[PATCH RFC] extent mapped page cache main code

Chris Mason
2007-07-24T20:03:21Z

Core Extentmap implementation

diff -r 126111346f94 -r 53cabea328f7 fs/Makefile
--- a/fs/Makefile Mon Jul 09 10:53:57 2007 -0400
+++ b/fs/Makefile Tue Jul 24 15:40:27 2007 -0400
@@ -11,7 +11,7 @@ obj-y := open.o read_write.o file_table.
attr.o bad_inode.o file.o filesystems.o namespace.o aio.o \
seq_file.o xattr.o libfs.o fs-writeback.o \
pnode.o drop_caches.o splice.o sync.o utimes.o \
- stack.o
+ stack.o extent_map.o

ifeq ($(CONFIG_BLOCK),y)
obj-y += buffer.o bio.o block_dev.o direct-io.o mpage.o ioprio.o
diff -r 126111346f94 -r 53cabea328f7 fs/extent_map.c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/fs/extent_map.c Tue Jul 24 15:40:27 2007 -0400
@@ -0,0 +1,1591 @@
+#include <linux/bitops.h>
+#include <linux/slab.h>
+#include <linux/bio.h>
+#include <linux/mm.h>
+#include <linux/gfp.h>
+#include <linux/pagemap.h>
+#include <linux/page-flags.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/blkdev.h>
+#include <linux/extent_map.h>
+
+static struct kmem_cache *extent_map_cache;
+static struct kmem_cache *extent_state_cache;
+
+struct tree_entry {
+ u64 start;
+ u64 end;
+ int in_tree;
+ struct rb_node rb_node;
+};
+
+
+/* bits for the extent state */
+#define EXTENT_DIRTY 1
+#define EXTENT_WRITEBACK (1 << 1)
+#define EXTENT_UPTODATE (1 << 2)
+#define EXTENT_LOCKED (1 << 3)
+#define EXTENT_NEW (1 << 4)
+
+#define EXTENT_IOBITS (EXTENT_LOCKED | EXTENT_WRITEBACK)
+
+void __init extent_map_init(void)
+{
+ extent_map_cache = kmem_cache_create("extent_map",
+ sizeof(struct extent_map), 0,
+ SLAB_RECLAIM_ACCOUNT |
+ SLAB_DESTROY_BY_RCU,
+ NULL, NULL);
+ extent_state_cache = kmem_cache_create("extent_state",
+ sizeof(struct extent_state), 0,
+ SLAB_RECLAIM_ACCOUNT |
+ SLAB_DESTROY_BY_RCU,
+ NULL, NULL);
+}
+
+void extent_map_tree_init(struct extent_map_tree *tree,
+ struct address_space *mapping, gfp_t mask)
+{
+ tree->map.rb_node = NULL;
+ tree->state.rb_node = NULL;
+ rwlock_init(&tree->lock);
+ tree->mapping = mapping;
+}
+EXPORT_SYMBOL(extent_map_tree_init);
+
+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;
+ atomic_set(&em->refs, 1);
+ return em;
+}
+EXPORT_SYMBOL(alloc_extent_map);
+
+void free_extent_map(struct extent_map *em)
+{
+ if (atomic_dec_and_test(&em->refs)) {
+ WARN_ON(em->in_tree);
+ kmem_cache_free(extent_map_cache, em);
+ }
+}
+EXPORT_SYMBOL(free_extent_map);
+
+struct extent_state *alloc_extent_state(gfp_t mask)
+{
+ struct extent_state *state;
+ state = kmem_cache_alloc(extent_state_cache, mask);
+ if (!state || IS_ERR(state))
+ return state;
+ state->state = 0;
+ state->in_tree = 0;
+ atomic_set(&state->refs, 1);
+ init_waitqueue_head(&state->wq);
+ return state;
+}
+EXPORT_SYMBOL(alloc_extent_state);
+
+void free_extent_state(struct extent_state *state)
+{
+ if (atomic_dec_and_test(&state->refs)) {
+ WARN_ON(state->in_tree);
+ kmem_cache_free(extent_state_cache, state);
+ }
+}
+EXPORT_SYMBOL(free_extent_state);
+
+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 tree_entry *entry;
+
+ while(*p) {
+ parent = *p;
+ entry = rb_entry(parent, struct tree_entry, rb_node);
+
+ if (offset < entry->end)
+ p = &(*p)->rb_left;
+ else if (offset > entry->end)
+ p = &(*p)->rb_right;
+ else
+ return parent;
+ }
+
+ entry = rb_entry(node, struct tree_entry, rb_node);
+ entry->in_tree = 1;
+ rb_link_node(node, parent, p);
+ rb_insert_color(node, root);
+ return NULL;
+}
+
+static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
+ struct rb_node **prev_ret)
+{
+ struct rb_node * n = root->rb_node;
+ struct rb_node *prev = NULL;
+ struct tree_entry *entry;
+ struct tree_entry *prev_entry = NULL;
+
+ while(n) {
+ entry = rb_entry(n, struct tree_entry, rb_node);
+ prev = n;
+ prev_entry = entry;
+
+ if (offset < entry->end)
+ n = n->rb_left;
+ else if (offset > entry->end)
+ n = n->rb_right;
+ else
+ return n;
+ }
+ if (!prev_ret)
+ return NULL;
+ while(prev && offset > prev_entry->end) {
+ prev = rb_next(prev);
+ prev_entry = rb_entry(prev, struct tree_entry, rb_node);
+ }
+ *prev_ret = prev;
+ return NULL;
+}
+
+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);
+ if (!ret)
+ return prev;
+ return ret;
+}
+
+static int tree_delete(struct rb_root *root, u64 offset)
+{
+ struct rb_node *node;
+ struct tree_entry *entry;
+
+ node = __tree_search(root, offset, NULL);
+ if (!node)
+ return -ENOENT;
+ entry = rb_entry(node, struct tree_entry, rb_node);
+ entry->in_tree = 0;
+ rb_erase(node, root);
+ return 0;
+}
+
+/*
+ * add_extent_mapping tries a simple 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).
+ */
+int add_extent_mapping(struct extent_map_tree *tree,
+ struct extent_map *em)
+{
+ int ret = 0;
+ struct extent_map *prev = NULL;
+ struct rb_node *rb;
+
+ atomic_inc(&em->refs);
+ write_lock_irq(&tree->lock);
+ rb = tree_insert(&tree->map, em->end, &em->rb_node);
+ if (rb) {
+ ret = -EEXIST;
+ goto out;
+ }
+ if (em->start != 0) {
+ rb = rb_prev(&em->rb_node);
+ if (rb)
+ prev = rb_entry(rb, struct extent_map, rb_node);
+ if (prev && prev->end + 1 == em->start &&
+ ((em->block_start == 0 && prev->block_start == 0) ||
+ (em->block_start == prev->block_end + 1))) {
+ em->start = prev->start;
+ em->block_start = prev->block_start;
+ rb_erase(&prev->rb_node, &tree->map);
+ prev->in_tree = 0;
+ free_extent_map(prev);
+ }
+ }
+ write_unlock_irq(&tree->lock);
+out:
+ return ret;
+}
+EXPORT_SYMBOL(add_extent_mapping);
+
+/*
+ * lookup_extent_mapping returns the first extent_map struct in the
+ * tree that intersects the [start, end] (inclusive) 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.
