Btrfs: Index extent buffers in an rbtree

Before, extent buffers were a temporary object, meant to map a number of pages
at once and collect operations on them.

But, a few extra fields have crept in, and they are also the best place to
store a per-tree block lock field as well.  This commit puts the extent
buffers into an rbtree, and ensures a single extent buffer for each
tree block.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 99bb385..86e84a8 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -381,7 +381,6 @@ int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
 
        end = min_t(u64, eb->len, PAGE_CACHE_SIZE);
        end = eb->start + end - 1;
-       release_extent_buffer_tail_pages(eb);
 err:
        free_extent_buffer(eb);
 out:
@@ -563,21 +562,21 @@ static int btree_releasepage(struct page *page, gfp_t gfp_flags)
        struct extent_map_tree *map;
        int ret;
 
-       if (page_count(page) > 3) {
-               /* once for page->private, once for the caller, once
-                * once for the page cache
-                */
-               return 0;
-       }
        tree = &BTRFS_I(page->mapping->host)->io_tree;
        map = &BTRFS_I(page->mapping->host)->extent_tree;
+
        ret = try_release_extent_state(map, tree, page, gfp_flags);
+       if (!ret) {
+               return 0;
+       }
+
+       ret = try_release_extent_buffer(tree, page);
        if (ret == 1) {
-               invalidate_extent_lru(tree, page_offset(page), PAGE_CACHE_SIZE);
                ClearPagePrivate(page);
                set_page_private(page, 0);
                page_cache_release(page);
        }
+
        return ret;
 }
 
@@ -588,7 +587,8 @@ static void btree_invalidatepage(struct page *page, unsigned long offset)
        extent_invalidatepage(tree, page, offset);
        btree_releasepage(page, GFP_NOFS);
        if (PagePrivate(page)) {
-               invalidate_extent_lru(tree, page_offset(page), PAGE_CACHE_SIZE);
+               printk("warning page private not zero on page %Lu\n",
+                      page_offset(page));
                ClearPagePrivate(page);
                set_page_private(page, 0);
                page_cache_release(page);
@@ -1456,7 +1456,6 @@ fail_tree_root:
        free_extent_buffer(tree_root->node);
 fail_sys_array:
 fail_sb_buffer:
-       extent_io_tree_empty_lru(&BTRFS_I(fs_info->btree_inode)->io_tree);
        btrfs_stop_workers(&fs_info->fixup_workers);
        btrfs_stop_workers(&fs_info->workers);
        btrfs_stop_workers(&fs_info->endio_workers);
@@ -1705,13 +1704,6 @@ int close_ctree(struct btrfs_root *root)
 
        filemap_write_and_wait(fs_info->btree_inode->i_mapping);
 
-       extent_io_tree_empty_lru(&fs_info->free_space_cache);
-       extent_io_tree_empty_lru(&fs_info->block_group_cache);
-       extent_io_tree_empty_lru(&fs_info->pinned_extents);
-       extent_io_tree_empty_lru(&fs_info->pending_del);
-       extent_io_tree_empty_lru(&fs_info->extent_ins);
-       extent_io_tree_empty_lru(&BTRFS_I(fs_info->btree_inode)->io_tree);
-
        truncate_inode_pages(fs_info->btree_inode->i_mapping, 0);
 
        btrfs_stop_workers(&fs_info->fixup_workers);

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d4a63ae..32bb4ed 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -91,29 +91,16 @@ void extent_io_tree_init(struct extent_io_tree *tree,
                          struct address_space *mapping, gfp_t mask)
 {
        tree->state.rb_node = NULL;
+       tree->buffer.rb_node = NULL;
        tree->ops = NULL;
        tree->dirty_bytes = 0;
        spin_lock_init(&tree->lock);
-       spin_lock_init(&tree->lru_lock);
+       spin_lock_init(&tree->buffer_lock);
        tree->mapping = mapping;
-       INIT_LIST_HEAD(&tree->buffer_lru);
-       tree->lru_size = 0;
        tree->last = NULL;
 }
 EXPORT_SYMBOL(extent_io_tree_init);
 
