[linux-2.6-block.git] / fs / btrfs / extent_map.c

#include <linux/err.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/hardirq.h>
#include "ctree.h"
#include "extent_map.h"


static struct kmem_cache *extent_map_cache;

int __init extent_map_init(void)
{
	extent_map_cache = kmem_cache_create("extent_map",
			sizeof(struct extent_map), 0,
			SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, 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_ROOT;
	rwlock_init(&tree->lock);
}

/**
 * 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)
		return NULL;
	em->in_tree = 0;
	em->flags = 0;
	em->compress_type = BTRFS_COMPRESS_NONE;
	atomic_set(&em->refs, 1);
	return em;
}

/**
 * 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);
	}
}

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;
}

/* 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 &&
	    ((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;
}

int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len)
{
	int ret = 0;
	struct extent_map *merge = NULL;
	struct rb_node *rb;
	struct extent_map *em;

	write_lock(&tree->lock);
	em = lookup_extent_mapping(tree, start, len);

	WARN_ON(!em || em->start != start);

	if (!em)
		goto out;

	clear_bit(EXTENT_FLAG_PINNED, &em->flags);

	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_len += merge->block_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;
		em->block_len += merge->len;
		rb_erase(&merge->rb_node, &tree->map);
		merge->in_tree = 0;
		free_extent_map(merge);
	}

	free_extent_map(em);
out:
	write_unlock(&tree->lock);
	return ret;

}

/**
 * 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 successfull.
 */
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;
	}
	rb = tree_insert(&tree->map, em->start, &em->rb_node);
	if (rb) {
		ret = -EEXIST;
		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_len += merge->block_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;
		em->block_len += merge->len;
		rb_erase(&merge->rb_node, &tree->map);
		merge->in_tree = 0;
		free_extent_map(merge);
	}
out:
	return ret;
}

/* 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);

	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_CAST(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;
}

/**
 * search_extent_mapping - find a nearby 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.
 *
 * If one can't be found, any nearby extent may be returned
 */
struct extent_map *search_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;

	rb_node = __tree_search(&tree->map, start, &prev, &next);
	if (!rb_node && prev) {
		em = rb_entry(prev, struct extent_map, rb_node);
		goto found;
	}
	if (!rb_node && next) {
		em = rb_entry(next, struct extent_map, rb_node);
		goto found;
	}
	if (!rb_node) {
		em = NULL;
		goto out;
	}
	if (IS_ERR(rb_node)) {
		em = ERR_CAST(rb_node);
		goto out;
	}
	em = rb_entry(rb_node, struct extent_map, rb_node);
	goto found;

	em = NULL;
	goto out;

