svn commit: r296715 - in head/sys: fs/autofs kern sys
Edward Tomasz Napierala
trasz at FreeBSD.org
Sat Mar 12 07:54:44 UTC 2016
Author: trasz
Date: Sat Mar 12 07:54:42 2016
New Revision: 296715
URL: https://svnweb.freebsd.org/changeset/base/296715
Log:
Fix autofs triggering problem. Assume you have an NFS server,
192.168.1.1, with share "share". This commit fixes a problem
where "mkdir /net/192.168.1.1/share/meh" would return spurious
error instead of creating the directory if the target filesystem
wasn't mounted yet; subsequent attempts would work correctly.
The failure scenario is kind of complicated to explain, but it all
boils down to calling VOP_MKDIR() for the target filesystem (NFS)
with wrong dvp - the autofs vnode instead of the filesystem root
mounted over it.
Reviewed by: kib@
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D5442
Modified:
head/sys/fs/autofs/autofs_vnops.c
head/sys/kern/vfs_lookup.c
head/sys/sys/errno.h
Modified: head/sys/fs/autofs/autofs_vnops.c
==============================================================================
--- head/sys/fs/autofs/autofs_vnops.c Sat Mar 12 07:13:20 2016 (r296714)
+++ head/sys/fs/autofs/autofs_vnops.c Sat Mar 12 07:54:42 2016 (r296715)
@@ -214,7 +214,7 @@ autofs_lookup(struct vop_lookup_args *ap
struct autofs_mount *amp;
struct autofs_node *anp, *child;
struct componentname *cnp;
- int error, lock_flags;
+ int error;
dvp = ap->a_dvp;
vpp = ap->a_vpp;
@@ -257,23 +257,13 @@ autofs_lookup(struct vop_lookup_args *ap
return (error);
if (newvp != NULL) {
- error = VOP_LOOKUP(newvp, ap->a_vpp, ap->a_cnp);
-
/*
- * Instead of figuring out whether our vnode should
- * be locked or not given the error and cnp flags,
- * just "copy" the lock status from vnode returned
- * by mounted filesystem's VOP_LOOKUP(). Get rid
- * of that new vnode afterwards.
+ * The target filesystem got automounted.
+ * Let the lookup(9) go around with the same
+ * path component.
*/
- lock_flags = VOP_ISLOCKED(newvp);
- if (lock_flags == 0) {
- VOP_UNLOCK(dvp, 0);
- vrele(newvp);
- } else {
- vput(newvp);
- }
- return (error);
+ vput(newvp);
+ return (ERELOOKUP);
}
}
Modified: head/sys/kern/vfs_lookup.c
==============================================================================
--- head/sys/kern/vfs_lookup.c Sat Mar 12 07:13:20 2016 (r296714)
+++ head/sys/kern/vfs_lookup.c Sat Mar 12 07:54:42 2016 (r296715)
@@ -495,6 +495,7 @@ lookup(struct nameidata *ndp)
int rdonly; /* lookup read-only flag bit */
int error = 0;
int dpunlocked = 0; /* dp has already been unlocked */
+ int relookup = 0; /* do not consume the path component */
struct componentname *cnp = &ndp->ni_cnd;
int lkflags_save;
int ni_dvp_unlocked;
@@ -745,6 +746,14 @@ unionlookup:
goto unionlookup;
}
+ if (error == ERELOOKUP) {
+ vref(dp);
+ ndp->ni_vp = dp;
+ error = 0;
+ relookup = 1;
+ goto good;
+ }
+
if (error != EJUSTRETURN)
goto bad;
/*
@@ -777,6 +786,8 @@ unionlookup:
goto success;
} else
cnp->cn_lkflags = lkflags_save;
+
+good:
#ifdef NAMEI_DIAGNOSTIC
printf("found\n");
#endif
@@ -856,6 +867,14 @@ nextname:
*/
KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/',
("lookup: invalid path state."));
+ if (relookup) {
+ relookup = 0;
+ if (ndp->ni_dvp != dp)
+ vput(ndp->ni_dvp);
+ else
+ vrele(ndp->ni_dvp);
+ goto dirloop;
+ }
if (*ndp->ni_next == '/') {
cnp->cn_nameptr = ndp->ni_next;
while (*cnp->cn_nameptr == '/') {
Modified: head/sys/sys/errno.h
==============================================================================
--- head/sys/sys/errno.h Sat Mar 12 07:13:20 2016 (r296714)
+++ head/sys/sys/errno.h Sat Mar 12 07:54:42 2016 (r296715)
@@ -190,6 +190,7 @@ __END_DECLS
#define EJUSTRETURN (-2) /* don't modify regs, just return */
#define ENOIOCTL (-3) /* ioctl not handled by this layer */
#define EDIRIOCTL (-4) /* do direct ioctl in GEOM */
+#define ERELOOKUP (-5) /* retry the directory lookup */
#endif
#endif
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