diff options
Diffstat (limited to 'fs/btrfs/extent_io.c')
| -rw-r--r-- | fs/btrfs/extent_io.c | 3717 |
1 files changed, 3717 insertions, 0 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c new file mode 100644 index 000000000000..e086d407f1fa --- /dev/null +++ b/fs/btrfs/extent_io.c @@ -0,0 +1,3717 @@ +#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/swap.h> +#include <linux/version.h> +#include <linux/writeback.h> +#include <linux/pagevec.h> +#include "extent_io.h" +#include "extent_map.h" +#include "compat.h" +#include "ctree.h" +#include "btrfs_inode.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_state_cache; +static struct kmem_cache *extent_buffer_cache; + +static LIST_HEAD(buffers); +static LIST_HEAD(states); + +#define LEAK_DEBUG 0 +#ifdef LEAK_DEBUG +static DEFINE_SPINLOCK(leak_lock); +#endif + +#define BUFFER_LRU_MAX 64 + +struct tree_entry { + u64 start; + u64 end; + struct rb_node rb_node; +}; + +struct extent_page_data { + struct bio *bio; + struct extent_io_tree *tree; + get_extent_t *get_extent; + + /* tells writepage not to lock the state bits for this range + * it still does the unlocking + */ + int extent_locked; +}; + +int __init extent_io_init(void) +{ + extent_state_cache = btrfs_cache_create("extent_state", + sizeof(struct extent_state), 0, + NULL); + if (!extent_state_cache) + return -ENOMEM; + + extent_buffer_cache = btrfs_cache_create("extent_buffers", + sizeof(struct extent_buffer), 0, + NULL); + if (!extent_buffer_cache) + goto free_state_cache; + return 0; + +free_state_cache: + kmem_cache_destroy(extent_state_cache); + return -ENOMEM; +} + +void extent_io_exit(void) +{ + struct extent_state *state; + struct extent_buffer *eb; + + while (!list_empty(&states)) { + state = list_entry(states.next, struct extent_state, leak_list); + printk(KERN_ERR "btrfs state leak: start %llu end %llu " + "state %lu in tree %p refs %d\n", + (unsigned long long)state->start, + (unsigned long long)state->end, + state->state, state->tree, atomic_read(&state->refs)); + list_del(&state->leak_list); + kmem_cache_free(extent_state_cache, state); + + } + + while (!list_empty(&buffers)) { + eb = list_entry(buffers.next, struct extent_buffer, leak_list); + printk(KERN_ERR "btrfs buffer leak start %llu len %lu " + "refs %d\n", (unsigned long long)eb->start, + eb->len, atomic_read(&eb->refs)); + list_del(&eb->leak_list); + kmem_cache_free(extent_buffer_cache, eb); + } + if (extent_state_cache) + kmem_cache_destroy(extent_state_cache); + if (extent_buffer_cache) + kmem_cache_destroy(extent_buffer_cache); +} + +void extent_io_tree_init(struct extent_io_tree *tree, + struct address_space *mapping, gfp_t mask) +{ + tree->state.rb_node = NULL; + tree->buffer.rb_node = NULL; + tree->ops = NULL; + tree->dirty_bytes = 0; + spin_lock_init(&tree->lock); + spin_lock_init(&tree->buffer_lock); + tree->mapping = mapping; +} + +static struct extent_state *alloc_extent_state(gfp_t mask) +{ + struct extent_state *state; +#ifdef LEAK_DEBUG + unsigned long flags; +#endif + + state = kmem_cache_alloc(extent_state_cache, mask); + if (!state) + return state; + state->state = 0; + state->private = 0; + state->tree = NULL; +#ifdef LEAK_DEBUG + spin_lock_irqsave(&leak_lock, flags); + list_add(&state->leak_list, &states); + spin_unlock_irqrestore(&leak_lock, flags); +#endif + atomic_set(&state->refs, 1); + init_waitqueue_head(&state->wq); + return state; +} + +static void free_extent_state(struct extent_state *state) +{ + if (!state) + return; + if (atomic_dec_and_test(&state->refs)) { +#ifdef LEAK_DEBUG + unsigned long flags; +#endif + WARN_ON(state->tree); +#ifdef LEAK_DEBUG + spin_lock_irqsave(&leak_lock, flags); + list_del(&state->leak_list); + spin_unlock_irqrestore(&leak_lock, flags); +#endif + kmem_cache_free(extent_state_cache, 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->start) + 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); + rb_link_node(node, parent, p); + rb_insert_color(node, root); + return NULL; +} + +static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset, + struct rb_node **prev_ret, + struct rb_node **next_ret) +{ + struct rb_root *root = &tree->state; + struct rb_node *n = root->rb_node; + struct rb_node *prev = NULL; + struct rb_node *orig_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->start) + n = n->rb_left; + else if (offset > entry->end) + n = n->rb_right; + else + return n; + } + + if (prev_ret) { + orig_prev = prev; + while (prev && offset > prev_entry->end) { + prev = rb_next(prev); + prev_entry = rb_entry(prev, struct tree_entry, rb_node); + } + *prev_ret = prev; + prev = orig_prev; + } + + if (next_ret) { + prev_entry = rb_entry(prev, struct tree_entry, rb_node); + while (prev && offset < prev_entry->start) { + prev = rb_prev(prev); + prev_entry = rb_entry(prev, struct tree_entry, rb_node); + } + *next_ret = prev; + } + return NULL; +} + +static inline struct rb_node *tree_search(struct extent_io_tree *tree, + u64 offset) +{ + struct rb_node *prev = NULL; + struct rb_node *ret; + + ret = __etree_search(tree, offset, &prev, NULL); + if (!ret) + return prev; + return ret; +} + +static struct extent_buffer *buffer_tree_insert(struct extent_io_tree *tree, + u64 offset, struct rb_node *node) +{ + struct rb_root *root = &tree->buffer; + struct rb_node **p = &root->rb_node; + struct rb_node *parent = NULL; + struct extent_buffer *eb; + + while (*p) { + parent = *p; + eb = rb_entry(parent, struct extent_buffer, rb_node); + + if (offset < eb->start) + p = &(*p)->rb_left; + else if (offset > eb->start) + p = &(*p)->rb_right; + else + return eb; + } + + rb_link_node(node, parent, p); + rb_insert_color(node, root); + return NULL; +} + +static struct extent_buffer *buffer_search(struct extent_io_tree *tree, + u64 offset) +{ + struct rb_root *root = &tree->buffer; + struct rb_node *n = root->rb_node; + struct extent_buffer *eb; + + while (n) { + eb = rb_entry(n, struct extent_buffer, rb_node); + if (offset < eb->start) + n = n->rb_left; + else if (offset > eb->start) + n = n->rb_right; + else + return eb; + } + return NULL; +} + +/* + * 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_io_tree *tree, + struct extent_state *state) +{ + struct extent_state *other; + struct rb_node *other_node; + + if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY)) + 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->tree = NULL; + 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->tree = NULL; + rb_erase(&state->rb_node, &tree->state); + free_extent_state(state); + } + } + return 0; +} + +static void set_state_cb(struct extent_io_tree *tree, + struct extent_state *state, + unsigned long bits) +{ + if (tree->ops && tree->ops->set_bit_hook) { + tree->ops->set_bit_hook(tree->mapping->host, state->start, + state->end, state->state, bits); + } +} + +static void clear_state_cb(struct extent_io_tree *tree, + struct extent_state *state, + unsigned long bits) +{ + if (tree->ops && tree->ops->clear_bit_hook) { + tree->ops->clear_bit_hook(tree->mapping->host, state->start, + state->end, state->state, bits); + } +} + +/* + * 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_io_tree *tree, + struct extent_state *state, u64 start, u64 end, + int bits) +{ + struct rb_node *node; + + if (end < start) { + printk(KERN_ERR "btrfs end < start %llu %llu\n", + (unsigned long long)end, + (unsigned long long)start); + WARN_ON(1); + } + if (bits & EXTENT_DIRTY) + tree->dirty_bytes += end - start + 1; + set_state_cb(tree, state, bits); + state->state |= bits; + state->start = start; + state->end = end; + node = tree_insert(&tree->state, end, &state->rb_node); + if (node) { + struct extent_state *found; + found = rb_entry(node, struct extent_state, rb_node); + printk(KERN_ERR "btrfs found node %llu %llu on insert of " + "%llu %llu\n", (unsigned long long)found->start, + (unsigned long long)found->end, + (unsigned long long)start, (unsigned long long)end); + free_extent_state(state); + return -EEXIST; + } + state->tree = tree; + 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_io_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; + orig->start = split; + + node = tree_insert(&tree->state, prealloc->end, &prealloc->rb_node); + if (node) { + struct extent_state *found; + found = rb_entry(node, struct extent_state, rb_node); + free_extent_state(prealloc); + return -EEXIST; + } + prealloc->tree = tree; + 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_io_tree *tree, + struct extent_state *state, int bits, int wake, + int delete) +{ + int ret = state->state & bits; + + if ((bits & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) { + u64 range = state->end - state->start + 1; + WARN_ON(range > tree->dirty_bytes); + tree->dirty_bytes -= range; + } + clear_state_cb(tree, state, bits); + state->state &= ~bits; + if (wake) + wake_up(&state->wq); + if (delete || state->state == 0) { + if (state->tree) { + clear_state_cb(tree, state, state->state); + rb_erase(&state->rb_node, &tree->state); + state->tree = NULL; + free_extent_state(state); + } else { + WARN_ON(1); + } + } 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_io_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 (!prealloc && (mask & __GFP_WAIT)) { + prealloc = alloc_extent_state(mask); + if (!prealloc) + return -ENOMEM; + } + + spin_lock(&tree->lock); + /* + * this search will find the extents that end after + * our range starts + */ + node = tree_search(tree, 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) { + if (!prealloc) + prealloc = alloc_extent_state(GFP_ATOMIC); + 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) { + if (!prealloc) + prealloc = alloc_extent_state(GFP_ATOMIC); + 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: + spin_unlock(&tree->lock); + if (prealloc) + free_extent_state(prealloc); + + return set; + +search_again: + if (start > end) + goto out; + spin_unlock(&tree->lock); + if (mask & __GFP_WAIT) + cond_resched(); + goto again; +} + +static int wait_on_state(struct extent_io_tree *tree, + struct extent_state *state) + __releases(tree->lock) + __acquires(tree->lock) +{ + DEFINE_WAIT(wait); + prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE); + spin_unlock(&tree->lock); + schedule(); + spin_lock(&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_io_tree *tree, u64 start, u64 end, int bits) +{ + struct extent_state *state; + struct rb_node *node; + + spin_lock(&tree->lock); +again: + while (1) { + /* + * this search will find all the extents that end after + * our range starts + */ + node = tree_search(tree, 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()) { + spin_unlock(&tree->lock); + cond_resched(); + spin_lock(&tree->lock); + } + } +out: + spin_unlock(&tree->lock); + return 0; +} + +static void set_state_bits(struct extent_io_tree *tree, + struct extent_state *state, + int bits) +{ + if ((bits & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) { + u64 range = state->end - state->start + 1; + tree->dirty_bytes += range; + } + set_state_cb(tree, state, bits); + state->state |= bits; +} + +/* + * 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. + */ +static int set_extent_bit(struct extent_io_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 (!prealloc && (mask & __GFP_WAIT)) { + prealloc = alloc_extent_state(mask); + if (!prealloc) + return -ENOMEM; + } + + spin_lock(&tree->lock); + /* + * this search will find all the extents that end after + * our range starts. + */ + node = tree_search(tree, 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; + } + set_state_bits(tree, 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) { + set_state_bits(tree, state, bits); + start = state->end + 1; + merge_state(tree, state); + } else { + start = state->start; + } + goto search_again; + } + /* + * | ---- 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; + if (end < last_start) + this_end = end; + else + this_end = last_start - 1; + 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; + } + /* + * | ---- 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); + + set_state_bits(tree, prealloc, bits); + merge_state(tree, prealloc); + prealloc = NULL; + goto out; + } + + goto search_again; + +out: + spin_unlock(&tree->lock); + if (prealloc) + free_extent_state(prealloc); + + return err; + +search_again: + if (start > end) + goto out; + spin_unlock(&tree->lock); + if (mask & __GFP_WAIT) + cond_resched(); + goto again; +} + +/* wrappers around set/clear extent bit */ +int set_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end, + gfp_t mask) +{ + return set_extent_bit(tree, start, end, EXTENT_DIRTY, 0, NULL, + mask); +} + +int set_extent_ordered(struct extent_io_tree *tree, u64 start, u64 end, + gfp_t mask) +{ + return set_extent_bit(tree, start, end, EXTENT_ORDERED, 0, NULL, mask); +} + +int set_extent_bits(struct extent_io_tree *tree, u64 start, u64 end, + int bits, gfp_t mask) +{ + return set_extent_bit(tree, start, end, bits, 0, NULL, + mask); +} + +int clear_extent_bits(struct extent_io_tree *tree, u64 start, u64 end, + int bits, gfp_t mask) +{ + return clear_extent_bit(tree, start, end, bits, 0, 0, mask); +} + +int set_extent_delalloc(struct extent_io_tree *tree, u64 start, u64 end, + gfp_t mask) +{ + return set_extent_bit(tree, start, end, + EXTENT_DELALLOC | EXTENT_DIRTY, + 0, NULL, mask); +} + +int clear_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end, + gfp_t mask) +{ + return clear_extent_bit(tree, start, end, + EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, mask); +} + +int clear_extent_ordered(struct extent_io_tree *tree, u64 start, u64 end, + gfp_t mask) +{ + return clear_extent_bit(tree, start, end, EXTENT_ORDERED, 1, 0, mask); +} + +int set_extent_new(struct extent_io_tree *tree, u64 start, u64 end, + gfp_t mask) +{ + return set_extent_bit(tree, start, end, EXTENT_NEW, 0, NULL, + mask); +} + +static int clear_extent_new(struct extent_io_tree *tree, u64 start, u64 end, + gfp_t mask) +{ + return clear_extent_bit(tree, start, end, EXTENT_NEW, 0, 0, mask); +} + +int set_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end, + gfp_t mask) +{ + return set_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, NULL, + mask); +} + +static int clear_extent_uptodate(struct extent_io_tree *tree, u64 start, + u64 end, gfp_t mask) +{ + return clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0, mask); +} + +static int set_extent_writeback(struct extent_io_tree *tree, u64 start, u64 end, + gfp_t mask) +{ + return set_extent_bit(tree, start, end, EXTENT_WRITEBACK, + 0, NULL, mask); +} + +static int clear_extent_writeback(struct extent_io_tree *tree, u64 start, + u64 end, gfp_t mask) +{ + return clear_extent_bit(tree, start, end, EXTENT_WRITEBACK, 1, 0, mask); +} + +int wait_on_extent_writeback(struct extent_io_tree *tree, u64 start, u64 end) +{ + return wait_extent_bit(tree, start, end, EXTENT_WRITEBACK); +} + +/* + * either insert or lock state struct between start and end use mask to tell + * us if waiting is desired. + */ +int lock_extent(struct extent_io_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; +} + +int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end, + gfp_t mask) +{ + int err; + u64 failed_start; + + err = set_extent_bit(tree, start, end, EXTENT_LOCKED, 1, + &failed_start, mask); + if (err == -EEXIST) { + if (failed_start > start) + clear_extent_bit(tree, start, failed_start - 1, + EXTENT_LOCKED, 1, 0, mask); + return 0; + } + return 1; +} + +int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end, + gfp_t mask) +{ + return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, mask); +} + +/* + * helper function to set pages and extents in the tree dirty + */ +int set_range_dirty(struct extent_io_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; +} + +/* + * helper function to set both pages and extents in the tree writeback + */ +static int set_range_writeback(struct extent_io_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; +} + +/* + * find the first offset in the io tree with 'bits' set. zero is + * returned if we find something, and *start_ret and *end_ret are + * set to reflect the state struct that was found. + * + * If nothing was found, 1 is returned, < 0 on error + */ +int find_first_extent_bit(struct extent_io_tree *tree, u64 start, + u64 *start_ret, u64 *end_ret, int bits) +{ + struct rb_node *node; + struct extent_state *state; + int ret = 1; + + spin_lock(&tree->lock); + /* + * this search will find all the extents that end after + * our range starts. + */ + node = tree_search(tree, start); + if (!node) + goto out; + + while (1) { + state = rb_entry(node, struct extent_state, rb_node); + if (state->end >= start && (state->state & bits)) { + *start_ret = state->start; + *end_ret = state->end; + ret = 0; + break; + } + node = rb_next(node); + if (!node) + break; + } +out: + spin_unlock(&tree->lock); + return ret; +} + +/* find the first state struct with 'bits' set after 'start', and + * return it. tree->lock must be held. NULL will returned if + * nothing was found after 'start' + */ +struct extent_state *find_first_extent_bit_state(struct extent_io_tree *tree, + u64 start, int bits) +{ + struct rb_node *node; + struct extent_state *state; + + /* + * this search will find all the extents that end after + * our range starts. + */ + node = tree_search(tree, start); + if (!node) + goto out; + + while (1) { + state = rb_entry(node, struct extent_state, rb_node); + if (state->end >= start && (state->state & bits)) + return state; + + node = rb_next(node); + if (!node) + break; + } +out: + return NULL; +} + +/* + * find a contiguous range of bytes in the file marked as delalloc, not + * more than 'max_bytes'. start and end are used to return the range, + * + * 1 is returned if we find something, 0 if nothing was in the tree + */ +static noinline u64 find_delalloc_range(struct extent_io_tree *tree, + u64 *start, u64 *end, u64 max_bytes) +{ + struct rb_node *node; + struct extent_state *state; + u64 cur_start = *start; + u64 found = 0; + u64 total_bytes = 0; + + spin_lock(&tree->lock); + + /* + * this search will find all the extents that end after + * our range starts. + */ + node = tree_search(tree, cur_start); + if (!node) { + if (!found) + *end = (u64)-1; + goto out; + } + + while (1) { + state = rb_entry(node, struct extent_state, rb_node); + if (found && (state->start != cur_start || + (state->state & EXTENT_BOUNDARY))) { + goto out; + } + if (!