Use shared vnode locks instead of exclusive vnode locks for the access(),

chdir(), chroot(), eaccess(), fpathconf(), fstat(), fstatfs(), lseek()
(when figuring out the current size of the file in the SEEK_END case),
pathconf(), readlink(), and statfs() system calls.

Submitted by:	ups (mostly)
Tested by:	pho
MFC after:	1 month

3 files changed, 16 insertions, 16 deletions

diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index ec07d0f..df92aca 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -1241,7 +1241,7 @@ fpathconf(struct thread *td, struct fpathconf_args *uap)
 	if (vp != NULL) {
 		int vfslocked;
 		vfslocked = VFS_LOCK_GIANT(vp->v_mount);
-		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
+		vn_lock(vp, LK_SHARED | LK_RETRY);
 		error = VOP_PATHCONF(vp, uap->name, td->td_retval);
 		VOP_UNLOCK(vp, 0);
 		VFS_UNLOCK_GIANT(vfslocked);
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index 32dc4d1..4bdfc09 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -286,8 +286,8 @@ kern_statfs(struct thread *td, char *path, enum uio_seg pathseg,
 	int error;
 	struct nameidata nd;
 
-	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | MPSAFE | AUDITVNODE1,
-	    pathseg, path, td);
+	NDINIT(&nd, LOOKUP, FOLLOW | LOCKSHARED | LOCKLEAF | MPSAFE |
+	    AUDITVNODE1, pathseg, path, td);
 	error = namei(&nd);
 	if (error)
 		return (error);
@@ -368,7 +368,7 @@ kern_fstatfs(struct thread *td, int fd, struct statfs *buf)
 		return (error);
 	vp = fp->f_vnode;
 	vfslocked = VFS_LOCK_GIANT(vp->v_mount);
-	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
+	vn_lock(vp, LK_SHARED | LK_RETRY);
 #ifdef AUDIT
 	AUDIT_ARG(vnode, vp, ARG_VNODE1);
 #endif
@@ -800,8 +800,8 @@ kern_chdir(struct thread *td, char *path, enum uio_seg pathseg)
 	struct vnode *vp;
 	int vfslocked;
 
-	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1 | MPSAFE,
-	    pathseg, path, td);
+	NDINIT(&nd, LOOKUP, FOLLOW | LOCKSHARED | LOCKLEAF | AUDITVNODE1 |
+	    MPSAFE, pathseg, path, td);
 	if ((error = namei(&nd)) != 0)
 		return (error);
 	vfslocked = NDHASGIANT(&nd);
@@ -886,8 +886,8 @@ chroot(td, uap)
 	error = priv_check(td, PRIV_VFS_CHROOT);
 	if (error)
 		return (error);
-	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | MPSAFE | AUDITVNODE1,
-	    UIO_USERSPACE, uap->path, td);
+	NDINIT(&nd, LOOKUP, FOLLOW | LOCKSHARED | LOCKLEAF | MPSAFE |
+	    AUDITVNODE1, UIO_USERSPACE, uap->path, td);
 	error = namei(&nd);
 	if (error)
 		goto error;
@@ -1938,7 +1938,7 @@ lseek(td, uap)
 		offset += fp->f_offset;
 		break;
 	case L_XTND:
-		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
+		vn_lock(vp, LK_SHARED | LK_RETRY);
 		error = VOP_GETATTR(vp, &vattr, cred);
 		VOP_UNLOCK(vp, 0);
 		if (error)
@@ -2125,8 +2125,8 @@ kern_accessat(struct thread *td, int fd, char *path, enum uio_seg pathseg,
 		td->td_ucred = tmpcred;
 	} else
 		cred = tmpcred = td->td_ucred;
-	NDINIT_AT(&nd, LOOKUP, FOLLOW | LOCKLEAF | MPSAFE | AUDITVNODE1,
-	    pathseg, path, fd, td);
+	NDINIT_AT(&nd, LOOKUP, FOLLOW | LOCKSHARED | LOCKLEAF | MPSAFE |
+	    AUDITVNODE1, pathseg, path, fd, td);
 	if ((error = namei(&nd)) != 0)
 		goto out1;
 	vfslocked = NDHASGIANT(&nd);
@@ -2492,8 +2492,8 @@ kern_pathconf(struct thread *td, char *path, enum uio_seg pathseg, int name)
 	struct nameidata nd;
 	int error, vfslocked;
 
-	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | MPSAFE | AUDITVNODE1,
-	    pathseg, path, td);
+	NDINIT(&nd, LOOKUP, FOLLOW | LOCKSHARED | LOCKLEAF | MPSAFE |
+	    AUDITVNODE1, pathseg, path, td);
 	if ((error = namei(&nd)) != 0)
 		return (error);
 	vfslocked = NDHASGIANT(&nd);
@@ -2568,8 +2568,8 @@ kern_readlinkat(struct thread *td, int fd, char *path, enum uio_seg pathseg,
 	struct nameidata nd;
 	int vfslocked;
 
-	NDINIT_AT(&nd, LOOKUP, NOFOLLOW | LOCKLEAF | MPSAFE | AUDITVNODE1,
-	    pathseg, path, fd, td);
+	NDINIT_AT(&nd, LOOKUP, NOFOLLOW | LOCKSHARED | LOCKLEAF | MPSAFE |
+	    AUDITVNODE1, pathseg, path, fd, td);
 
 	if ((error = namei(&nd)) != 0)
 		return (error);
diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index b272a94..f631508 100644
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -673,7 +673,7 @@ vn_statfile(fp, sb, active_cred, td)
 	int error;
 
 	vfslocked = VFS_LOCK_GIANT(vp->v_mount);
-	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
+	vn_lock(vp, LK_SHARED | LK_RETRY);
 	error = vn_stat(vp, sb, active_cred, fp->f_cred, td);
 	VOP_UNLOCK(vp, 0);
 	VFS_UNLOCK_GIANT(vfslocked);