Btrfs: don't do extra bitmap search in one bit case
When we make ctl->unit allocations from a bitmap there is no point in searching
for the next 0 in the bitmap. If we've found a bit we're done and can just exit
the loop. Thanks,
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index e10c966..0948d34 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1730,7 +1730,7 @@
*/
static int search_bitmap(struct btrfs_free_space_ctl *ctl,
struct btrfs_free_space *bitmap_info, u64 *offset,
- u64 *bytes)
+ u64 *bytes, bool for_alloc)
{
unsigned long found_bits = 0;
unsigned long max_bits = 0;
@@ -1742,7 +1742,8 @@
* Skip searching the bitmap if we don't have a contiguous section that
* is large enough for this allocation.
*/
- if (bitmap_info->max_extent_size &&
+ if (for_alloc &&
+ bitmap_info->max_extent_size &&
bitmap_info->max_extent_size < *bytes) {
*bytes = bitmap_info->max_extent_size;
return -1;
@@ -1753,6 +1754,10 @@
bits = bytes_to_bits(*bytes, ctl->unit);
for_each_set_bit_from(i, bitmap_info->bitmap, BITS_PER_BITMAP) {
+ if (for_alloc && bits == 1) {
+ found_bits = 1;
+ break;
+ }
next_zero = find_next_zero_bit(bitmap_info->bitmap,
BITS_PER_BITMAP, i);
extent_bits = next_zero - i;
@@ -1824,7 +1829,7 @@
if (entry->bitmap) {
u64 size = *bytes;
- ret = search_bitmap(ctl, entry, &tmp, &size);
+ ret = search_bitmap(ctl, entry, &tmp, &size, true);
if (!ret) {
*offset = tmp;
*bytes = size;
@@ -1885,7 +1890,8 @@
search_start = *offset;
search_bytes = ctl->unit;
search_bytes = min(search_bytes, end - search_start + 1);
- ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
+ ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes,
+ false);
if (ret < 0 || search_start != *offset)
return -EINVAL;
@@ -1930,7 +1936,7 @@
search_start = *offset;
search_bytes = ctl->unit;
ret = search_bitmap(ctl, bitmap_info, &search_start,
- &search_bytes);
+ &search_bytes, false);
if (ret < 0 || search_start != *offset)
return -EAGAIN;
@@ -2685,7 +2691,7 @@
search_start = min_start;
search_bytes = bytes;
- err = search_bitmap(ctl, entry, &search_start, &search_bytes);
+ err = search_bitmap(ctl, entry, &search_start, &search_bytes, true);
if (err) {
if (search_bytes > *max_extent_size)
*max_extent_size = search_bytes;
@@ -3262,7 +3268,7 @@
}
bytes = minlen;
- ret2 = search_bitmap(ctl, entry, &start, &bytes);
+ ret2 = search_bitmap(ctl, entry, &start, &bytes, false);
if (ret2 || start >= end) {
spin_unlock(&ctl->tree_lock);
mutex_unlock(&ctl->cache_writeout_mutex);
@@ -3415,7 +3421,7 @@
u64 count = 1;
int ret;
- ret = search_bitmap(ctl, entry, &offset, &count);
+ ret = search_bitmap(ctl, entry, &offset, &count, true);
/* Logic error; Should be empty if it can't find anything */
ASSERT(!ret);
@@ -3600,10 +3606,6 @@
bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
- /* We used the newly allocated info, set the max_extent_size to bytes */
- if (!info)
- bitmap_info->max_extent_size = bytes_added;
-
bytes -= bytes_added;
offset += bytes_added;
spin_unlock(&ctl->tree_lock);
@@ -3647,7 +3649,7 @@
bit_off = offset;
bit_bytes = ctl->unit;
- ret = search_bitmap(ctl, info, &bit_off, &bit_bytes);
+ ret = search_bitmap(ctl, info, &bit_off, &bit_bytes, false);
if (!ret) {
if (bit_off == offset) {
ret = 1;