-void extent_io_tree_empty_lru(struct extent_io_tree *tree)
-{
-       struct extent_buffer *eb;
-       while(!list_empty(&tree->buffer_lru)) {
-               eb = list_entry(tree->buffer_lru.next, struct extent_buffer,
-                               lru);
-               list_del_init(&eb->lru);
-               free_extent_buffer(eb);
-       }
-}
-EXPORT_SYMBOL(extent_io_tree_empty_lru);
-
 struct extent_state *alloc_extent_state(gfp_t mask)
 {
        struct extent_state *state;
@@ -245,6 +232,50 @@ static inline struct rb_node *tree_search(struct extent_io_tree *tree,
        return ret;
 }
 
+static struct extent_buffer *buffer_tree_insert(struct extent_io_tree *tree,
+                                         u64 offset, struct rb_node *node)
+{
+       struct rb_root *root = &tree->buffer;
+       struct rb_node ** p = &root->rb_node;
+       struct rb_node * parent = NULL;
+       struct extent_buffer *eb;
+
+       while(*p) {
+               parent = *p;
+               eb = rb_entry(parent, struct extent_buffer, rb_node);
+
+               if (offset < eb->start)
+                       p = &(*p)->rb_left;
+               else if (offset > eb->start)
+                       p = &(*p)->rb_right;
+               else
+                       return eb;
+       }
+
+       rb_link_node(node, parent, p);
+       rb_insert_color(node, root);
+       return NULL;
+}
+
+static struct extent_buffer *buffer_search(struct extent_io_tree *tree,
+                                          u64 offset)
+{
+       struct rb_root *root = &tree->buffer;
+       struct rb_node * n = root->rb_node;
+       struct extent_buffer *eb;
+
+       while(n) {
+               eb = rb_entry(n, struct extent_buffer, rb_node);
+               if (offset < eb->start)
+                       n = n->rb_left;
+               else if (offset > eb->start)
+                       n = n->rb_right;
+               else
+                       return eb;
+       }
+       return NULL;
+}
+
 /*
  * utility function to look for merge candidates inside a given range.
  * Any extents with matching state are merged together into a single
@@ -1817,9 +1848,8 @@ void set_page_extent_mapped(struct page *page)
 {
        if (!PagePrivate(page)) {
                SetPagePrivate(page);
-               WARN_ON(!page->mapping->a_ops->invalidatepage);
-               set_page_private(page, EXTENT_PAGE_PRIVATE);
                page_cache_get(page);
+               set_page_private(page, EXTENT_PAGE_PRIVATE);
        }
 }
 
@@ -2627,51 +2657,6 @@ out:
        return sector;
 }
 
-static int add_lru(struct extent_io_tree *tree, struct extent_buffer *eb)
-{
-       if (list_empty(&eb->lru)) {
-               extent_buffer_get(eb);
-               list_add(&eb->lru, &tree->buffer_lru);
-               tree->lru_size++;
-               if (tree->lru_size >= BUFFER_LRU_MAX) {
-                       struct extent_buffer *rm;
-                       rm = list_entry(tree->buffer_lru.prev,
-                                       struct extent_buffer, lru);
-                       tree->lru_size--;
-                       list_del_init(&rm->lru);
-                       free_extent_buffer(rm);
-               }
-       } else
-               list_move(&eb->lru, &tree->buffer_lru);
-       return 0;
-}
-static struct extent_buffer *find_lru(struct extent_io_tree *tree,
-                                     u64 start, unsigned long len)
-{
-       struct list_head *lru = &tree->buffer_lru;
-       struct list_head *cur = lru->next;
-       struct extent_buffer *eb;
-
-       if (list_empty(lru))
-               return NULL;
-
-       do {
-               eb = list_entry(cur, struct extent_buffer, lru);
-               if (eb->start == start && eb->len == len) {
-                       extent_buffer_get(eb);
-                       return eb;
-               }
-               cur = cur->next;
-       } while (cur != lru);
-       return NULL;
-}
-
-static inline unsigned long num_extent_pages(u64 start, u64 len)
-{
-       return ((start + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -
-               (start >> PAGE_CACHE_SHIFT);
-}
-
 static inline struct page *extent_buffer_page(struct extent_buffer *eb,
                                              unsigned long i)
 {
@@ -2688,44 +2673,10 @@ static inline struct page *extent_buffer_page(struct extent_buffer *eb,
        return p;
 }
 
