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Date: Fri, 18 Nov 2016 14:50:56 +0300
From: Konstantin Khlebnikov <koct9i@...il.com>
To: Matthew Wilcox <mawilcox@...uxonhyperv.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Ross Zwisler <ross.zwisler@...ux.intel.com>,
linux-fsdevel <linux-fsdevel@...r.kernel.org>,
Matthew Wilcox <mawilcox@...rosoft.com>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCH 21/29] radix-tree: Delete radix_tree_locate_item()
On Thu, Nov 17, 2016 at 3:17 AM, Matthew Wilcox
<mawilcox@...uxonhyperv.com> wrote:
> From: Matthew Wilcox <mawilcox@...rosoft.com>
>
> This rather complicated function can be better implemented as an iterator.
> It has only one caller, so move the functionality to the only place that
> needs it. Update the test suite to follow the same pattern.
Looks good. I suppose this patch could be applied separately.
>
> Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
> ---
> include/linux/radix-tree.h | 1 -
> lib/radix-tree.c | 99 -----------------------------------
> mm/shmem.c | 26 ++++++++-
> tools/testing/radix-tree/main.c | 8 +--
> tools/testing/radix-tree/multiorder.c | 2 +-
> tools/testing/radix-tree/test.c | 22 ++++++++
> tools/testing/radix-tree/test.h | 2 +
> 7 files changed, 54 insertions(+), 106 deletions(-)
>
> diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
> index 36c6175..57bf635 100644
> --- a/include/linux/radix-tree.h
> +++ b/include/linux/radix-tree.h
> @@ -306,7 +306,6 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
> unsigned long nr_to_tag,
> unsigned int fromtag, unsigned int totag);
> int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag);
> -unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item);
>
> static inline void radix_tree_preload_end(void)
> {
> diff --git a/lib/radix-tree.c b/lib/radix-tree.c
> index 27b53ef..7e70ac9 100644
> --- a/lib/radix-tree.c
> +++ b/lib/radix-tree.c
> @@ -1605,105 +1605,6 @@ radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
> }
> EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
>
> -#if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP)
> -#include <linux/sched.h> /* for cond_resched() */
> -
> -struct locate_info {
> - unsigned long found_index;
> - bool stop;
> -};
> -
> -/*
> - * This linear search is at present only useful to shmem_unuse_inode().
> - */
> -static unsigned long __locate(struct radix_tree_node *slot, void *item,
> - unsigned long index, struct locate_info *info)
> -{
> - unsigned long i;
> -
> - do {
> - unsigned int shift = slot->shift;
> -
> - for (i = (index >> shift) & RADIX_TREE_MAP_MASK;
> - i < RADIX_TREE_MAP_SIZE;
> - i++, index += (1UL << shift)) {
> - struct radix_tree_node *node =
> - rcu_dereference_raw(slot->slots[i]);
> - if (node == RADIX_TREE_RETRY)
> - goto out;
> - if (!radix_tree_is_internal_node(node)) {
> - if (node == item) {
> - info->found_index = index;
> - info->stop = true;
> - goto out;
> - }
> - continue;
> - }
> - node = entry_to_node(node);
> - if (is_sibling_entry(slot, node))
> - continue;
> - slot = node;
> - break;
> - }
> - } while (i < RADIX_TREE_MAP_SIZE);
> -
> -out:
> - if ((index == 0) && (i == RADIX_TREE_MAP_SIZE))
> - info->stop = true;
> - return index;
> -}
> -
> -/**
> - * radix_tree_locate_item - search through radix tree for item
> - * @root: radix tree root
> - * @item: item to be found
> - *
> - * Returns index where item was found, or -1 if not found.
> - * Caller must hold no lock (since this time-consuming function needs
> - * to be preemptible), and must check afterwards if item is still there.
> - */
> -unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
> -{
> - struct radix_tree_node *node;
> - unsigned long max_index;
> - unsigned long cur_index = 0;
> - struct locate_info info = {
> - .found_index = -1,
> - .stop = false,
> - };
> -
> - do {
> - rcu_read_lock();
> - node = rcu_dereference_raw(root->rnode);
> - if (!radix_tree_is_internal_node(node)) {
> - rcu_read_unlock();
> - if (node == item)
> - info.found_index = 0;
> - break;
> - }
> -
> - node = entry_to_node(node);
> -
> - max_index = node_maxindex(node);
> - if (cur_index > max_index) {
> - rcu_read_unlock();
> - break;
> - }
> -
> - cur_index = __locate(node, item, cur_index, &info);
> - rcu_read_unlock();
> - cond_resched();
> - } while (!info.stop && cur_index <= max_index);
> -
> - return info.found_index;
> -}
> -#else
> -unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
> -{
> - return -1;
> -}
> -#endif /* CONFIG_SHMEM && CONFIG_SWAP */
> -
> /**
> * radix_tree_shrink - shrink radix tree to minimum height
> * @root radix tree root
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 0b3fe33..8f9c9aa 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1046,6 +1046,30 @@ static void shmem_evict_inode(struct inode *inode)
> clear_inode(inode);
> }
>
> +static unsigned long find_swap_entry(struct radix_tree_root *root, void *item)
> +{
> + struct radix_tree_iter iter;
> + void **slot;
> + unsigned long found = -1;
> + unsigned int checked = 0;
> +
> + rcu_read_lock();
> + radix_tree_for_each_slot(slot, root, &iter, 0) {
> + if (*slot == item) {
> + found = iter.index;
> + break;
> + }
> + checked++;
> + if ((checked % 4096) != 0)
> + continue;
> + slot = radix_tree_iter_next(slot, &iter);
> + cond_resched_rcu();
> + }
> +
> + rcu_read_unlock();
> + return found;
> +}
> +
> /*
> * If swap found in inode, free it and move page from swapcache to filecache.
