[net-next-2.6.git] / fs / btrfs / extent_map.c

#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;

	/*
	 * 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;
}

/**
 * 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_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;
}
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);
Commit	Line	Data
d1310b2e	1	#include <linux/err.h>
a52d9a80	2	#include <linux/gfp.h>
d1310b2e	3	#include <linux/slab.h>
a52d9a80 CM	4	#include <linux/module.h>
a52d9a80 CM	5	#include <linux/spinlock.h>
0a2118df	6	#include <linux/version.h>
d1310b2e	7	#include <linux/hardirq.h>
a52d9a80 CM	8	#include "extent_map.h"
a52d9a80 CM	9
86479a04 CM	10	/* temporary define until extent_map moves out of btrfs */
	11	struct kmem_cache btrfs_cache_create(const char name, size_t size,
	12	unsigned long extra_flags,
	13	void (ctor)(void , struct kmem_cache *,
	14	unsigned long));
	15
a52d9a80	16	static struct kmem_cache *extent_map_cache;
ca664626	17
2f4cbe64	18	int __init extent_map_init(void)
a52d9a80	19	{
86479a04	20	extent_map_cache = btrfs_cache_create("extent_map",
6d36dcd4	21	sizeof(struct extent_map), 0,
a52d9a80	22	NULL);
2f4cbe64 WB	23	if (!extent_map_cache)
2f4cbe64 WB	24	return -ENOMEM;
2f4cbe64	25	return 0;
a52d9a80 CM	26	}
a52d9a80 CM	27
17636e03	28	void extent_map_exit(void)
a52d9a80	29	{
a52d9a80 CM	30	if (extent_map_cache)
a52d9a80 CM	31	kmem_cache_destroy(extent_map_cache);
a52d9a80 CM	32	}
a52d9a80 CM	33
9d2423c5 CH	34	/**
	35	* extent_map_tree_init - initialize extent map tree
	36	* @tree: tree to initialize
	37	* @mask: flags for memory allocations during tree operations
	38	*
	39	* Initialize the extent tree @tree. Should be called for each new inode
	40	* or other user of the extent_map interface.
	41	*/
d1310b2e	42	void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
a52d9a80 CM	43	{
a52d9a80 CM	44	tree->map.rb_node = NULL;
d1310b2e	45	spin_lock_init(&tree->lock);
a52d9a80 CM	46	}
	47	EXPORT_SYMBOL(extent_map_tree_init);
	48
9d2423c5 CH	49	/**
	50	* alloc_extent_map - allocate new extent map structure
	51	* @mask: memory allocation flags
	52	*
	53	* Allocate a new extent_map structure. The new structure is
	54	* returned with a reference count of one and needs to be
	55	* freed using free_extent_map()
	56	*/
a52d9a80 CM	57	struct extent_map *alloc_extent_map(gfp_t mask)
	58	{
	59	struct extent_map *em;
	60	em = kmem_cache_alloc(extent_map_cache, mask);
	61	if (!em \|\| IS_ERR(em))
	62	return em;
	63	em->in_tree = 0;
d1310b2e	64	em->flags = 0;
a52d9a80 CM	65	atomic_set(&em->refs, 1);
	66	return em;
	67	}
	68	EXPORT_SYMBOL(alloc_extent_map);
	69
9d2423c5 CH	70	/**
	71	* free_extent_map - drop reference count of an extent_map
	72	* @em: extent map beeing releasead
	73	*
	74	* Drops the reference out on @em by one and free the structure
	75	* if the reference count hits zero.
	76	*/
a52d9a80 CM	77	void free_extent_map(struct extent_map *em)
a52d9a80 CM	78	{
2bf5a725 CM	79	if (!em)
2bf5a725 CM	80	return;
d1310b2e	81	WARN_ON(atomic_read(&em->refs) == 0);
a52d9a80 CM	82	if (atomic_dec_and_test(&em->refs)) {
	83	WARN_ON(em->in_tree);
	84	kmem_cache_free(extent_map_cache, em);
	85	}
	86	}
	87	EXPORT_SYMBOL(free_extent_map);
	88
a52d9a80 CM	89	static struct rb_node tree_insert(struct rb_root root, u64 offset,
	90	struct rb_node *node)
	91	{
	92	struct rb_node ** p = &root->rb_node;
	93	struct rb_node * parent = NULL;
d1310b2e	94	struct extent_map *entry;
a52d9a80 CM	95
	96	while(*p) {
	97	parent = *p;
d1310b2e CM	98	entry = rb_entry(parent, struct extent_map, rb_node);
	99
	100	WARN_ON(!entry->in_tree);
a52d9a80 CM	101
	102	if (offset < entry->start)
	103	p = &(*p)->rb_left;
d1310b2e	104	else if (offset >= extent_map_end(entry))
a52d9a80 CM	105	p = &(*p)->rb_right;
	106	else
	107	return parent;
	108	}
	109
