The bin search jumps over the extent buffer item keys, comparing
directly the bytes if the key is in one page, or storing it in a
temporary buffer in case it spans two pages.
The mapping start and length are obtained from map_private_extent_buffer,
which is heavy weight compared to what we need. We know the key size and
can find out the eb page in a simple way. For keys spanning two pages
the fallback read_extent_buffer is used.
The temporary variables are reduced and moved to the scope of use.
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
---
fs/btrfs/ctree.c | 43 +++++++++++++++----------------------------
1 file changed, 15 insertions(+), 28 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 6dbeb23c59ec..746dec22f250 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1668,15 +1668,8 @@ static noinline int generic_bin_search(struct extent_buffer *eb,
{
int low = 0;
int high = max;
- int mid;
int ret;
- struct btrfs_disk_key *tmp = NULL;
- struct btrfs_disk_key unaligned;
- unsigned long offset;
- char *kaddr = NULL;
- unsigned long map_start = 0;
- unsigned long map_len = 0;
- int err;
+ const int key_size = sizeof(struct btrfs_disk_key);
if (low > high) {
btrfs_err(eb->fs_info,
@@ -1687,32 +1680,26 @@ static noinline int generic_bin_search(struct extent_buffer *eb,
}
while (low < high) {
+ unsigned long oip;
+ unsigned long offset;
+ struct btrfs_disk_key *tmp;
+ struct btrfs_disk_key unaligned;
+ int mid;
+
mid = (low + high) / 2;
offset = p + mid * item_size;
+ oip = offset_in_page(offset);
- if (!kaddr || offset < map_start ||
- (offset + sizeof(struct btrfs_disk_key)) >
- map_start + map_len) {
-
- err = map_private_extent_buffer(eb, offset,
- sizeof(struct btrfs_disk_key),
- &kaddr, &map_start, &map_len);
-
- if (!err) {
- tmp = (struct btrfs_disk_key *)(kaddr + offset -
- map_start);
- } else if (err == 1) {
- read_extent_buffer(eb, &unaligned,
- offset, sizeof(unaligned));
- tmp = &unaligned;
- } else {
- return err;
- }
+ if (oip + key_size <= PAGE_SIZE) {
+ const unsigned long idx = offset >> PAGE_SHIFT;
+ char *kaddr = page_address(eb->pages[idx]);
+ tmp = (struct btrfs_disk_key *)(kaddr + oip);
} else {
- tmp = (struct btrfs_disk_key *)(kaddr + offset -
- map_start);
+ read_extent_buffer(eb, &unaligned, offset, key_size);
+ tmp = &unaligned;
}
+
ret = comp_keys(tmp, key);
if (ret < 0)
--
2.25.0