(state->state & EXTENT_DELALLOC)) { + if (!found) + *end = state->end; + goto out; + } + if (!found) + *start = state->start; + found++; + *end = state->end; + cur_start = state->end + 1; + node = rb_next(node); + if (!node) + break; + total_bytes += state->end - state->start + 1; + if (total_bytes >= max_bytes) + break; + } +out: + spin_unlock(&tree->lock); + return found; +} + +static noinline int __unlock_for_delalloc(struct inode *inode, + struct page *locked_page, + u64 start, u64 end) +{ + int ret; + struct page *pages[16]; + unsigned long index = start >> PAGE_CACHE_SHIFT; + unsigned long end_index = end >> PAGE_CACHE_SHIFT; + unsigned long nr_pages = end_index - index + 1; + int i; + + if (index == locked_page->index && end_index == index) + return 0; + + while (nr_pages > 0) { + ret = find_get_pages_contig(inode->i_mapping, index, + min_t(unsigned long, nr_pages, + ARRAY_SIZE(pages)), pages); + for (i = 0; i < ret; i++) { + if (pages[i] != locked_page) + unlock_page(pages[i]); + page_cache_release(pages[i]); + } + nr_pages -= ret; + index += ret; + cond_resched(); + } + return 0; +} + +static noinline int lock_delalloc_pages(struct inode *inode, + struct page *locked_page, + u64 delalloc_start, + u64 delalloc_end) +{ + unsigned long index = delalloc_start >> PAGE_CACHE_SHIFT; + unsigned long start_index = index; + unsigned long end_index = delalloc_end >> PAGE_CACHE_SHIFT; + unsigned long pages_locked = 0; + struct page *pages[16]; + unsigned long nrpages; + int ret; + int i; + + /* the caller is responsible for locking the start index */ + if (index == locked_page->index && index == end_index) + return 0; + + /* skip the page at the start index */ + nrpages = end_index - index + 1; + while (nrpages > 0) { + ret = find_get_pages_contig(inode->i_mapping, index, + min_t(unsigned long, + nrpages, ARRAY_SIZE(pages)), pages); + if (ret == 0) { + ret = -EAGAIN; + goto done; + } + /* now we have an array of pages, lock them all */ + for (i = 0; i < ret; i++) { + /* + * the caller is taking responsibility for + * locked_page + */ + if (pages[i] != locked_page) { + lock_page(pages[i]); + if (!PageDirty(pages[i]) || + pages[i]->mapping != inode->i_mapping) { + ret = -EAGAIN; + unlock_page(pages[i]); + page_cache_release(pages[i]); + goto done; + } + } + page_cache_release(pages[i]); + pages_locked++; + } + nrpages -= ret; + index += ret; + cond_resched(); + } + ret = 0; +done: + if (ret && pages_locked) { + __unlock_for_delalloc(inode, locked_page, + delalloc_start, + ((u64)(start_index + pages_locked - 1)) << + PAGE_CACHE_SHIFT); + } + return ret; +} + +/* + * find a contiguous range of bytes in the file marked as delalloc, not + * more than 'max_bytes'. start and end are used to return the range, + * + * 1 is returned if we find something, 0 if nothing was in the tree + */ +static noinline u64 find_lock_delalloc_range(struct inode *inode, + struct extent_io_tree *tree, + struct page *locked_page, + u64 *start, u64 *end, + u64 max_bytes) +{ + u64 delalloc_start; + u64 delalloc_end; + u64 found; + int ret; + int loops = 0; + +again: + /* step one, find a bunch of delalloc bytes starting at start */ + delalloc_start = *start; + delalloc_end = 0; + found = find_delalloc_range(tree, &delalloc_start, &delalloc_end, + max_bytes); + if (!found || delalloc_end <= *start) { + *start = delalloc_start; + *end = delalloc_end; + return found; + } + + /* + * start comes from the offset of locked_page. We have to lock + * pages in order, so we can't process delalloc bytes before + * locked_page + */ + if (delalloc_start < *start) + delalloc_start = *start; + + /* + * make sure to limit the number of pages we try to lock down + * if we're looping. + */ + if (delalloc_end + 1 - delalloc_start > max_bytes && loops) + delalloc_end = delalloc_start + PAGE_CACHE_SIZE - 1; + + /* step two, lock all the pages after the page that has start */ + ret = lock_delalloc_pages(inode, locked_page, + delalloc_start, delalloc_end); + if (ret == -EAGAIN) { + /* some of the pages are gone, lets avoid looping by + * shortening the size of the delalloc range we're searching + */ + if (!loops) { + unsigned long offset = (*start) & (PAGE_CACHE_SIZE - 1); + max_bytes = PAGE_CACHE_SIZE - offset; + loops = 1; + goto again; + } else { + found = 0; + goto out_failed; + } + } + BUG_ON(ret); + + /* step three, lock the state bits for the whole range */ + lock_extent(tree, delalloc_start, delalloc_end, GFP_NOFS); + + /* then test to make sure it is all still delalloc */ + ret = test_range_bit(tree, delalloc_start, delalloc_end, + EXTENT_DELALLOC, 1); + if (!ret) { + unlock_extent(tree, delalloc_start, delalloc_end, GFP_NOFS); + __unlock_for_delalloc(inode, locked_page, + delalloc_start, delalloc_end); + cond_resched(); + goto again; + } + *start = delalloc_start; + *end = delalloc_end; +out_failed: + return found; +} + +int extent_clear_unlock_delalloc(struct inode *inode, + struct extent_io_tree *tree, + u64 start, u64 end, struct page *locked_page, + int unlock_pages, + int clear_unlock, + int clear_delalloc, int clear_dirty, + int set_writeback, + int end_writeback) +{ + int ret; + struct page *pages[16]; + unsigned long index = start >> PAGE_CACHE_SHIFT; + unsigned long end_index = end >> PAGE_CACHE_SHIFT; + unsigned long nr_pages = end_index - index + 1; + int i; + int clear_bits = 0; + + if (clear_unlock) + clear_bits |= EXTENT_LOCKED; + if (clear_dirty) + clear_bits |= EXTENT_DIRTY; + + if (clear_delalloc) + clear_bits |= EXTENT_DELALLOC; + + clear_extent_bit(tree, start, end, clear_bits, 1, 0, GFP_NOFS); + if (!(unlock_pages || clear_dirty || set_writeback || end_writeback)) + return 0; + + while (nr_pages > 0) { + ret = find_get_pages_contig(inode->i_mapping, index, + min_t(unsigned long, + nr_pages, ARRAY_SIZE(pages)), pages); + for (i = 0; i < ret; i++) { + if (pages[i] == locked_page) { + page_cache_release(pages[i]); + continue; + } + if (clear_dirty) + clear_page_dirty_for_io(pages[i]); + if (set_writeback) + set_page_writeback(pages[i]); + if (end_writeback) + end_page_writeback(pages[i]); + if (unlock_pages) + unlock_page(pages[i]); + page_cache_release(pages[i]); + } + nr_pages -= ret; + index += ret; + cond_resched(); + } + return 0; +} + +/* + * count the number of bytes in the tree that have a given bit(s) + * set. This can be fairly slow, except for EXTENT_DIRTY which is + * cached. The total number found is returned. + */ +u64 count_range_bits(struct extent_io_tree *tree, + u64 *start, u64 search_end, u64 max_bytes, + unsigned long bits) +{ + struct rb_node *node; + struct extent_state *state; + u64 cur_start = *start; + u64 total_bytes = 0; + int found = 0; + + if (search_end <= cur_start) { + WARN_ON(1); + return 0; + } + + spin_lock(&tree->lock); + if (cur_start == 0 && bits == EXTENT_DIRTY) { + total_bytes = tree->dirty_bytes; + goto out; + } + /* + * this search will find all the extents that end after + * our range starts. + */ + node = tree_search(tree, cur_start); + if (!node) + goto out; + + while (1) { + state = rb_entry(node, struct extent_state, rb_node); + if (state->start > search_end) + break; + if (state->end >= cur_start && (state->state & bits)) { + total_bytes += min(search_end, state->end) + 1 - + max(cur_start, state->start); + if (total_bytes >= max_bytes) + break; + if (!found) { + *start = state->start; + found = 1; + } + } + node = rb_next(node); + if (!node) + break; + } +out: + spin_unlock(&tree->lock); + return total_bytes; +} + +#if 0 +/* + * helper function to lock both pages and extents in the tree. + * pages must be locked first. + */ +static int lock_range(struct extent_io_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; +} + +/* + * helper function to unlock both pages and extents in the tree. + */ +static int unlock_range(struct extent_io_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; +} +#endif + +/* + * set the private field for a given byte offset in the tree. If there isn't + * an extent_state there already, this does nothing. + */ +int set_state_private(struct extent_io_tree *tree, u64 start, u64 private) +{ + struct rb_node *node; + struct extent_state *state; + int ret = 0; + + spin_lock(&tree->lock); + /* + * this search will find all the extents that end after + * our range starts. + */ + node = tree_search(tree, start); + if (!node) { + ret = -ENOENT; + goto out; + } + state = rb_entry(node, struct extent_state, rb_node); + if (state->start != start) { + ret = -ENOENT; + goto out; + } + state->private = private; +out: + spin_unlock(&tree->lock); + return ret; +} + +int get_state_private(struct extent_io_tree *tree, u64 start, u64 *private) +{ + struct rb_node *node; + struct extent_state *state; + int ret = 0; + + spin_lock(&tree->lock); + /* + * this search will find all the extents that end after + * our range starts. + */ + node = tree_search(tree, start); + if (!node) { + ret = -ENOENT; + goto out; + } + state = rb_entry(node, struct extent_state, rb_node); + if (state->start != start) { + ret = -ENOENT; + goto out; + } + *private = state->private; +out: + spin_unlock(&tree->lock); + return ret; +} + +/* + * searches a range in the state tree for a given mask. + * If 'filled' == 1, this returns 1 only if every extent in the tree + * has the bits set. Otherwise, 1 is returned if any bit in the + * range is found set. + */ +int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end, + int bits, int filled) +{ + struct extent_state *state = NULL; + struct rb_node *node; + int bitset = 0; + + spin_lock(&tree->lock); + node = tree_search(tree, start); + while (node && start <= end) { + state = rb_entry(node, struct extent_state, rb_node); + + if (filled && state->start > start) { + bitset = 0; + break; + } + + if (state->start > end) + 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); + if (!node) { + if (filled) + bitset = 0; + break; + } + } + spin_unlock(&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_io_tree *tree, + struct page *page) +{ + u64 start = (u64)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_io_tree *tree, + struct page *page) +{ + u64 start = (u64)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_io_tree *tree, + struct page *page) +{ + u64 start = (u64)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 void end_bio_extent_writepage(struct bio *bio, int err) +{ + int uptodate = err == 0; + struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1; + struct extent_io_tree *tree; + u64 start; + u64 end; + int whole_page; + int ret; + + do { + struct page *page = bvec->bv_page; + tree = &BTRFS_I(page->mapping->host)->io_tree; + + start = ((u64)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 (tree->ops && tree->ops->writepage_end_io_hook) { + ret = tree->ops->writepage_end_io_hook(page, start, + end, NULL, uptodate); + if (ret) + uptodate = 0; + } + + if (!uptodate && tree->ops && + tree->ops->writepage_io_failed_hook) { + ret = tree->ops->writepage_io_failed_hook(bio, page, + start, end, NULL); + if (ret == 0) { + uptodate = (err == 0); + continue; + } + } + + 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); +} + +/* + * 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 void end_bio_extent_readpage(struct bio *bio, int err) +{ + int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); + struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1; + struct extent_io_tree *tree; + u64 start; + u64 end; + int whole_page; + int ret; + + if (err) + uptodate = 0; + + do { + struct page *page = bvec->bv_page; + tree = &BTRFS_I(page->mapping->host)->io_tree; + + start = ((u64)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 && tree->ops && tree->ops->readpage_end_io_hook) { + ret = tree->ops->readpage_end_io_hook(page, start, end, + NULL); + if (ret) + uptodate = 0; + } + if (!uptodate && tree->ops && + tree->ops->readpage_io_failed_hook) { + ret = tree->ops->readpage_io_failed_hook(bio, page, + start, end, NULL); + if (ret == 0) { + uptodate = + test_bit(BIO_UPTODATE, &bio->bi_flags); + if (err) + uptodate = 0; + continue; + } + } + + if (uptodate) { + set_extent_uptodate(tree, start, end, + GFP_ATOMIC); + } + unlock_extent(tree, start, end, GFP_ATOMIC); + + if (whole_page) { + if (uptodate) { + SetPageUptodate(page); + } else { + ClearPageUptodate(page); + SetPageError(page); + } + unlock_page(page); + } else { + if (uptodate) { + check_page_uptodate(tree, page); + } else { + ClearPageUptodate(page); + SetPageError(page); + } + check_page_locked(tree, page); + } + } while (bvec >= bio->bi_io_vec); + + bio_put(bio); +} + +/* + * 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 void end_bio_extent_preparewrite(struct bio *bio, 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_io_tree *tree; + u64 start; + u64 end; + + do { + struct page *page = bvec->bv_page; + tree = &BTRFS_I(page->mapping->host)->io_tree; + + start = ((u64)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); +} + +static struct bio * +extent_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs, + gfp_t gfp_flags) +{ + struct bio *bio; + + bio = bio_alloc(gfp_flags, nr_vecs); + + if (bio == NULL && (current->flags & PF_MEMALLOC)) { + while (!bio && (nr_vecs /= 2)) + bio = bio_alloc(gfp_flags, nr_vecs); + } + + if (bio) { + bio->bi_size = 0; + bio->bi_bdev = bdev; + bio->bi_sector = first_sector; + } + return bio; +} + +static int submit_one_bio(int rw, struct bio *bio, int mirror_num, + unsigned long bio_flags) +{ + int ret = 0; + struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1; + struct page *page = bvec->bv_page; + struct extent_io_tree *tree = bio->bi_private; + u64 start; + u64 end; + + start = ((u64)page->index << PAGE_CACHE_SHIFT) + bvec->bv_offset; + end = start + bvec->bv_len - 1; + + bio->bi_private = NULL; + + bio_get(bio); + + if (tree->ops && tree->ops->submit_bio_hook) + tree->ops->submit_bio_hook(page->mapping->host, rw, bio, + mirror_num, bio_flags); + else + submit_bio(rw, bio); + if (bio_flagged(bio, BIO_EOPNOTSUPP)) + ret = -EOPNOTSUPP; + bio_put(bio); + return ret; +} + +static int submit_extent_page(int rw, struct extent_io_tree *tree, + struct page *page, sector_t sector, + size_t size, unsigned long offset, + struct block_device *bdev, + struct bio **bio_ret, + unsigned long max_pages, + bio_end_io_t end_io_func, + int mirror_num, + unsigned long prev_bio_flags, + unsigned long bio_flags) +{ + int ret = 0; + struct bio *bio; + int nr; + int contig = 0; + int this_compressed = bio_flags & EXTENT_BIO_COMPRESSED; + int old_compressed = prev_bio_flags & EXTENT_BIO_COMPRESSED; + size_t page_size = min_t(size_t, size, PAGE_CACHE_SIZE); + + if (bio_ret && *bio_ret) { + bio = *bio_ret; + if (old_compressed) + contig = bio->bi_sector == sector; + else + contig = bio->bi_sector + (bio->bi_size >> 9) == + sector; + + if (prev_bio_flags != bio_flags || !contig || + (tree->ops && tree->ops->merge_bio_hook && + tree->ops->merge_bio_hook(page, offset, page_size, bio, + bio_flags)) || + bio_add_page(bio, page, page_size, offset) < page_size) { + ret = submit_one_bio(rw, bio, mirror_num, + prev_bio_flags); + bio = NULL; + } else { + return 0; + } + } + if (this_compressed) + nr = BIO_MAX_PAGES; + else + nr = bio_get_nr_vecs(bdev); + + bio = extent_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH); + + bio_add_page(bio, page, page_size, offset); + bio->bi_end_io = end_io_func; + bio->bi_private = tree; + + if (bio_ret) + *bio_ret = bio; + else + ret = submit_one_bio(rw, bio, mirror_num, bio_flags); + + return ret; +} + +void set_page_extent_mapped(struct page *page) +{ + if (!PagePrivate(page)) { + SetPagePrivate(page); + page_cache_get(page); + set_page_private(page, EXTENT_PAGE_PRIVATE); + } +} + +static void set_page_extent_head(struct page *page, unsigned long len) +{ + set_page_private(page, EXTENT_PAGE_PRIVATE_FIRST_PAGE | len << 2); +} + +/* + * 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) + */ +static int __extent_read_full_page(struct extent_io_tree *tree, + struct page *page, + get_extent_t *get_extent, + struct bio **bio, int mirror_num, + unsigned long *bio_flags) +{ + struct inode *inode = page->mapping->host; + u64 start = (u64)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; + u64 cur_end; + 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 disk_io_size; + size_t blocksize = inode->i_sb->s_blocksize; + unsigned long this_bio_flag = 0; + + set_page_extent_mapped(page); + + end = page_end; + lock_extent(tree, start, end, GFP_NOFS); + + if (page->index == last_byte >> PAGE_CACHE_SHIFT) { + char *userpage; + size_t zero_offset = last_byte & (PAGE_CACHE_SIZE - 1); + + if (zero_offset) { + iosize = PAGE_CACHE_SIZE - zero_offset; + userpage = kmap_atomic(page, KM_USER0); + memset(userpage + zero_offset, 0, iosize); + flush_dcache_page(page); + kunmap_atomic(userpage, KM_USER0); + } + } + while (cur <= end) { + if (cur >= last_byte) { + char *userpage; + iosize = PAGE_CACHE_SIZE - page_offset; + userpage = kmap_atomic(page, KM_USER0); + memset(userpage + page_offset, 0, iosize); + flush_dcache_page(page); + kunmap_atomic(userpage, KM_USER0); + set_extent_uptodate(tree, cur, cur + iosize - 1, + GFP_NOFS); + unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS); + break; + } + em = get_extent(inode, page, page_offset, cur, + end - cur + 1, 0); + if (IS_ERR(em) || !em) { + SetPageError(page); + unlock_extent(tree, cur, end, GFP_NOFS); + break; + } + extent_offset = cur - em->start; + BUG_ON(extent_map_end(em) <= cur); + BUG_ON(end < cur); + + if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) + this_bio_flag = EXTENT_BIO_COMPRESSED; + + iosize = min(extent_map_end(em) - cur, end - cur + 1); + cur_end = min(extent_map_end(em) - 1, end); + iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1); + if (this_bio_flag & EXTENT_BIO_COMPRESSED) { + disk_io_size = em->block_len; + sector = em->block_start >> 9; + } else { + sector = (em->block_start + extent_offset) >> 9; + disk_io_size = iosize; + } + bdev = em->bdev; + block_start = em->block_start; + if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) + block_start = EXTENT_MAP_HOLE; + free_extent_map(em); + em = NULL; + + /* we've found a hole, just zero and go on */ + if (block_start == EXTENT_MAP_HOLE) { + char *userpage; + userpage = kmap_atomic(page, KM_USER0); + memset(userpage + page_offset, 0, iosize); + flush_dcache_page(page); + kunmap_atomic(userpage, 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_end, EXTENT_UPTODATE, 1)) { + check_page_uptodate(tree, page); + unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS); + cur = cur + iosize; + page_offset += iosize; + continue; + } + /* we have an inline extent but it didn't get marked up + * to date. Error out + */ + if (block_start == EXTENT_MAP_INLINE) { + SetPageError(page); + unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS); + cur = cur + iosize; + page_offset += iosize; + continue; + } + + ret = 0; + if (tree->ops && tree->ops->readpage_io_hook) { + ret = tree->ops->readpage_io_hook(page, cur, + cur + iosize - 1); + } + if (!ret) { + unsigned long pnr = (last_byte >> PAGE_CACHE_SHIFT) + 1; + pnr -= page->index; + ret = submit_extent_page(READ, tree, page, + sector, disk_io_size, page_offset, + bdev, bio, pnr, + end_bio_extent_readpage, mirror_num, + *bio_flags, + this_bio_flag); + nr++; + *bio_flags = this_bio_flag; + } + if (ret) + SetPageError(page); + cur = cur + iosize; + page_offset += iosize; + } + if (!nr) { + if (!PageError(page)) + SetPageUptodate(page); + unlock_page(page); + } + return 