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f2fs: remove costly bit operations for f2fs_find_entry 

It turns out that a bit operation like find_next_bit is not always fast enough
for f2fs_find_entry.
Instead, it is pretty much simple and fast to traverse each dentries.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
hifive-unleashed-5.1
Jaegeuk Kim 2014-02-27 13:57:53 +09:00
parent 8b8343fa9d
commit 5d0c667121
1 changed files with 17 additions and 15 deletions
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32
fs/f2fs/dir.c
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@ -93,16 +93,20 @@ static struct f2fs_dir_entry *find_in_block(struct page *dentry_page,
f2fs_hash_t namehash, struct page **res_page)
{
struct f2fs_dir_entry *de;
unsigned long bit_pos, end_pos, next_pos;
unsigned long bit_pos = 0;
struct f2fs_dentry_block *dentry_blk = kmap(dentry_page);
int slots;
int max_len = 0;
bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
NR_DENTRY_IN_BLOCK, 0);
while (bit_pos < NR_DENTRY_IN_BLOCK) {
de = &dentry_blk->dentry[bit_pos];
slots = GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
if (!test_bit_le(bit_pos, &dentry_blk->dentry_bitmap)) {
if (bit_pos == 0)
max_len = 1;
else if (!test_bit_le(bit_pos - 1, &dentry_blk->dentry_bitmap))
max_len++;
bit_pos++;
continue;
}
if (early_match_name(name, namelen, namehash, de)) {
if (!memcmp(dentry_blk->filename[bit_pos],
name, namelen)) {
@ -110,20 +114,18 @@ static struct f2fs_dir_entry *find_in_block(struct page *dentry_page,
goto found;
}
}
next_pos = bit_pos + slots;
bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
NR_DENTRY_IN_BLOCK, next_pos);
if (bit_pos >= NR_DENTRY_IN_BLOCK)
end_pos = NR_DENTRY_IN_BLOCK;
else
end_pos = bit_pos;
if (*max_slots < end_pos - next_pos)
*max_slots = end_pos - next_pos;
if (max_len > *max_slots) {
*max_slots = max_len;
max_len = 0;
}
bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
}
de = NULL;
kunmap(dentry_page);
found:
if (max_len > *max_slots)
*max_slots = max_len;
return de;
}