d1310b2e	110	entry = rb_entry(node, struct extent_map, rb_node);
a52d9a80 CM	111	entry->in_tree = 1;
	112	rb_link_node(node, parent, p);
	113	rb_insert_color(node, root);
	114	return NULL;
	115	}
	116
d352ac68 CM	117	/*
	118	* search through the tree for an extent_map with a given offset. If
	119	* it can't be found, try to find some neighboring extents
	120	*/
a52d9a80	121	static struct rb_node __tree_search(struct rb_root root, u64 offset,
5f56406a CM	122	struct rb_node **prev_ret,
5f56406a CM	123	struct rb_node **next_ret)
a52d9a80 CM	124	{
	125	struct rb_node * n = root->rb_node;
	126	struct rb_node *prev = NULL;
5f56406a	127	struct rb_node *orig_prev = NULL;
d1310b2e CM	128	struct extent_map *entry;
d1310b2e CM	129	struct extent_map *prev_entry = NULL;
a52d9a80 CM	130
a52d9a80 CM	131	while(n) {
d1310b2e	132	entry = rb_entry(n, struct extent_map, rb_node);
a52d9a80 CM	133	prev = n;
	134	prev_entry = entry;
	135
d1310b2e CM	136	WARN_ON(!entry->in_tree);
d1310b2e CM	137
a52d9a80 CM	138	if (offset < entry->start)
a52d9a80 CM	139	n = n->rb_left;
d1310b2e	140	else if (offset >= extent_map_end(entry))
a52d9a80 CM	141	n = n->rb_right;
	142	else
	143	return n;
	144	}
5f56406a CM	145
	146	if (prev_ret) {
	147	orig_prev = prev;
d1310b2e	148	while(prev && offset >= extent_map_end(prev_entry)) {
5f56406a	149	prev = rb_next(prev);
d1310b2e	150	prev_entry = rb_entry(prev, struct extent_map, rb_node);
5f56406a CM	151	}
	152	*prev_ret = prev;
	153	prev = orig_prev;
	154	}
	155
	156	if (next_ret) {
d1310b2e	157	prev_entry = rb_entry(prev, struct extent_map, rb_node);
5f56406a CM	158	while(prev && offset < prev_entry->start) {
5f56406a CM	159	prev = rb_prev(prev);
d1310b2e	160	prev_entry = rb_entry(prev, struct extent_map, rb_node);
5f56406a CM	161	}
5f56406a CM	162	*next_ret = prev;
a52d9a80	163	}
a52d9a80 CM	164	return NULL;
	165	}
	166
d352ac68 CM	167	/*
	168	* look for an offset in the tree, and if it can't be found, return
	169	* the first offset we can find smaller than 'offset'.
	170	*/
a52d9a80 CM	171	static inline struct rb_node tree_search(struct rb_root root, u64 offset)
	172	{
	173	struct rb_node *prev;
	174	struct rb_node *ret;
5f56406a	175	ret = __tree_search(root, offset, &prev, NULL);
a52d9a80 CM	176	if (!ret)
	177	return prev;
	178	return ret;
	179	}
	180
d352ac68	181	/* check to see if two extent_map structs are adjacent and safe to merge */
d1310b2e	182	static int mergable_maps(struct extent_map prev, struct extent_map next)
a52d9a80	183	{
7f3c74fb CM	184	if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
	185	return 0;
	186
c8b97818 CM	187	/*
	188	* don't merge compressed extents, we need to know their
	189	* actual size
	190	*/
	191	if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
	192	return 0;
	193
d1310b2e CM	194	if (extent_map_end(prev) == next->start &&
	195	prev->flags == next->flags &&
	196	prev->bdev == next->bdev &&
	197	((next->block_start == EXTENT_MAP_HOLE &&
	198	prev->block_start == EXTENT_MAP_HOLE) \|\|
	199	(next->block_start == EXTENT_MAP_INLINE &&
	200	prev->block_start == EXTENT_MAP_INLINE) \|\|
	201	(next->block_start == EXTENT_MAP_DELALLOC &&
	202	prev->block_start == EXTENT_MAP_DELALLOC) \|\|
	203	(next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
	204	next->block_start == extent_map_block_end(prev)))) {
	205	return 1;
	206	}
a52d9a80 CM	207	return 0;
	208	}
	209
9d2423c5 CH	210	/**
	211	* add_extent_mapping - add new extent map to the extent tree
	212	* @tree: tree to insert new map in
	213	* @em: map to insert
	214	*
	215	* Insert @em into @tree or perform a simple forward/backward merge with
	216	* existing mappings. The extent_map struct passed in will be inserted
	217	* into the tree directly, with an additional reference taken, or a
	218	* reference dropped if the merge attempt was sucessfull.
