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Commit 0c8c2053 authored by Al Viro's avatar Al Viro Committed by Greg Kroah-Hartman
Browse files

new helper: lookup_positive_unlocked() 



[ Upstream commit 6c2d4798a8d16cf4f3a28c3cd4af4f1dcbbb4d04 ]

Most of the callers of lookup_one_len_unlocked() treat negatives are
ERR_PTR(-ENOENT).  Provide a helper that would do just that.  Note
that a pinned positive dentry remains positive - it's ->d_inode is
stable, etc.; a pinned _negative_ dentry can become positive at any
point as long as you are not holding its parent at least shared.
So using lookup_one_len_unlocked() needs to be careful;
lookup_positive_unlocked() is safer and that's what the callers
end up open-coding anyway.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Stable-dep-of: 0d5a4f8f775f ("fs: Fix error checking for d_hash_and_lookup()")
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0a2b1eb8

fs/cifs/cifsfs.c

+1 −6
Original line number Diff line number Diff line
@@ -738,11 +738,6 @@ cifs_get_root(struct smb_vol *vol, struct super_block *sb) 
		struct inode *dir = d_inode(dentry);

		struct dentry *child;



		if (!dir) {

			dput(dentry);

			dentry = ERR_PTR(-ENOENT);

			break;

		}

		if (!S_ISDIR(dir->i_mode)) {

			dput(dentry);

			dentry = ERR_PTR(-ENOTDIR);
@@ -759,7 +754,7 @@ cifs_get_root(struct smb_vol *vol, struct super_block *sb) 
		while (*s && *s != sep)

			s++;



		child = lookup_one_len_unlocked(p, dentry, s - p);

		child = lookup_positive_unlocked(p, dentry, s - p);

		dput(dentry);

		dentry = child;

	} while (!IS_ERR(dentry));

fs/debugfs/inode.c

+1 −5
Original line number Diff line number Diff line
@@ -299,13 +299,9 @@ struct dentry *debugfs_lookup(const char *name, struct dentry *parent) 
	if (!parent)

		parent = debugfs_mount->mnt_root;



	dentry = lookup_one_len_unlocked(name, parent, strlen(name));

	dentry = lookup_positive_unlocked(name, parent, strlen(name));

	if (IS_ERR(dentry))

		return NULL;

	if (!d_really_is_positive(dentry)) {

		dput(dentry);

		return NULL;

	}

	return dentry;

}

EXPORT_SYMBOL_GPL(debugfs_lookup);

fs/kernfs/mount.c

+1 −1
Original line number Diff line number Diff line
@@ -200,7 +200,7 @@ struct dentry *kernfs_node_dentry(struct kernfs_node *kn, 
			dput(dentry);

			return ERR_PTR(-EINVAL);

		}

		dtmp = lookup_one_len_unlocked(kntmp->name, dentry,

		dtmp = lookup_positive_unlocked(kntmp->name, dentry,

					       strlen(kntmp->name));

		dput(dentry);

		if (IS_ERR(dtmp))

fs/namei.c

+20 −0
Original line number Diff line number Diff line
@@ -2565,6 +2565,26 @@ struct dentry *lookup_one_len_unlocked(const char *name, 
}

EXPORT_SYMBOL(lookup_one_len_unlocked);



/*

 * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT)

 * on negatives.  Returns known positive or ERR_PTR(); that's what

 * most of the users want.  Note that pinned negative with unlocked parent

 * _can_ become positive at any time, so callers of lookup_one_len_unlocked()

 * need to be very careful; pinned positives have ->d_inode stable, so

 * this one avoids such problems.

 */

struct dentry *lookup_positive_unlocked(const char *name,

				       struct dentry *base, int len)

{

	struct dentry *ret = lookup_one_len_unlocked(name, base, len);

	if (!IS_ERR(ret) && d_is_negative(ret)) {

		dput(ret);

		ret = ERR_PTR(-ENOENT);

	}

	return ret;

}

EXPORT_SYMBOL(lookup_positive_unlocked);



#ifdef CONFIG_UNIX98_PTYS

int path_pts(struct path *path)

{

fs/nfsd/nfs3xdr.c

+1 −3
Original line number Diff line number Diff line
@@ -868,13 +868,11 @@ compose_entry_fh(struct nfsd3_readdirres *cd, struct svc_fh *fhp, 
		} else

			dchild = dget(dparent);

	} else

		dchild = lookup_one_len_unlocked(name, dparent, namlen);

		dchild = lookup_positive_unlocked(name, dparent, namlen);

	if (IS_ERR(dchild))

		return rv;

	if (d_mountpoint(dchild))

		goto out;

	if (d_really_is_negative(dchild))

		goto out;

	if (dchild->d_inode->i_ino != ino)

		goto out;

	rv = fh_compose(fhp, exp, dchild, &cd->fh);