Commit 705304a8 authored by Ryusuke Konishi's avatar Ryusuke Konishi Committed by Linus Torvalds
Browse files

nilfs2: fix the nilfs_iget() vs. nilfs_new_inode() races 



Same story as in commit 41080b5a ("nfsd race fixes: ext2") (similar
ext2 fix) except that nilfs2 needs to use insert_inode_locked4() instead
of insert_inode_locked() and a bug of a check for dead inodes needs to
be fixed.

If nilfs_iget() is called from nfsd after nilfs_new_inode() calls
insert_inode_locked4(), nilfs_iget() will wait for unlock_new_inode() at
the end of nilfs_mkdir()/nilfs_create()/etc to unlock the inode.

If nilfs_iget() is called before nilfs_new_inode() calls
insert_inode_locked4(), it will create an in-core inode and read its
data from the on-disk inode.  But, nilfs_iget() will find i_nlink equals
zero and fail at nilfs_read_inode_common(), which will lead it to call
iget_failed() and cleanly fail.

However, this sanity check doesn't work as expected for reused on-disk
inodes because they leave a non-zero value in i_mode field and it
hinders the test of i_nlink.  This patch also fixes the issue by
removing the test on i_mode that nilfs2 doesn't need.

Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 72b9918e

fs/nilfs2/inode.c

+24 −8
Original line number Diff line number Diff line
@@ -49,6 +49,8 @@ struct nilfs_iget_args { 
	int for_gc;

};



static int nilfs_iget_test(struct inode *inode, void *opaque);



void nilfs_inode_add_blocks(struct inode *inode, int n)

{

	struct nilfs_root *root = NILFS_I(inode)->i_root;
@@ -348,6 +350,17 @@ const struct address_space_operations nilfs_aops = { 
	.is_partially_uptodate  = block_is_partially_uptodate,

};



static int nilfs_insert_inode_locked(struct inode *inode,

				     struct nilfs_root *root,

				     unsigned long ino)

{

	struct nilfs_iget_args args = {

		.ino = ino, .root = root, .cno = 0, .for_gc = 0

	};



	return insert_inode_locked4(inode, ino, nilfs_iget_test, &args);

}



struct inode *nilfs_new_inode(struct inode *dir, umode_t mode)

{

	struct super_block *sb = dir->i_sb;
@@ -383,7 +396,7 @@ struct inode *nilfs_new_inode(struct inode *dir, umode_t mode) 
	if (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)) {

		err = nilfs_bmap_read(ii->i_bmap, NULL);

		if (err < 0)

			goto failed_bmap;

			goto failed_after_creation;



		set_bit(NILFS_I_BMAP, &ii->i_state);

		/* No lock is needed; iget() ensures it. */
@@ -399,21 +412,24 @@ struct inode *nilfs_new_inode(struct inode *dir, umode_t mode) 
	spin_lock(&nilfs->ns_next_gen_lock);

	inode->i_generation = nilfs->ns_next_generation++;

	spin_unlock(&nilfs->ns_next_gen_lock);

	insert_inode_hash(inode);

	if (nilfs_insert_inode_locked(inode, root, ino) < 0) {

		err = -EIO;

		goto failed_after_creation;

	}



	err = nilfs_init_acl(inode, dir);

	if (unlikely(err))

		goto failed_acl; /* never occur. When supporting

		goto failed_after_creation; /* never occur. When supporting

				    nilfs_init_acl(), proper cancellation of

				    above jobs should be considered */



	return inode;



 failed_acl:

 failed_bmap:

 failed_after_creation:

	clear_nlink(inode);

	unlock_new_inode(inode);

	iput(inode);  /* raw_inode will be deleted through

			 generic_delete_inode() */

			 nilfs_evict_inode() */

	goto failed;



 failed_ifile_create_inode:
@@ -461,8 +477,8 @@ int nilfs_read_inode_common(struct inode *inode, 
	inode->i_atime.tv_nsec = le32_to_cpu(raw_inode->i_mtime_nsec);

	inode->i_ctime.tv_nsec = le32_to_cpu(raw_inode->i_ctime_nsec);

	inode->i_mtime.tv_nsec = le32_to_cpu(raw_inode->i_mtime_nsec);

	if (inode->i_nlink == 0 && inode->i_mode == 0)

		return -EINVAL; /* this inode is deleted */

	if (inode->i_nlink == 0)

		return -ESTALE; /* this inode is deleted */



	inode->i_blocks = le64_to_cpu(raw_inode->i_blocks);

	ii->i_flags = le32_to_cpu(raw_inode->i_flags);

fs/nilfs2/namei.c

+12 −3
Original line number Diff line number Diff line
@@ -51,9 +51,11 @@ static inline int nilfs_add_nondir(struct dentry *dentry, struct inode *inode) 
	int err = nilfs_add_link(dentry, inode);

	if (!err) {

		d_instantiate(dentry, inode);

		unlock_new_inode(inode);

		return 0;

	}

	inode_dec_link_count(inode);

	unlock_new_inode(inode);

	iput(inode);

	return err;

}
@@ -182,6 +184,7 @@ out: 
out_fail:

	drop_nlink(inode);

	nilfs_mark_inode_dirty(inode);

	unlock_new_inode(inode);

	iput(inode);

	goto out;

}
@@ -201,11 +204,15 @@ static int nilfs_link(struct dentry *old_dentry, struct inode *dir, 
	inode_inc_link_count(inode);

	ihold(inode);



	err = nilfs_add_nondir(dentry, inode);

	if (!err)

	err = nilfs_add_link(dentry, inode);

	if (!err) {

		d_instantiate(dentry, inode);

		err = nilfs_transaction_commit(dir->i_sb);

	else

	} else {

		inode_dec_link_count(inode);

		iput(inode);

		nilfs_transaction_abort(dir->i_sb);

	}



	return err;

}
@@ -243,6 +250,7 @@ static int nilfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 


	nilfs_mark_inode_dirty(inode);

	d_instantiate(dentry, inode);

	unlock_new_inode(inode);

out:

	if (!err)

		err = nilfs_transaction_commit(dir->i_sb);
@@ -255,6 +263,7 @@ out_fail: 
	drop_nlink(inode);

	drop_nlink(inode);

	nilfs_mark_inode_dirty(inode);

	unlock_new_inode(inode);

	iput(inode);

out_dir:

	drop_nlink(dir);