Commit aa60cfc3 authored by Jeff Layton's avatar Jeff Layton Committed by Ilya Dryomov
Browse files

ceph: don't use d_add in ceph_handle_snapdir 



It's possible ceph_get_snapdir could end up finding a (disconnected)
inode that already exists in the cache. Change the prototype for
ceph_handle_snapdir to return a dentry pointer and have it use
d_splice_alias so we don't end up with an aliased dentry in the cache.

Reported-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent d3c51ae1

fs/ceph/dir.c

+19 −11
Original line number Diff line number Diff line
@@ -667,7 +667,7 @@ static loff_t ceph_dir_llseek(struct file *file, loff_t offset, int whence) 
/*

 * Handle lookups for the hidden .snap directory.

 */

int ceph_handle_snapdir(struct ceph_mds_request *req,

struct dentry *ceph_handle_snapdir(struct ceph_mds_request *req,

				   struct dentry *dentry, int err)

{

	struct ceph_fs_client *fsc = ceph_sb_to_client(dentry->d_sb);
@@ -676,16 +676,17 @@ int ceph_handle_snapdir(struct ceph_mds_request *req, 
	/* .snap dir? */

	if (err == -ENOENT &&

	    ceph_snap(parent) == CEPH_NOSNAP &&

	    strcmp(dentry->d_name.name,

		   fsc->mount_options->snapdir_name) == 0) {

	    strcmp(dentry->d_name.name, fsc->mount_options->snapdir_name) == 0) {

		struct dentry *res;

		struct inode *inode = ceph_get_snapdir(parent);

		dout("ENOENT on snapdir %p '%pd', linking to snapdir %p\n",

		     dentry, dentry, inode);

		BUG_ON(!d_unhashed(dentry));

		d_add(dentry, inode);

		err = 0;



		res = d_splice_alias(inode, dentry);

		dout("ENOENT on snapdir %p '%pd', linking to snapdir %p. Spliced dentry %p\n",

		     dentry, dentry, inode, res);

		if (res)

			dentry = res;

	}

	return err;

	return dentry;

}



/*
@@ -741,6 +742,7 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry, 
	struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb);

	struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(dir->i_sb);

	struct ceph_mds_request *req;

	struct dentry *res;

	int op;

	int mask;

	int err;
@@ -791,7 +793,13 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry, 
	req->r_parent = dir;

	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);

	err = ceph_mdsc_do_request(mdsc, NULL, req);

	err = ceph_handle_snapdir(req, dentry, err);

	res = ceph_handle_snapdir(req, dentry, err);

	if (IS_ERR(res)) {

		err = PTR_ERR(res);

	} else {

		dentry = res;

		err = 0;

	}

	dentry = ceph_finish_lookup(req, dentry, err);

	ceph_mdsc_put_request(req);  /* will dput(dentry) */

	dout("lookup result=%p\n", dentry);

fs/ceph/file.c

+5 −2
Original line number Diff line number Diff line
@@ -739,9 +739,12 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry, 
	err = ceph_mdsc_do_request(mdsc,

				   (flags & (O_CREAT|O_TRUNC)) ? dir : NULL,

				   req);

	err = ceph_handle_snapdir(req, dentry, err);

	if (err)

	dentry = ceph_handle_snapdir(req, dentry, err);

	if (IS_ERR(dentry)) {

		err = PTR_ERR(dentry);

		goto out_req;

	}

	err = 0;



	if ((flags & O_CREAT) && !req->r_reply_info.head->is_dentry)

		err = ceph_handle_notrace_create(dir, dentry);

fs/ceph/super.h

+1 −1
Original line number Diff line number Diff line
@@ -1193,7 +1193,7 @@ extern const struct dentry_operations ceph_dentry_ops; 


extern loff_t ceph_make_fpos(unsigned high, unsigned off, bool hash_order);

extern int ceph_handle_notrace_create(struct inode *dir, struct dentry *dentry);

extern int ceph_handle_snapdir(struct ceph_mds_request *req,

extern struct dentry *ceph_handle_snapdir(struct ceph_mds_request *req,

			       struct dentry *dentry, int err);

extern struct dentry *ceph_finish_lookup(struct ceph_mds_request *req,

					 struct dentry *dentry, int err);