+ */
+struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
+ u64 start, u64 end)
+{
+ struct extent_map *em;
+ struct rb_node *rb_node;
+
+ read_lock_irq(&tree->lock);
+ rb_node = tree_search(&tree->map, start);
+ 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 (em->end < start || em->start > end) {
+ em = NULL;
+ goto out;
+ }
+ atomic_inc(&em->refs);
+out:
+ read_unlock_irq(&tree->lock);
+ 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
+ */
+int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
+{
+ int ret;
+
+ write_lock_irq(&tree->lock);
+ ret = tree_delete(&tree->map, em->end);
+ write_unlock_irq(&tree->lock);
+ return ret;
+}
+EXPORT_SYMBOL(remove_extent_mapping);
+
+/*
+ * utility function to look for merge candidates inside a given range.
+ * Any extents with matching state are merged together into a single
+ * extent in the tree. Extents with EXTENT_IO in their state field
+ * are not merged because the end_io handlers need to be able to do
+ * operations on them without sleeping (or doing allocations/splits).
+ *
+ * This should be called with the tree lock held.
+ */
+static int merge_state(struct extent_map_tree *tree,
+ struct extent_state *state)
+{
+ struct extent_state *other;
+ struct rb_node *other_node;
+
+ if (state->state & EXTENT_IOBITS)
+ return 0;
+
+ other_node = rb_prev(&state->rb_node);
+ if (other_node) {
+ other = rb_entry(other_node, struct extent_state, rb_node);
+ if (other->end == state->start - 1 &&
+ other->state == state->state) {
+ state->start = other->start;
+ other->in_tree = 0;
+ rb_erase(&other->rb_node, &tree->state);
+ free_extent_state(other);
+ }
+ }
+ other_node = rb_next(&state->rb_node);
+ if (other_node) {
+ other = rb_entry(other_node, struct extent_state, rb_node);
+ if (other->start == state->end + 1 &&
+ other->state == state->state) {
+ other->start = state->start;
+ state->in_tree = 0;
+ rb_erase(&state->rb_node, &tree->state);
+ free_extent_state(state);
+ }
+ }
+ return 0;
+}
+
+/*
+ * insert an extent_state struct into the tree. 'bits' are set on the
+ * struct before it is inserted.
+ *
+ * This may return -EEXIST if the extent is already there, in which case the
+ * state struct is freed.
+ *
+ * The tree lock is not taken internally. This is a utility function and
+ * probably isn't what you want to call (see set/clear_extent_bit).
+ */
+static int insert_state(struct extent_map_tree *tree,
+ struct extent_state *state, u64 start, u64 end,
+ int bits)
+{
+ struct rb_node *node;
+
+ state->state |= bits;
+ state->start = start;
+ state->end = end;
+ node = tree_insert(&tree->state, end, &state->rb_node);
+ if (node) {
+ free_extent_state(state);
+ return -EEXIST;
+ }
+ merge_state(tree, state);
+ return 0;
+}
+
+/*
+ * split a given extent state struct in two, inserting the preallocated
+ * struct 'prealloc' as the newly created second half. 'split' indicates an
+ * offset inside 'orig' where it should be split.
+ *
+ * Before calling,
+ * the tree has 'orig' at [orig->start, orig->end]. After calling, there
+ * are two extent state structs in the tree:
+ * prealloc: [orig->start, split - 1]
+ * orig: [ split, orig->end ]
+ *
+ * The tree locks are not taken by this function. They need to be held
+ * by the caller.
+ */
+static int split_state(struct extent_map_tree *tree, struct extent_state *orig,
+ struct extent_state *prealloc, u64 split)
+{
+ struct rb_node *node;
+ prealloc->start = orig->start;
+ prealloc->end = split - 1;
+ prealloc->state = orig->state;
+ node = tree_insert(&tree->state, prealloc->end, &prealloc->rb_node);
+ if (node) {
+ free_extent_state(prealloc);
+ return -EEXIST;
+ }
+ orig->start = split;
+ return 0;
+}
+
+/*
+ * utility function to clear some bits in an extent state struct.
+ * it will optionally wake up any one waiting on this state (wake == 1), or
+ * forcibly remove the state from the tree (delete == 1).
+ *
+ * If no bits are set on the state struct after clearing things, the
+ * struct is freed and removed from the tree
+ */
+static int clear_state_bit(struct extent_map_tree *tree,
+ struct extent_state *state, int bits, int wake,
+ int delete)
+{
+ int ret = state->state & bits;
+ state->state &= ~bits;
+
+ if (wake)
+ wake_up(&state->wq);
+ if (delete || state->state == 0) {
+ if (state->in_tree) {
+ rb_erase(&state->rb_node, &tree->state);
+ state->in_tree = 0;
+ free_extent_state(state);
+ }
+ } else {
+ merge_state(tree, state);
+ }
+ return ret;
+}
+
+/*
+ * clear some bits on a range in the tree. This may require splitting
+ * or inserting elements in the tree, so the gfp mask is used to
+ * indicate which allocations or sleeping are allowed.
+ *
+ * pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove
+ * the given range from the tree regardless of state (ie for truncate).
+ *
+ * the range [start, end] is inclusive.
+ *
+ * This takes the tree lock, and returns < 0 on error, > 0 if any of the
+ * bits were already set, or zero if none of the bits were already set.
+ */
+int clear_extent_bit(struct extent_map_tree *tree, u64 start, u64 end,
+ int bits, int wake, int delete, gfp_t mask)
+{
+ struct extent_state *state;
+ struct extent_state *prealloc = NULL;
+ struct rb_node *node;
+ int err;
+ int set = 0;
+
+again:
+ if (mask & __GFP_WAIT) {
+ if (!prealloc) {
+ prealloc = alloc_extent_state(mask);
+ if (!prealloc)
+ return -ENOMEM;
+ }
+ }
+
+ write_lock_irq(&tree->lock);
+ /*
+ * this search will find the extents that end after
+ * our range starts
+ */
+ node = tree_search(&tree->state, start);
+ if (!node)
+ goto out;
+ state = rb_entry(node, struct extent_state, rb_node);
+ if (state->start > end)
+ goto out;
+ WARN_ON(state->end < start);
+
+ /*
+ * | ---- desired range ---- |
+ * | state | or
+ * | ------------- state -------------- |
+ *
+ * We need to split the extent we found, and may flip
+ * bits on second half.
