Merge branch 'master' of ssh://mason@master.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable

1 files changed, 342 insertions, 0 deletions

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
new file mode 100644
index 000000000000..74b2a29880d3
--- /dev/null
+++ b/fs/btrfs/extent_map.c
@@ -0,0 +1,342 @@
+#include <linux/err.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/version.h>
+#include <linux/hardirq.h>
+#include "extent_map.h"
+
+/* temporary define until extent_map moves out of btrfs */
+struct kmem_cache *btrfs_cache_create(const char *name, size_t size,
+                                       unsigned long extra_flags,
+                                       void (*ctor)(void *, struct kmem_cache *,
+                                                    unsigned long));
+
+static struct kmem_cache *extent_map_cache;
+
+int __init extent_map_init(void)
+{
+        extent_map_cache = btrfs_cache_create("extent_map",
+                                            sizeof(struct extent_map), 0,
+                                            NULL);
+        if (!extent_map_cache)
+                return -ENOMEM;
+        return 0;
+}
+
+void extent_map_exit(void)
+{
+        if (extent_map_cache)
+                kmem_cache_destroy(extent_map_cache);
+}
+
+/**
+ * extent_map_tree_init - initialize extent map tree
+ * @tree:               tree to initialize
+ * @mask:               flags for memory allocations during tree operations
+ *
+ * Initialize the extent tree @tree.  Should be called for each new inode
+ * or other user of the extent_map interface.
+ */
+void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
+{
+        tree->map.rb_node = NULL;
+        spin_lock_init(&tree->lock);
+}
+EXPORT_SYMBOL(extent_map_tree_init);
+
+/**
+ * alloc_extent_map - allocate new extent map structure
+ * @mask:       memory allocation flags
+ *
+ * Allocate a new extent_map structure.  The new structure is
+ * returned with a reference count of one and needs to be
+ * freed using free_extent_map()
+ */
+struct extent_map *alloc_extent_map(gfp_t mask)
+{
+        struct extent_map *em;
+        em = kmem_cache_alloc(extent_map_cache, mask);
+        if (!em || IS_ERR(em))
+                return em;
+        em->in_tree = 0;
+        em->flags = 0;
+        atomic_set(&em->refs, 1);
+        return em;
+}
+EXPORT_SYMBOL(alloc_extent_map);
+
+/**
+ * free_extent_map - drop reference count of an extent_map
+ * @em:         extent map beeing releasead
+ *
+ * Drops the reference out on @em by one and free the structure
+ * if the reference count hits zero.
+ */
+void free_extent_map(struct extent_map *em)
+{
+        if (!em)
+                return;
+        WARN_ON(atomic_read(&em->refs) == 0);
+        if (atomic_dec_and_test(&em->refs)) {
+                WARN_ON(em->in_tree);
+                kmem_cache_free(extent_map_cache, em);
+        }
+}
+EXPORT_SYMBOL(free_extent_map);
+
+static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
+                                   struct rb_node *node)
+{
+        struct rb_node ** p = &root->rb_node;
+        struct rb_node * parent = NULL;
+        struct extent_map *entry;
+
+        while(*p) {
+                parent = *p;
+                entry = rb_entry(parent, struct extent_map, rb_node);
+
+                WARN_ON(!entry->in_tree);
+
+                if (offset < entry->start)
+                        p = &(*p)->rb_left;
+                else if (offset >= extent_map_end(entry))
+                        p = &(*p)->rb_right;
+                else
+                        return parent;
+        }
+
+        entry = rb_entry(node, struct extent_map, rb_node);
+        entry->in_tree = 1;
+        rb_link_node(node, parent, p);
+        rb_insert_color(node, root);
+        return NULL;
+}
+
+/*
+ * search through the tree for an extent_map with a given offset.  If
+ * it can't be found, try to find some neighboring extents
+ */
+static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
+                                     struct rb_node **prev_ret,
+                                     struct rb_node **next_ret)
+{
+        struct rb_node * n = root->rb_node;
+        struct rb_node *prev = NULL;
+        struct rb_node *orig_prev = NULL;
+        struct extent_map *entry;
+        struct extent_map *prev_entry = NULL;
+
+        while(n) {
+                entry = rb_entry(n, struct extent_map, rb_node);
+                prev = n;
+                prev_entry = entry;
+
+                WARN_ON(!entry->in_tree);
+
+                if (offset < entry->start)
+                        n = n->rb_left;
+                else if (offset >= extent_map_end(entry))
+                        n = n->rb_right;
+                else
+                        return n;
+        }
+
+        if (prev_ret) {
+                orig_prev = prev;
+                while(prev && offset >= extent_map_end(prev_entry)) {
+                        prev = rb_next(prev);
+                        prev_entry = rb_entry(prev, struct extent_map, rb_node);
+                }
+                *prev_ret = prev;
+                prev = orig_prev;
+        }
+
+        if (next_ret) {
+                prev_entry = rb_entry(prev, struct extent_map, rb_node);
+                while(prev && offset < prev_entry->start) {
+                        prev = rb_prev(prev);
+                        prev_entry = rb_entry(prev, struct extent_map, rb_node);
+                }
+                *next_ret = prev;
+        }
+        return NULL;
+}
+
+/*
+ * look for an offset in the tree, and if it can't be found, return
+ * the first offset we can find smaller than 'offset'.
