ceph: search cache postion for dcache readdir
use binary search to find cache index that corresponds to readdir
postion.
Signed-off-by: Yan, Zheng <zyan@redhat.com>
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 4fb2bbc..cdea450 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -110,6 +110,50 @@
return 0;
}
+
+static struct dentry *
+__dcache_find_get_entry(struct dentry *parent, u64 idx,
+ struct ceph_readdir_cache_control *cache_ctl)
+{
+ struct inode *dir = d_inode(parent);
+ struct dentry *dentry;
+ unsigned idx_mask = (PAGE_SIZE / sizeof(struct dentry *)) - 1;
+ loff_t ptr_pos = idx * sizeof(struct dentry *);
+ pgoff_t ptr_pgoff = ptr_pos >> PAGE_SHIFT;
+
+ if (ptr_pos >= i_size_read(dir))
+ return NULL;
+
+ if (!cache_ctl->page || ptr_pgoff != page_index(cache_ctl->page)) {
+ ceph_readdir_cache_release(cache_ctl);
+ cache_ctl->page = find_lock_page(&dir->i_data, ptr_pgoff);
+ if (!cache_ctl->page) {
+ dout(" page %lu not found\n", ptr_pgoff);
+ return ERR_PTR(-EAGAIN);
+ }
+ /* reading/filling the cache are serialized by
+ i_mutex, no need to use page lock */
+ unlock_page(cache_ctl->page);
+ cache_ctl->dentries = kmap(cache_ctl->page);
+ }
+
+ cache_ctl->index = idx & idx_mask;
+
+ rcu_read_lock();
+ spin_lock(&parent->d_lock);
+ /* check i_size again here, because empty directory can be
+ * marked as complete while not holding the i_mutex. */
+ if (ceph_dir_is_complete_ordered(dir) && ptr_pos < i_size_read(dir))
+ dentry = cache_ctl->dentries[cache_ctl->index];
+ else
+ dentry = NULL;
+ spin_unlock(&parent->d_lock);
+ if (dentry && !lockref_get_not_dead(&dentry->d_lockref))
+ dentry = NULL;
+ rcu_read_unlock();
+ return dentry ? : ERR_PTR(-EAGAIN);
+}
+
/*
* When possible, we try to satisfy a readdir by peeking at the
* dcache. We make this work by carefully ordering dentries on
@@ -129,62 +173,57 @@
struct inode *dir = d_inode(parent);
struct dentry *dentry, *last = NULL;
struct ceph_dentry_info *di;
- unsigned nsize = PAGE_SIZE / sizeof(struct dentry *);
- int err = 0;
- loff_t ptr_pos = 0;
struct ceph_readdir_cache_control cache_ctl = {};
+ u64 idx = 0;
+ int err = 0;
dout("__dcache_readdir %p v%u at %llu\n", dir, shared_gen, ctx->pos);
- /* we can calculate cache index for the first dirfrag */
- if (ceph_frag_is_leftmost(fpos_frag(ctx->pos))) {
- cache_ctl.index = fpos_off(ctx->pos) - 2;
- BUG_ON(cache_ctl.index < 0);
- ptr_pos = cache_ctl.index * sizeof(struct dentry *);
+ /* search start position */
+ if (ctx->pos > 2) {
+ u64 count = div_u64(i_size_read(dir), sizeof(struct dentry *));
+ while (count > 0) {
+ u64 step = count >> 1;
+ dentry = __dcache_find_get_entry(parent, idx + step,
+ &cache_ctl);
+ if (!dentry) {
+ /* use linar search */
+ idx = 0;
+ break;
+ }
+ if (IS_ERR(dentry)) {
+ err = PTR_ERR(dentry);
+ goto out;
+ }
+ di = ceph_dentry(dentry);
+ spin_lock(&dentry->d_lock);
+ if (fpos_cmp(di->offset, ctx->pos) < 0) {
+ idx += step + 1;
+ count -= step + 1;
+ } else {
+ count = step;
+ }
+ spin_unlock(&dentry->d_lock);
+ dput(dentry);
+ }
+
+ dout("__dcache_readdir %p cache idx %llu\n", dir, idx);
}
- while (true) {
- pgoff_t pgoff;
- bool emit_dentry;
- if (ptr_pos >= i_size_read(dir)) {
+ for (;;) {
+ bool emit_dentry = false;
+ dentry = __dcache_find_get_entry(parent, idx++, &cache_ctl);
+ if (!dentry) {
fi->flags |= CEPH_F_ATEND;
err = 0;
break;
}
-
- err = -EAGAIN;
- pgoff = ptr_pos >> PAGE_SHIFT;
- if (!cache_ctl.page || pgoff != page_index(cache_ctl.page)) {
- ceph_readdir_cache_release(&cache_ctl);
- cache_ctl.page = find_lock_page(&dir->i_data, pgoff);
- if (!cache_ctl.page) {
- dout(" page %lu not found\n", pgoff);
- break;
- }
- /* reading/filling the cache are serialized by
- * i_mutex, no need to use page lock */
- unlock_page(cache_ctl.page);
- cache_ctl.dentries = kmap(cache_ctl.page);
+ if (IS_ERR(dentry)) {
+ err = PTR_ERR(dentry);
+ goto out;
}
- rcu_read_lock();
- spin_lock(&parent->d_lock);
- /* check i_size again here, because empty directory can be
- * marked as complete while not holding the i_mutex. */
- if (ceph_dir_is_complete_ordered(dir) &&
- ptr_pos < i_size_read(dir))
- dentry = cache_ctl.dentries[cache_ctl.index % nsize];
- else
- dentry = NULL;
- spin_unlock(&parent->d_lock);
- if (dentry && !lockref_get_not_dead(&dentry->d_lockref))
- dentry = NULL;
- rcu_read_unlock();
- if (!dentry)
- break;
-
- emit_dentry = false;
di = ceph_dentry(dentry);
spin_lock(&dentry->d_lock);
if (di->lease_shared_gen == shared_gen &&
@@ -217,10 +256,8 @@
} else {
dput(dentry);
}
-
- cache_ctl.index++;
- ptr_pos += sizeof(struct dentry *);
}
+out:
ceph_readdir_cache_release(&cache_ctl);
if (last) {
int ret;