• Ryusuke Konishi's avatar
    nilfs2: fix the nilfs_iget() vs. nilfs_new_inode() races · 344e833f
    Ryusuke Konishi authored
    commit 705304a863cc41585508c0f476f6d3ec28cf7e00 upstream.
    
    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>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    344e833f
namei.c 13.3 KB