• Nikolay Borisov's avatar
    btrfs: Remove needless tree locking in iterate_inode_extrefs · 5c623d33
    Nikolay Borisov authored
    In iterate_inode_exrefs the eb is cloned via btrfs_clone_extent_buffer
    which creates a private extent buffer with the dummy flag set and ref
    count of 1. Then this buffer is locked for reading and its ref count is
    incremented by 1. Finally it's fed to the passed iterate_irefs_t
    function. The actual iterate call back is inode_to_path (coming from
    paths_from_inode) which feeds the eb to btrfs_ref_to_path. In this final
    function the passed eb is only read by first assigning it to the local
    eb variable. This variable is only modified in the case another eb was
    referenced from the passed path that is eb != eb_in check triggers.
    
    Considering this there is no point in locking the cloned eb in
    iterate_inode_refs since it's never being modified and is not published
    anywhere. Furthermore the cloned eb is completely fine having its ref
    count be 1.
    Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
    Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
    Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
    5c623d33
backref.c 59.1 KB