+ *
+ * If the extent we found extends past our range, we
+ * just split and search again. It'll get split again
+ * the next time though.
+ *
+ * If the extent we found is inside our range, we clear
+ * the desired bit on it.
+ */
+
+ if (state->start < start) {
+ err = split_state(tree, state, prealloc, start);
+ BUG_ON(err == -EEXIST);
+ prealloc = NULL;
+ if (err)
+ goto out;
+ if (state->end <= end) {
+ start = state->end + 1;
+ set |= clear_state_bit(tree, state, bits,
+ wake, delete);
+ } else {
+ start = state->start;
+ }
+ goto search_again;
+ }
+ /*
+ * | ---- desired range ---- |
+ * | state |
+ * We need to split the extent, and clear the bit
+ * on the first half
+ */
+ if (state->start <= end && state->end > end) {
+ err = split_state(tree, state, prealloc, end + 1);
+ BUG_ON(err == -EEXIST);
+
+ if (wake)
+ wake_up(&state->wq);
+ set |= clear_state_bit(tree, prealloc, bits,
+ wake, delete);
+ prealloc = NULL;
+ goto out;
+ }
+
+ start = state->end + 1;
+ set |= clear_state_bit(tree, state, bits, wake, delete);
+ goto search_again;
+
+out:
+ write_unlock_irq(&tree->lock);
+ if (prealloc)
+ free_extent_state(prealloc);
+
+ return set;
+
+search_again:
+ if (start >= end)
+ goto out;
+ write_unlock_irq(&tree->lock);
+ if (mask & __GFP_WAIT)
+ cond_resched();
+ goto again;
+}
+EXPORT_SYMBOL(clear_extent_bit);
+
+static int wait_on_state(struct extent_map_tree *tree,
+ struct extent_state *state)
+{
+ DEFINE_WAIT(wait);
+ prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
+ read_unlock_irq(&tree->lock);
+ schedule();
+ read_lock_irq(&tree->lock);
+ finish_wait(&state->wq, &wait);
+ return 0;
+}
+
+/*
+ * waits for one or more bits to clear on a range in the state tree.
+ * The range [start, end] is inclusive.
+ * The tree lock is taken by this function
+ */
+int wait_extent_bit(struct extent_map_tree *tree, u64 start, u64 end, int bits)
+{
+ struct extent_state *state;
+ struct rb_node *node;
+
+ read_lock_irq(&tree->lock);
+again:
+ while (1) {
+ /*
+ * this search will find all the extents that end after
+ * our range starts
+ */
+ node = tree_search(&tree->state, start);
+ if (!node)
+ break;
+
+ state = rb_entry(node, struct extent_state, rb_node);
+
+ if (state->start > end)
+ goto out;
+
+ if (state->state & bits) {
+ start = state->start;
+ atomic_inc(&state->refs);
+ wait_on_state(tree, state);
+ free_extent_state(state);
+ goto again;
+ }
+ start = state->end + 1;
+
+ if (start > end)
+ break;
+
+ if (need_resched()) {
+ read_unlock_irq(&tree->lock);
+ cond_resched();
+ read_lock_irq(&tree->lock);
+ }
+ }
+out:
+ read_unlock_irq(&tree->lock);
+ return 0;
+}
+EXPORT_SYMBOL(wait_extent_bit);
+
+/*
+ * set some bits on a range in the tree. This may require allocations
+ * or sleeping, so the gfp mask is used to indicate what is allowed.
+ *
+ * If 'exclusive' == 1, this will fail with -EEXIST if some part of the
+ * range already has the desired bits set. The start of the existing
+ * range is returned in failed_start in this case.
+ *
+ * [start, end] is inclusive
+ * This takes the tree lock.
+ */
+int set_extent_bit(struct extent_map_tree *tree, u64 start, u64 end, int bits,
+ int exclusive, u64 *failed_start, gfp_t mask)
+{
+ struct extent_state *state;
+ struct extent_state *prealloc = NULL;
+ struct rb_node *node;
+ int err = 0;
+ int set;
+ u64 last_start;
+ u64 last_end;
+
+again:
+ if (mask & __GFP_WAIT) {
+ prealloc = alloc_extent_state(mask);
+ if (!prealloc)
+ return -ENOMEM;
+ }
+
+ write_lock_irq(&tree->lock);
+ /*
+ * this search will find all the extents that end after
+ * our range starts.
+ */
+ node = tree_search(&tree->state, start);
+ if (!node) {
+ err = insert_state(tree, prealloc, start, end, bits);
+ prealloc = NULL;
+ BUG_ON(err == -EEXIST);
+ goto out;
+ }
+
+ state = rb_entry(node, struct extent_state, rb_node);
+ last_start = state->start;
+ last_end = state->end;
+
+ /*
+ * | ---- desired range ---- |
+ * | state |
+ *
+ * Just lock what we found and keep going
+ */
+ if (state->start == start && state->end <= end) {
+ set = state->state & bits;
+ if (set && exclusive) {
+ *failed_start = state->start;
+ err = -EEXIST;
+ goto out;
+ }
+ state->state |= bits;
+ start = state->end + 1;
+ merge_state(tree, state);
+ goto search_again;
+ }
+
+ /*
+ * | ---- desired range ---- |
+ * | state |
+ * or
+ * | ------------- state -------------- |
+ *
+ * We need to split the extent we found, and may flip bits on
+ * second half.
+ *
+ * If the extent we found extends past our
+ * range, we just split and search again. It'll get split
+ * again the next time though.
+ *
+ * If the extent we found is inside our range, we set the
+ * desired bit on it.
+ */
+ if (state->start < start) {
+ set = state->state & bits;
+ if (exclusive && set) {
+ *failed_start = start;
+ err = -EEXIST;
+ goto out;
+ }
+ err = split_state(tree, state, prealloc, start);
+ BUG_ON(err == -EEXIST);
+ prealloc = NULL;
+ if (err)
+ goto out;
+ if (state->end <= end) {
+ state->state |= bits;
+ start = state->end + 1;
+ merge_state(tree, state);
+ } else {
+ start = state->start;
+ }
+ goto search_again;
+ }
+ /*
+ * | ---- desired range ---- |
+ * | state |
+ * We need to split the extent, and set the bit
+ * on the first half
+ */
+ if (state->start <= end && state->end > end) {
+ set = state->state & bits;
+ if (exclusive && set) {
+ *failed_start = start;
+ err = -EEXIST;
+ goto out;
+ }
+ err = split_state(tree, state, prealloc, end + 1);
+ BUG_ON(err == -EEXIST);
+
+ prealloc->state |= bits;
+ merge_state(tree, prealloc);
+ prealloc = NULL;
+ goto out;
+ }
+
+ /*
+ * | ---- desired range ---- |
+ * | state | or | state |
+ *
+ * There's a hole, we need to insert something in it and
+ * ignore the extent we found.
