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
129
fs/ceph/dir.c
129
fs/ceph/dir.c
|
|
@ -110,6 +110,50 @@ static int note_last_dentry(struct ceph_file_info *fi, const char *name,
|
|||
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 @@ static int __dcache_readdir(struct file *file, struct dir_context *ctx,
|
|||
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 @@ static int __dcache_readdir(struct file *file, struct dir_context *ctx,
|
|||
} else {
|
||||
dput(dentry);
|
||||
}
|
||||
|
||||
cache_ctl.index++;
|
||||
ptr_pos += sizeof(struct dentry *);
|
||||
}
|
||||
out:
|
||||
ceph_readdir_cache_release(&cache_ctl);
|
||||
if (last) {
|
||||
int ret;
|
||||
|
|
|
|||
Loading…
Reference in New Issue