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-rw-r--r--sys/conf/options1
-rw-r--r--sys/kern/vfs_cache.c63
-rw-r--r--sys/kern/vfs_extattr.c5
-rw-r--r--sys/kern/vfs_syscalls.c5
-rw-r--r--sys/kern/vfs_vnops.c34
-rw-r--r--sys/sys/namei.h7
6 files changed, 112 insertions, 3 deletions
diff --git a/sys/conf/options b/sys/conf/options
index c3101df..fede7fd 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -383,6 +383,7 @@ BLKDEV_IOSIZE opt_global.h
DEBUG opt_global.h
DEBUG_LOCKS opt_global.h
DEBUG_VFS_LOCKS opt_global.h
+LOOKUP_SHARED opt_global.h
DIAGNOSTIC opt_global.h
ENABLE_VFS_IOOPT opt_global.h
INVARIANT_SUPPORT opt_global.h
diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c
index 08e0397..529efd1 100644
--- a/sys/kern/vfs_cache.c
+++ b/sys/kern/vfs_cache.c
@@ -570,8 +570,35 @@ vfs_cache_lookup(ap)
error = cache_lookup(dvp, vpp, cnp);
+#ifdef LOOKUP_SHARED
+ if (!error) {
+ /* We do this because the rest of the system now expects to get
+ * a shared lock, which is later upgraded if LOCKSHARED is not
+ * set. We have so many cases here because of bugs that yield
+ * inconsistant lock states. This all badly needs to be fixed
+ */
+ error = VOP_CACHEDLOOKUP(dvp, vpp, cnp);
+ if (!error) {
+ int flock;
+
+ flock = VOP_ISLOCKED(*vpp, td);
+ if (flock != LK_EXCLUSIVE) {
+ if (flock == 0) {
+ if ((flags & ISLASTCN) &&
+ (flags & LOCKSHARED))
+ VOP_LOCK(*vpp, LK_SHARED, td);
+ else
+ VOP_LOCK(*vpp, LK_EXCLUSIVE, td);
+ }
+ } else if ((flags & ISLASTCN) && (flags & LOCKSHARED))
+ VOP_LOCK(*vpp, LK_DOWNGRADE, td);
+ }
+ return (error);
+ }
+#else
if (!error)
return (VOP_CACHEDLOOKUP(dvp, vpp, cnp));
+#endif
if (error == ENOENT)
return (error);
@@ -585,13 +612,28 @@ vfs_cache_lookup(ap)
} else if (flags & ISDOTDOT) {
VOP_UNLOCK(dvp, 0, td);
cnp->cn_flags |= PDIRUNLOCK;
+#ifdef LOOKUP_SHARED
+ if ((flags & ISLASTCN) && (flags & LOCKSHARED))
+ error = vget(vp, LK_SHARED, td);
+ else
+ error = vget(vp, LK_EXCLUSIVE, td);
+#else
error = vget(vp, LK_EXCLUSIVE, td);
+#endif
+
if (!error && lockparent && (flags & ISLASTCN)) {
if ((error = vn_lock(dvp, LK_EXCLUSIVE, td)) == 0)
cnp->cn_flags &= ~PDIRUNLOCK;
}
} else {
+#ifdef LOOKUP_SHARED
+ if ((flags & ISLASTCN) && (flags & LOCKSHARED))
+ error = vget(vp, LK_SHARED, td);
+ else
+ error = vget(vp, LK_EXCLUSIVE, td);
+#else
error = vget(vp, LK_EXCLUSIVE, td);
+#endif
if (!lockparent || error || !(flags & ISLASTCN)) {
VOP_UNLOCK(dvp, 0, td);
cnp->cn_flags |= PDIRUNLOCK;
@@ -616,7 +658,28 @@ vfs_cache_lookup(ap)
return (error);
cnp->cn_flags &= ~PDIRUNLOCK;
}
+#ifdef LOOKUP_SHARED
+ error = VOP_CACHEDLOOKUP(dvp, vpp, cnp);
+
+ if (!error) {
+ int flock = 0;
+
+ flock = VOP_ISLOCKED(*vpp, td);
+ if (flock != LK_EXCLUSIVE) {
+ if (flock == 0) {
+ if ((flags & ISLASTCN) && (flags & LOCKSHARED))
+ VOP_LOCK(*vpp, LK_SHARED, td);
+ else
+ VOP_LOCK(*vpp, LK_EXCLUSIVE, td);
+ }
+ } else if ((flags & ISLASTCN) && (flags & LOCKSHARED))
+ VOP_LOCK(*vpp, LK_DOWNGRADE, td);
+ }
+
+ return (error);
+#else
return (VOP_CACHEDLOOKUP(dvp, vpp, cnp));
+#endif
}
diff --git a/sys/kern/vfs_extattr.c b/sys/kern/vfs_extattr.c
index fd22602..31b1244 100644
--- a/sys/kern/vfs_extattr.c
+++ b/sys/kern/vfs_extattr.c
@@ -2029,8 +2029,13 @@ stat(td, uap)
int error;
struct nameidata nd;
+#ifdef LOOKUP_SHARED
+ NDINIT(&nd, LOOKUP, FOLLOW | LOCKSHARED | LOCKLEAF | NOOBJ,
+ UIO_USERSPACE, SCARG(uap, path), td);
+#else
NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | NOOBJ, UIO_USERSPACE,
SCARG(uap, path), td);
+#endif
if ((error = namei(&nd)) != 0)
return (error);
error = vn_stat(nd.ni_vp, &sb, td);
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index fd22602..31b1244 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -2029,8 +2029,13 @@ stat(td, uap)
int error;
struct nameidata nd;
+#ifdef LOOKUP_SHARED