> */
> @@ -1059,7 +1083,7 @@ static int shmem_unuse_inode(struct shmem_inode_info *info,
> int error = 0;
>
> radswap = swp_to_radix_entry(swap);
> - index = radix_tree_locate_item(&mapping->page_tree, radswap);
> + index = find_swap_entry(&mapping->page_tree, radswap);
> if (index == -1)
> return -EAGAIN; /* tell shmem_unuse we found nothing */
>
> diff --git a/tools/testing/radix-tree/main.c b/tools/testing/radix-tree/main.c
> index 8621542..93a77f9 100644
> --- a/tools/testing/radix-tree/main.c
> +++ b/tools/testing/radix-tree/main.c
> @@ -239,7 +239,7 @@ static void __locate_check(struct radix_tree_root *tree, unsigned long index,
>
> item_insert_order(tree, index, order);
> item = item_lookup(tree, index);
> - index2 = radix_tree_locate_item(tree, item);
> + index2 = find_item(tree, item);
> if (index != index2) {
> printf("index %ld order %d inserted; found %ld\n",
> index, order, index2);
> @@ -273,17 +273,17 @@ static void locate_check(void)
> index += (1UL << order)) {
> __locate_check(&tree, index + offset, order);
> }
> - if (radix_tree_locate_item(&tree, &tree) != -1)
> + if (find_item(&tree, &tree) != -1)
> abort();
>
> item_kill_tree(&tree);
> }
> }
>
> - if (radix_tree_locate_item(&tree, &tree) != -1)
> + if (find_item(&tree, &tree) != -1)
> abort();
> __locate_check(&tree, -1, 0);
> - if (radix_tree_locate_item(&tree, &tree) != -1)
> + if (find_item(&tree, &tree) != -1)
> abort();
> item_kill_tree(&tree);
> }
> diff --git a/tools/testing/radix-tree/multiorder.c b/tools/testing/radix-tree/multiorder.c
> index 588209a..400de5c 100644
> --- a/tools/testing/radix-tree/multiorder.c
> +++ b/tools/testing/radix-tree/multiorder.c
> @@ -347,7 +347,7 @@ static void __multiorder_join(unsigned long index,
> item_insert_order(&tree, index, order2);
> item = radix_tree_lookup(&tree, index);
> radix_tree_join(&tree, index + 1, order1, item2);
> - loc = radix_tree_locate_item(&tree, item);
> + loc = find_item(&tree, item);
> if (loc == -1)
> free(item);
> item = radix_tree_lookup(&tree, index + 1);
> diff --git a/tools/testing/radix-tree/test.c b/tools/testing/radix-tree/test.c
> index a6e8099..a68ed3b 100644
> --- a/tools/testing/radix-tree/test.c
> +++ b/tools/testing/radix-tree/test.c
> @@ -142,6 +142,28 @@ void item_full_scan(struct radix_tree_root *root, unsigned long start,
> assert(nfound == 0);
> }
>
> +/* Use the same pattern as find_swap_entry() in mm/shmem.c */
> +unsigned long find_item(struct radix_tree_root *root, void *item)
> +{
> + struct radix_tree_iter iter;
> + void **slot;
> + unsigned long found = -1;
> + unsigned long checked = 0;
> +
> + radix_tree_for_each_slot(slot, root, &iter, 0) {
> + if (*slot == item) {
> + found = iter.index;
> + break;
> + }
> + checked++;
> + if ((checked % 4) != 0)
> + continue;
> + slot = radix_tree_iter_next(slot, &iter);
> + }
> +
> + return found;
> +}
> +
> static int verify_node(struct radix_tree_node *slot, unsigned int tag,
> int tagged)
> {
> diff --git a/tools/testing/radix-tree/test.h b/tools/testing/radix-tree/test.h
> index b678f13..ccdd3c1 100644
> --- a/tools/testing/radix-tree/test.h
> +++ b/tools/testing/radix-tree/test.h
> @@ -27,6 +27,8 @@ void item_full_scan(struct radix_tree_root *root, unsigned long start,
> unsigned long nr, int chunk);
> void item_kill_tree(struct radix_tree_root *root);
>
> +unsigned long find_item(struct radix_tree_root *, void *item);
> +
> void tag_check(void);
> void multiorder_checks(void);
> void iteration_test(void);
> --
> 2.10.2
>
> --
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