• Eric Dumazet's avatar
    [PATCH] net: don't insert socket dentries into dentry_hashtable · 304e61e6
    Eric Dumazet authored
    We currently insert socket dentries into the global dentry hashtable.  This
    is suboptimal because there is currently no way these entries can be used
    for a lookup().  (/proc/xxx/fd/xxx uses a different mechanism).  Inserting
    them in dentry hashtable slows dcache lookups.
    
    To let __dpath() still work correctly (ie not adding a " (deleted)") after
    dentry name, we do :
    
    - Right after d_alloc(), pretend they are hashed by clearing the
      DCACHE_UNHASHED bit.
    
    - Call d_instantiate() instead of d_add() : dentry is not inserted in
      hash table.
    
      __dpath() & friends work as intended during dentry lifetime.
    
    - At dismantle time, once dput() must clear the dentry, setting again
      DCACHE_UNHASHED bit inside the custom d_delete() function provided by
      socket code, so that dput() can just kill_it.
    Signed-off-by: default avatarEric Dumazet <dada1@cosmosbay.com>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Acked-by: default avatar"David S. Miller" <davem@davemloft.net>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    304e61e6
socket.c 53.3 KB