-int release_extent_buffer_tail_pages(struct extent_buffer *eb)
-{
-       unsigned long num_pages = num_extent_pages(eb->start, eb->len);
-       struct page *page;
-       unsigned long i;
-
-       if (num_pages == 1)
-               return 0;
-       for (i = 1; i < num_pages; i++) {
-               page = extent_buffer_page(eb, i);
-               page_cache_release(page);
-       }
-       return 0;
-}
-
-
-int invalidate_extent_lru(struct extent_io_tree *tree, u64 start,
-                         unsigned long len)
+static inline unsigned long num_extent_pages(u64 start, u64 len)
 {
-       struct list_head *lru = &tree->buffer_lru;
-       struct list_head *cur = lru->next;
-       struct extent_buffer *eb;
-       int found = 0;
-
-       spin_lock(&tree->lru_lock);
-       if (list_empty(lru))
-               goto out;
-
-       do {
-               eb = list_entry(cur, struct extent_buffer, lru);
-               if (eb->start <= start && eb->start + eb->len > start) {
-                       eb->flags &= ~EXTENT_UPTODATE;
-               }
-               cur = cur->next;
-       } while (cur != lru);
-out:
-       spin_unlock(&tree->lru_lock);
-       return found;
+       return ((start + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -
+               (start >> PAGE_CACHE_SHIFT);
 }
 
 static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
@@ -2736,15 +2687,7 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
        struct extent_buffer *eb = NULL;
        unsigned long flags;
 
-       spin_lock(&tree->lru_lock);
-       eb = find_lru(tree, start, len);
-       spin_unlock(&tree->lru_lock);
-       if (eb) {
-               return eb;
-       }
-
        eb = kmem_cache_zalloc(extent_buffer_cache, mask);
-       INIT_LIST_HEAD(&eb->lru);
        eb->start = start;
        eb->len = len;
        spin_lock_irqsave(&leak_lock, flags);
@@ -2773,17 +2716,24 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
        unsigned long i;
        unsigned long index = start >> PAGE_CACHE_SHIFT;
        struct extent_buffer *eb;
+       struct extent_buffer *exists = NULL;
        struct page *p;
        struct address_space *mapping = tree->mapping;
        int uptodate = 1;
 
+       spin_lock(&tree->buffer_lock);
+       eb = buffer_search(tree, start);
+       if (eb) {
+               atomic_inc(&eb->refs);
+               spin_unlock(&tree->buffer_lock);
+               return eb;
+       }
+       spin_unlock(&tree->buffer_lock);
+
        eb = __alloc_extent_buffer(tree, start, len, mask);
        if (!eb)
                return NULL;
 
-       if (eb->flags & EXTENT_BUFFER_FILLED)
-               goto lru_add;
-
        if (page0) {
                eb->first_page = page0;
                i = 1;
@@ -2800,7 +2750,7 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
                p = find_or_create_page(mapping, index, mask | __GFP_HIGHMEM);
                if (!p) {
                        WARN_ON(1);
-                       goto fail;
+                       goto free_eb;
                }
                set_page_extent_mapped(p);
                mark_page_accessed(p);
@@ -2818,25 +2768,28 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
                eb->flags |= EXTENT_UPTODATE;
        eb->flags |= EXTENT_BUFFER_FILLED;
 
-lru_add:
-       spin_lock(&tree->lru_lock);
-       add_lru(tree, eb);
-       spin_unlock(&tree->lru_lock);
+       spin_lock(&tree->buffer_lock);
+       exists = buffer_tree_insert(tree, start, &eb->rb_node);
+       if (exists) {
+               /* add one reference for the caller */
+               atomic_inc(&exists->refs);
+               spin_unlock(&tree->buffer_lock);
+               goto free_eb;
+       }
+       spin_unlock(&tree->buffer_lock);
+
+       /* add one reference for the tree */
+       atomic_inc(&eb->refs);
        return eb;
 