+ */
+static inline struct rb_node *tree_search(struct rb_root *root, u64 offset)
+{
+        struct rb_node *prev;
+        struct rb_node *ret;
+        ret = __tree_search(root, offset, &prev, NULL);
+        if (!ret)
+                return prev;
+        return ret;
+}
+
+/* check to see if two extent_map structs are adjacent and safe to merge */
+static int mergable_maps(struct extent_map *prev, struct extent_map *next)
+{
+        if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
+                return 0;
+
+        if (extent_map_end(prev) == next->start &&
+            prev->flags == next->flags &&
+            prev->bdev == next->bdev &&
+            ((next->block_start == EXTENT_MAP_HOLE &&
+              prev->block_start == EXTENT_MAP_HOLE) ||
+             (next->block_start == EXTENT_MAP_INLINE &&
+              prev->block_start == EXTENT_MAP_INLINE) ||
+             (next->block_start == EXTENT_MAP_DELALLOC &&
+              prev->block_start == EXTENT_MAP_DELALLOC) ||
+             (next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
+              next->block_start == extent_map_block_end(prev)))) {
+                return 1;
+        }
+        return 0;
+}
+
+/**
+ * add_extent_mapping - add new extent map to the extent tree
+ * @tree:       tree to insert new map in
+ * @em:         map to insert
+ *
+ * Insert @em into @tree or perform a simple forward/backward merge with
+ * existing mappings.  The extent_map struct passed in will be inserted
+ * into the tree directly, with an additional reference taken, or a
+ * reference dropped if the merge attempt was sucessfull.
+ */
+int add_extent_mapping(struct extent_map_tree *tree,
+                       struct extent_map *em)
+{
+        int ret = 0;
+        struct extent_map *merge = NULL;
+        struct rb_node *rb;
+        struct extent_map *exist;
+
+        exist = lookup_extent_mapping(tree, em->start, em->len);
+        if (exist) {
+                free_extent_map(exist);
+                ret = -EEXIST;
+                goto out;
+        }
+        assert_spin_locked(&tree->lock);
+        rb = tree_insert(&tree->map, em->start, &em->rb_node);
+        if (rb) {
+                ret = -EEXIST;
+                free_extent_map(merge);
+                goto out;
+        }
+        atomic_inc(&em->refs);
+        if (em->start != 0) {
+                rb = rb_prev(&em->rb_node);
+                if (rb)
+                        merge = rb_entry(rb, struct extent_map, rb_node);
+                if (rb && mergable_maps(merge, em)) {
+                        em->start = merge->start;
+                        em->len += merge->len;
+                        em->block_start = merge->block_start;
+                        merge->in_tree = 0;
+                        rb_erase(&merge->rb_node, &tree->map);
+                        free_extent_map(merge);
+                }
+         }
+        rb = rb_next(&em->rb_node);
+        if (rb)
+                merge = rb_entry(rb, struct extent_map, rb_node);
+        if (rb && mergable_maps(em, merge)) {
+                em->len += merge->len;
+                rb_erase(&merge->rb_node, &tree->map);
+                merge->in_tree = 0;
+                free_extent_map(merge);
+        }
+out:
+        return ret;
+}
+EXPORT_SYMBOL(add_extent_mapping);
+
+/* simple helper to do math around the end of an extent, handling wrap */
+static u64 range_end(u64 start, u64 len)
+{
+        if (start + len < start)
+                return (u64)-1;
+        return start + len;
+}
+
+/**
+ * lookup_extent_mapping - lookup extent_map
+ * @tree:       tree to lookup in
+ * @start:      byte offset to start the search
+ * @len:        length of the lookup range
+ *
+ * Find and return the first extent_map struct in @tree that intersects the
+ * [start, len] range.  There may be additional objects in the tree that
+ * intersect, so check the object returned carefully to make sure that no
+ * additional lookups are needed.
+ */
+struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
+                                         u64 start, u64 len)
+{
+        struct extent_map *em;
+        struct rb_node *rb_node;
+        struct rb_node *prev = NULL;
+        struct rb_node *next = NULL;
+        u64 end = range_end(start, len);
+
+        assert_spin_locked(&tree->lock);
+        rb_node = __tree_search(&tree->map, start, &prev, &next);
+        if (!rb_node && prev) {
+                em = rb_entry(prev, struct extent_map, rb_node);
+                if (end > em->start && start < extent_map_end(em))
+                        goto found;
+        }
+        if (!rb_node && next) {
+                em = rb_entry(next, struct extent_map, rb_node);
+                if (end > em->start && start < extent_map_end(em))
+                        goto found;
+        }
+        if (!rb_node) {
+                em = NULL;
+                goto out;
+        }
+        if (IS_ERR(rb_node)) {
+                em = ERR_PTR(PTR_ERR(rb_node));
+                goto out;
+        }
+        em = rb_entry(rb_node, struct extent_map, rb_node);
+        if (end > em->start && start < extent_map_end(em))
+                goto found;
+
+        em = NULL;
+        goto out;
+
+found:
+        atomic_inc(&em->refs);
+out:
+        return em;
+}
+EXPORT_SYMBOL(lookup_extent_mapping);
+
+/**
+ * remove_extent_mapping - removes an extent_map from the extent tree
+ * @tree:       extent tree to remove from
+ * @em:         extent map beeing removed
+ *
+ * Removes @em from @tree.  No reference counts are dropped, and no checks
+ * are done to see if the range is in use
+ */
+int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
+{
+        int ret = 0;
+
+        WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
+        assert_spin_locked(&tree->lock);
+        rb_erase(&em->rb_node, &tree->map);
+        em->in_tree = 0;
+        return ret;
+}
+EXPORT_SYMBOL(remove_extent_mapping);