found:
	atomic_inc(&em->refs);
out:
	return em;
}

/**
 * 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));
	rb_erase(&em->rb_node, &tree->map);
	em->in_tree = 0;
	return ret;
}
Commit	Line	Data
d1310b2e	1	#include <linux/err.h>
d1310b2e	2	#include <linux/slab.h>
a52d9a80 CM	3	#include <linux/module.h>
a52d9a80 CM	4	#include <linux/spinlock.h>
d1310b2e	5	#include <linux/hardirq.h>
261507a0	6	#include "ctree.h"
a52d9a80 CM	7	#include "extent_map.h"
a52d9a80 CM	8
86479a04	9
a52d9a80	10	static struct kmem_cache *extent_map_cache;
ca664626	11
2f4cbe64	12	int __init extent_map_init(void)
a52d9a80	13	{
9601e3f6 CH	14	extent_map_cache = kmem_cache_create("extent_map",
	15	sizeof(struct extent_map), 0,
	16	SLAB_RECLAIM_ACCOUNT \| SLAB_MEM_SPREAD, NULL);
2f4cbe64 WB	17	if (!extent_map_cache)
2f4cbe64 WB	18	return -ENOMEM;
2f4cbe64	19	return 0;
a52d9a80 CM	20	}
a52d9a80 CM	21
17636e03	22	void extent_map_exit(void)
a52d9a80	23	{
a52d9a80 CM	24	if (extent_map_cache)
a52d9a80 CM	25	kmem_cache_destroy(extent_map_cache);
a52d9a80 CM	26	}
a52d9a80 CM	27
9d2423c5 CH	28	/**
	29	* extent_map_tree_init - initialize extent map tree
	30	* @tree: tree to initialize
	31	* @mask: flags for memory allocations during tree operations
	32	*
	33	* Initialize the extent tree @tree. Should be called for each new inode
	34	* or other user of the extent_map interface.
	35	*/
d1310b2e	36	void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
a52d9a80	37	{
6bef4d31	38	tree->map = RB_ROOT;
890871be	39	rwlock_init(&tree->lock);
a52d9a80	40	}
a52d9a80	41
9d2423c5 CH	42	/**
	43	* alloc_extent_map - allocate new extent map structure
	44	* @mask: memory allocation flags
	45	*
	46	* Allocate a new extent_map structure. The new structure is
	47	* returned with a reference count of one and needs to be
	48	* freed using free_extent_map()
	49	*/
a52d9a80 CM	50	struct extent_map *alloc_extent_map(gfp_t mask)
	51	{
	52	struct extent_map *em;
	53	em = kmem_cache_alloc(extent_map_cache, mask);
c26a9203 TI	54	if (!em)
c26a9203 TI	55	return NULL;
a52d9a80	56	em->in_tree = 0;
d1310b2e	57	em->flags = 0;
261507a0	58	em->compress_type = BTRFS_COMPRESS_NONE;
a52d9a80 CM	59	atomic_set(&em->refs, 1);
	60	return em;
	61	}
a52d9a80	62
9d2423c5 CH	63	/**
	64	* free_extent_map - drop reference count of an extent_map
	65	* @em: extent map beeing releasead
	66	*
	67	* Drops the reference out on @em by one and free the structure
	68	* if the reference count hits zero.
	69	*/
a52d9a80 CM	70	void free_extent_map(struct extent_map *em)
a52d9a80 CM	71	{
2bf5a725 CM	72	if (!em)
2bf5a725 CM	73	return;
d1310b2e	74	WARN_ON(atomic_read(&em->refs) == 0);
a52d9a80 CM	75	if (atomic_dec_and_test(&em->refs)) {
	76	WARN_ON(em->in_tree);
	77	kmem_cache_free(extent_map_cache, em);
	78	}
	79	}
a52d9a80	80
a52d9a80 CM	81	static struct rb_node tree_insert(struct rb_root root, u64 offset,
	82	struct rb_node *node)
	83	{
d397712b CM	84	struct rb_node **p = &root->rb_node;
d397712b CM	85	struct rb_node *parent = NULL;
d1310b2e	86	struct extent_map *entry;
a52d9a80	87
d397712b	88	while (*p) {
a52d9a80	89	parent = *p;
d1310b2e CM	90	entry = rb_entry(parent, struct extent_map, rb_node);
	91
	92	WARN_ON(!entry->in_tree);
a52d9a80 CM	93
	94	if (offset < entry->start)
	95	p = &(*p)->rb_left;
d1310b2e	96	else if (offset >= extent_map_end(entry))
a52d9a80 CM	97	p = &(*p)->rb_right;
