fstype, M_TEMP);
-	if (error)
-		return (error);
-	if (vfsp == NULL)
+	if (vfsp == NULL) {
+		mtx_unlock(&Giant);
 		return (ENOENT);
-	if (vfsp->vfc_vfsops->vfs_cmount == NULL)
+	}
+	if (vfsp->vfc_vfsops->vfs_cmount == NULL) {
+		mtx_unlock(&Giant);
 		return (EOPNOTSUPP);
+	}
 
 	ma = mount_argsu(ma, "fstype", uap->type, MNAMELEN);
 	ma = mount_argsu(ma, "fspath", uap->path, MNAMELEN);
@@ -765,6 +769,7 @@ mount(td, uap)
 	ma = mount_argb(ma, !(uap->flags & MNT_NOEXEC), "noexec");
 
 	error = vfsp->vfc_vfsops->vfs_cmount(ma, uap->data, uap->flags, td);
+	mtx_unlock(&Giant);
 	return (error);
 }
 
@@ -1063,9 +1068,11 @@ unmount(td, uap)
 		return (error);
 	}
 	AUDIT_ARG(upath, td, pathbuf, ARG_UPATH1);
+	mtx_lock(&Giant);
 	if (uap->flags & MNT_BYFSID) {
 		/* Decode the filesystem ID. */
 		if (sscanf(pathbuf, "FSID:%d:%d", &id0, &id1) != 2) {
+			mtx_unlock(&Giant);
 			free(pathbuf, M_TEMP);
 			return (EINVAL);
 		}
@@ -1093,6 +1100,7 @@ unmount(td, uap)
 		 * now, so in the !MNT_BYFSID case return the more likely
 		 * EINVAL for compatibility.
 		 */
+		mtx_unlock(&Giant);
 		return ((uap->flags & MNT_BYFSID) ? ENOENT : EINVAL);
 	}
 
@@ -1101,15 +1109,18 @@ unmount(td, uap)
 	 * original mount is permitted to unmount this filesystem.
 	 */
 	error = vfs_suser(mp, td);
-	if (error)
+	if (error) {
+		mtx_unlock(&Giant);
 		return (error);
+	}
 
 	/*
 	 * Don't allow unmounting the root filesystem.
 	 */
-	if (mp->mnt_flag & MNT_ROOTFS)
+	if (mp->mnt_flag & MNT_ROOTFS) {
+		mtx_unlock(&Giant);
 		return (EINVAL);
-	mtx_lock(&Giant);
+	}
 	error = dounmount(mp, uap->flags, td);
 	mtx_unlock(&Giant);
 	return (error);