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XArray: Add private interface for workingset node deletion

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Move the tricky bits of dealing with the XArray from the workingset
code to the XArray.  Make it clear in the documentation that this is a
private interface, and only export it for the benefit of the test suite.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2020-08-18 09:05:56 -04:00
parent 8446466c9d
commit f82cd2f0b5
4 changed files with 28 additions and 17 deletions
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2
include/linux/xarray.h
View File

@ -1286,6 +1286,8 @@ static inline bool xa_is_advanced(const void *entry)
*/
typedef void (*xa_update_node_t)(struct xa_node *node);
void xa_delete_node(struct xa_node *, xa_update_node_t);
/*
* The xa_state is opaque to its users. It contains various different pieces
* of state involved in the current operation on the XArray. It should be

7
lib/test_xarray.c
View File

@ -1600,14 +1600,9 @@ static noinline void shadow_remove(struct xarray *xa)
xa_lock(xa);
while ((node = list_first_entry_or_null(&shadow_nodes,
struct xa_node, private_list))) {
XA_STATE(xas, node->array, 0);
XA_BUG_ON(xa, node->array != xa);
list_del_init(&node->private_list);
xas.xa_node = xa_parent_locked(node->array, node);
xas.xa_offset = node->offset;
xas.xa_shift = node->shift + XA_CHUNK_SHIFT;
xas_set_update(&xas, test_update_node);
xas_store(&xas, NULL);
xa_delete_node(node, test_update_node);
}
xa_unlock(xa);
}

23
lib/xarray.c
View File

@ -1973,6 +1973,29 @@ unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
}
EXPORT_SYMBOL(xa_extract);
/**
* xa_delete_node() - Private interface for workingset code.
* @node: Node to be removed from the tree.
* @update: Function to call to update ancestor nodes.
*
* Context: xa_lock must be held on entry and will not be released.
*/
void xa_delete_node(struct xa_node *node, xa_update_node_t update)
{
struct xa_state xas = {
.xa = node->array,
.xa_index = (unsigned long)node->offset <<
(node->shift + XA_CHUNK_SHIFT),
.xa_shift = node->shift + XA_CHUNK_SHIFT,
.xa_offset = node->offset,
.xa_node = xa_parent_locked(node->array, node),
.xa_update = update,
};
xas_store(&xas, NULL);
}
EXPORT_SYMBOL_GPL(xa_delete_node); /* For the benefit of the test suite */
/**
* xa_destroy() - Free all internal data structures.
* @xa: XArray.

13
mm/workingset.c
View File

@ -519,12 +519,11 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
void *arg) __must_hold(lru_lock)
{
struct xa_node *node = container_of(item, struct xa_node, private_list);
XA_STATE(xas, node->array, 0);
struct address_space *mapping;
int ret;
/*
* Page cache insertions and deletions synchroneously maintain
* Page cache insertions and deletions synchronously maintain
* the shadow node LRU under the i_pages lock and the
* lru_lock. Because the page cache tree is emptied before
* the inode can be destroyed, holding the lru_lock pins any
@ -559,15 +558,7 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
if (WARN_ON_ONCE(node->count != node->nr_values))
goto out_invalid;
mapping->nrexceptional -= node->nr_values;
xas.xa_node = xa_parent_locked(&mapping->i_pages, node);
xas.xa_offset = node->offset;
xas.xa_shift = node->shift + XA_CHUNK_SHIFT;
xas_set_update(&xas, workingset_update_node);
/*
* We could store a shadow entry here which was the minimum of the
* shadow entries we were tracking ...
*/
xas_store(&xas, NULL);
xa_delete_node(node, workingset_update_node);
__inc_lruvec_slab_state(node, WORKINGSET_NODERECLAIM);
out_invalid: