Commit 070c5ac2 authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Linus Torvalds

radix-tree: fix radix_tree_range_tag_if_tagged() for multiorder entries

I had previously decided that tagging a single multiorder entry would
count as tagging 2^order entries for the purposes of 'nr_to_tag'.  I now
believe that decision to be a mistake, and it should count as a single
entry.  That's more likely to be what callers expect.

When walking back up the tree from a newly-tagged entry, the current
code assumed we were starting from the lowest level of the tree; if we
have a multiorder entry with an order at least RADIX_TREE_MAP_SHIFT in
size then we need to shift the index by 'shift' before we start walking
back up the tree, or we will end up not setting tags on higher entries,
and then mistakenly thinking that entries below a certain point in the
tree are not tagged.

If the first index we examine is a sibling entry of a tagged multiorder
entry, we were not tagging it.  We need to examine the canonical entry,
and the easiest way to do that is to use radix_tree_descend().  We then
have to skip over sibling slots when looking for the next entry in the
tree or we will end up walking back to the canonical entry.

Add several tests for radix_tree_range_tag_if_tagged().
Signed-off-by: default avatarMatthew Wilcox <willy@linux.intel.com>
Reviewed-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jan Kara <jack@suse.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent eb73f7f3
...@@ -1033,14 +1033,13 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, ...@@ -1033,14 +1033,13 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
unsigned long nr_to_tag, unsigned long nr_to_tag,
unsigned int iftag, unsigned int settag) unsigned int iftag, unsigned int settag)
{ {
unsigned int height = root->height; struct radix_tree_node *slot, *node = NULL;
struct radix_tree_node *node = NULL; unsigned long maxindex;
struct radix_tree_node *slot; unsigned int shift = radix_tree_load_root(root, &slot, &maxindex);
unsigned int shift;
unsigned long tagged = 0; unsigned long tagged = 0;
unsigned long index = *first_indexp; unsigned long index = *first_indexp;
last_index = min(last_index, radix_tree_maxindex(height)); last_index = min(last_index, maxindex);
if (index > last_index) if (index > last_index)
return 0; return 0;
if (!nr_to_tag) if (!nr_to_tag)
...@@ -1049,80 +1048,71 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, ...@@ -1049,80 +1048,71 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
*first_indexp = last_index + 1; *first_indexp = last_index + 1;
return 0; return 0;
} }
if (height == 0) { if (!radix_tree_is_indirect_ptr(slot)) {
*first_indexp = last_index + 1; *first_indexp = last_index + 1;
root_tag_set(root, settag); root_tag_set(root, settag);
return 1; return 1;
} }
shift = (height - 1) * RADIX_TREE_MAP_SHIFT; node = indirect_to_ptr(slot);
slot = indirect_to_ptr(root->rnode); shift -= RADIX_TREE_MAP_SHIFT;
for (;;) { for (;;) {
unsigned long upindex; unsigned long upindex;
int offset; unsigned offset;
offset = (index >> shift) & RADIX_TREE_MAP_MASK; offset = (index >> shift) & RADIX_TREE_MAP_MASK;
if (!slot->slots[offset]) offset = radix_tree_descend(node, &slot, offset);
if (!slot)
goto next; goto next;
if (!tag_get(slot, iftag, offset)) if (!tag_get(node, iftag, offset))
goto next; goto next;
if (shift) { /* Sibling slots never have tags set on them */
node = slot;
slot = slot->slots[offset];
if (radix_tree_is_indirect_ptr(slot)) { if (radix_tree_is_indirect_ptr(slot)) {
slot = indirect_to_ptr(slot); node = indirect_to_ptr(slot);
shift -= RADIX_TREE_MAP_SHIFT; shift -= RADIX_TREE_MAP_SHIFT;
continue; continue;
} else {
slot = node;
node = node->parent;
}
} }
/* tag the leaf */ /* tag the leaf */
tagged += 1 << shift; tagged++;
tag_set(slot, settag, offset); tag_set(node, settag, offset);
slot = node->parent;
/* walk back up the path tagging interior nodes */ /* walk back up the path tagging interior nodes */
upindex = index; upindex = index >> shift;
while (node) { while (slot) {
upindex >>= RADIX_TREE_MAP_SHIFT; upindex >>= RADIX_TREE_MAP_SHIFT;
offset = upindex & RADIX_TREE_MAP_MASK; offset = upindex & RADIX_TREE_MAP_MASK;
/* stop if we find a node with the tag already set */ /* stop if we find a node with the tag already set */
if (tag_get(node, settag, offset)) if (tag_get(slot, settag, offset))
break; break;
tag_set(node, settag, offset); tag_set(slot, settag, offset);
node = node->parent; slot = slot->parent;
} }
/* next:
* Small optimization: now clear that node pointer.
* Since all of this slot's ancestors now have the tag set
* from setting it above, we have no further need to walk
* back up the tree setting tags, until we update slot to
* point to another radix_tree_node.
*/
node = NULL;
next:
/* Go to next item at level determined by 'shift' */ /* Go to next item at level determined by 'shift' */
index = ((index >> shift) + 1) << shift; index = ((index >> shift) + 1) << shift;
/* Overflow can happen when last_index is ~0UL... */ /* Overflow can happen when last_index is ~0UL... */
if (index > last_index || !index) if (index > last_index || !index)
break; break;
if (tagged >= nr_to_tag) offset = (index >> shift) & RADIX_TREE_MAP_MASK;
break; while (offset == 0) {
while (((index >> shift) & RADIX_TREE_MAP_MASK) == 0) {
/* /*
* We've fully scanned this node. Go up. Because * We've fully scanned this node. Go up. Because
* last_index is guaranteed to be in the tree, what * last_index is guaranteed to be in the tree, what
* we do below cannot wander astray. * we do below cannot wander astray.
*/ */
slot = slot->parent; node = node->parent;
shift += RADIX_TREE_MAP_SHIFT; shift += RADIX_TREE_MAP_SHIFT;
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
} }
if (is_sibling_entry(node, node->slots[offset]))
goto next;
if (tagged >= nr_to_tag)
break;
} }
/* /*
* We need not to tag the root tag if there is no tag which is set with * We need not to tag the root tag if there is no tag which is set with
......
...@@ -26,6 +26,7 @@ static void __multiorder_tag_test(int index, int order) ...@@ -26,6 +26,7 @@ static void __multiorder_tag_test(int index, int order)
{ {
RADIX_TREE(tree, GFP_KERNEL); RADIX_TREE(tree, GFP_KERNEL);
int base, err, i; int base, err, i;
unsigned long first = 0;
/* our canonical entry */ /* our canonical entry */
base = index & ~((1 << order) - 1); base = index & ~((1 << order) - 1);
...@@ -59,13 +60,16 @@ static void __multiorder_tag_test(int index, int order) ...@@ -59,13 +60,16 @@ static void __multiorder_tag_test(int index, int order)
assert(!radix_tree_tag_get(&tree, i, 1)); assert(!radix_tree_tag_get(&tree, i, 1));
} }
assert(radix_tree_range_tag_if_tagged(&tree, &first, ~0UL, 10, 0, 1) == 1);
assert(radix_tree_tag_clear(&tree, index, 0)); assert(radix_tree_tag_clear(&tree, index, 0));
for_each_index(i, base, order) { for_each_index(i, base, order) {
assert(!radix_tree_tag_get(&tree, i, 0)); assert(!radix_tree_tag_get(&tree, i, 0));
assert(!radix_tree_tag_get(&tree, i, 1)); assert(radix_tree_tag_get(&tree, i, 1));
} }
assert(radix_tree_tag_clear(&tree, index, 1));
assert(!radix_tree_tagged(&tree, 0)); assert(!radix_tree_tagged(&tree, 0));
assert(!radix_tree_tagged(&tree, 1)); assert(!radix_tree_tagged(&tree, 1));
...@@ -244,6 +248,7 @@ void multiorder_tagged_iteration(void) ...@@ -244,6 +248,7 @@ void multiorder_tagged_iteration(void)
RADIX_TREE(tree, GFP_KERNEL); RADIX_TREE(tree, GFP_KERNEL);
struct radix_tree_iter iter; struct radix_tree_iter iter;
void **slot; void **slot;
unsigned long first = 0;
int i; int i;
printf("Multiorder tagged iteration test\n"); printf("Multiorder tagged iteration test\n");
...@@ -280,6 +285,24 @@ void multiorder_tagged_iteration(void) ...@@ -280,6 +285,24 @@ void multiorder_tagged_iteration(void)
i++; i++;
} }
radix_tree_range_tag_if_tagged(&tree, &first, ~0UL,
MT_NUM_ENTRIES, 1, 2);
i = 0;
radix_tree_for_each_tagged(slot, &tree, &iter, 1, 2) {
assert(iter.index == tag_index[i]);
i++;
}
first = 1;
radix_tree_range_tag_if_tagged(&tree, &first, ~0UL,
MT_NUM_ENTRIES, 1, 0);
i = 0;
radix_tree_for_each_tagged(slot, &tree, &iter, 0, 0) {
assert(iter.index == tag_index[i]);
i++;
}
item_kill_tree(&tree); item_kill_tree(&tree);
} }
......
...@@ -12,6 +12,7 @@ ...@@ -12,6 +12,7 @@
static void static void
__simple_checks(struct radix_tree_root *tree, unsigned long index, int tag) __simple_checks(struct radix_tree_root *tree, unsigned long index, int tag)
{ {
unsigned long first = 0;
int ret; int ret;
item_check_absent(tree, index); item_check_absent(tree, index);
...@@ -22,6 +23,10 @@ __simple_checks(struct radix_tree_root *tree, unsigned long index, int tag) ...@@ -22,6 +23,10 @@ __simple_checks(struct radix_tree_root *tree, unsigned long index, int tag)
item_tag_set(tree, index, tag); item_tag_set(tree, index, tag);
ret = item_tag_get(tree, index, tag); ret = item_tag_get(tree, index, tag);
assert(ret != 0); assert(ret != 0);
ret = radix_tree_range_tag_if_tagged(tree, &first, ~0UL, 10, tag, !tag);
assert(ret == 1);
ret = item_tag_get(tree, index, !tag);
assert(ret != 0);
ret = item_delete(tree, index); ret = item_delete(tree, index);
assert(ret != 0); assert(ret != 0);
item_insert(tree, index); item_insert(tree, index);
...@@ -304,6 +309,7 @@ static void single_check(void) ...@@ -304,6 +309,7 @@ static void single_check(void)
struct item *items[BATCH]; struct item *items[BATCH];
RADIX_TREE(tree, GFP_KERNEL); RADIX_TREE(tree, GFP_KERNEL);
int ret; int ret;
unsigned long first = 0;
item_insert(&tree, 0); item_insert(&tree, 0);
item_tag_set(&tree, 0, 0); item_tag_set(&tree, 0, 0);
...@@ -313,6 +319,10 @@ static void single_check(void) ...@@ -313,6 +319,10 @@ static void single_check(void)
assert(ret == 0); assert(ret == 0);
verify_tag_consistency(&tree, 0); verify_tag_consistency(&tree, 0);
verify_tag_consistency(&tree, 1); verify_tag_consistency(&tree, 1);
ret = radix_tree_range_tag_if_tagged(&tree, &first, 10, 10, 0, 1);
assert(ret == 1);
ret = radix_tree_gang_lookup_tag(&tree, (void **)items, 0, BATCH, 1);
assert(ret == 1);
item_kill_tree(&tree); item_kill_tree(&tree);
} }
......
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