* Throw away a dentry - free the inode, dput the parent. This requires that
* the LRU list has already been removed.
*
- * If prune_parents is true, try to prune ancestors as well.
+ * Try to prune ancestors as well. This is necessary to prevent
+ * quadratic behavior of shrink_dcache_parent(), but is also expected
+ * to be beneficial in reducing dentry cache fragmentation.
*
* Called with dcache_lock, drops it and then regains.
* Called with dentry->d_lock held, drops it.
*/
-static void prune_one_dentry(struct dentry * dentry, int prune_parents)
+static void prune_one_dentry(struct dentry * dentry)
{
__d_drop(dentry);
dentry = d_kill(dentry);
- if (!prune_parents) {
- dput(dentry);
- spin_lock(&dcache_lock);
- return;
- }
/*
* Prune ancestors. Locking is simpler than in dput(),
* @count: number of entries to try and free
* @sb: if given, ignore dentries for other superblocks
* which are being unmounted.
- * @prune_parents: if true, try to prune ancestors as well in one go
*
* Shrink the dcache. This is done when we need
* more memory, or simply when we need to unmount
* all the dentries are in use.
*/
-static void prune_dcache(int count, struct super_block *sb, int prune_parents)
+static void prune_dcache(int count, struct super_block *sb)
{
spin_lock(&dcache_lock);
for (; count ; count--) {
* without taking the s_umount lock (I already hold it).
*/
if (sb && dentry->d_sb == sb) {
- prune_one_dentry(dentry, prune_parents);
+ prune_one_dentry(dentry);
continue;
}
/*
s_umount = &dentry->d_sb->s_umount;
if (down_read_trylock(s_umount)) {
if (dentry->d_sb->s_root != NULL) {
- prune_one_dentry(dentry, prune_parents);
+ prune_one_dentry(dentry);
up_read(s_umount);
continue;
}
spin_unlock(&dentry->d_lock);
continue;
}
- prune_one_dentry(dentry, 1);
+ prune_one_dentry(dentry);
cond_resched_lock(&dcache_lock);
goto repeat;
}
int found;
while ((found = select_parent(parent)) != 0)
- prune_dcache(found, parent->d_sb, 1);
+ prune_dcache(found, parent->d_sb);
}
/*
if (nr) {
if (!(gfp_mask & __GFP_FS))
return -1;
- prune_dcache(nr, NULL, 1);
+ prune_dcache(nr, NULL);
}
return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
}