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__d_move(): fold manipulations with ->d_child/->d_subdirs
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list_del() + list_add() is a slightly pessimised list_move()
list_del() + INIT_LIST_HEAD() is a slightly pessimised list_del_init()

Interleaving those makes the resulting code even worse.  And harder to follow...

Signed-off-by: Al Viro <[email protected]>
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Al Viro committed Sep 27, 2014
1 parent 8527dd7 commit 9d8cd30
Showing 1 changed file with 3 additions and 5 deletions.
8 changes: 3 additions & 5 deletions fs/dcache.c
Original file line number Diff line number Diff line change
Expand Up @@ -2506,8 +2506,6 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
d_hash(dentry->d_parent, dentry->d_name.hash));
}

list_del(&dentry->d_u.d_child);
list_del(&target->d_u.d_child);

/* Switch the names.. */
switch_names(dentry, target);
Expand All @@ -2517,15 +2515,15 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
if (IS_ROOT(dentry)) {
dentry->d_parent = target->d_parent;
target->d_parent = target;
INIT_LIST_HEAD(&target->d_u.d_child);
list_del_init(&target->d_u.d_child);
} else {
swap(dentry->d_parent, target->d_parent);

/* And add them back to the (new) parent lists */
list_add(&target->d_u.d_child, &target->d_parent->d_subdirs);
list_move(&target->d_u.d_child, &target->d_parent->d_subdirs);
}

list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
list_move(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);

write_seqcount_end(&target->d_seq);
write_seqcount_end(&dentry->d_seq);
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