0; +} + +int extent_read_full_page(struct extent_io_tree *tree, struct page *page, + get_extent_t *get_extent) +{ + struct bio *bio = NULL; + unsigned long bio_flags = 0; + int ret; + + ret = __extent_read_full_page(tree, page, get_extent, &bio, 0, + &bio_flags); + if (bio) + submit_one_bio(READ, bio, 0, bio_flags); + return ret; +} + +/* + * 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 + */ +static int __extent_writepage(struct page *page, struct writeback_control *wbc, + void *data) +{ + struct inode *inode = page->mapping->host; + struct extent_page_data *epd = data; + struct extent_io_tree *tree = epd->tree; + u64 start = (u64)page->index << PAGE_CACHE_SHIFT; + u64 delalloc_start; + 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; + u64 iosize; + u64 unlock_start; + sector_t sector; + struct extent_map *em; + struct block_device *bdev; + int ret; + int nr = 0; + size_t pg_offset = 0; + size_t blocksize; + loff_t i_size = i_size_read(inode); + unsigned long end_index = i_size >> PAGE_CACHE_SHIFT; + u64 nr_delalloc; + u64 delalloc_end; + int page_started; + int compressed; + unsigned long nr_written = 0; + + WARN_ON(!PageLocked(page)); + pg_offset = i_size & (PAGE_CACHE_SIZE - 1); + if (page->index > end_index || + (page->index == end_index && !pg_offset)) { + page->mapping->a_ops->invalidatepage(page, 0); + unlock_page(page); + return 0; + } + + if (page->index == end_index) { + char *userpage; + + userpage = kmap_atomic(page, KM_USER0); + memset(userpage + pg_offset, 0, + PAGE_CACHE_SIZE - pg_offset); + kunmap_atomic(userpage, KM_USER0); + flush_dcache_page(page); + } + pg_offset = 0; + + set_page_extent_mapped(page); + + delalloc_start = start; + delalloc_end = 0; + page_started = 0; + if (!epd->extent_locked) { + while (delalloc_end < page_end) { + nr_delalloc = find_lock_delalloc_range(inode, tree, + page, + &delalloc_start, + &delalloc_end, + 128 * 1024 * 1024); + if (nr_delalloc == 0) { + delalloc_start = delalloc_end + 1; + continue; + } + tree->ops->fill_delalloc(inode, page, delalloc_start, + delalloc_end, &page_started, + &nr_written); + delalloc_start = delalloc_end + 1; + } + + /* did the fill delalloc function already unlock and start + * the IO? + */ + if (page_started) { + ret = 0; + goto update_nr_written; + } + } + lock_extent(tree, start, page_end, GFP_NOFS); + + unlock_start = start; + + if (tree->ops && tree->ops->writepage_start_hook) { + ret = tree->ops->writepage_start_hook(page, start, + page_end); + if (ret == -EAGAIN) { + unlock_extent(tree, start, page_end, GFP_NOFS); + redirty_page_for_writepage(wbc, page); + unlock_page(page); + ret = 0; + goto update_nr_written; + } + } + + nr_written++; + + end = page_end; + if (test_range_bit(tree, start, page_end, EXTENT_DELALLOC, 0)) + printk(KERN_ERR "btrfs delalloc bits after lock_extent\n"); + + if (last_byte <= start) { + clear_extent_dirty(tree, start, page_end, GFP_NOFS); + unlock_extent(tree, start, page_end, GFP_NOFS); + if (tree->ops && tree->ops->writepage_end_io_hook) + tree->ops->writepage_end_io_hook(page, start, + page_end, NULL, 1); + unlock_start = page_end + 1; + goto done; + } + + set_extent_uptodate(tree, start, page_end, GFP_NOFS); + blocksize = inode->i_sb->s_blocksize; + + while (cur <= end) { + if (cur >= last_byte) { + clear_extent_dirty(tree, cur, page_end, GFP_NOFS); + unlock_extent(tree, unlock_start, page_end, GFP_NOFS); + if (tree->ops && tree->ops->writepage_end_io_hook) + tree->ops->writepage_end_io_hook(page, cur, + page_end, NULL, 1); + unlock_start = page_end + 1; + break; + } + em = epd->get_extent(inode, page, pg_offset, cur, + end - cur + 1, 1); + if (IS_ERR(em) || !em) { + SetPageError(page); + break; + } + + extent_offset = cur - em->start; + BUG_ON(extent_map_end(em) <= cur); + BUG_ON(end < cur); + iosize = min(extent_map_end(em) - 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; + compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags); + free_extent_map(em); + em = NULL; + + /* + * compressed and inline extents are written through other + * paths in the FS + */ + if (compressed || block_start == EXTENT_MAP_HOLE || + block_start == EXTENT_MAP_INLINE) { + clear_extent_dirty(tree, cur, + cur + iosize - 1, GFP_NOFS); + + unlock_extent(tree, unlock_start, cur + iosize - 1, + GFP_NOFS); + + /* + * end_io notification does not happen here for + * compressed extents + */ + if (!compressed && tree->ops && + tree->ops->writepage_end_io_hook) + tree->ops->writepage_end_io_hook(page, cur, + cur + iosize - 1, + NULL, 1); + else if (compressed) { + /* we don't want to end_page_writeback on + * a compressed extent. this happens + * elsewhere + */ + nr++; + } + + cur += iosize; + pg_offset += iosize; + unlock_start = cur; + 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; + pg_offset += iosize; + continue; + } + + clear_extent_dirty(tree, cur, cur + iosize - 1, GFP_NOFS); + if (tree->ops && tree->ops->writepage_io_hook) { + ret = tree->ops->writepage_io_hook(page, cur, + cur + iosize - 1); + } else { + ret = 0; + } + if (ret) { + SetPageError(page); + } else { + unsigned long max_nr = end_index + 1; + + set_range_writeback(tree, cur, cur + iosize - 1); + if (!PageWriteback(page)) { + printk(KERN_ERR "btrfs warning page %lu not " + "writeback, cur %llu end %llu\n", + page->index, (unsigned long long)cur, + (unsigned long long)end); + } + + ret = submit_extent_page(WRITE, tree, page, sector, + iosize, pg_offset, bdev, + &epd->bio, max_nr, + end_bio_extent_writepage, + 0, 0, 0); + if (ret) + SetPageError(page); + } + cur = cur + iosize; + pg_offset += iosize; + nr++; + } +done: + if (nr == 0) { + /* make sure the mapping tag for page dirty gets cleared */ + set_page_writeback(page); + end_page_writeback(page); + } + if (unlock_start <= page_end) + unlock_extent(tree, unlock_start, page_end, GFP_NOFS); + unlock_page(page); + +update_nr_written: + wbc->nr_to_write -= nr_written; + if (wbc->range_cyclic || (wbc->nr_to_write > 0 && + wbc->range_start == 0 && wbc->range_end == LLONG_MAX)) + page->mapping->writeback_index = page->index + nr_written; + return 0; +} + +/** + * write_cache_pages - walk the list of dirty pages of the given address space and write all of them. + * @mapping: address space structure to write + * @wbc: subtract the number of written pages from *@wbc->nr_to_write + * @writepage: function called for each page + * @data: data passed to writepage function + * + * If a page is already under I/O, write_cache_pages() skips it, even + * if it's dirty. This is desirable behaviour for memory-cleaning writeback, + * but it is INCORRECT for data-integrity system calls such as fsync(). fsync() + * and msync() need to guarantee that all the data which was dirty at the time + * the call was made get new I/O started against them. If wbc->sync_mode is + * WB_SYNC_ALL then we were called for data integrity and we must wait for + * existing IO to complete. + */ +static int extent_write_cache_pages(struct extent_io_tree *tree, + struct address_space *mapping, + struct writeback_control *wbc, + writepage_t writepage, void *data, + void (*flush_fn)(void *)) +{ + struct backing_dev_info *bdi = mapping->backing_dev_info; + int ret = 0; + int done = 0; + struct pagevec pvec; + int nr_pages; + pgoff_t index; + pgoff_t end; /* Inclusive */ + int scanned = 0; + int range_whole = 0; + + if (wbc->nonblocking && bdi_write_congested(bdi)) { + wbc->encountered_congestion = 1; + return 0; + } + + pagevec_init(&pvec, 0); + if (wbc->range_cyclic) { + index = mapping->writeback_index; /* Start from prev offset */ + end = -1; + } else { + index = wbc->range_start >> PAGE_CACHE_SHIFT; + end = wbc->range_end >> PAGE_CACHE_SHIFT; + if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) + range_whole = 1; + scanned = 1; + } +retry: + while (!done && (index <= end) && + (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, + PAGECACHE_TAG_DIRTY, min(end - index, + (pgoff_t)PAGEVEC_SIZE-1) + 1))) { + unsigned i; + + scanned = 1; + for (i = 0; i < nr_pages; i++) { + struct page *page = pvec.pages[i]; + + /* + * At this point we hold neither mapping->tree_lock nor + * lock on the page itself: the page may be truncated or + * invalidated (changing page->mapping to NULL), or even + * swizzled back from swapper_space to tmpfs file + * mapping + */ + if (tree->ops && tree->ops->write_cache_pages_lock_hook) + tree->ops->write_cache_pages_lock_hook(page); + else + lock_page(page); + + if (unlikely(page->mapping != mapping)) { + unlock_page(page); + continue; + } + + if (!wbc->range_cyclic && page->index > end) { + done = 1; + unlock_page(page); + continue; + } + + if (wbc->sync_mode != WB_SYNC_NONE) { + if (PageWriteback(page)) + flush_fn(data); + wait_on_page_writeback(page); + } + + if (PageWriteback(page) || + !clear_page_dirty_for_io(page)) { + unlock_page(page); + continue; + } + + ret = (*writepage)(page, wbc, data); + + if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) { + unlock_page(page); + ret = 0; + } + if (ret || wbc->nr_to_write <= 0) + done = 1; + if (wbc->nonblocking && bdi_write_congested(bdi)) { + wbc->encountered_congestion = 1; + done = 1; + } + } + pagevec_release(&pvec); + cond_resched(); + } + if (!scanned && !done) { + /* + * We hit the last page and there is more work to be done: wrap + * back to the start of the file + */ + scanned = 1; + index = 0; + goto retry; + } + return ret; +} + +static noinline void flush_write_bio(void *data) +{ + struct extent_page_data *epd = data; + if (epd->bio) { + submit_one_bio(WRITE, epd->bio, 0, 0); + epd->bio = NULL; + } +} + +int extent_write_full_page(struct extent_io_tree *tree, struct page *page, + get_extent_t *get_extent, + struct writeback_control *wbc) +{ + int ret; + struct address_space *mapping = page->mapping; + struct extent_page_data epd = { + .bio = NULL, + .tree = tree, + .get_extent = get_extent, + .extent_locked = 0, + }; + struct writeback_control wbc_writepages = { + .bdi = wbc->bdi, + .sync_mode = WB_SYNC_NONE, + .older_than_this = NULL, + .nr_to_write = 64, + .range_start = page_offset(page) + PAGE_CACHE_SIZE, + .range_end = (loff_t)-1, + }; + + + ret = __extent_writepage(page, wbc, &epd); + + extent_write_cache_pages(tree, mapping, &wbc_writepages, + __extent_writepage, &epd, flush_write_bio); + if (epd.bio) + submit_one_bio(WRITE, epd.bio, 0, 0); + return ret; +} + +int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode, + u64 start, u64 end, get_extent_t *get_extent, + int mode) +{ + int ret = 0; + struct address_space *mapping = inode->i_mapping; + struct page *page; + unsigned long nr_pages = (end - start + PAGE_CACHE_SIZE) >> + PAGE_CACHE_SHIFT; + + struct extent_page_data epd = { + .bio = NULL, + .tree = tree, + .get_extent = get_extent, + .extent_locked = 1, + }; + struct writeback_control wbc_writepages = { + .bdi = inode->i_mapping->backing_dev_info, + .sync_mode = mode, + .older_than_this = NULL, + .nr_to_write = nr_pages * 2, + .range_start = start, + .range_end = end + 1, + }; + + while (start <= end) { + page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT); + if (clear_page_dirty_for_io(page)) + ret = __extent_writepage(page, &wbc_writepages, &epd); + else { + if (tree->ops && tree->ops->writepage_end_io_hook) + tree->ops->writepage_end_io_hook(page, start, + start + PAGE_CACHE_SIZE - 1, + NULL, 1); + unlock_page(page); + } + page_cache_release(page); + start += PAGE_CACHE_SIZE; + } + + if (epd.bio) + submit_one_bio(WRITE, epd.bio, 0, 0); + return ret; +} + +int extent_writepages(struct extent_io_tree *tree, + struct address_space *mapping, + get_extent_t *get_extent, + struct writeback_control *wbc) +{ + int ret = 0; + struct extent_page_data epd = { + .bio = NULL, + .tree = tree, + .get_extent = get_extent, + .extent_locked = 0, + }; + + ret = extent_write_cache_pages(tree, mapping, wbc, + __extent_writepage, &epd, + flush_write_bio); + if (epd.bio) + submit_one_bio(WRITE, epd.bio, 0, 0); + return ret; +} + +int extent_readpages(struct extent_io_tree *tree, + struct address_space *mapping, + struct list_head *pages, unsigned nr_pages, + get_extent_t get_extent) +{ + struct bio *bio = NULL; + unsigned page_idx; + struct pagevec pvec; + unsigned long bio_flags = 0; + + pagevec_init(&pvec, 0); + for (page_idx = 0; page_idx < nr_pages; page_idx++) { + struct page *page = list_entry(pages->prev, struct page, lru); + + prefetchw(&page->flags); + list_del(&page->lru); + /* + * what we want to do here is call add_to_page_cache_lru, + * but that isn't exported, so we reproduce it here + */ + if (!add_to_page_cache(page, mapping, + page->index, GFP_KERNEL)) { + + /* open coding of lru_cache_add, also not exported */ + page_cache_get(page); + if (!pagevec_add(&pvec, page)) + __pagevec_lru_add_file(&pvec); + __extent_read_full_page(tree, page, get_extent, + &bio, 0, &bio_flags); + } + page_cache_release(page); + } + if (pagevec_count(&pvec)) + __pagevec_lru_add_file(&pvec); + BUG_ON(!list_empty(pages)); + if (bio) + submit_one_bio(READ, bio, 0, bio_flags); + return 0; +} + +/* + * 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_io_tree *tree, + struct page *page, unsigned long offset) +{ + u64 start = ((u64)page->index << PAGE_CACHE_SHIFT); + u64 end = start + PAGE_CACHE_SIZE - 1; + size_t blocksize = page->mapping->host->i_sb->s_blocksize; + + start += (offset + blocksize - 1) & ~(blocksize - 1); + if (start > end) + return 0; + + lock_extent(tree, start, end, GFP_NOFS); + wait_on_extent_writeback(tree, start, end); + clear_extent_bit(tree, start, end, + EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC, + 1, 1, GFP_NOFS); + return 0; +} + +/* + * 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_io_tree *tree, + struct inode *inode, struct page *page, + unsigned from, unsigned to) +{ + loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; + + set_page_extent_mapped(page); + set_page_dirty(page); + + if (pos > inode->i_size) { + i_size_write(inode, pos); + mark_inode_dirty(inode); + } + return 0; +} + +int extent_prepare_write(struct extent_io_tree *tree, + struct inode *inode, struct page *page, + unsigned from, unsigned to, get_extent_t *get_extent) +{ + u64 page_start = (u64)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; + + set_page_extent_mapped(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 - block_start + 1, 1); + if (IS_ERR(em) || !em) + goto err; + + cur_end = min(block_end, extent_map_end(em) - 1); + 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 ((em->block_start != EXTENT_MAP_HOLE && + em->block_start != EXTENT_MAP_INLINE) && + !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) & + ~((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, + NULL, 1, + end_bio_extent_preparewrite, 0, + 0, 0); + 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; +} + +/* + * a helper for releasepage, this tests for areas of the page that + * are locked or under IO and drops the related state bits if it is safe + * to drop the page. + */ +int try_release_extent_state(struct extent_map_tree *map, + struct extent_io_tree *tree, struct page *page, + gfp_t mask) +{ + u64 start = (u64)page->index << PAGE_CACHE_SHIFT; + u64 end = start + PAGE_CACHE_SIZE - 1; + int ret = 1; + + if (test_range_bit(tree, start, end, + EXTENT_IOBITS | EXTENT_ORDERED, 0)) + ret = 0; + else { + if ((mask & GFP_NOFS) == GFP_NOFS) + mask = GFP_NOFS; + clear_extent_bit(tree, start, end, EXTENT_UPTODATE, + 1, 1, mask); + } + return ret; +} + +/* + * 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 *map, + struct extent_io_tree *tree, struct page *page, + gfp_t mask) +{ + struct extent_map *em; + u64 start = (u64)page->index << PAGE_CACHE_SHIFT; + u64 end = start + PAGE_CACHE_SIZE - 1; + + if ((mask & __GFP_WAIT) && + page->mapping->host->i_size > 16 * 1024 * 1024) { + u64 len; + while (start <= end) { + len = end - start + 1; + spin_lock(&map->lock); + em = lookup_extent_mapping(map, start, len); + if (!em || IS_ERR(em)) { + spin_unlock(&map->lock); + break; + } + if (test_bit(EXTENT_FLAG_PINNED, &em->flags) || + em->start != start) { + spin_unlock(&map->lock); + free_extent_map(em); + break; + } + if (!test_range_bit(tree, em->start, + extent_map_end(em) - 1, + EXTENT_LOCKED | EXTENT_WRITEBACK | + EXTENT_ORDERED, + 0)) { + remove_extent_mapping(map, em); + /* once for the rb tree */ + free_extent_map(em); + } + start = extent_map_end(em); + spin_unlock(&map->lock); + + /* once for us */ + free_extent_map(em); + } + } + return try_release_extent_state(map, tree, page, mask); +} + +sector_t extent_bmap(struct address_space *mapping, sector_t iblock, + get_extent_t *get_extent) +{ + struct inode *inode = mapping->host; + u64 start = iblock << inode->i_blkbits; + sector_t sector = 0; + size_t blksize = (1 << inode->i_blkbits); + struct extent_map *em; + + lock_extent(&BTRFS_I(inode)->io_tree, start, start + blksize - 1, + GFP_NOFS); + em = get_extent(inode, NULL, 0, start, blksize, 0); + unlock_extent(&BTRFS_I(inode)->io_tree, start, start + blksize - 1, + GFP_NOFS); + if (!em || IS_ERR(em)) + return 0; + + if (em->block_start > EXTENT_MAP_LAST_BYTE) + goto out; + + sector = (em->block_start + start - em->start) >> inode->i_blkbits; +out: + free_extent_map(em); + return sector; +} + +static inline struct page *extent_buffer_page(struct extent_buffer *eb, + unsigned long i) +{ + struct page *p; + struct address_space *mapping; + + if (i == 0) + return eb->first_page; + i += eb->start >> PAGE_CACHE_SHIFT; + mapping = eb->first_page->mapping; + if (!mapping) + return NULL; + + /* + * extent_buffer_page is only called after pinning the page + * by increasing the reference count. So we know the page must + * be in the radix tree. + */ + rcu_read_lock(); + p = radix_tree_lookup(&mapping->page_tree, i); + rcu_read_unlock(); + + return p; +} + +static inline unsigned long num_extent_pages(u64 start, u64 len) +{ + return ((start + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) - + (start >> PAGE_CACHE_SHIFT); +} + +static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree, + u64 start, + unsigned long len, + gfp_t mask) +{ + struct extent_buffer *eb = NULL; +#ifdef LEAK_DEBUG + unsigned long flags; +#endif + + eb = kmem_cache_zalloc(extent_buffer_cache, mask); + eb->start = start; + eb->len = len; + mutex_init(&eb->mutex); +#ifdef LEAK_DEBUG + spin_lock_irqsave(&leak_lock, flags); + list_add(&eb->leak_list, &buffers); + spin_unlock_irqrestore(&leak_lock, flags); +#endif + atomic_set(&eb->refs, 1); + + return eb; +} + +static void __free_extent_buffer(struct extent_buffer *eb) +{ +#ifdef LEAK_DEBUG + unsigned long flags; + spin_lock_irqsave(&leak_lock, flags); + list_del(&eb->leak_list); + spin_unlock_irqrestore(&leak_lock, flags); +#endif + kmem_cache_free(extent_buffer_cache, eb); +} + +struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, + u64 start, unsigned long len, + struct page *page0, + gfp_t mask) +{ + unsigned long num_pages = num_extent_pages(start, len); + unsigned long i; + unsigned