+ NDINIT(&nd, LOOKUP, FOLLOW | LOCKSHARED | LOCKLEAF | NOOBJ,
+ UIO_USERSPACE, SCARG(uap, path), td);
+#else
NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | NOOBJ, UIO_USERSPACE,
SCARG(uap, path), td);
+#endif
if ((error = namei(&nd)) != 0)
return (error);
error = vn_stat(nd.ni_vp, &sb, td);
diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index 461cb1e..336086c 100644
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -105,6 +105,11 @@ vn_open_cred(ndp, flagp, cmode, cred)
struct vattr vat;
struct vattr *vap = &vat;
int mode, fmode, error;
+#ifdef LOOKUP_SHARED
+ int exclusive; /* The current intended lock state */
+
+ exclusive = 0;
+#endif
restart:
fmode = *flagp;
@@ -143,6 +148,9 @@ restart:
ASSERT_VOP_LOCKED(ndp->ni_vp, "create");
fmode &= ~O_TRUNC;
vp = ndp->ni_vp;
+#ifdef LOOKUP_SHARED
+ exclusive = 1;
+#endif
} else {
if (ndp->ni_dvp == ndp->ni_vp)
vrele(ndp->ni_dvp);
@@ -158,8 +166,14 @@ restart:
}
} else {
ndp->ni_cnd.cn_nameiop = LOOKUP;
+#ifdef LOOKUP_SHARED
+ ndp->ni_cnd.cn_flags =
+ ((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) |
+ LOCKSHARED | LOCKLEAF;
+#else
ndp->ni_cnd.cn_flags =
((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) | LOCKLEAF;
+#endif
if ((error = namei(ndp)) != 0)
return (error);
vp = ndp->ni_vp;
@@ -198,6 +212,21 @@ restart:
* Make sure that a VM object is created for VMIO support.
*/
if (vn_canvmio(vp) == TRUE) {
+#ifdef LOOKUP_SHARED
+ int flock;
+
+ if (!exclusive && vp->v_object == NULL)
+ VOP_LOCK(vp, LK_UPGRADE, td);
+ /*
+ * In cases where the object is marked as dead object_create
+ * will unlock and relock exclusive. It is safe to call in
+ * here with a shared lock because we only examine fields that
+ * the shared lock guarantees will be stable. In the UPGRADE
+ * case it is not likely that anyone has used this vnode yet
+ * so there will be no contention. The logic after this call
+ * restores the requested locking state.
+ */
+#endif
if ((error = vfs_object_create(vp, td, cred)) != 0) {
VOP_UNLOCK(vp, 0, td);
VOP_CLOSE(vp, fmode, cred, td);
@@ -206,6 +235,11 @@ restart:
*flagp = fmode;
return (error);
}
+#ifdef LOOKUP_SHARED
+ flock = VOP_ISLOCKED(vp, td);
+ if (!exclusive && flock == LK_EXCLUSIVE)
+ VOP_LOCK(vp, LK_DOWNGRADE, td);
+#endif
}
if (fmode & FWRITE)
diff --git a/sys/sys/namei.h b/sys/sys/namei.h
index 5b133cc..1ae6120 100644
--- a/sys/sys/namei.h
+++ b/sys/sys/namei.h
@@ -113,8 +113,9 @@ struct nameidata {
#define NOCACHE 0x0020 /* name must not be left in cache */
#define FOLLOW 0x0040 /* follow symbolic links */
#define NOOBJ 0x0080 /* don't create object */
+#define LOCKSHARED 0x0100 /* Shared lock leaf */
#define NOFOLLOW 0x0000 /* do not follow symbolic links (pseudo) */
-#define MODMASK 0x00fc /* mask of operational modifiers */
+#define MODMASK 0x01fc /* mask of operational modifiers */
/*
* Namei parameter descriptors.
*
@@ -129,7 +130,6 @@ struct nameidata {
* name being sought. The caller is responsible for releasing the
* buffer and for vrele'ing ni_startdir.
*/
-#define NOCROSSMOUNT 0x000100 /* do not cross mount points */
#define RDONLY 0x000200 /* lookup with read-only semantics */
#define HASBUF 0x000400 /* has allocated pathname buffer */
#define SAVENAME 0x000800 /* save pathname buffer */
@@ -143,7 +143,8 @@ struct nameidata {
#define WILLBEDIR 0x080000 /* new files will be dirs; allow trailing / */
#define ISUNICODE 0x100000 /* current component name is unicode*/
#define PDIRUNLOCK 0x200000 /* file system lookup() unlocked parent dir */
-#define PARAMASK 0x1fff00 /* mask of parameter descriptors */
+#define NOCROSSMOUNT 0x400000 /* do not cross mount points */
+#define PARAMASK 0x3ffe00 /* mask of parameter descriptors */
/*
* Initialization of an nameidata structure.
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