[deliverable/linux.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/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);
}

/**
 * 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;
}

/**
 * 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;
}

/*
 * 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;
		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);

	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;
}

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