[PATCH] NFS: Fix lookup intent handling
We should never apply a lookup intent to anything other than the last
path component in an open(), create() or access() call.
Introduce the helper nfs_lookup_check_intent() which always returns
zero if LOOKUP_CONTINUE or LOOKUP_PARENT are set, and returns the
intent flags if we're on the last component of the lookup.
By doing so, we fix a bug in open(O_EXCL), where we may end up
optimizing away a real lookup of the parent directory.
Problem noticed by Linda Dunaphant <linda.dunaphant@ccur.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 73f96ac..ff6155f 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -528,19 +528,39 @@
dentry->d_time = jiffies;
}
+/*
+ * Return the intent data that applies to this particular path component
+ *
+ * Note that the current set of intents only apply to the very last
+ * component of the path.
+ * We check for this using LOOKUP_CONTINUE and LOOKUP_PARENT.
+ */
+static inline unsigned int nfs_lookup_check_intent(struct nameidata *nd, unsigned int mask)
+{
+ if (nd->flags & (LOOKUP_CONTINUE|LOOKUP_PARENT))
+ return 0;
+ return nd->flags & mask;
+}
+
+/*
+ * Inode and filehandle revalidation for lookups.
+ *
+ * We force revalidation in the cases where the VFS sets LOOKUP_REVAL,
+ * or if the intent information indicates that we're about to open this
+ * particular file and the "nocto" mount flag is not set.
+ *
+ */
static inline
int nfs_lookup_verify_inode(struct inode *inode, struct nameidata *nd)
{
struct nfs_server *server = NFS_SERVER(inode);
if (nd != NULL) {
- int ndflags = nd->flags;
/* VFS wants an on-the-wire revalidation */
- if (ndflags & LOOKUP_REVAL)
+ if (nd->flags & LOOKUP_REVAL)
goto out_force;
/* This is an open(2) */
- if ((ndflags & LOOKUP_OPEN) &&
- !(ndflags & LOOKUP_CONTINUE) &&
+ if (nfs_lookup_check_intent(nd, LOOKUP_OPEN) != 0 &&
!(server->flags & NFS_MOUNT_NOCTO))
goto out_force;
}
@@ -560,12 +580,8 @@
int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry,
struct nameidata *nd)
{
- int ndflags = 0;
-
- if (nd)
- ndflags = nd->flags;
/* Don't revalidate a negative dentry if we're creating a new file */
- if ((ndflags & LOOKUP_CREATE) && !(ndflags & LOOKUP_CONTINUE))
+ if (nd != NULL && nfs_lookup_check_intent(nd, LOOKUP_CREATE) != 0)
return 0;
return !nfs_check_verifier(dir, dentry);
}
@@ -700,12 +716,16 @@
.d_iput = nfs_dentry_iput,
};
+/*
+ * Use intent information to check whether or not we're going to do
+ * an O_EXCL create using this path component.
+ */
static inline
int nfs_is_exclusive_create(struct inode *dir, struct nameidata *nd)
{
if (NFS_PROTO(dir)->version == 2)
return 0;
- if (!nd || (nd->flags & LOOKUP_CONTINUE) || !(nd->flags & LOOKUP_CREATE))
+ if (nd == NULL || nfs_lookup_check_intent(nd, LOOKUP_CREATE) == 0)
return 0;
return (nd->intent.open.flags & O_EXCL) != 0;
}
@@ -772,12 +792,13 @@
.d_iput = nfs_dentry_iput,
};
+/*
+ * Use intent information to determine whether we need to substitute
+ * the NFSv4-style stateful OPEN for the LOOKUP call
+ */
static int is_atomic_open(struct inode *dir, struct nameidata *nd)
{
- if (!nd)
- return 0;
- /* Check that we are indeed trying to open this file */
- if ((nd->flags & LOOKUP_CONTINUE) || !(nd->flags & LOOKUP_OPEN))
+ if (nd == NULL || nfs_lookup_check_intent(nd, LOOKUP_OPEN) == 0)
return 0;
/* NFS does not (yet) have a stateful open for directories */
if (nd->flags & LOOKUP_DIRECTORY)