	98	else
	99	return parent;
	100	}
	101
d1310b2e	102	entry = rb_entry(node, struct extent_map, rb_node);
a52d9a80 CM	103	entry->in_tree = 1;
	104	rb_link_node(node, parent, p);
	105	rb_insert_color(node, root);
	106	return NULL;
	107	}
	108
d352ac68 CM	109	/*
	110	* search through the tree for an extent_map with a given offset. If
	111	* it can't be found, try to find some neighboring extents
	112	*/
a52d9a80	113	static struct rb_node __tree_search(struct rb_root root, u64 offset,
5f56406a CM	114	struct rb_node **prev_ret,
5f56406a CM	115	struct rb_node **next_ret)
a52d9a80	116	{
d397712b	117	struct rb_node *n = root->rb_node;
a52d9a80	118	struct rb_node *prev = NULL;
5f56406a	119	struct rb_node *orig_prev = NULL;
d1310b2e CM	120	struct extent_map *entry;
d1310b2e CM	121	struct extent_map *prev_entry = NULL;
a52d9a80	122
d397712b	123	while (n) {
d1310b2e	124	entry = rb_entry(n, struct extent_map, rb_node);
a52d9a80 CM	125	prev = n;
	126	prev_entry = entry;
	127
d1310b2e CM	128	WARN_ON(!entry->in_tree);
d1310b2e CM	129
a52d9a80 CM	130	if (offset < entry->start)
a52d9a80 CM	131	n = n->rb_left;
d1310b2e	132	else if (offset >= extent_map_end(entry))
a52d9a80 CM	133	n = n->rb_right;
	134	else
	135	return n;
	136	}
5f56406a CM	137
	138	if (prev_ret) {
	139	orig_prev = prev;
d397712b	140	while (prev && offset >= extent_map_end(prev_entry)) {
5f56406a	141	prev = rb_next(prev);
d1310b2e	142	prev_entry = rb_entry(prev, struct extent_map, rb_node);
5f56406a CM	143	}
	144	*prev_ret = prev;
	145	prev = orig_prev;
	146	}
	147
	148	if (next_ret) {
d1310b2e	149	prev_entry = rb_entry(prev, struct extent_map, rb_node);
d397712b	150	while (prev && offset < prev_entry->start) {
5f56406a	151	prev = rb_prev(prev);
d1310b2e	152	prev_entry = rb_entry(prev, struct extent_map, rb_node);
5f56406a CM	153	}
5f56406a CM	154	*next_ret = prev;
a52d9a80	155	}
a52d9a80 CM	156	return NULL;
	157	}
	158
d352ac68	159	/* check to see if two extent_map structs are adjacent and safe to merge */
d1310b2e	160	static int mergable_maps(struct extent_map prev, struct extent_map next)
a52d9a80	161	{
7f3c74fb CM	162	if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
	163	return 0;
	164
c8b97818 CM	165	/*
	166	* don't merge compressed extents, we need to know their
	167	* actual size
	168	*/
	169	if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
	170	return 0;
	171
d1310b2e CM	172	if (extent_map_end(prev) == next->start &&
	173	prev->flags == next->flags &&
	174	prev->bdev == next->bdev &&
	175	((next->block_start == EXTENT_MAP_HOLE &&
	176	prev->block_start == EXTENT_MAP_HOLE) \|\|
	177	(next->block_start == EXTENT_MAP_INLINE &&
	178	prev->block_start == EXTENT_MAP_INLINE) \|\|
	179	(next->block_start == EXTENT_MAP_DELALLOC &&
	180	prev->block_start == EXTENT_MAP_DELALLOC) \|\|
	181	(next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
	182	next->block_start == extent_map_block_end(prev)))) {
	183	return 1;
	184	}
a52d9a80 CM	185	return 0;
	186	}
	187
a1ed835e CM	188	int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len)
	189	{
	190	int ret = 0;
	191	struct extent_map *merge = NULL;
	192	struct rb_node *rb;
	193	struct extent_map *em;
	194
	195	write_lock(&tree->lock);
	196	em = lookup_extent_mapping(tree, start, len);
	197
4eb3991c	198	WARN_ON(!em \|\| em->start != start);
a1ed835e CM	199
	200	if (!em)
	201	goto out;
	202
