[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>
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49
fs/nfs/dir.c
49
fs/nfs/dir.c
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@ -528,19 +528,39 @@ static inline void nfs_renew_times(struct dentry * dentry)
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dentry->d_time = jiffies;
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}
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/*
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* Return the intent data that applies to this particular path component
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*
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* Note that the current set of intents only apply to the very last
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* component of the path.
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* We check for this using LOOKUP_CONTINUE and LOOKUP_PARENT.
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*/
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static inline unsigned int nfs_lookup_check_intent(struct nameidata *nd, unsigned int mask)
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{
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if (nd->flags & (LOOKUP_CONTINUE|LOOKUP_PARENT))
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return 0;
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return nd->flags & mask;
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}
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/*
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* Inode and filehandle revalidation for lookups.
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*
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* We force revalidation in the cases where the VFS sets LOOKUP_REVAL,
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* or if the intent information indicates that we're about to open this
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* particular file and the "nocto" mount flag is not set.
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*
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*/
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static inline
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int nfs_lookup_verify_inode(struct inode *inode, struct nameidata *nd)
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{
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struct nfs_server *server = NFS_SERVER(inode);
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if (nd != NULL) {
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int ndflags = nd->flags;
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/* VFS wants an on-the-wire revalidation */
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if (ndflags & LOOKUP_REVAL)
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if (nd->flags & LOOKUP_REVAL)
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goto out_force;
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/* This is an open(2) */
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if ((ndflags & LOOKUP_OPEN) &&
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!(ndflags & LOOKUP_CONTINUE) &&
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if (nfs_lookup_check_intent(nd, LOOKUP_OPEN) != 0 &&
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!(server->flags & NFS_MOUNT_NOCTO))
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goto out_force;
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}
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@ -560,12 +580,8 @@ static inline
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int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry,
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struct nameidata *nd)
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{
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int ndflags = 0;
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if (nd)
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ndflags = nd->flags;
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/* Don't revalidate a negative dentry if we're creating a new file */
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if ((ndflags & LOOKUP_CREATE) && !(ndflags & LOOKUP_CONTINUE))
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if (nd != NULL && nfs_lookup_check_intent(nd, LOOKUP_CREATE) != 0)
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return 0;
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return !nfs_check_verifier(dir, dentry);
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}
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@ -700,12 +716,16 @@ struct dentry_operations nfs_dentry_operations = {
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.d_iput = nfs_dentry_iput,
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};
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/*
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* Use intent information to check whether or not we're going to do
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* an O_EXCL create using this path component.
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*/
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static inline
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int nfs_is_exclusive_create(struct inode *dir, struct nameidata *nd)
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{
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if (NFS_PROTO(dir)->version == 2)
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return 0;
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if (!nd || (nd->flags & LOOKUP_CONTINUE) || !(nd->flags & LOOKUP_CREATE))
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if (nd == NULL || nfs_lookup_check_intent(nd, LOOKUP_CREATE) == 0)
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return 0;
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return (nd->intent.open.flags & O_EXCL) != 0;
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}
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@ -772,12 +792,13 @@ struct dentry_operations nfs4_dentry_operations = {
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.d_iput = nfs_dentry_iput,
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};
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/*
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* Use intent information to determine whether we need to substitute
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* the NFSv4-style stateful OPEN for the LOOKUP call
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*/
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static int is_atomic_open(struct inode *dir, struct nameidata *nd)
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{
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if (!nd)
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return 0;
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/* Check that we are indeed trying to open this file */
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if ((nd->flags & LOOKUP_CONTINUE) || !(nd->flags & LOOKUP_OPEN))
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if (nd == NULL || nfs_lookup_check_intent(nd, LOOKUP_OPEN) == 0)
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return 0;
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/* NFS does not (yet) have a stateful open for directories */
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if (nd->flags & LOOKUP_DIRECTORY)
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