long index = start >> PAGE_CACHE_SHIFT; + struct extent_buffer *eb; + struct extent_buffer *exists = NULL; + struct page *p; + struct address_space *mapping = tree->mapping; + int uptodate = 1; + + spin_lock(&tree->buffer_lock); + eb = buffer_search(tree, start); + if (eb) { + atomic_inc(&eb->refs); + spin_unlock(&tree->buffer_lock); + mark_page_accessed(eb->first_page); + return eb; + } + spin_unlock(&tree->buffer_lock); + + eb = __alloc_extent_buffer(tree, start, len, mask); + if (!eb) + return NULL; + + if (page0) { + eb->first_page = page0; + i = 1; + index++; + page_cache_get(page0); + mark_page_accessed(page0); + set_page_extent_mapped(page0); + set_page_extent_head(page0, len); + uptodate = PageUptodate(page0); + } else { + i = 0; + } + for (; i < num_pages; i++, index++) { + p = find_or_create_page(mapping, index, mask | __GFP_HIGHMEM); + if (!p) { + WARN_ON(1); + goto free_eb; + } + set_page_extent_mapped(p); + mark_page_accessed(p); + if (i == 0) { + eb->first_page = p; + set_page_extent_head(p, len); + } else { + set_page_private(p, EXTENT_PAGE_PRIVATE); + } + if (!PageUptodate(p)) + uptodate = 0; + unlock_page(p); + } + if (uptodate) + eb->flags |= EXTENT_UPTODATE; + eb->flags |= EXTENT_BUFFER_FILLED; + + spin_lock(&tree->buffer_lock); + exists = buffer_tree_insert(tree, start, &eb->rb_node); + if (exists) { + /* add one reference for the caller */ + atomic_inc(&exists->refs); + spin_unlock(&tree->buffer_lock); + goto free_eb; + } + spin_unlock(&tree->buffer_lock); + + /* add one reference for the tree */ + atomic_inc(&eb->refs); + return eb; + +free_eb: + if (!atomic_dec_and_test(&eb->refs)) + return exists; + for (index = 1; index < i; index++) + page_cache_release(extent_buffer_page(eb, index)); + page_cache_release(extent_buffer_page(eb, 0)); + __free_extent_buffer(eb); + return exists; +} + +struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree, + u64 start, unsigned long len, + gfp_t mask) +{ + struct extent_buffer *eb; + + spin_lock(&tree->buffer_lock); + eb = buffer_search(tree, start); + if (eb) + atomic_inc(&eb->refs); + spin_unlock(&tree->buffer_lock); + + if (eb) + mark_page_accessed(eb->first_page); + + return eb; +} + +void free_extent_buffer(struct extent_buffer *eb) +{ + if (!eb) + return; + + if (!atomic_dec_and_test(&eb->refs)) + return; + + WARN_ON(1); +} + +int clear_extent_buffer_dirty(struct extent_io_tree *tree, + struct extent_buffer *eb) +{ + int set; + unsigned long i; + unsigned long num_pages; + struct page *page; + + u64 start = eb->start; + u64 end = start + eb->len - 1; + + set = clear_extent_dirty(tree, start, end, GFP_NOFS); + num_pages = num_extent_pages(eb->start, eb->len); + + for (i = 0; i < num_pages; i++) { + page = extent_buffer_page(eb, i); + if (!set && !PageDirty(page)) + continue; + + lock_page(page); + if (i == 0) + set_page_extent_head(page, eb->len); + else + set_page_private(page, EXTENT_PAGE_PRIVATE); + + /* + * if we're on the last page or the first page and the + * block isn't aligned on a page boundary, do extra checks + * to make sure we don't clean page that is partially dirty + */ + if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) || + ((i == num_pages - 1) && + ((eb->start + eb->len) & (PAGE_CACHE_SIZE - 1)))) { + start = (u64)page->index << PAGE_CACHE_SHIFT; + end = start + PAGE_CACHE_SIZE - 1; + if (test_range_bit(tree, start, end, + EXTENT_DIRTY, 0)) { + unlock_page(page); + continue; + } + } + clear_page_dirty_for_io(page); + spin_lock_irq(&page->mapping->tree_lock); + if (!PageDirty(page)) { + radix_tree_tag_clear(&page->mapping->page_tree, + page_index(page), + PAGECACHE_TAG_DIRTY); + } + spin_unlock_irq(&page->mapping->tree_lock); + unlock_page(page); + } + return 0; +} + +int wait_on_extent_buffer_writeback(struct extent_io_tree *tree, + struct extent_buffer *eb) +{ + return wait_on_extent_writeback(tree, eb->start, + eb->start + eb->len - 1); +} + +int set_extent_buffer_dirty(struct extent_io_tree *tree, + struct extent_buffer *eb) +{ + unsigned long i; + unsigned long num_pages; + + num_pages = num_extent_pages(eb->start, eb->len); + for (i = 0; i < num_pages; i++) { + struct page *page = extent_buffer_page(eb, i); + /* writepage may need to do something special for the + * first page, we have to make sure page->private is + * properly set. releasepage may drop page->private + * on us if the page isn't already dirty. + */ + lock_page(page); + if (i == 0) { + set_page_extent_head(page, eb->len); + } else if (PagePrivate(page) && + page->private != EXTENT_PAGE_PRIVATE) { + set_page_extent_mapped(page); + } + __set_page_dirty_nobuffers(extent_buffer_page(eb, i)); + set_extent_dirty(tree, page_offset(page), + page_offset(page) + PAGE_CACHE_SIZE - 1, + GFP_NOFS); + unlock_page(page); + } + return 0; +} + +int clear_extent_buffer_uptodate(struct extent_io_tree *tree, + struct extent_buffer *eb) +{ + unsigned long i; + struct page *page; + unsigned long num_pages; + + num_pages = num_extent_pages(eb->start, eb->len); + eb->flags &= ~EXTENT_UPTODATE; + + clear_extent_uptodate(tree, eb->start, eb->start + eb->len - 1, + GFP_NOFS); + for (i = 0; i < num_pages; i++) { + page = extent_buffer_page(eb, i); + if (page) + ClearPageUptodate(page); + } + return 0; +} + +int set_extent_buffer_uptodate(struct extent_io_tree *tree, + struct extent_buffer *eb) +{ + unsigned long i; + struct page *page; + unsigned long num_pages; + + num_pages = num_extent_pages(eb->start, eb->len); + + set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1, + GFP_NOFS); + for (i = 0; i < num_pages; i++) { + page = extent_buffer_page(eb, i); + if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) || + ((i == num_pages - 1) && + ((eb->start + eb->len) & (PAGE_CACHE_SIZE - 1)))) { + check_page_uptodate(tree, page); + continue; + } + SetPageUptodate(page); + } + return 0; +} + +int extent_range_uptodate(struct extent_io_tree *tree, + u64 start, u64 end) +{ + struct page *page; + int ret; + int pg_uptodate = 1; + int uptodate; + unsigned long index; + + ret = test_range_bit(tree, start, end, EXTENT_UPTODATE, 1); + if (ret) + return 1; + while (start <= end) { + index = start >> PAGE_CACHE_SHIFT; + page = find_get_page(tree->mapping, index); + uptodate = PageUptodate(page); + page_cache_release(page); + if (!uptodate) { + pg_uptodate = 0; + break; + } + start += PAGE_CACHE_SIZE; + } + return pg_uptodate; +} + +int extent_buffer_uptodate(struct extent_io_tree *tree, + struct extent_buffer *eb) +{ + int ret = 0; + unsigned long num_pages; + unsigned long i; + struct page *page; + int pg_uptodate = 1; + + if (eb->flags & EXTENT_UPTODATE) + return 1; + + ret = test_range_bit(tree, eb->start, eb->start + eb->len - 1, + EXTENT_UPTODATE, 1); + if (ret) + return ret; + + num_pages = num_extent_pages(eb->start, eb->len); + for (i = 0; i < num_pages; i++) { + page = extent_buffer_page(eb, i); + if (!PageUptodate(page)) { + pg_uptodate = 0; + break; + } + } + return pg_uptodate; +} + +int read_extent_buffer_pages(struct extent_io_tree *tree, + struct extent_buffer *eb, + u64 start, int wait, + get_extent_t *get_extent, int mirror_num) +{ + unsigned long i; + unsigned long start_i; + struct page *page; + int err; + int ret = 0; + int locked_pages = 0; + int all_uptodate = 1; + int inc_all_pages = 0; + unsigned long num_pages; + struct bio *bio = NULL; + unsigned long bio_flags = 0; + + if (eb->flags & EXTENT_UPTODATE) + return 0; + + if (test_range_bit(tree, eb->start, eb->start + eb->len - 1, + EXTENT_UPTODATE, 1)) { + return 0; + } + + if (start) { + WARN_ON(start < eb->start); + start_i = (start >> PAGE_CACHE_SHIFT) - + (eb->start >> PAGE_CACHE_SHIFT); + } else { + start_i = 0; + } + + num_pages = num_extent_pages(eb->start, eb->len); + for (i = start_i; i < num_pages; i++) { + page = extent_buffer_page(eb, i); + if (!wait) { + if (!trylock_page(page)) + goto unlock_exit; + } else { + lock_page(page); + } + locked_pages++; + if (!PageUptodate(page)) + all_uptodate = 0; + } + if (all_uptodate) { + if (start_i == 0) + eb->flags |= EXTENT_UPTODATE; + goto unlock_exit; + } + + for (i = start_i; i < num_pages; i++) { + page = extent_buffer_page(eb, i); + if (inc_all_pages) + page_cache_get(page); + if (!PageUptodate(page)) { + if (start_i == 0) + inc_all_pages = 1; + ClearPageError(page); + err = __extent_read_full_page(tree, page, + get_extent, &bio, + mirror_num, &bio_flags); + if (err) + ret = err; + } else { + unlock_page(page); + } + } + + if (bio) + submit_one_bio(READ, bio, mirror_num, bio_flags); + + if (ret || !wait) + return ret; + + for (i = start_i; i < num_pages; i++) { + page = extent_buffer_page(eb, i); + wait_on_page_locked(page); + if (!PageUptodate(page)) + ret = -EIO; + } + + if (!ret) + eb->flags |= EXTENT_UPTODATE; + return ret; + +unlock_exit: + i = start_i; + while (locked_pages > 0) { + page = extent_buffer_page(eb, i); + i++; + unlock_page(page); + locked_pages--; + } + return ret; +} + +void read_extent_buffer(struct extent_buffer *eb, void *dstv, + unsigned long start, + unsigned long len) +{ + size_t cur; + size_t offset; + struct page *page; + char *kaddr; + char *dst = (char *)dstv; + size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1); + unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT; + + WARN_ON(start > eb->len); + WARN_ON(start + len > eb->start + eb->len); + + offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1); + + while (len > 0) { + page = extent_buffer_page(eb, i); + + cur = min(len, (PAGE_CACHE_SIZE - offset)); + kaddr = kmap_atomic(page, KM_USER1); + memcpy(dst, kaddr + offset, cur); + kunmap_atomic(kaddr, KM_USER1); + + dst += cur; + len -= cur; + offset = 0; + i++; + } +} + +int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start, + unsigned long min_len, char **token, char **map, + unsigned long *map_start, + unsigned long *map_len, int km) +{ + size_t offset = start & (PAGE_CACHE_SIZE - 1); + char *kaddr; + struct page *p; + size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1); + unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT; + unsigned long end_i = (start_offset + start + min_len - 1) >> + PAGE_CACHE_SHIFT; + + if (i != end_i) + return -EINVAL; + + if (i == 0) { + offset = start_offset; + *map_start = 0; + } else { + offset = 0; + *map_start = ((u64)i << PAGE_CACHE_SHIFT) - start_offset; + } + + if (start + min_len > eb->len) { + printk(KERN_ERR "btrfs bad mapping eb start %llu len %lu, " + "wanted %lu %lu\n", (unsigned long long)eb->start, + eb->len, start, min_len); + WARN_ON(1); + } + + p = extent_buffer_page(eb, i); + kaddr = kmap_atomic(p, km); + *token = kaddr; + *map = kaddr + offset; + *map_len = PAGE_CACHE_SIZE - offset; + return 0; +} + +int map_extent_buffer(struct extent_buffer *eb, unsigned long start, + unsigned long min_len, + char **token, char **map, + unsigned long *map_start, + unsigned long *map_len, int km) +{ + int err; + int save = 0; + if (eb->map_token) { + unmap_extent_buffer(eb, eb->map_token, km); + eb->map_token = NULL; + save = 1; + WARN_ON(!mutex_is_locked(&eb->mutex)); + } + err = map_private_extent_buffer(eb, start, min_len, token, map, + map_start, map_len, km); + if (!err && save) { + eb->map_token = *token; + eb->kaddr = *map; + eb->map_start = *map_start; + eb->map_len = *map_len; + } + return err; +} + +void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km) +{ + kunmap_atomic(token, km); +} + +int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv, + unsigned long start, + unsigned long len) +{ + size_t cur; + size_t offset; + struct page *page; + char *kaddr; + char *ptr = (char *)ptrv; + size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1); + unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT; + int ret = 0; + + WARN_ON(start > eb->len); + WARN_ON(start + len > eb->start + eb->len); + + offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1); + + while (len > 0) { + page = extent_buffer_page(eb, i); + + cur = min(len, (PAGE_CACHE_SIZE - offset)); + + kaddr = kmap_atomic(page, KM_USER0); + ret = memcmp(ptr, kaddr + offset, cur); + kunmap_atomic(kaddr, KM_USER0); + if (ret) + break; + + ptr += cur; + len -= cur; + offset = 0; + i++; + } + return ret; +} + +void write_extent_buffer(struct extent_buffer *eb, const void *srcv, + unsigned long start, unsigned long len) +{ + size_t cur; + size_t offset; + struct page *page; + char *kaddr; + char *src = (char *)srcv; + size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1); + unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT; + + WARN_ON(start > eb->len); + WARN_ON(start + len > eb->start + eb->len); + + offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1); + + while (len > 0) { + page = extent_buffer_page(eb, i); + WARN_ON(!PageUptodate(page)); + + cur = min(len, PAGE_CACHE_SIZE - offset); + kaddr = kmap_atomic(page, KM_USER1); + memcpy(kaddr + offset, src, cur); + kunmap_atomic(kaddr, KM_USER1); + + src += cur; + len -= cur; + offset = 0; + i++; + } +} + +void memset_extent_buffer(struct extent_buffer *eb, char c, + unsigned long start, unsigned long len) +{ + size_t cur; + size_t offset; + struct page *page; + char *kaddr; + size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1); + unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT; + + WARN_ON(start > eb->len); + WARN_ON(start + len > eb->start + eb->len); + + offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1); + + while (len > 0) { + page = extent_buffer_page(eb, i); + WARN_ON(!PageUptodate(page)); + + cur = min(len, PAGE_CACHE_SIZE - offset); + kaddr = kmap_atomic(page, KM_USER0); + memset(kaddr + offset, c, cur); + kunmap_atomic(kaddr, KM_USER0); + + len -= cur; + offset = 0; + i++; + } +} + +void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src, + unsigned long dst_offset, unsigned long src_offset, + unsigned long len) +{ + u64 dst_len = dst->len; + size_t cur; + size_t offset; + struct page *page; + char *kaddr; + size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1); + unsigned long i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT; + + WARN_ON(src->len != dst_len); + + offset = (start_offset + dst_offset) & + ((unsigned long)PAGE_CACHE_SIZE - 1); + + while (len > 0) { + page = extent_buffer_page(dst, i); + WARN_ON(!PageUptodate(page)); + + cur = min(len, (unsigned long)(PAGE_CACHE_SIZE - offset)); + + kaddr = kmap_atomic(page, KM_USER0); + read_extent_buffer(src, kaddr + offset, src_offset, cur); + kunmap_atomic(kaddr, KM_USER0); + + src_offset += cur; + len -= cur; + offset = 0; + i++; + } +} + +static void move_pages(struct page *dst_page, struct page *src_page, + unsigned long dst_off, unsigned long src_off, + unsigned long len) +{ + char *dst_kaddr = kmap_atomic(dst_page, KM_USER0); + if (dst_page == src_page) { + memmove(dst_kaddr + dst_off, dst_kaddr + src_off, len); + } else { + char *src_kaddr = kmap_atomic(src_page, KM_USER1); + char *p = dst_kaddr + dst_off + len; + char *s = src_kaddr + src_off + len; + + while (len--) + *--p = *--s; + + kunmap_atomic(src_kaddr, KM_USER1); + } + kunmap_atomic(dst_kaddr, KM_USER0); +} + +static void copy_pages(struct page *dst_page, struct page *src_page, + unsigned long dst_off, unsigned long src_off, + unsigned long len) +{ + char *dst_kaddr = kmap_atomic(dst_page, KM_USER0); + char *src_kaddr; + + if (dst_page != src_page) + src_kaddr = kmap_atomic(src_page, KM_USER1); + else + src_kaddr = dst_kaddr; + + memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len); + kunmap_atomic(dst_kaddr, KM_USER0); + if (dst_page != src_page) + kunmap_atomic(src_kaddr, KM_USER1); +} + +void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset, + unsigned long src_offset, unsigned long len) +{ + size_t cur; + size_t dst_off_in_page; + size_t src_off_in_page; + size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1); + unsigned long dst_i; + unsigned long src_i; + + if (src_offset + len > dst->len) { + printk(KERN_ERR "btrfs memmove bogus src_offset %lu move " + "len %lu dst len %lu\n", src_offset, len, dst->len); + BUG_ON(1); + } + if (dst_offset + len > dst->len) { + printk(KERN_ERR "btrfs memmove bogus dst_offset %lu move " + "len %lu dst len %lu\n", dst_offset, len, dst->len); + BUG_ON(1); + } + + while (len > 0) { + dst_off_in_page = (start_offset + dst_offset) & + ((unsigned long)PAGE_CACHE_SIZE - 1); + src_off_in_page = (start_offset + src_offset) & + ((unsigned long)PAGE_CACHE_SIZE - 1); + + dst_i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT; + src_i = (start_offset + src_offset) >> PAGE_CACHE_SHIFT; + + cur = min(len, (unsigned long)(PAGE_CACHE_SIZE - + src_off_in_page)); + cur = min_t(unsigned long, cur, + (unsigned long)(PAGE_CACHE_SIZE - dst_off_in_page)); + + copy_pages(extent_buffer_page(dst, dst_i), + extent_buffer_page(dst, src_i), + dst_off_in_page, src_off_in_page, cur); + + src_offset += cur; + dst_offset += cur; + len -= cur; + } +} + +void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset, + unsigned long src_offset, unsigned long len) +{ + size_t cur; + size_t dst_off_in_page; + size_t src_off_in_page; + unsigned long dst_end = dst_offset + len - 1; + unsigned long src_end = src_offset + len - 1; + size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1); + unsigned long dst_i; + unsigned long src_i; + + if (src_offset + len > dst->len) { + printk(KERN_ERR "btrfs memmove bogus src_offset %lu move " + "len %lu len %lu\n", src_offset, len, dst->len); + BUG_ON(1); + } + if (dst_offset + len > dst->len) { + printk(KERN_ERR "btrfs memmove bogus dst_offset %lu move " + "len %lu len %lu\n", dst_offset, len, dst->len); + BUG_ON(1); + } + if (dst_offset < src_offset) { + memcpy_extent_buffer(dst, dst_offset, src_offset, len); + return; + } + while (len > 0) { + dst_i = (start_offset + dst_end) >> PAGE_CACHE_SHIFT; + src_i = (start_offset + src_end) >> PAGE_CACHE_SHIFT; + + dst_off_in_page = (start_offset + dst_end) & + ((unsigned long)PAGE_CACHE_SIZE - 1); + src_off_in_page = (start_offset + src_end) & + ((unsigned long)PAGE_CACHE_SIZE - 1); + + cur = min_t(unsigned long, len, src_off_in_page + 1); + cur = min(cur, dst_off_in_page + 1); + move_pages(extent_buffer_page(dst, dst_i), + extent_buffer_page(dst, src_i), + dst_off_in_page - cur + 1, + src_off_in_page - cur + 1, cur); + + dst_end -= cur; + src_end -= cur; + len -= cur; + } +} + +int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page) +{ + u64 start = page_offset(page); + struct extent_buffer *eb; + int ret = 1; + unsigned long i; + unsigned long num_pages; + + spin_lock(&tree->buffer_lock); + eb = buffer_search(tree, start); + if (!eb) + goto out; + + if (atomic_read(&eb->refs) > 1) { + ret = 0; + goto out; + } + /* at this point we can safely release the extent buffer */ + num_pages = num_extent_pages(eb->start, eb->len); + for (i = 0; i < num_pages; i++) + page_cache_release(extent_buffer_page(eb, i)); + rb_erase(&eb->rb_node, &tree->buffer); + __free_extent_buffer(eb); +out: + spin_unlock(&tree->buffer_lock); + return ret; +} |