	203	clear_bit(EXTENT_FLAG_PINNED, &em->flags);
	204
	205	if (em->start != 0) {
	206	rb = rb_prev(&em->rb_node);
	207	if (rb)
	208	merge = rb_entry(rb, struct extent_map, rb_node);
	209	if (rb && mergable_maps(merge, em)) {
	210	em->start = merge->start;
	211	em->len += merge->len;
	212	em->block_len += merge->block_len;
	213	em->block_start = merge->block_start;
	214	merge->in_tree = 0;
	215	rb_erase(&merge->rb_node, &tree->map);
	216	free_extent_map(merge);
	217	}
	218	}
	219
	220	rb = rb_next(&em->rb_node);
	221	if (rb)
	222	merge = rb_entry(rb, struct extent_map, rb_node);
	223	if (rb && mergable_maps(em, merge)) {
	224	em->len += merge->len;
	225	em->block_len += merge->len;
	226	rb_erase(&merge->rb_node, &tree->map);
	227	merge->in_tree = 0;
	228	free_extent_map(merge);
	229	}
	230
	231	free_extent_map(em);
	232	out:
	233	write_unlock(&tree->lock);
	234	return ret;
	235
	236	}
	237
9d2423c5 CH	238	/**
	239	* add_extent_mapping - add new extent map to the extent tree
	240	* @tree: tree to insert new map in
	241	* @em: map to insert
	242	*
	243	* Insert @em into @tree or perform a simple forward/backward merge with
	244	* existing mappings. The extent_map struct passed in will be inserted
	245	* into the tree directly, with an additional reference taken, or a
af901ca1	246	* reference dropped if the merge attempt was successfull.
a52d9a80 CM	247	*/
	248	int add_extent_mapping(struct extent_map_tree *tree,
	249	struct extent_map *em)
	250	{
	251	int ret = 0;
d1310b2e	252	struct extent_map *merge = NULL;
a52d9a80	253	struct rb_node *rb;
7c2fe32a	254	struct extent_map *exist;
a52d9a80	255
7c2fe32a CM	256	exist = lookup_extent_mapping(tree, em->start, em->len);
	257	if (exist) {
	258	free_extent_map(exist);
	259	ret = -EEXIST;
	260	goto out;
	261	}
d1310b2e	262	rb = tree_insert(&tree->map, em->start, &em->rb_node);
a52d9a80	263	if (rb) {
a52d9a80 CM	264	ret = -EEXIST;
	265	goto out;
	266	}
	267	atomic_inc(&em->refs);
	268	if (em->start != 0) {
	269	rb = rb_prev(&em->rb_node);
	270	if (rb)
d1310b2e CM	271	merge = rb_entry(rb, struct extent_map, rb_node);
	272	if (rb && mergable_maps(merge, em)) {
	273	em->start = merge->start;
	274	em->len += merge->len;
c8b97818	275	em->block_len += merge->block_len;
d1310b2e CM	276	em->block_start = merge->block_start;
	277	merge->in_tree = 0;
	278	rb_erase(&merge->rb_node, &tree->map);
	279	free_extent_map(merge);
a52d9a80 CM	280	}
a52d9a80 CM	281	}
d1310b2e CM	282	rb = rb_next(&em->rb_node);
	283	if (rb)
	284	merge = rb_entry(rb, struct extent_map, rb_node);
	285	if (rb && mergable_maps(em, merge)) {
	286	em->len += merge->len;
c8b97818	287	em->block_len += merge->len;
d1310b2e CM	288	rb_erase(&merge->rb_node, &tree->map);
	289	merge->in_tree = 0;
	290	free_extent_map(merge);
	291	}
a52d9a80	292	out:
a52d9a80 CM	293	return ret;
a52d9a80 CM	294	}
a52d9a80	295
d352ac68	296	/* simple helper to do math around the end of an extent, handling wrap */
d1310b2e CM	297	static u64 range_end(u64 start, u64 len)
	298	{
	299	if (start + len < start)
	300	return (u64)-1;
	301	return start + len;
	302	}
	303
9d2423c5 CH	304	/**
	305	* lookup_extent_mapping - lookup extent_map
	306	* @tree: tree to lookup in
	307	* @start: byte offset to start the search
	308	* @len: length of the lookup range
	309	*
	310	* Find and return the first extent_map struct in @tree that intersects the
