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ceph: rework dcache readdir

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Previously our dcache readdir code relies on that child dentries in
directory dentry's d_subdir list are sorted by dentry's offset in
descending order. When adding dentries to the dcache, if a dentry
already exists, our readdir code moves it to head of directory
dentry's d_subdir list. This design relies on dcache internals.
Al Viro suggests using ncpfs's approach: keeping array of pointers
to dentries in page cache of directory inode. the validity of those
pointers are presented by directory inode's complete and ordered
flags. When a dentry gets pruned, we clear directory inode's complete
flag in the d_prune() callback. Before moving a dentry to other
directory, we clear the ordered flag for both old and new directory.

Signed-off-by: Yan, Zheng <zyan@redhat.com>
This commit is contained in:
Yan, Zheng
2015-06-16 20:48:56 +08:00
committed by Ilya Dryomov
parent b459be739f
commit fdd4e15838
6 changed files with 298 additions and 218 deletions
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118
fs/ceph/inode.c
View File

@@ -390,9 +390,10 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
ci->i_inline_version = 0;
ci->i_time_warp_seq = 0;
ci->i_ceph_flags = 0;
ci->i_ordered_count = 0;
atomic_set(&ci->i_release_count, 1);
atomic_set(&ci->i_complete_count, 0);
atomic64_set(&ci->i_ordered_count, 1);
atomic64_set(&ci->i_release_count, 1);
atomic64_set(&ci->i_complete_seq[0], 0);
atomic64_set(&ci->i_complete_seq[1], 0);
ci->i_symlink = NULL;
memset(&ci->i_dir_layout, 0, sizeof(ci->i_dir_layout));
@@ -860,9 +861,10 @@ static int fill_inode(struct inode *inode, struct page *locked_page,
(issued & CEPH_CAP_FILE_EXCL) == 0 &&
!__ceph_dir_is_complete(ci)) {
dout(" marking %p complete (empty)\n", inode);
i_size_write(inode, 0);
__ceph_dir_set_complete(ci,
atomic_read(&ci->i_release_count),
ci->i_ordered_count);
atomic64_read(&ci->i_release_count),
atomic64_read(&ci->i_ordered_count));
}
wake = true;
@@ -1214,6 +1216,10 @@ retry_lookup:
dout("fill_trace doing d_move %p -> %p\n",
req->r_old_dentry, dn);
/* d_move screws up sibling dentries' offsets */
ceph_dir_clear_ordered(dir);
ceph_dir_clear_ordered(olddir);
d_move(req->r_old_dentry, dn);
dout(" src %p '%pd' dst %p '%pd'\n",
req->r_old_dentry,
@@ -1224,10 +1230,6 @@ retry_lookup:
rehashing bug in vfs_rename_dir */
ceph_invalidate_dentry_lease(dn);
/* d_move screws up sibling dentries' offsets */
ceph_dir_clear_ordered(dir);
ceph_dir_clear_ordered(olddir);
dout("dn %p gets new offset %lld\n", req->r_old_dentry,
ceph_dentry(req->r_old_dentry)->offset);
@@ -1335,6 +1337,49 @@ static int readdir_prepopulate_inodes_only(struct ceph_mds_request *req,
return err;
}
void ceph_readdir_cache_release(struct ceph_readdir_cache_control *ctl)
{
if (ctl->page) {
kunmap(ctl->page);
page_cache_release(ctl->page);
ctl->page = NULL;
}
}
static int fill_readdir_cache(struct inode *dir, struct dentry *dn,
struct ceph_readdir_cache_control *ctl,
struct ceph_mds_request *req)
{
struct ceph_inode_info *ci = ceph_inode(dir);
unsigned nsize = PAGE_CACHE_SIZE / sizeof(struct dentry*);
unsigned idx = ctl->index % nsize;
pgoff_t pgoff = ctl->index / nsize;
if (!ctl->page || pgoff != page_index(ctl->page)) {
ceph_readdir_cache_release(ctl);
ctl->page = grab_cache_page(&dir->i_data, pgoff);
if (!ctl->page) {
ctl->index = -1;
return -ENOMEM;
}
/* reading/filling the cache are serialized by
