• Al Viro's avatar
    much milder d_walk() race · ba65dc5e
    Al Viro authored
    d_walk() relies upon the tree not getting rearranged under it without
    rename_lock being touched.  And we do grab rename_lock around the
    places that change the tree topology.  Unfortunately, branch reordering
    is just as bad from d_walk() POV and we have two places that do it
    without touching rename_lock - one in handling of cursors (for ramfs-style
    directories) and another in autofs.  autofs one is a separate story; this
    commit deals with the cursors.
    	* mark cursor dentries explicitly at allocation time
    	* make __dentry_kill() leave ->d_child.next pointing to the next
    non-cursor sibling, making sure that it won't be moved around unnoticed
    before the parent is relocked on ascend-to-parent path in d_walk().
    	* make d_walk() skip cursors explicitly; strictly speaking it's
    not necessary (all callbacks we pass to d_walk() are no-ops on cursors),
    but it makes analysis easier.
    Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
dcache.c 96.2 KB