	311	* [start, len] range. There may be additional objects in the tree that
	312	* intersect, so check the object returned carefully to make sure that no
	313	* additional lookups are needed.
a52d9a80 CM	314	*/
a52d9a80 CM	315	struct extent_map lookup_extent_mapping(struct extent_map_tree tree,
d1310b2e	316	u64 start, u64 len)
a52d9a80 CM	317	{
	318	struct extent_map *em;
	319	struct rb_node *rb_node;
306929f3 CH	320	struct rb_node *prev = NULL;
	321	struct rb_node *next = NULL;
	322	u64 end = range_end(start, len);
	323
5f56406a CM	324	rb_node = __tree_search(&tree->map, start, &prev, &next);
	325	if (!rb_node && prev) {
	326	em = rb_entry(prev, struct extent_map, rb_node);
d1310b2e	327	if (end > em->start && start < extent_map_end(em))
5f56406a CM	328	goto found;
	329	}
	330	if (!rb_node && next) {
	331	em = rb_entry(next, struct extent_map, rb_node);
d1310b2e	332	if (end > em->start && start < extent_map_end(em))
5f56406a CM	333	goto found;
5f56406a CM	334	}
a52d9a80 CM	335	if (!rb_node) {
	336	em = NULL;
	337	goto out;
	338	}
	339	if (IS_ERR(rb_node)) {
d0b678cb	340	em = ERR_CAST(rb_node);
a52d9a80 CM	341	goto out;
	342	}
	343	em = rb_entry(rb_node, struct extent_map, rb_node);
d1310b2e CM	344	if (end > em->start && start < extent_map_end(em))
	345	goto found;
	346
	347	em = NULL;
	348	goto out;
	349
5f56406a	350	found:
a52d9a80 CM	351	atomic_inc(&em->refs);
a52d9a80 CM	352	out:
a52d9a80 CM	353	return em;
a52d9a80 CM	354	}
a52d9a80	355
b917b7c3 CM	356	/**
	357	* search_extent_mapping - find a nearby extent map
	358	* @tree: tree to lookup in
	359	* @start: byte offset to start the search
	360	* @len: length of the lookup range
	361	*
	362	* Find and return the first extent_map struct in @tree that intersects the
	363	* [start, len] range.
	364	*
	365	* If one can't be found, any nearby extent may be returned
	366	*/
	367	struct extent_map search_extent_mapping(struct extent_map_tree tree,
	368	u64 start, u64 len)
	369	{
	370	struct extent_map *em;
	371	struct rb_node *rb_node;
	372	struct rb_node *prev = NULL;
	373	struct rb_node *next = NULL;
	374
	375	rb_node = __tree_search(&tree->map, start, &prev, &next);
	376	if (!rb_node && prev) {
	377	em = rb_entry(prev, struct extent_map, rb_node);
	378	goto found;
	379	}
	380	if (!rb_node && next) {
	381	em = rb_entry(next, struct extent_map, rb_node);
	382	goto found;
	383	}
	384	if (!rb_node) {
	385	em = NULL;
	386	goto out;
	387	}
	388	if (IS_ERR(rb_node)) {
d0b678cb	389	em = ERR_CAST(rb_node);
b917b7c3 CM	390	goto out;
	391	}
	392	em = rb_entry(rb_node, struct extent_map, rb_node);
	393	goto found;
	394
	395	em = NULL;
	396	goto out;
	397
	398	found:
	399	atomic_inc(&em->refs);
	400	out:
	401	return em;
	402	}
	403
9d2423c5 CH	404	/**
	405	* remove_extent_mapping - removes an extent_map from the extent tree
	406	* @tree: extent tree to remove from
	407	* @em: extent map beeing removed
	408	*
	409	* Removes @em from @tree. No reference counts are dropped, and no checks
	410	* are done to see if the range is in use
a52d9a80 CM	411	*/
	412	int remove_extent_mapping(struct extent_map_tree tree, struct extent_map em)
	413	{
d1310b2e	414	int ret = 0;
a52d9a80	415
7f3c74fb	416	WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
d1310b2e CM	417	rb_erase(&em->rb_node, &tree->map);
d1310b2e CM	418	em->in_tree = 0;
a52d9a80 CM	419	return ret;
a52d9a80 CM	420	}