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[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>
wifi-calibration
Trond Myklebust 2005-06-07 18:37:01 -04:00 committed by Linus Torvalds
parent eba4f669d6
commit 1d6757fbff
1 changed files with 35 additions and 14 deletions
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49
fs/nfs/dir.c
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@ -528,19 +528,39 @@ static inline void nfs_renew_times(struct dentry * dentry)
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 @@ static inline
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 @@ struct dentry_operations nfs_dentry_operations = {
.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 @@ struct dentry_operations nfs4_dentry_operations = {
.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)