a52d9a80 CM	219	*/
	220	int add_extent_mapping(struct extent_map_tree *tree,
	221	struct extent_map *em)
	222	{
	223	int ret = 0;
d1310b2e	224	struct extent_map *merge = NULL;
a52d9a80	225	struct rb_node *rb;
7c2fe32a	226	struct extent_map *exist;
a52d9a80	227
7c2fe32a CM	228	exist = lookup_extent_mapping(tree, em->start, em->len);
	229	if (exist) {
	230	free_extent_map(exist);
	231	ret = -EEXIST;
	232	goto out;
	233	}
64f26f74	234	assert_spin_locked(&tree->lock);
d1310b2e	235	rb = tree_insert(&tree->map, em->start, &em->rb_node);
a52d9a80	236	if (rb) {
a52d9a80	237	ret = -EEXIST;
e6dcd2dc	238	free_extent_map(merge);
a52d9a80 CM	239	goto out;
	240	}
	241	atomic_inc(&em->refs);
	242	if (em->start != 0) {
	243	rb = rb_prev(&em->rb_node);
	244	if (rb)
d1310b2e CM	245	merge = rb_entry(rb, struct extent_map, rb_node);
	246	if (rb && mergable_maps(merge, em)) {
	247	em->start = merge->start;
	248	em->len += merge->len;
c8b97818	249	em->block_len += merge->block_len;
d1310b2e CM	250	em->block_start = merge->block_start;
	251	merge->in_tree = 0;
	252	rb_erase(&merge->rb_node, &tree->map);
	253	free_extent_map(merge);
a52d9a80 CM	254	}
a52d9a80 CM	255	}
d1310b2e CM	256	rb = rb_next(&em->rb_node);
	257	if (rb)
	258	merge = rb_entry(rb, struct extent_map, rb_node);
	259	if (rb && mergable_maps(em, merge)) {
	260	em->len += merge->len;
c8b97818	261	em->block_len += merge->len;
d1310b2e CM	262	rb_erase(&merge->rb_node, &tree->map);
	263	merge->in_tree = 0;
	264	free_extent_map(merge);
	265	}
a52d9a80	266	out:
a52d9a80 CM	267	return ret;
	268	}
	269	EXPORT_SYMBOL(add_extent_mapping);
	270
d352ac68	271	/* simple helper to do math around the end of an extent, handling wrap */
d1310b2e CM	272	static u64 range_end(u64 start, u64 len)
	273	{
	274	if (start + len < start)
	275	return (u64)-1;
	276	return start + len;
	277	}
	278
9d2423c5 CH	279	/**
	280	* lookup_extent_mapping - lookup extent_map
	281	* @tree: tree to lookup in
	282	* @start: byte offset to start the search
	283	* @len: length of the lookup range
	284	*
	285	* Find and return the first extent_map struct in @tree that intersects the
	286	* [start, len] range. There may be additional objects in the tree that
	287	* intersect, so check the object returned carefully to make sure that no
	288	* additional lookups are needed.
a52d9a80 CM	289	*/
a52d9a80 CM	290	struct extent_map lookup_extent_mapping(struct extent_map_tree tree,
d1310b2e	291	u64 start, u64 len)
a52d9a80 CM	292	{
	293	struct extent_map *em;
	294	struct rb_node *rb_node;
306929f3 CH	295	struct rb_node *prev = NULL;
	296	struct rb_node *next = NULL;
	297	u64 end = range_end(start, len);
	298
64f26f74	299	assert_spin_locked(&tree->lock);
5f56406a CM	300	rb_node = __tree_search(&tree->map, start, &prev, &next);
	301	if (!rb_node && prev) {
	302	em = rb_entry(prev, struct extent_map, rb_node);
d1310b2e	303	if (end > em->start && start < extent_map_end(em))
5f56406a CM	304	goto found;
	305	}
	306	if (!rb_node && next) {
	307	em = rb_entry(next, struct extent_map, rb_node);
d1310b2e	308	if (end > em->start && start < extent_map_end(em))
5f56406a CM	309	goto found;
5f56406a CM	310	}
a52d9a80 CM	311	if (!rb_node) {
	312	em = NULL;
	313	goto out;
	314	}
	315	if (IS_ERR(rb_node)) {
	316	em = ERR_PTR(PTR_ERR(rb_node));
	317	goto out;
	318	}
	319	em = rb_entry(rb_node, struct extent_map, rb_node);
d1310b2e CM	320	if (end > em->start && start < extent_map_end(em))
	321	goto found;
	322
	323	em = NULL;
	324	goto out;
	325
5f56406a	326	found:
a52d9a80 CM	327	atomic_inc(&em->refs);
a52d9a80 CM	328	out:
a52d9a80 CM	329	return em;
	330	}
	331	EXPORT_SYMBOL(lookup_extent_mapping);
	332
9d2423c5 CH	333	/**
	334	* remove_extent_mapping - removes an extent_map from the extent tree
	335	* @tree: extent tree to remove from
	336	* @em: extent map beeing removed
	337	*
	338	* Removes @em from @tree. No reference counts are dropped, and no checks
	339	* are done to see if the range is in use
a52d9a80 CM	340	*/
	341	int remove_extent_mapping(struct extent_map_tree tree, struct extent_map em)
	342	{
d1310b2e	343	int ret = 0;
a52d9a80	344
7f3c74fb	345	WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
64f26f74	346	assert_spin_locked(&tree->lock);
d1310b2e CM	347	rb_erase(&em->rb_node, &tree->map);
d1310b2e CM	348	em->in_tree = 0;
a52d9a80 CM	349	return ret;
	350	}
	351	EXPORT_SYMBOL(remove_extent_mapping);