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Commit df09348f authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 

Pull vfs fixes from Al Viro:

 - backport-friendly part of lock_parent() race fix

 - a fix for an assumption in the heurisic used by path_connected() that
   is not true on NFS

 - livelock fixes for d_alloc_parallel()

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs: Teach path_connected to handle nfs filesystems with multiple roots.
  fs: dcache: Use READ_ONCE when accessing i_dir_seq
  fs: dcache: Avoid livelock between d_alloc_parallel and __d_add
  lock_parent() needs to recheck if dentry got __dentry_kill'ed under it
parents cfb61b5e 95dd7758

fs/dcache.c

+16 −5
Original line number Original line Diff line number Diff line
@@ -647,11 +647,16 @@ static inline struct dentry *lock_parent(struct dentry *dentry) 
		spin_unlock(&parent->d_lock);

		spin_unlock(&parent->d_lock);

		goto again;

		goto again;

	}

	}

	rcu_read_unlock();

	if (parent != dentry) {

	if (parent != dentry)

		spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);

		spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);

	else

		if (unlikely(dentry->d_lockref.count < 0)) {

			spin_unlock(&parent->d_lock);

			parent = NULL;

			parent = NULL;

		}

	} else {

		parent = NULL;

	}

	rcu_read_unlock();

	return parent;

	return parent;

}

}
@@ -2474,7 +2479,7 @@ struct dentry *d_alloc_parallel(struct dentry *parent, 




retry:

retry:

	rcu_read_lock();

	rcu_read_lock();

	seq = smp_load_acquire(&parent->d_inode->i_dir_seq) & ~1;

	seq = smp_load_acquire(&parent->d_inode->i_dir_seq);

	r_seq = read_seqbegin(&rename_lock);

	r_seq = read_seqbegin(&rename_lock);

	dentry = __d_lookup_rcu(parent, name, &d_seq);

	dentry = __d_lookup_rcu(parent, name, &d_seq);

	if (unlikely(dentry)) {

	if (unlikely(dentry)) {
@@ -2495,8 +2500,14 @@ struct dentry *d_alloc_parallel(struct dentry *parent, 
		rcu_read_unlock();

		rcu_read_unlock();

		goto retry;

		goto retry;

	}

	}



	if (unlikely(seq & 1)) {

		rcu_read_unlock();

		goto retry;

	}



	hlist_bl_lock(b);

	hlist_bl_lock(b);

	if (unlikely(parent->d_inode->i_dir_seq != seq)) {

	if (unlikely(READ_ONCE(parent->d_inode->i_dir_seq) != seq)) {

		hlist_bl_unlock(b);

		hlist_bl_unlock(b);

		rcu_read_unlock();

		rcu_read_unlock();

		goto retry;

		goto retry;

fs/namei.c

+3 −2
Original line number Original line Diff line number Diff line
@@ -559,9 +559,10 @@ static int __nd_alloc_stack(struct nameidata *nd) 
static bool path_connected(const struct path *path)

static bool path_connected(const struct path *path)

{

{

	struct vfsmount *mnt = path->mnt;

	struct vfsmount *mnt = path->mnt;

	struct super_block *sb = mnt->mnt_sb;





	/* Only bind mounts can have disconnected paths */

	/* Bind mounts and multi-root filesystems can have disconnected paths */

	if (mnt->mnt_root == mnt->mnt_sb->s_root)

	if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root))

		return true;

		return true;





	return is_subdir(path->dentry, mnt->mnt_root);

	return is_subdir(path->dentry, mnt->mnt_root);

fs/nfs/super.c

+2 −0
Original line number Original line Diff line number Diff line
@@ -2631,6 +2631,8 @@ struct dentry *nfs_fs_mount_common(struct nfs_server *server, 
		/* initial superblock/root creation */

		/* initial superblock/root creation */

		mount_info->fill_super(s, mount_info);

		mount_info->fill_super(s, mount_info);

		nfs_get_cache_cookie(s, mount_info->parsed, mount_info->cloned);

		nfs_get_cache_cookie(s, mount_info->parsed, mount_info->cloned);

		if (!(server->flags & NFS_MOUNT_UNSHARED))

			s->s_iflags |= SB_I_MULTIROOT;

	}

	}





	mntroot = nfs_get_root(s, mount_info->mntfh, dev_name);

	mntroot = nfs_get_root(s, mount_info->mntfh, dev_name);

include/linux/fs.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -1317,6 +1317,7 @@ extern int send_sigurg(struct fown_struct *fown); 
#define SB_I_CGROUPWB	0x00000001	/* cgroup-aware writeback enabled */

#define SB_I_CGROUPWB	0x00000001	/* cgroup-aware writeback enabled */

#define SB_I_NOEXEC	0x00000002	/* Ignore executables on this fs */

#define SB_I_NOEXEC	0x00000002	/* Ignore executables on this fs */

#define SB_I_NODEV	0x00000004	/* Ignore devices on this fs */

#define SB_I_NODEV	0x00000004	/* Ignore devices on this fs */

#define SB_I_MULTIROOT	0x00000008	/* Multiple roots to the dentry tree */





/* sb->s_iflags to limit user namespace mounts */

/* sb->s_iflags to limit user namespace mounts */

#define SB_I_USERNS_VISIBLE		0x00000010 /* fstype already mounted */

#define SB_I_USERNS_VISIBLE		0x00000010 /* fstype already mounted */