+ */
+ if (state->start > start) {
+ u64 this_end = min(end, last_start);
+ err = insert_state(tree, prealloc, start, this_end,
+ bits);
+ prealloc = NULL;
+ BUG_ON(err == -EEXIST);
+ if (err)
+ goto out;
+ start = this_end + 1;
+ goto search_again;
+ }
+ goto search_again;
+
+out:
+ write_unlock_irq(&tree->lock);
+ if (prealloc)
+ free_extent_state(prealloc);
+
+ return err;
+
+search_again:
+ if (start > end)
+ goto out;
+ write_unlock_irq(&tree->lock);
+ if (mask & __GFP_WAIT)
+ cond_resched();
+ goto again;
+}
+EXPORT_SYMBOL(set_extent_bit);
+
+/* wrappers around set/clear extent bit */
+int set_extent_dirty(struct extent_map_tree *tree, u64 start, u64 end,
+ gfp_t mask)
+{
+ return set_extent_bit(tree, start, end, EXTENT_DIRTY, 0, NULL,
+ mask);
+}
+EXPORT_SYMBOL(set_extent_dirty);
+
+int clear_extent_dirty(struct extent_map_tree *tree, u64 start, u64 end,
+ gfp_t mask)
+{
+ return clear_extent_bit(tree, start, end, EXTENT_DIRTY, 0, 0, mask);
+}
+EXPORT_SYMBOL(clear_extent_dirty);
+
+int set_extent_new(struct extent_map_tree *tree, u64 start, u64 end,
+ gfp_t mask)
+{
+ return set_extent_bit(tree, start, end, EXTENT_NEW, 0, NULL,
+ mask);
+}
+EXPORT_SYMBOL(set_extent_new);
+
+int clear_extent_new(struct extent_map_tree *tree, u64 start, u64 end,
+ gfp_t mask)
+{
+ return clear_extent_bit(tree, start, end, EXTENT_NEW, 0, 0, mask);
+}
+EXPORT_SYMBOL(clear_extent_new);
+
+int set_extent_uptodate(struct extent_map_tree *tree, u64 start, u64 end,
+ gfp_t mask)
+{
+ return set_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, NULL,
+ mask);
+}
+EXPORT_SYMBOL(set_extent_uptodate);
+
+int clear_extent_uptodate(struct extent_map_tree *tree, u64 start, u64 end,
+ gfp_t mask)
+{
+ return clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0, mask);
+}
+EXPORT_SYMBOL(clear_extent_uptodate);
+
+int set_extent_writeback(struct extent_map_tree *tree, u64 start, u64 end,
+ gfp_t mask)
+{
+ return set_extent_bit(tree, start, end, EXTENT_WRITEBACK,
+ 0, NULL, mask);
+}
+EXPORT_SYMBOL(set_extent_writeback);
+
+int clear_extent_writeback(struct extent_map_tree *tree, u64 start, u64 end,
+ gfp_t mask)
+{
+ return clear_extent_bit(tree, start, end, EXTENT_WRITEBACK, 1, 0, mask);
+}
+EXPORT_SYMBOL(clear_extent_writeback);
+
+int wait_on_extent_writeback(struct extent_map_tree *tree, u64 start, u64 end)
+{
+ return wait_extent_bit(tree, start, end, EXTENT_WRITEBACK);
+}
+EXPORT_SYMBOL(wait_on_extent_writeback);
+
+/*
+ * locks a range in ascending order, waiting for any locked regions
+ * it hits on the way. [start,end] are inclusive, and this will sleep.
+ */
+int lock_extent(struct extent_map_tree *tree, u64 start, u64 end, gfp_t mask)
+{
+ int err;
+ u64 failed_start;
+ while (1) {
+ err = set_extent_bit(tree, start, end, EXTENT_LOCKED, 1,
+ &failed_start, mask);
+ if (err == -EEXIST && (mask & __GFP_WAIT)) {
+ wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
+ start = failed_start;
+ } else {
+ break;
+ }
+ WARN_ON(start > end);
+ }
+ return err;
+}
+EXPORT_SYMBOL(lock_extent);
+
+int unlock_extent(struct extent_map_tree *tree, u64 start, u64 end,
+ gfp_t mask)
+{
+ return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, mask);
+}
+EXPORT_SYMBOL(unlock_extent);
+
+/*
+ * helper function to set pages and extents in the tree dirty
+ */
+int set_range_dirty(struct extent_map_tree *tree, u64 start, u64 end)
+{
+ unsigned long index = start >> PAGE_CACHE_SHIFT;
+ unsigned long end_index = end >> PAGE_CACHE_SHIFT;
+ struct page *page;
+
+ while (index <= end_index) {
+ page = find_get_page(tree->mapping, index);
+ BUG_ON(!page);
+ __set_page_dirty_nobuffers(page);
+ page_cache_release(page);
+ index++;
+ }
+ set_extent_dirty(tree, start, end, GFP_NOFS);
+ return 0;
+}
+EXPORT_SYMBOL(set_range_dirty);
+
+/*
+ * helper function to set both pages and extents in the tree writeback
+ */
+int set_range_writeback(struct extent_map_tree *tree, u64 start, u64 end)
+{
+ unsigned long index = start >> PAGE_CACHE_SHIFT;
+ unsigned long end_index = end >> PAGE_CACHE_SHIFT;
+ struct page *page;
+
+ while (index <= end_index) {
+ page = find_get_page(tree->mapping, index);
+ BUG_ON(!page);
+ set_page_writeback(page);
+ page_cache_release(page);
+ index++;
+ }
+ set_extent_writeback(tree, start, end, GFP_NOFS);
+ return 0;
+}
+EXPORT_SYMBOL(set_range_writeback);
+
+/*
+ * helper function to lock both pages and extents in the tree.
+ * pages must be locked first.
