Commit 5cd17f34 authored by David Sterba's avatar David Sterba

btrfs: speed up and simplify generic_bin_search

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.
Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent ce7afe87
...@@ -1668,15 +1668,8 @@ static noinline int generic_bin_search(struct extent_buffer *eb, ...@@ -1668,15 +1668,8 @@ static noinline int generic_bin_search(struct extent_buffer *eb,
{ {
int low = 0; int low = 0;
int high = max; int high = max;
int mid;
int ret; int ret;
struct btrfs_disk_key *tmp = NULL; const int key_size = sizeof(struct btrfs_disk_key);
struct btrfs_disk_key unaligned;
unsigned long offset;
char *kaddr = NULL;
unsigned long map_start = 0;
unsigned long map_len = 0;
int err;
if (low > high) { if (low > high) {
btrfs_err(eb->fs_info, btrfs_err(eb->fs_info,
...@@ -1687,32 +1680,26 @@ static noinline int generic_bin_search(struct extent_buffer *eb, ...@@ -1687,32 +1680,26 @@ static noinline int generic_bin_search(struct extent_buffer *eb,
} }
while (low < high) { 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; mid = (low + high) / 2;
offset = p + mid * item_size; offset = p + mid * item_size;
oip = offset_in_page(offset);
if (!kaddr || offset < map_start || if (oip + key_size <= PAGE_SIZE) {
(offset + sizeof(struct btrfs_disk_key)) > const unsigned long idx = offset >> PAGE_SHIFT;
map_start + map_len) { char *kaddr = page_address(eb->pages[idx]);
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;
}
tmp = (struct btrfs_disk_key *)(kaddr + oip);
} else { } else {
tmp = (struct btrfs_disk_key *)(kaddr + offset - read_extent_buffer(eb, &unaligned, offset, key_size);
map_start); tmp = &unaligned;
} }
ret = comp_keys(tmp, key); ret = comp_keys(tmp, key);
if (ret < 0) if (ret < 0)
......
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