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>
This commit is contained in:
Yan, Zheng
Ilya Dryomov
parent
04303d8ad0
commit
c530cd24c2
1 changed files with 83 additions and 46 deletions
129
fs/ceph/dir.c
129
fs/ceph/dir.c
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@ -110,6 +110,50 @@ static int note_last_dentry(struct ceph_file_info *fi, const char *name,
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return 0;
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}
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static struct dentry *
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__dcache_find_get_entry(struct dentry *parent, u64 idx,
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struct ceph_readdir_cache_control *cache_ctl)
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{
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struct inode *dir = d_inode(parent);
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struct dentry *dentry;
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unsigned idx_mask = (PAGE_SIZE / sizeof(struct dentry *)) - 1;
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loff_t ptr_pos = idx * sizeof(struct dentry *);
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pgoff_t ptr_pgoff = ptr_pos >> PAGE_SHIFT;
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if (ptr_pos >= i_size_read(dir))
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return NULL;
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if (!cache_ctl->page || ptr_pgoff != page_index(cache_ctl->page)) {
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ceph_readdir_cache_release(cache_ctl);
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cache_ctl->page = find_lock_page(&dir->i_data, ptr_pgoff);
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if (!cache_ctl->page) {
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dout(" page %lu not found\n", ptr_pgoff);
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return ERR_PTR(-EAGAIN);
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}
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/* reading/filling the cache are serialized by
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i_mutex, no need to use page lock */
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unlock_page(cache_ctl->page);
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cache_ctl->dentries = kmap(cache_ctl->page);
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}
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cache_ctl->index = idx & idx_mask;
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rcu_read_lock();
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spin_lock(&parent->d_lock);
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/* check i_size again here, because empty directory can be
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* marked as complete while not holding the i_mutex. */
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if (ceph_dir_is_complete_ordered(dir) && ptr_pos < i_size_read(dir))
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dentry = cache_ctl->dentries[cache_ctl->index];
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else
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dentry = NULL;
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spin_unlock(&parent->d_lock);
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if (dentry && !lockref_get_not_dead(&dentry->d_lockref))
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dentry = NULL;
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rcu_read_unlock();
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return dentry ? : ERR_PTR(-EAGAIN);
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}
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/*
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* When possible, we try to satisfy a readdir by peeking at the
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* dcache. We make this work by carefully ordering dentries on
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@ -129,62 +173,57 @@ static int __dcache_readdir(struct file *file, struct dir_context *ctx,
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struct inode *dir = d_inode(parent);
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struct dentry *dentry, *last = NULL;
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struct ceph_dentry_info *di;
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unsigned nsize = PAGE_SIZE / sizeof(struct dentry *);
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int err = 0;
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loff_t ptr_pos = 0;
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struct ceph_readdir_cache_control cache_ctl = {};
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u64 idx = 0;
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int err = 0;
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dout("__dcache_readdir %p v%u at %llu\n", dir, shared_gen, ctx->pos);
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/* we can calculate cache index for the first dirfrag */
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if (ceph_frag_is_leftmost(fpos_frag(ctx->pos))) {
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cache_ctl.index = fpos_off(ctx->pos) - 2;
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BUG_ON(cache_ctl.index < 0);
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ptr_pos = cache_ctl.index * sizeof(struct dentry *);
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/* search start position */
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if (ctx->pos > 2) {
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u64 count = div_u64(i_size_read(dir), sizeof(struct dentry *));
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while (count > 0) {
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u64 step = count >> 1;
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dentry = __dcache_find_get_entry(parent, idx + step,
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&cache_ctl);
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if (!dentry) {
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/* use linar search */
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idx = 0;
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break;
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}
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if (IS_ERR(dentry)) {
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err = PTR_ERR(dentry);
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goto out;
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}
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di = ceph_dentry(dentry);
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spin_lock(&dentry->d_lock);
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if (fpos_cmp(di->offset, ctx->pos) < 0) {
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idx += step + 1;
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count -= step + 1;
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} else {
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count = step;
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}
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spin_unlock(&dentry->d_lock);
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dput(dentry);
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}
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dout("__dcache_readdir %p cache idx %llu\n", dir, idx);
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}
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while (true) {
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pgoff_t pgoff;
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bool emit_dentry;
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if (ptr_pos >= i_size_read(dir)) {
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for (;;) {
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bool emit_dentry = false;
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dentry = __dcache_find_get_entry(parent, idx++, &cache_ctl);
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if (!dentry) {
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fi->flags |= CEPH_F_ATEND;
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err = 0;
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break;
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}
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err = -EAGAIN;
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pgoff = ptr_pos >> PAGE_SHIFT;
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if (!cache_ctl.page || pgoff != page_index(cache_ctl.page)) {
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ceph_readdir_cache_release(&cache_ctl);
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cache_ctl.page = find_lock_page(&dir->i_data, pgoff);
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if (!cache_ctl.page) {
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dout(" page %lu not found\n", pgoff);
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break;
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}
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/* reading/filling the cache are serialized by
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* i_mutex, no need to use page lock */
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unlock_page(cache_ctl.page);
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cache_ctl.dentries = kmap(cache_ctl.page);
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if (IS_ERR(dentry)) {
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err = PTR_ERR(dentry);
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goto out;
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}
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rcu_read_lock();
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spin_lock(&parent->d_lock);
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/* check i_size again here, because empty directory can be
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* marked as complete while not holding the i_mutex. */
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if (ceph_dir_is_complete_ordered(dir) &&
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ptr_pos < i_size_read(dir))
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dentry = cache_ctl.dentries[cache_ctl.index % nsize];
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else
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dentry = NULL;
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spin_unlock(&parent->d_lock);
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if (dentry && !lockref_get_not_dead(&dentry->d_lockref))
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dentry = NULL;
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rcu_read_unlock();
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if (!dentry)
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break;
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emit_dentry = false;
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di = ceph_dentry(dentry);
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spin_lock(&dentry->d_lock);
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if (di->lease_shared_gen == shared_gen &&
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@ -217,10 +256,8 @@ static int __dcache_readdir(struct file *file, struct dir_context *ctx,
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} else {
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dput(dentry);
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}
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cache_ctl.index++;
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ptr_pos += sizeof(struct dentry *);
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}
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out:
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ceph_readdir_cache_release(&cache_ctl);
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if (last) {
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int ret;
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