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staging: lustre: llite: refine ll_find_alias based on d_exact_alias 

The task of ll_find_alias() is now very similar to d_exact_alias().
We cannot use that function directly, but we can copy much of
the structure so that the similarities and differences are more
obvious.
Examining d_exact_alias() shows that the d_lock spinlock does not
need to be held in ll_find_alias as much as it currently is.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
NeilBrown 2018-02-13 08:30:48 +11:00 committed by Greg Kroah-Hartman
parent 7e08e9a894
commit 8016ab9ebb
1 changed files with 20 additions and 10 deletions
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24
drivers/staging/lustre/lustre/llite/namei.c
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@ -381,6 +381,10 @@ void ll_i2gids(__u32 *suppgids, struct inode *i1, struct inode *i2)
/* /*
* Try to reuse unhashed or invalidated dentries. * Try to reuse unhashed or invalidated dentries.
* This is very similar to d_exact_alias(), and any changes in one should be
* considered for inclusion in the other. The differences are that we don't
* need an unhashed alias, and we don't want d_compare to be used for
* comparison.
*/ */
static struct dentry *ll_find_alias(struct inode *inode, struct dentry *dentry) static struct dentry *ll_find_alias(struct inode *inode, struct dentry *dentry)
{ {
@ -392,20 +396,26 @@ static struct dentry *ll_find_alias(struct inode *inode, struct dentry *dentry)
spin_lock(&inode->i_lock); spin_lock(&inode->i_lock);
hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
LASSERT(alias != dentry); LASSERT(alias != dentry);
/*
* Don't need alias->d_lock here, because aliases with
* d_parent == entry->d_parent are not subject to name or
* parent changes, because the parent inode i_mutex is held.
*/
spin_lock(&alias->d_lock); if (alias->d_parent != dentry->d_parent)
if (alias->d_parent == dentry->d_parent && continue;
alias->d_name.hash == dentry->d_name.hash && if (alias->d_name.hash != dentry->d_name.hash)
alias->d_name.len == dentry->d_name.len && continue;
if (alias->d_name.len != dentry->d_name.len ||
memcmp(alias->d_name.name, dentry->d_name.name, memcmp(alias->d_name.name, dentry->d_name.name,
dentry->d_name.len) == 0) { dentry->d_name.len) != 0)
continue;
spin_lock(&alias->d_lock);
dget_dlock(alias); dget_dlock(alias);
spin_unlock(&alias->d_lock); spin_unlock(&alias->d_lock);
spin_unlock(&inode->i_lock); spin_unlock(&inode->i_lock);
return alias; return alias;
} }
spin_unlock(&alias->d_lock);
}
spin_unlock(&inode->i_lock); spin_unlock(&inode->i_lock);
return NULL; return NULL;