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md/bitmap: remove some pointless locking. 

There is nothing gained by holding a lock while we check if a pointer
is NULL or not.  If there could be a race, then it could become NULL
immediately after the unlock - but there is no race here.

So just remove the locking.

Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2012-03-19 12:46:40 +11:00
parent 278c1ca2f2
commit 5a6c824ebb
1 changed files with 2 additions and 12 deletions
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14
drivers/md/bitmap.c
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@ -446,18 +446,13 @@ static struct page *read_page(struct file *file, unsigned long index,
void bitmap_update_sb(struct bitmap *bitmap)
{
bitmap_super_t *sb;
unsigned long flags;
if (!bitmap || !bitmap->mddev) /* no bitmap for this array */
return;
if (bitmap->mddev->bitmap_info.external)
return;
spin_lock_irqsave(&bitmap->lock, flags);
if (!bitmap->sb_page) { /* no superblock */
spin_unlock_irqrestore(&bitmap->lock, flags);
if (!bitmap->sb_page) /* no superblock */
return;
}
spin_unlock_irqrestore(&bitmap->lock, flags);
sb = kmap_atomic(bitmap->sb_page, KM_USER0);
sb->events = cpu_to_le64(bitmap->mddev->events);
if (bitmap->mddev->events < bitmap->events_cleared)
@ -683,15 +678,10 @@ static int bitmap_mask_state(struct bitmap *bitmap, enum bitmap_state bits,
enum bitmap_mask_op op)
{
bitmap_super_t *sb;
unsigned long flags;
int old;
spin_lock_irqsave(&bitmap->lock, flags);
if (!bitmap->sb_page) { /* can't set the state */
spin_unlock_irqrestore(&bitmap->lock, flags);
if (!bitmap->sb_page) /* can't set the state */
return 0;
}
spin_unlock_irqrestore(&bitmap->lock, flags);
sb = kmap_atomic(bitmap->sb_page, KM_USER0);
old = le32_to_cpu(sb->state) & bits;
switch (op) {