-fail:
-       spin_lock(&tree->lru_lock);
-       list_del_init(&eb->lru);
-       spin_unlock(&tree->lru_lock);
+free_eb:
        if (!atomic_dec_and_test(&eb->refs))
-               return NULL;
-       for (index = 1; index < i; index++) {
+               return exists;
+       for (index = 1; index < i; index++)
                page_cache_release(extent_buffer_page(eb, index));
-       }
-       if (i > 0)
-               page_cache_release(extent_buffer_page(eb, 0));
+       page_cache_release(extent_buffer_page(eb, 0));
        __free_extent_buffer(eb);
-       return NULL;
+       return exists;
 }
 EXPORT_SYMBOL(alloc_extent_buffer);
 
@@ -2844,89 +2797,27 @@ struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
                                         u64 start, unsigned long len,
                                          gfp_t mask)
 {
-       unsigned long num_pages = num_extent_pages(start, len);
-       unsigned long i;
-       unsigned long index = start >> PAGE_CACHE_SHIFT;
        struct extent_buffer *eb;
-       struct page *p;
-       struct address_space *mapping = tree->mapping;
-       int uptodate = 1;
 
-       eb = __alloc_extent_buffer(tree, start, len, mask);
-       if (!eb)
-               return NULL;
-
-       if (eb->flags & EXTENT_BUFFER_FILLED)
-               goto lru_add;
-
-       for (i = 0; i < num_pages; i++, index++) {
-               p = find_get_page(mapping, index);
-               if (!p) {
-                       goto fail;
-               }
-               if (TestSetPageLocked(p)) {
-                       page_cache_release(p);
-                       goto fail;
-               }
-
-               set_page_extent_mapped(p);
-               mark_page_accessed(p);
-
-               if (i == 0) {
-                       eb->first_page = p;
-                       set_page_extent_head(p, len);
-               } else {
-                       set_page_private(p, EXTENT_PAGE_PRIVATE);
-               }
-
-               if (!PageUptodate(p))
-                       uptodate = 0;
-               unlock_page(p);
-       }
-       if (uptodate)
-               eb->flags |= EXTENT_UPTODATE;
-       eb->flags |= EXTENT_BUFFER_FILLED;
+       spin_lock(&tree->buffer_lock);
+       eb = buffer_search(tree, start);
+       if (eb)
+               atomic_inc(&eb->refs);
+       spin_unlock(&tree->buffer_lock);
 
-lru_add:
-       spin_lock(&tree->lru_lock);
-       add_lru(tree, eb);
-       spin_unlock(&tree->lru_lock);
        return eb;
-fail:
-       spin_lock(&tree->lru_lock);
-       list_del_init(&eb->lru);
-       spin_unlock(&tree->lru_lock);
-       if (!atomic_dec_and_test(&eb->refs))
-               return NULL;
-       for (index = 1; index < i; index++) {
-               page_cache_release(extent_buffer_page(eb, index));
-       }
-       if (i > 0)
-               page_cache_release(extent_buffer_page(eb, 0));
-       __free_extent_buffer(eb);
-       return NULL;
 }
 EXPORT_SYMBOL(find_extent_buffer);
 
 void free_extent_buffer(struct extent_buffer *eb)
 {
-       unsigned long i;
-       unsigned long num_pages;
-
        if (!eb)
                return;
 
        if (!atomic_dec_and_test(&eb->refs))
                return;
 
-       WARN_ON(!list_empty(&eb->lru));
-       num_pages = num_extent_pages(eb->start, eb->len);
-
-       for (i = 1; i < num_pages; i++) {
-               page_cache_release(extent_buffer_page(eb, i));
-       }
-       page_cache_release(extent_buffer_page(eb, 0));
-       __free_extent_buffer(eb);
+       WARN_ON(1);
 }
 EXPORT_SYMBOL(free_extent_buffer);
 