+ */
+int lock_range(struct extent_map_tree *tree, u64 start, u64 end)
+{
+ unsigned long index = start >> PAGE_CACHE_SHIFT;
+ unsigned long end_index = end >> PAGE_CACHE_SHIFT;
+ struct page *page;
+ int err;
+
+ while (index <= end_index) {
+ page = grab_cache_page(tree->mapping, index);
+ if (!page) {
+ err = -ENOMEM;
+ goto failed;
+ }
+ if (IS_ERR(page)) {
+ err = PTR_ERR(page);
+ goto failed;
+ }
+ index++;
+ }
+ lock_extent(tree, start, end, GFP_NOFS);
+ return 0;
+
+failed:
+ /*
+ * we failed above in getting the page at 'index', so we undo here
+ * up to but not including the page at 'index'
+ */
+ end_index = index;
+ index = start >> PAGE_CACHE_SHIFT;
+ while (index < end_index) {
+ page = find_get_page(tree->mapping, index);
+ unlock_page(page);
+ page_cache_release(page);
+ index++;
+ }
+ return err;
+}
+EXPORT_SYMBOL(lock_range);
+
+/*
+ * helper function to unlock both pages and extents in the tree.
+ */
+int unlock_range(struct extent_map_tree *tree, u64 start, u64 end)
+{
+ unsigned long index = start >> PAGE_CACHE_SHIFT;
+ unsigned long end_index = end >> PAGE_CACHE_SHIFT;
+ struct page *page;
+
+ while (index <= end_index) {
+ page = find_get_page(tree->mapping, index);
+ unlock_page(page);
+ page_cache_release(page);
+ index++;
+ }
+ unlock_extent(tree, start, end, GFP_NOFS);
+ return 0;
+}
+EXPORT_SYMBOL(unlock_range);
+
+/*
+ * searches a range in the state tree for a given mask.
+ * If 'filled' == 1, this returns 1 only if ever extent in the tree
+ * has the bits set. Otherwise, 1 is returned if any bit in the
+ * range is found set.
+ */
+static int test_range_bit(struct extent_map_tree *tree, u64 start, u64 end,
+ int bits, int filled)
+{
+ struct extent_state *state = NULL;
+ struct rb_node *node;
+ int bitset = 0;
+
+ read_lock_irq(&tree->lock);
+ node = tree_search(&tree->state, start);
+ while (node && start <= end) {
+ state = rb_entry(node, struct extent_state, rb_node);
+ if (state->start > end)
+ break;
+
+ if (filled && state->start > start) {
+ bitset = 0;
+ break;
+ }
+ if (state->state & bits) {
+ bitset = 1;
+ if (!filled)
+ break;
+ } else if (filled) {
+ bitset = 0;
+ break;
+ }
+ start = state->end + 1;
+ if (start > end)
+ break;
+ node = rb_next(node);
+ }
+ read_unlock_irq(&tree->lock);
+ return bitset;
+}
+
+/*
+ * helper function to set a given page up to date if all the
+ * extents in the tree for that page are up to date
+ */
+static int check_page_uptodate(struct extent_map_tree *tree,
+ struct page *page)
+{
+ u64 start = page->index << PAGE_CACHE_SHIFT;
+ u64 end = start + PAGE_CACHE_SIZE - 1;
+ if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1))
+ SetPageUptodate(page);
+ return 0;
+}
+
+/*
+ * helper function to unlock a page if all the extents in the tree
+ * for that page are unlocked
+ */
+static int check_page_locked(struct extent_map_tree *tree,
+ struct page *page)
+{
+ u64 start = page->index << PAGE_CACHE_SHIFT;
+ u64 end = start + PAGE_CACHE_SIZE - 1;
+ if (!test_range_bit(tree, start, end, EXTENT_LOCKED, 0))
+ unlock_page(page);
+ return 0;
+}
+
+/*
+ * helper function to end page writeback if all the extents
+ * in the tree for that page are done with writeback
+ */
+static int check_page_writeback(struct extent_map_tree *tree,
+ struct page *page)
+{
+ u64 start = page->index << PAGE_CACHE_SHIFT;
+ u64 end = start + PAGE_CACHE_SIZE - 1;
+ if (!test_range_bit(tree, start, end, EXTENT_WRITEBACK, 0))
+ end_page_writeback(page);
+ return 0;
+}
+
+/* lots and lots of room for performance fixes in the end_bio funcs */
+
+/*
+ * after a writepage IO is done, we need to:
+ * clear the uptodate bits on error
+ * clear the writeback bits in the extent tree for this IO
+ * end_page_writeback if the page has no more pending IO
+ *
+ * Scheduling is not allowed, so the extent state tree is expected
+ * to have one and only one object corresponding to this IO.
+ */
+static int end_bio_extent_writepage(struct bio *bio,
+ unsigned int bytes_done, int err)
+{
+ const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+ struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
+ struct extent_map_tree *tree = bio->bi_private;
+ u64 start;
+ u64 end;
+ int whole_page;
+
+ if (bio->bi_size)
+ return 1;
+
+ do {
+ struct page *page = bvec->bv_page;
+ start = (page->index << PAGE_CACHE_SHIFT) + bvec->bv_offset;
+ end = start + bvec->bv_len - 1;
+
+ if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
+ whole_page = 1;
+ else
+ whole_page = 0;
+
+ if (--bvec >= bio->bi_io_vec)
+ prefetchw(&bvec->bv_page->flags);
+
+ if (!uptodate) {
+ clear_extent_uptodate(tree, start, end, GFP_ATOMIC);
+ ClearPageUptodate(page);
+ SetPageError(page);
+ }
+ clear_extent_writeback(tree, start, end, GFP_ATOMIC);
+
+ if (whole_page)
+ end_page_writeback(page);
+ else
+ check_page_writeback(tree, page);
+ } while (bvec >= bio->bi_io_vec);
+
+ bio_put(bio);
+ return 0;
+}
+
+/*
+ * after a readpage IO is done, we need to:
+ * clear the uptodate bits on error
+ * set the uptodate bits if things worked
+ * set the page up to date if all extents in the tree are uptodate
+ * clear the lock bit in the extent tree
+ * unlock the page if there are no other extents locked for it
+ *
+ * Scheduling is not allowed, so the extent state tree is expected
+ * to have one and only one object corresponding to this IO.
+ */
+static int end_bio_extent_readpage(struct bio *bio,
+ unsigned int bytes_done, int err)
+{
+ const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+ struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
+ struct extent_map_tree *tree = bio->bi_private;
+ u64 start;
+ u64 end;
+ int whole_page;
+
+ if (bio->bi_size)
+ return 1;
+
+ do {
+ struct page *page = bvec->bv_page;
+ start = (page->index << PAGE_CACHE_SHIFT) + bvec->bv_offset;
+ end = start + bvec->bv_len - 1;
+
+ if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
+ whole_page = 1;
+ else
+ whole_page = 0;
+
+ if (--bvec >= bio->bi_io_vec)
+ prefetchw(&bvec->bv_page->flags);
+
+ if (uptodate) {
+ set_extent_uptodate(tree, start, end, GFP_ATOMIC);
+ if (whole_page)
+ SetPageUptodate(page);
+ else
+ check_page_uptodate(tree, page);
+ } else {
+ ClearPageUptodate(page);
+ SetPageError(page);
+ }
+
+ unlock_extent(tree, start, end, GFP_ATOMIC);
+
+ if (whole_page)
+ unlock_page(page);
+ else
+ check_page_locked(tree, page);
+ } while (bvec >= bio->bi_io_vec);
+
+ bio_put(bio);
+ return 0;
+}
+
+/*
+ * IO done from prepare_write is pretty simple, we just unlock
+ * the structs in the extent tree when done, and set the uptodate bits
+ * as appropriate.
