• Hugh Dickins's avatar
    tmpfs: convert shmem_unuse_inode to radix-swap · 46f65ec1
    Hugh Dickins authored
    Convert shmem_unuse_inode() to use a lockless gang lookup of the radix
    tree, searching for matching swap.
    This is somewhat slower than the old method: because of repeated radix
    tree descents, because of copying entries up, but probably most because
    the old method noted and skipped once a vector page was cleared of swap.
    Perhaps we can devise a use of radix tree tagging to achieve that later.
    shmem_add_to_page_cache() uses shmem_radix_tree_replace() to compensate
    for the lockless lookup by checking that the expected entry is in place,
    under lock.  It is not very satisfactory to be copying this much from
    add_to_page_cache_locked(), but I think easier to sell than insisting
    that every caller of add_to_page_cache*() go through the extras.
    Signed-off-by: default avatarHugh Dickins <hughd@google.com>
    Acked-by: default avatarRik van Riel <riel@redhat.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
shmem.c 67.3 KB