* i_mutex, no need to use page lock */
unlock_page(ctl->page);
ctl->dentries = kmap(ctl->page);
}
if (req->r_dir_release_cnt == atomic64_read(&ci->i_release_count) &&
req->r_dir_ordered_cnt == atomic64_read(&ci->i_ordered_count)) {
dout("readdir cache dn %p idx %d\n", dn, ctl->index);
ctl->dentries[idx] = dn;
ctl->index++;
} else {
dout("disable readdir cache\n");
ctl->index = -1;
}
return 0;
}
int ceph_readdir_prepopulate(struct ceph_mds_request *req,
struct ceph_mds_session *session)
{
@@ -1347,8 +1392,11 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
struct inode *snapdir = NULL;
struct ceph_mds_request_head *rhead = req->r_request->front.iov_base;
struct ceph_dentry_info *di;
u64 r_readdir_offset = req->r_readdir_offset;
u32 frag = le32_to_cpu(rhead->args.readdir.frag);
struct ceph_readdir_cache_control cache_ctl = {};
if (req->r_aborted)
return readdir_prepopulate_inodes_only(req, session);
if (rinfo->dir_dir &&
le32_to_cpu(rinfo->dir_dir->frag) != frag) {
@@ -1356,14 +1404,11 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
frag, le32_to_cpu(rinfo->dir_dir->frag));
frag = le32_to_cpu(rinfo->dir_dir->frag);
if (ceph_frag_is_leftmost(frag))
r_readdir_offset = 2;
req->r_readdir_offset = 2;
else
r_readdir_offset = 0;
req->r_readdir_offset = 0;
}
if (req->r_aborted)
return readdir_prepopulate_inodes_only(req, session);
if (le32_to_cpu(rinfo->head->op) == CEPH_MDS_OP_LSSNAP) {
snapdir = ceph_get_snapdir(d_inode(parent));
parent = d_find_alias(snapdir);
@@ -1376,6 +1421,17 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
ceph_fill_dirfrag(d_inode(parent), rinfo->dir_dir);
}
if (ceph_frag_is_leftmost(frag) && req->r_readdir_offset == 2) {
/* note dir version at start of readdir so we can tell
* if any dentries get dropped */
struct ceph_inode_info *ci = ceph_inode(d_inode(parent));
req->r_dir_release_cnt = atomic64_read(&ci->i_release_count);
req->r_dir_ordered_cnt = atomic64_read(&ci->i_ordered_count);
req->r_readdir_cache_idx = 0;
}
cache_ctl.index = req->r_readdir_cache_idx;
/* FIXME: release caps/leases if error occurs */
for (i = 0; i < rinfo->dir_nr; i++) {
struct ceph_vino vino;
@@ -1415,13 +1471,6 @@ retry_lookup:
d_delete(dn);
dput(dn);
goto retry_lookup;
} else {
/* reorder parent's d_subdirs */
spin_lock(&parent->d_lock);
spin_lock_nested(&dn->d_lock, DENTRY_D_LOCK_NESTED);
list_move(&dn->d_child, &parent->d_subdirs);
spin_unlock(&dn->d_lock);
spin_unlock(&parent->d_lock);
}
/* inode */
@@ -1438,13 +1487,15 @@ retry_lookup:
}
}
if (fill_inode(in, NULL, &rinfo->dir_in[i], NULL, session,
req->r_request_started, -1,
&req->r_caps_reservation) < 0) {
ret = fill_inode(in, NULL, &rinfo->dir_in[i], NULL, session,
req->r_request_started, -1,
&req->r_caps_reservation);
if (ret < 0) {
pr_err("fill_inode badness on %p\n", in);
if (d_really_is_negative(dn))
iput(in);
d_drop(dn);
err = ret;
goto next_item;
}
@@ -1460,19 +1511,28 @@ retry_lookup:
}
di = dn->d_fsdata;
di->offset = ceph_make_fpos(frag, i + r_readdir_offset);
di->offset = ceph_make_fpos(frag, i + req->r_readdir_offset);
update_dentry_lease(dn, rinfo->dir_dlease[i],
req->r_session,
req->r_request_started);
if (err == 0 && cache_ctl.index >= 0) {
ret = fill_readdir_cache(d_inode(parent), dn,
&cache_ctl, req);
if (ret < 0)
err = ret;
}
next_item:
if (dn)
dput(dn);
}
if (err == 0)
req->r_did_prepopulate = true;
out:
if (err == 0) {
req->r_did_prepopulate = true;
req->r_readdir_cache_idx = cache_ctl.index;
}
ceph_readdir_cache_release(&cache_ctl);
if (snapdir) {
iput(snapdir);
dput(parent);