+ */
+static int end_bio_extent_preparewrite(struct bio *bio,
+ unsigned int bytes_done, int err)
+{
+ const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+ struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
+ struct extent_map_tree *tree = bio->bi_private;
+ u64 start;
+ u64 end;
+
+ if (bio->bi_size)
+ return 1;
+
+ do {
+ struct page *page = bvec->bv_page;
+ start = (page->index << PAGE_CACHE_SHIFT) + bvec->bv_offset;
+ end = start + bvec->bv_len - 1;
+
+ if (--bvec >= bio->bi_io_vec)
+ prefetchw(&bvec->bv_page->flags);
+
+ if (uptodate) {
+ set_extent_uptodate(tree, start, end, GFP_ATOMIC);
+ } else {
+ ClearPageUptodate(page);
+ SetPageError(page);
+ }
+
+ unlock_extent(tree, start, end, GFP_ATOMIC);
+
+ } while (bvec >= bio->bi_io_vec);
+
+ bio_put(bio);
+ return 0;
+}
+
+static int submit_extent_page(int rw, struct extent_map_tree *tree,
+ struct page *page, sector_t sector,
+ size_t size, unsigned long offset,
+ struct block_device *bdev,
+ bio_end_io_t end_io_func)
+{
+ struct bio *bio;
+ int ret = 0;
+
+ bio = bio_alloc(GFP_NOIO, 1);
+
+ bio->bi_sector = sector;
+ bio->bi_bdev = bdev;
+ bio->bi_io_vec[0].bv_page = page;
+ bio->bi_io_vec[0].bv_len = size;
+ bio->bi_io_vec[0].bv_offset = offset;
+
+ bio->bi_vcnt = 1;
+ bio->bi_idx = 0;
+ bio->bi_size = size;
+
+ bio->bi_end_io = end_io_func;
+ bio->bi_private = tree;
+
+ bio_get(bio);
+ submit_bio(rw, bio);
+
+ if (bio_flagged(bio, BIO_EOPNOTSUPP))
+ ret = -EOPNOTSUPP;
+
+ bio_put(bio);
+ return ret;
+}
+
+/*
+ * basic readpage implementation. Locked extent state structs are inserted
+ * into the tree that are removed when the IO is done (by the end_io
+ * handlers)
+ */
+int extent_read_full_page(struct extent_map_tree *tree, struct page *page,
+ get_extent_t *get_extent)
+{
+ struct inode *inode = page->mapping->host;
+ u64 start = page->index << PAGE_CACHE_SHIFT;
+ u64 page_end = start + PAGE_CACHE_SIZE - 1;
+ u64 end;
+ u64 cur = start;
+ u64 extent_offset;
+ u64 last_byte = i_size_read(inode);
+ u64 block_start;
+ sector_t sector;
+ struct extent_map *em;
+ struct block_device *bdev;
+ int ret;
+ int nr = 0;
+ size_t page_offset = 0;
+ size_t iosize;
+ size_t blocksize = inode->i_sb->s_blocksize;
+
+ if (!PagePrivate(page)) {
+ SetPagePrivate(page);
+ set_page_private(page, 1);
+ page_cache_get(page);
+ }
+
+ end = min(page_end, last_byte - 1);
+ end = end | (blocksize - 1);
+ lock_extent(tree, start, end, GFP_NOFS);
+
+ if (last_byte <= start)
+ goto done;
+
+ while (cur <= end) {
+ em = get_extent(inode, page, page_offset, cur, end, 0);
+ if (IS_ERR(em) || !em) {
+ SetPageError(page);
+ break;
+ }
+
+ extent_offset = cur - em->start;
+ BUG_ON(em->end < cur);
+ BUG_ON(end < cur);
+
+ iosize = min(em->end - cur, end - cur) + 1;
+ iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
+ sector = (em->block_start + extent_offset) >> 9;
+ bdev = em->bdev;
+ block_start = em->block_start;
+ free_extent_map(em);
+ em = NULL;
+
+ /* we've found a hole, just zero and go on */
+ if (block_start == 0) {
+ zero_user_page(page, page_offset, iosize, KM_USER0);
+ set_extent_uptodate(tree, cur, cur + iosize - 1,
+ GFP_NOFS);
+ unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
+ cur = cur + iosize;
+ page_offset += iosize;
+ continue;
+ }
+
+ /* the get_extent function already copied into the page */
+ if (test_range_bit(tree, cur, cur + iosize - 1,
+ EXTENT_UPTODATE, 1)) {
+ unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
+ cur = cur + iosize;
+ page_offset += iosize;
+ continue;
+ }
+ ret = submit_extent_page(READ, tree, page,
+ sector, iosize, page_offset, bdev,
+ end_bio_extent_readpage);
+ if (ret)
+ SetPageError(page);
+ cur = cur + iosize;
+ page_offset += iosize;
+ nr++;
+ }
+done:
+ if (last_byte - 1 < page_end) {
+ size_t last_off = last_byte & (PAGE_CACHE_SIZE - 1);
+ zero_user_page(page, last_off, PAGE_CACHE_SIZE - last_off,
+ KM_USER0);
+ }
+ if (!nr) {
+ if (!PageError(page))
+ SetPageUptodate(page);
+ unlock_extent(tree, start, end, GFP_NOFS);
+ unlock_page(page);
+ }
+ return 0;
+}
+EXPORT_SYMBOL(extent_read_full_page);
+
+/*
+ * the writepage semantics are similar to regular writepage. extent
+ * records are inserted to lock ranges in the tree, and as dirty areas
+ * are found, they are marked writeback. Then the lock bits are removed
+ * and the end_io handler clears the writeback ranges
+ */
+int extent_write_full_page(struct extent_map_tree *tree, struct page *page,
+ get_extent_t *get_extent,
+ struct writeback_control *wbc)
+{
+ struct inode *inode = page->mapping->host;
+ u64 start = page->index << PAGE_CACHE_SHIFT;
+ u64 page_end = start + PAGE_CACHE_SIZE - 1;
+ u64 end;
+ u64 cur = start;
+ u64 extent_offset;
+ u64 last_byte = i_size_read(inode);
+ u64 block_start;
+ sector_t sector;
+ struct extent_map *em;
+ struct block_device *bdev;
+ int ret;
+ int nr = 0;
+ size_t page_offset = 0;
+ size_t iosize;
+ size_t blocksize;
+ loff_t i_size = i_size_read(inode);
+ unsigned long end_index = i_size >> PAGE_CACHE_SHIFT;
+
+ if (page->index > end_index) {
+ unlock_page(page);
+ return 0;
