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Btrfs: Limit btree writeback to prevent seeks 

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2007-11-26 16:34:41 -08:00
parent 015a739c7c
commit 793955bca6
3 changed files with 51 additions and 0 deletions
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9
fs/btrfs/disk-io.c
View File

@ -210,6 +210,15 @@ static int btree_writepages(struct address_space *mapping,
{
struct extent_map_tree *tree;
tree = &BTRFS_I(mapping->host)->extent_tree;
if (wbc->sync_mode == WB_SYNC_NONE) {
u64 num_dirty;
u64 start = 0;
unsigned long thresh = 96 * 1024 * 1024;
num_dirty = count_range_bits(tree, &start, thresh, EXTENT_DIRTY);
if (num_dirty < thresh) {
return 0;
}
}
return extent_writepages(tree, mapping, btree_get_extent, wbc);
}

39
fs/btrfs/extent_map.c
View File

@ -1106,6 +1106,45 @@ out:
return found;
}
u64 count_range_bits(struct extent_map_tree *tree,
u64 *start, 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;
write_lock_irq(&tree->lock);
/*
* this search will find all the extents that end after
* our range starts.
*/
node = tree_search(&tree->state, cur_start);
if (!node || IS_ERR(node)) {
goto out;
}
while(1) {
state = rb_entry(node, struct extent_state, rb_node);
if ((state->state & bits)) {
total_bytes += state->end - state->start + 1;
if (total_bytes >= max_bytes)
break;
if (!found) {
*start = state->start;
found = 1;
}
}
node = rb_next(node);
if (!node)
break;
}
out:
write_unlock_irq(&tree->lock);
return total_bytes;
}
/*
* helper function to lock both pages and extents in the tree.
* pages must be locked first.

3
fs/btrfs/extent_map.h
View File

@ -113,6 +113,9 @@ int extent_read_full_page(struct extent_map_tree *tree, struct page *page,
int __init extent_map_init(void);
void __exit extent_map_exit(void);
u64 count_range_bits(struct extent_map_tree *tree,
u64 *start, u64 max_bytes, unsigned long bits);
int test_range_bit(struct extent_map_tree *tree, u64 start, u64 end,
int bits, int filled);
int clear_extent_bits(struct extent_map_tree *tree, u64 start, u64 end,