static void recalculate_thresholds(struct btrfs_block_group_cache *block_group)
{
- u64 max_bytes, possible_bytes;
+ u64 max_bytes;
+ u64 bitmap_bytes;
+ u64 extent_bytes;
/*
* The goal is to keep the total amount of memory used per 1gb of space
max_bytes = MAX_CACHE_BYTES_PER_GIG *
(div64_u64(block_group->key.offset, 1024 * 1024 * 1024));
- possible_bytes = (block_group->total_bitmaps * PAGE_CACHE_SIZE) +
- (sizeof(struct btrfs_free_space) *
- block_group->extents_thresh);
+ /*
+ * we want to account for 1 more bitmap than what we have so we can make
+ * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
+ * we add more bitmaps.
+ */
+ bitmap_bytes = (block_group->total_bitmaps + 1) * PAGE_CACHE_SIZE;
- if (possible_bytes > max_bytes) {
- int extent_bytes = max_bytes -
- (block_group->total_bitmaps * PAGE_CACHE_SIZE);
+ if (bitmap_bytes >= max_bytes) {
+ block_group->extents_thresh = 0;
+ return;
+ }
- if (extent_bytes <= 0) {
- block_group->extents_thresh = 0;
- return;
- }
+ /*
+ * we want the extent entry threshold to always be at most 1/2 the maxw
+ * bytes we can have, or whatever is less than that.
+ */
+ extent_bytes = max_bytes - bitmap_bytes;
+ extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
- block_group->extents_thresh = extent_bytes /
- (sizeof(struct btrfs_free_space));
- }
+ block_group->extents_thresh =
+ div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
}
static void bitmap_clear_bits(struct btrfs_block_group_cache *block_group,
BUG_ON(block_group->total_bitmaps >= max_bitmaps);
info->offset = offset_to_bitmap(block_group, offset);
+ info->bytes = 0;
link_free_space(block_group, info);
block_group->total_bitmaps++;
u64 *offset, u64 *bytes)
{
u64 end;
+ u64 search_start, search_bytes;
+ int ret;
again:
end = bitmap_info->offset +
(u64)(BITS_PER_BITMAP * block_group->sectorsize) - 1;
+ /*
+ * XXX - this can go away after a few releases.
+ *
+ * since the only user of btrfs_remove_free_space is the tree logging
+ * stuff, and the only way to test that is under crash conditions, we
+ * want to have this debug stuff here just in case somethings not
+ * working. Search the bitmap for the space we are trying to use to
+ * make sure its actually there. If its not there then we need to stop
+ * because something has gone wrong.
+ */
+ search_start = *offset;
+ search_bytes = *bytes;
+ ret = search_bitmap(block_group, bitmap_info, &search_start,
+ &search_bytes);
+ BUG_ON(ret < 0 || search_start != *offset);
+
if (*offset > bitmap_info->offset && *offset + *bytes > end) {
bitmap_clear_bits(block_group, bitmap_info, *offset,
end - *offset + 1);
}
if (*bytes) {
+ struct rb_node *next = rb_next(&bitmap_info->offset_index);
if (!bitmap_info->bytes) {
unlink_free_space(block_group, bitmap_info);
kfree(bitmap_info->bitmap);
recalculate_thresholds(block_group);
}
- bitmap_info = tree_search_offset(block_group,
- offset_to_bitmap(block_group,
- *offset),
- 1, 0);
- if (!bitmap_info)
+ /*
+ * no entry after this bitmap, but we still have bytes to
+ * remove, so something has gone wrong.
+ */
+ if (!next)
return -EINVAL;
+ bitmap_info = rb_entry(next, struct btrfs_free_space,
+ offset_index);
+
+ /*
+ * if the next entry isn't a bitmap we need to return to let the
+ * extent stuff do its work.
+ */
if (!bitmap_info->bitmap)
return -EAGAIN;
+ /*
+ * Ok the next item is a bitmap, but it may not actually hold
+ * the information for the rest of this free space stuff, so
+ * look for it, and if we don't find it return so we can try
+ * everything over again.
+ */
+ search_start = *offset;
+ search_bytes = *bytes;
+ ret = search_bitmap(block_group, bitmap_info, &search_start,
+ &search_bytes);
+ if (ret < 0 || search_start != *offset)
+ return -EAGAIN;
+
goto again;
} else if (!bitmap_info->bytes) {
unlink_free_space(block_group, bitmap_info);
again:
info = tree_search_offset(block_group, offset, 0, 0);
if (!info) {
- WARN_ON(1);
- goto out_lock;
+ /*
+ * oops didn't find an extent that matched the space we wanted
+ * to remove, look for a bitmap instead
+ */
+ info = tree_search_offset(block_group,
+ offset_to_bitmap(block_group, offset),
+ 1, 0);
+ if (!info) {
+ WARN_ON(1);
+ goto out_lock;
+ }
}
if (info->bytes < bytes && rb_next(&info->offset_index)) {
if (cluster->block_group != block_group)
goto out;
- entry = tree_search_offset(block_group, search_start, 0, 0);
-
+ /*
+ * search_start is the beginning of the bitmap, but at some point it may
+ * be a good idea to point to the actual start of the free area in the
+ * bitmap, so do the offset_to_bitmap trick anyway, and set bitmap_only
+ * to 1 to make sure we get the bitmap entry
+ */
+ entry = tree_search_offset(block_group,
+ offset_to_bitmap(block_group, search_start),
+ 1, 0);
if (!entry || !entry->bitmap)
goto out;
window_start = entry->offset;
window_free = entry->bytes;
last = entry;
- max_extent = 0;
+ max_extent = entry->bytes;
} else {
last = next;
window_free += next->bytes;
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff