#include <linux/slab.h>
#include <linux/module.h>
#include <linux/spinlock.h>
-#include <linux/version.h>
#include <linux/hardirq.h>
#include "extent_map.h"
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;
- tree->last = 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;
}
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)
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 rb_node **p = &root->rb_node;
+ struct rb_node *parent = NULL;
struct extent_map *entry;
- while(*p) {
+ while (*p) {
parent = *p;
entry = rb_entry(parent, struct extent_map, rb_node);
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 *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) {
+ while (n) {
entry = rb_entry(n, struct extent_map, rb_node);
prev = n;
prev_entry = entry;
if (prev_ret) {
orig_prev = prev;
- while(prev && offset >= extent_map_end(prev_entry)) {
+ while (prev && offset >= extent_map_end(prev_entry)) {
prev = rb_next(prev);
prev_entry = rb_entry(prev, struct extent_map, rb_node);
}
if (next_ret) {
prev_entry = rb_entry(prev, struct extent_map, rb_node);
- while(prev && offset < prev_entry->start) {
+ while (prev && offset < prev_entry->start) {
prev = rb_prev(prev);
prev_entry = rb_entry(prev, struct extent_map, rb_node);
}
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;
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;
+
+ /*
+ * don't merge compressed extents, we need to know their
+ * actual size
+ */
+ if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
+ return 0;
+
if (extent_map_end(prev) == next->start &&
prev->flags == next->flags &&
prev->bdev == next->bdev &&
return 0;
}
-/*
- * add_extent_mapping tries a simple forward/backward merge with existing
- * mappings. The extent_map struct passed in will be inserted into
- * the tree directly (no copies made, just a reference taken).
+/**
+ * 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) {
- merge = rb_entry(rb, struct extent_map, rb_node);
ret = -EEXIST;
+ free_extent_map(merge);
goto out;
}
atomic_inc(&em->refs);
if (rb && mergable_maps(merge, em)) {
em->start = merge->start;
em->len += merge->len;
+ em->block_len += merge->block_len;
em->block_start = merge->block_start;
merge->in_tree = 0;
rb_erase(&merge->rb_node, &tree->map);
merge = rb_entry(rb, struct extent_map, rb_node);
if (rb && mergable_maps(em, merge)) {
em->len += merge->len;
+ em->block_len += merge->len;
rb_erase(&merge->rb_node, &tree->map);
merge->in_tree = 0;
free_extent_map(merge);
}
- tree->last = em;
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 start + len;
}
-/*
- * lookup_extent_mapping returns the first extent_map struct in the
- * 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 you don't need additional lookups.
+/**
+ * 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); em = tree->last; if (em && end > em->start && start < extent_map_end(em)) goto found;
+ 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);
found:
atomic_inc(&em->refs);
- tree->last = em;
out:
return em;
}
EXPORT_SYMBOL(lookup_extent_mapping);
-/*
- * removes an extent_map struct from the tree. No reference counts are
- * dropped, and no checks are done to see if the range is in use
+/**
+ * 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;
- if (tree->last == em)
- tree->last = NULL;
return ret;
}
EXPORT_SYMBOL(remove_extent_mapping);
git.openpandora.org / pandora-kernel.git / blobdiff