@@ -3583,3 +3474,35 @@ void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
        }
 }
 EXPORT_SYMBOL(memmove_extent_buffer);
+
+int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page)
+{
+       u64 start = page_offset(page);
+       struct extent_buffer *eb;
+       int ret = 1;
+       unsigned long i;
+       unsigned long num_pages;
+
+       spin_lock(&tree->buffer_lock);
+       eb = buffer_search(tree, start);
+       if (!eb)
+               goto out;
+
+       if (atomic_read(&eb->refs) > 1) {
+               ret = 0;
+               goto out;
+       }
+       /* at this point we can safely release the extent buffer */
+       num_pages = num_extent_pages(eb->start, eb->len);
+       for (i = 0; i < num_pages; i++) {
+               struct page *page = extent_buffer_page(eb, i);
+               page_cache_release(page);
+       }
+       rb_erase(&eb->rb_node, &tree->buffer);
+       __free_extent_buffer(eb);
+out:
+       spin_unlock(&tree->buffer_lock);
+       return ret;
+}
+EXPORT_SYMBOL(try_release_extent_buffer);
+

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 23affd2..dd36761 100644 (file)
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -54,13 +54,12 @@ struct extent_io_ops {
 
 struct extent_io_tree {
        struct rb_root state;
+       struct rb_root buffer;
        struct address_space *mapping;
        u64 dirty_bytes;
        spinlock_t lock;
+       spinlock_t buffer_lock;
        struct extent_io_ops *ops;
-       spinlock_t lru_lock;
-       struct list_head buffer_lru;
-       int lru_size;
        struct extent_state *last;
 };
 
@@ -87,10 +86,10 @@ struct extent_buffer {
        unsigned long map_start;
        unsigned long map_len;
        struct page *first_page;
-       struct list_head lru;
        atomic_t refs;
        int flags;
        struct list_head leak_list;
+       struct rb_node rb_node;
 };
 
 struct extent_map_tree;
@@ -112,10 +111,10 @@ typedef struct extent_map *(get_extent_t)(struct inode *inode,
 
 void extent_io_tree_init(struct extent_io_tree *tree,
                          struct address_space *mapping, gfp_t mask);
-void extent_io_tree_empty_lru(struct extent_io_tree *tree);
 int try_release_extent_mapping(struct extent_map_tree *map,
                               struct extent_io_tree *tree, struct page *page,
                               gfp_t mask);
+int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page);
 int try_release_extent_state(struct extent_map_tree *map,
                             struct extent_io_tree *tree, struct page *page,
                             gfp_t mask);
@@ -241,8 +240,6 @@ int map_private_extent_buffer(struct extent_buffer *eb, unsigned long offset,
                      unsigned long *map_start,
                      unsigned long *map_len, int km);
 void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km);
-int invalidate_extent_lru(struct extent_io_tree *tree, u64 start,
-                         unsigned long len);
 int release_extent_buffer_tail_pages(struct extent_buffer *eb);
 int extent_range_uptodate(struct extent_io_tree *tree,
                          u64 start, u64 end);

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8fb6dc2..60852ad 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2670,7 +2670,6 @@ static int __btrfs_releasepage(struct page *page, gfp_t gfp_flags)
        map = &BTRFS_I(page->mapping->host)->extent_tree;
        ret = try_release_extent_mapping(map, tree, page, gfp_flags);
        if (ret == 1) {
-               invalidate_extent_lru(tree, page_offset(page), PAGE_CACHE_SIZE);
                ClearPagePrivate(page);
                set_page_private(page, 0);
                page_cache_release(page);
@@ -2721,8 +2720,6 @@ static void btrfs_invalidatepage(struct page *page, unsigned long offset)
 
        ClearPageChecked(page);
        if (PagePrivate(page)) {
-               invalidate_extent_lru(tree, page_offset(page),
-                                     PAGE_CACHE_SIZE);
                ClearPagePrivate(page);
                set_page_private(page, 0);
                page_cache_release(page);