+ }
+
+ if (page->index == end_index) {
+ size_t offset = i_size & (PAGE_CACHE_SIZE - 1);
+ zero_user_page(page, offset,
+ PAGE_CACHE_SIZE - offset, KM_USER0);
+ }
+
+ if (!PagePrivate(page)) {
+ SetPagePrivate(page);
+ set_page_private(page, 1);
+ page_cache_get(page);
+ }
+
+ end = min(page_end, last_byte - 1);
+ lock_extent(tree, start, page_end, GFP_NOFS);
+
+ if (last_byte <= start)
+ goto done;
+
+ set_extent_uptodate(tree, start, page_end, GFP_NOFS);
+ blocksize = inode->i_sb->s_blocksize;
+
+ while (cur <= end) {
+ em = get_extent(inode, page, page_offset, cur, end, 1);
+ if (IS_ERR(em) || !em) {
+ SetPageError(page);
+ break;
+ }
+
+ extent_offset = cur - em->start;
+ BUG_ON(em->end < cur);
+ BUG_ON(end < cur);
+ iosize = min(em->end - cur, end - cur) + 1;
+ iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
+ sector = (em->block_start + extent_offset) >> 9;
+ bdev = em->bdev;
+ block_start = em->block_start;
+ free_extent_map(em);
+ em = NULL;
+
+ if (block_start == 0) {
+ clear_extent_dirty(tree, cur,
+ cur + iosize - 1, GFP_NOFS);
+ cur = cur + iosize;
+ page_offset += iosize;
+ continue;
+ }
+
+ /* leave this out until we have a page_mkwrite call */
+ if (0 && !test_range_bit(tree, cur, cur + iosize - 1,
+ EXTENT_DIRTY, 0)) {
+ cur = cur + iosize;
+ page_offset += iosize;
+ continue;
+ }
+ clear_extent_dirty(tree, cur, cur + iosize - 1, GFP_NOFS);
+ set_range_writeback(tree, cur, cur + iosize - 1);
+ ret = submit_extent_page(WRITE, tree, page,
+ sector, iosize, page_offset, bdev,
+ end_bio_extent_writepage);
+ if (ret)
+ SetPageError(page);
+ cur = cur + iosize;
+ page_offset += iosize;
+ nr++;
+ }
+done:
+ unlock_extent(tree, start, page_end, GFP_NOFS);
+ unlock_page(page);
+ return 0;
+}
+EXPORT_SYMBOL(extent_write_full_page);
+
+/*
+ * basic invalidatepage code, this waits on any locked or writeback
+ * ranges corresponding to the page, and then deletes any extent state
+ * records from the tree
+ */
+int extent_invalidatepage(struct extent_map_tree *tree,
+ struct page *page, unsigned long offset)
+{
+ u64 start = (page->index << PAGE_CACHE_SHIFT) + offset;
+ u64 end = start + PAGE_CACHE_SIZE - 1 - offset;
+ lock_extent(tree, start, end, GFP_NOFS);
+ wait_on_extent_writeback(tree, start, end);
+ clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 1, GFP_NOFS);
+ return 0;
+}
+EXPORT_SYMBOL(extent_invalidatepage);
+
+/*
+ * simple commit_write call, set_range_dirty is used to mark both
+ * the pages and the extent records as dirty
+ */
+int extent_commit_write(struct extent_map_tree *tree,
+ struct inode *inode, struct page *page,
+ unsigned from, unsigned to)
+{
+ loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
+
+ if (!PagePrivate(page)) {
+ SetPagePrivate(page);
+ set_page_private(page, 1);
+ page_cache_get(page);
+ }
+
+ set_page_dirty(page);
+
+ if (pos > inode->i_size) {
+ i_size_write(inode, pos);
+ mark_inode_dirty(inode);
+ }
+ return 0;
+}
+EXPORT_SYMBOL(extent_commit_write);
+
+int extent_prepare_write(struct extent_map_tree *tree,
+ struct inode *inode, struct page *page,
+ unsigned from, unsigned to, get_extent_t *get_extent)
+{
+ u64 page_start = page->index << PAGE_CACHE_SHIFT;
+ u64 page_end = page_start + PAGE_CACHE_SIZE - 1;
+ u64 block_start;
+ u64 orig_block_start;
+ u64 block_end;
+ u64 cur_end;
+ struct extent_map *em;
+ unsigned blocksize = 1 << inode->i_blkbits;
+ size_t page_offset = 0;
+ size_t block_off_start;
+ size_t block_off_end;
+ int err = 0;
+ int iocount = 0;
+ int ret = 0;
+ int isnew;
+
+ if (!PagePrivate(page)) {
+ SetPagePrivate(page);
+ set_page_private(page, 1);
+ page_cache_get(page);
+ }
+ block_start = (page_start + from) & ~((u64)blocksize - 1);
+ block_end = (page_start + to - 1) | (blocksize - 1);
+ orig_block_start = block_start;
+
+ lock_extent(tree, page_start, page_end, GFP_NOFS);
+ while(block_start <= block_end) {
+ em = get_extent(inode, page, page_offset, block_start,
+ block_end, 1);
+ if (IS_ERR(em) || !em) {
+ goto err;
+ }
+ cur_end = min(block_end, em->end);
+ block_off_start = block_start & (PAGE_CACHE_SIZE - 1);
+ block_off_end = block_off_start + blocksize;
+ isnew = clear_extent_new(tree, block_start, cur_end, GFP_NOFS);
+
+ if (!PageUptodate(page) && isnew &&
+ (block_off_end > to || block_off_start < from)) {
+ void *kaddr;
+
+ kaddr = kmap_atomic(page, KM_USER0);
+ if (block_off_end > to)
+ memset(kaddr + to, 0, block_off_end - to);
+ if (block_off_start < from)
+ memset(kaddr + block_off_start, 0,
+ from - block_off_start);
+ flush_dcache_page(page);
+ kunmap_atomic(kaddr, KM_USER0);
+ }
+ if (!isnew && !PageUptodate(page) &&
+ (block_off_end > to || block_off_start < from) &&
+ !test_range_bit(tree, block_start, cur_end,
+ EXTENT_UPTODATE, 1)) {
+ u64 sector;
+ u64 extent_offset = block_start - em->start;
+ size_t iosize;
+ sector = (em->block_start + extent_offset) >> 9;
+ iosize = (cur_end - block_start + blocksize - 1) &
+ ~((u64)blocksize - 1);
+ /*
+ * we've already got the extent locked, but we
+ * need to split the state such that our end_bio
+ * handler can clear the lock.
