Commit c7944ebb authored by Trond Myklebust's avatar Trond Myklebust
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NFSv4: Fix lookup revalidate of regular files 



If we're revalidating an existing dentry in order to open a file, we need
to ensure that we check the directory has not changed before we optimise
away the lookup.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent 5ceb9d7f

fs/nfs/dir.c

+39 −40
Original line number Diff line number Diff line
@@ -1231,7 +1231,8 @@ out_bad: 
}



static int

nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)

__nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags,

			int (*reval)(struct inode *, struct dentry *, unsigned int))

{

	struct dentry *parent;

	struct inode *dir;
@@ -1242,17 +1243,22 @@ nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags) 
		dir = d_inode_rcu(parent);

		if (!dir)

			return -ECHILD;

		ret = nfs_do_lookup_revalidate(dir, dentry, flags);

		ret = reval(dir, dentry, flags);

		if (parent != READ_ONCE(dentry->d_parent))

			return -ECHILD;

	} else {

		parent = dget_parent(dentry);

		ret = nfs_do_lookup_revalidate(d_inode(parent), dentry, flags);

		ret = reval(d_inode(parent), dentry, flags);

		dput(parent);

	}

	return ret;

}



static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)

{

	return __nfs_lookup_revalidate(dentry, flags, nfs_do_lookup_revalidate);

}



/*

 * A weaker form of d_revalidate for revalidating just the d_inode(dentry)

 * when we don't really care about the dentry name. This is called when a
@@ -1609,62 +1615,55 @@ no_open: 
}

EXPORT_SYMBOL_GPL(nfs_atomic_open);



static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)

static int

nfs4_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,

			  unsigned int flags)

{

	struct inode *inode;

	int ret = 0;



	if (!(flags & LOOKUP_OPEN) || (flags & LOOKUP_DIRECTORY))

		goto no_open;

		goto full_reval;

	if (d_mountpoint(dentry))

		goto no_open;

	if (NFS_SB(dentry->d_sb)->caps & NFS_CAP_ATOMIC_OPEN_V1)

		goto no_open;

		goto full_reval;



	inode = d_inode(dentry);



	/* We can't create new files in nfs_open_revalidate(), so we

	 * optimize away revalidation of negative dentries.

	 */

	if (inode == NULL) {

		struct dentry *parent;

		struct inode *dir;

	if (inode == NULL)

		goto full_reval;



		if (flags & LOOKUP_RCU) {

			parent = READ_ONCE(dentry->d_parent);

			dir = d_inode_rcu(parent);

			if (!dir)

				return -ECHILD;

		} else {

			parent = dget_parent(dentry);

			dir = d_inode(parent);

		}

		if (!nfs_neg_need_reval(dir, dentry, flags))

			ret = 1;

		else if (flags & LOOKUP_RCU)

			ret = -ECHILD;

		if (!(flags & LOOKUP_RCU))

			dput(parent);

		else if (parent != READ_ONCE(dentry->d_parent))

			return -ECHILD;

		goto out;

	}

	if (NFS_PROTO(dir)->have_delegation(inode, FMODE_READ))

		return nfs_lookup_revalidate_delegated(dir, dentry, inode);



	/* NFS only supports OPEN on regular files */

	if (!S_ISREG(inode->i_mode))

		goto no_open;

		goto full_reval;



	/* We cannot do exclusive creation on a positive dentry */

	if (flags & LOOKUP_EXCL)

		goto no_open;

	if (flags & (LOOKUP_EXCL | LOOKUP_REVAL))

		goto reval_dentry;



	/* Check if the directory changed */

	if (!nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU))

		goto reval_dentry;



	/* Let f_op->open() actually open (and revalidate) the file */

	ret = 1;

	return 1;

reval_dentry:

	if (flags & LOOKUP_RCU)

		return -ECHILD;

	return nfs_lookup_revalidate_dentry(dir, dentry, inode);;



out:

	return ret;

full_reval:

	return nfs_do_lookup_revalidate(dir, dentry, flags);

}



no_open:

	return nfs_lookup_revalidate(dentry, flags);

static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)

{

	return __nfs_lookup_revalidate(dentry, flags,

			nfs4_do_lookup_revalidate);

}



#endif /* CONFIG_NFSV4 */