+ */
+ set_extent_bit(tree, block_start,
+ block_start + iosize - 1,
+ EXTENT_LOCKED, 0, NULL, GFP_NOFS);
+ ret = submit_extent_page(READ, tree, page,
+ sector, iosize, page_offset, em->bdev,
+ end_bio_extent_preparewrite);
+ iocount++;
+ block_start = block_start + iosize;
+ } else {
+ set_extent_uptodate(tree, block_start, cur_end,
+ GFP_NOFS);
+ unlock_extent(tree, block_start, cur_end, GFP_NOFS);
+ block_start = cur_end + 1;
+ }
+ page_offset = block_start & (PAGE_CACHE_SIZE - 1);
+ free_extent_map(em);
+ }
+ if (iocount) {
+ wait_extent_bit(tree, orig_block_start,
+ block_end, EXTENT_LOCKED);
+ }
+ check_page_uptodate(tree, page);
+err:
+ /* FIXME, zero out newly allocated blocks on error */
+ return err;
+}
+EXPORT_SYMBOL(extent_prepare_write);
+
+/*
+ * a helper for releasepage. As long as there are no locked extents
+ * in the range corresponding to the page, both state records and extent
+ * map records are removed
+ */
+int try_release_extent_mapping(struct extent_map_tree *tree, struct page *page)
+{
+ struct extent_map *em;
+ u64 start = page->index << PAGE_CACHE_SHIFT;
+ u64 end = start + PAGE_CACHE_SIZE - 1;
+ u64 orig_start = start;
+
+ while (start <= end) {
+ em = lookup_extent_mapping(tree, start, end);
+ if (!em || IS_ERR(em))
+ break;
+ if (test_range_bit(tree, em->start, em->end,
+ EXTENT_LOCKED, 0)) {
+ free_extent_map(em);
+ start = em->end + 1;
+ break;
+ }
+ remove_extent_mapping(tree, em);
+ start = em->end + 1;
+ /* once for the rb tree */
+ free_extent_map(em);
+ /* once for us */
+ free_extent_map(em);
+ }
+ WARN_ON(test_range_bit(tree, orig_start, end, EXTENT_WRITEBACK, 0));
+ clear_extent_bit(tree, orig_start, end, EXTENT_UPTODATE,
+ 1, 1, GFP_NOFS);
+ return 1;
+}
+EXPORT_SYMBOL(try_release_extent_mapping);
+
diff -r 126111346f94 -r 53cabea328f7 include/linux/extent_map.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/linux/extent_map.h Tue Jul 24 15:40:27 2007 -0400
@@ -0,0 +1,82 @@
+#ifndef __EXTENTMAP__
+#define __EXTENTMAP__
+
+#include <linux/rbtree.h>
+
+struct extent_map_tree {
+ struct rb_root map;
+ struct rb_root state;
+ struct address_space *mapping;
+ rwlock_t lock;
+};
+
+/* note, this must start with the same fields as fs/extent_map.c:tree_entry */
+struct extent_map {
+ u64 start;
+ u64 end; /* inclusive */
+ int in_tree;
+ struct rb_node rb_node;
+ /* block_start and block_end are in bytes */
+ u64 block_start;
+ u64 block_end; /* inclusive */
+ struct block_device *bdev;
+ atomic_t refs;
+};
+
+/* note, this must start with the same fields as fs/extent_map.c:tree_entry */
+struct extent_state {
+ u64 start;
+ u64 end; /* inclusive */
+ int in_tree;
+ struct rb_node rb_node;
+ wait_queue_head_t wq;
+ atomic_t refs;
+ unsigned long state;
+};
+
+struct extent_buffer {
+ u64 start;
+ u64 end; /* inclusive */
+ char *addr;
+ struct page *pages[];
+};
+
+typedef struct extent_map *(get_extent_t)(struct inode *inode,
+ struct page *page,
+ size_t page_offset,
+ u64 start, u64 end,
+ int create);
+
+void extent_map_tree_init(struct extent_map_tree *tree,
+ struct address_space *mapping, gfp_t mask);
+struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
+ u64 start, u64 end);
+int add_extent_mapping(struct extent_map_tree *tree,
+ struct extent_map *em);
+int try_release_extent_mapping(struct extent_map_tree *tree, struct page *page);
+int lock_extent(struct extent_map_tree *tree, u64 start, u64 end, gfp_t mask);
+int unlock_extent(struct extent_map_tree *tree, u64 start, u64 end, gfp_t mask);
+struct extent_map *alloc_extent_map(gfp_t mask);
+void free_extent_map(struct extent_map *em);
+int extent_read_full_page(struct extent_map_tree *tree, struct page *page,
+ get_extent_t *get_extent);
+void __init extent_map_init(void);
+void __exit extent_map_exit(void);
+int extent_clean_all_trees(struct extent_map_tree *tree);
+int set_extent_uptodate(struct extent_map_tree *tree, u64 start, u64 end,
+ gfp_t mask);
+int set_extent_new(struct extent_map_tree *tree, u64 start, u64 end,
+ gfp_t mask);
+int extent_invalidatepage(struct extent_map_tree *tree,
+ struct page *page, unsigned long offset);
+int extent_write_full_page(struct extent_map_tree *tree, struct page *page,
+ get_extent_t *get_extent,
+ struct writeback_control *wbc);
+int extent_prepare_write(struct extent_map_tree *tree,
+ struct inode *inode, struct page *page,
+ unsigned from, unsigned to, get_extent_t *get_extent);
+int extent_commit_write(struct extent_map_tree *tree,
+ struct inode *inode, struct page *page,
+ unsigned from, unsigned to);
+int set_range_dirty(struct extent_map_tree *tree, u64 start, u64 end);
+#endif
diff -r 126111346f94 -r 53cabea328f7 init/main.c
--- a/init/main.c Mon Jul 09 10:53:57 2007 -0400
+++ b/init/main.c Tue Jul 24 15:40:27 2007 -0400
@@ -94,6 +94,7 @@ extern void pidmap_init(void);
extern void pidmap_init(void);
extern void prio_tree_init(void);
extern void radix_tree_init(void);
+extern void extent_map_init(void);
extern void free_initmem(void);
#ifdef CONFIG_ACPI
extern void acpi_early_init(void);
@@ -618,6 +619,7 @@ asmlinkage void __init start_kernel(void
security_init();
vfs_caches_init(num_physpages);
radix_tree_init();
+ extent_map_init();
signals_init();
/* rootfs populating might need page-writeback */
page_writeback_init();