On Mon, 2019-01-07 at 14:31 +0800, Yan, Zheng wrote:
> ceph_getattr() return zero dev ID for head inodes and set dev ID to
> snapid directly for snaphost inodes. This is not good because userspace
> utilities may consider device ID of 0 as invalid, snapid may conflict
> with other device's ID.
>
> This patch introduces "snapids to anonymous bdev IDs" map. we create a
> new mapping when we see a snapid for the first time. we trim unused
> mapping after it is ilde for 5 minutes.
>
> Signed-off-by: "Yan, Zheng" <zyan@xxxxxxxxxx>
> ---
> fs/ceph/inode.c | 37 +++++++----
> fs/ceph/mds_client.c | 8 +++
> fs/ceph/mds_client.h | 13 ++++
> fs/ceph/snap.c | 154 +++++++++++++++++++++++++++++++++++++++++++
> fs/ceph/super.h | 13 +++-
> 5 files changed, 210 insertions(+), 15 deletions(-)
>
> Changes since v1
> change the code that handles leaked snap map on umount
>
> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> index c080b133c08b..7f82ceff510a 100644
> --- a/fs/ceph/inode.c
> +++ b/fs/ceph/inode.c
> @@ -548,17 +548,22 @@ void ceph_destroy_inode(struct inode *inode)
> */
> if (ci->i_snap_realm) {
> struct ceph_mds_client *mdsc =
> - ceph_sb_to_client(ci->vfs_inode.i_sb)->mdsc;
> - struct ceph_snap_realm *realm = ci->i_snap_realm;
> -
> - dout(" dropping residual ref to snap realm %p\n", realm);
> - spin_lock(&realm->inodes_with_caps_lock);
> - list_del_init(&ci->i_snap_realm_item);
> - ci->i_snap_realm = NULL;
> - if (realm->ino == ci->i_vino.ino)
> - realm->inode = NULL;
> - spin_unlock(&realm->inodes_with_caps_lock);
> - ceph_put_snap_realm(mdsc, realm);
> + ceph_inode_to_client(inode)->mdsc;
> + if (ceph_snap(inode) == CEPH_NOSNAP) {
> + struct ceph_snap_realm *realm = ci->i_snap_realm;
> + dout(" dropping residual ref to snap realm %p\n",
> + realm);
> + spin_lock(&realm->inodes_with_caps_lock);
> + list_del_init(&ci->i_snap_realm_item);
> + ci->i_snap_realm = NULL;
> + if (realm->ino == ci->i_vino.ino)
> + realm->inode = NULL;
> + spin_unlock(&realm->inodes_with_caps_lock);
> + ceph_put_snap_realm(mdsc, realm);
> + } else {
> + ceph_put_snapid_map(mdsc, ci->i_snapid_map);
> + ci->i_snap_realm = NULL;
> + }
> }
>
> kfree(ci->i_symlink);
> @@ -776,6 +781,9 @@ static int fill_inode(struct inode *inode, struct page *locked_page,
> pool_ns = ceph_find_or_create_string(iinfo->pool_ns_data,
> iinfo->pool_ns_len);
>
> + if (ceph_snap(inode) != CEPH_NOSNAP && !ci->i_snapid_map)
> + ci->i_snapid_map = ceph_get_snapid_map(mdsc, ceph_snap(inode));
> +
> spin_lock(&ci->i_ceph_lock);
>
> /*
> @@ -2260,10 +2268,11 @@ int ceph_getattr(const struct path *path, struct kstat *stat,
> if (!err) {
> generic_fillattr(inode, stat);
> stat->ino = ceph_translate_ino(inode->i_sb, inode->i_ino);
> - if (ceph_snap(inode) != CEPH_NOSNAP)
> - stat->dev = ceph_snap(inode);
> + if (ceph_snap(inode) == CEPH_NOSNAP)
> + stat->dev = inode->i_sb->s_dev;
> else
> - stat->dev = 0;
> + stat->dev = ci->i_snapid_map ? ci->i_snapid_map->dev : 0;
> +
> if (S_ISDIR(inode->i_mode)) {
> if (ceph_test_mount_opt(ceph_sb_to_client(inode->i_sb),
> RBYTES))
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 32f627517fd0..1ff490c2d38e 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -3789,6 +3789,8 @@ static void delayed_work(struct work_struct *work)
> dout("mdsc delayed_work\n");
> ceph_check_delayed_caps(mdsc);
>
> + ceph_trim_snapid_map(mdsc);
> +
> mutex_lock(&mdsc->mutex);
> renew_interval = mdsc->mdsmap->m_session_timeout >> 2;
> renew_caps = time_after_eq(jiffies, HZ*renew_interval +
> @@ -3891,6 +3893,10 @@ int ceph_mdsc_init(struct ceph_fs_client *fsc)
> ceph_caps_init(mdsc);
> ceph_adjust_min_caps(mdsc, fsc->min_caps);
>
> + spin_lock_init(&mdsc->snapid_map_lock);
> + mdsc->snapid_map_tree = RB_ROOT;
> + INIT_LIST_HEAD(&mdsc->snapid_map_lru);
> +
> init_rwsem(&mdsc->pool_perm_rwsem);
> mdsc->pool_perm_tree = RB_ROOT;
>
> @@ -4084,6 +4090,8 @@ void ceph_mdsc_close_sessions(struct ceph_mds_client *mdsc)
> WARN_ON(!list_empty(&mdsc->cap_delay_list));
> mutex_unlock(&mdsc->mutex);
>
> + ceph_cleanup_snapid_map(mdsc);
> +
> ceph_cleanup_empty_realms(mdsc);
>
> cancel_delayed_work_sync(&mdsc->delayed_work); /* cancel timer */
> diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
> index 4f962642fee4..d3a5c4046316 100644
> --- a/fs/ceph/mds_client.h
> +++ b/fs/ceph/mds_client.h
> @@ -313,6 +313,15 @@ struct ceph_pool_perm {
> char pool_ns[];
> };
>
> +struct ceph_snapid_map {
> + struct rb_node node;
> + struct list_head lru;
> + atomic_t ref;
> + u64 snap;
> + dev_t dev;
> + unsigned long last_used;
> +};
> +
> /*
> * mds client state
> */
> @@ -390,6 +399,10 @@ struct ceph_mds_client {
> struct list_head dentry_lru;
> int num_dentry;
>
> + spinlock_t snapid_map_lock;
> + struct rb_root snapid_map_tree;
> + struct list_head snapid_map_lru;
> +
> struct rw_semaphore pool_perm_rwsem;
> struct rb_root pool_perm_tree;
>
> diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
> index d7359628fd1f..c3fd66d6e03a 100644
> --- a/fs/ceph/snap.c
> +++ b/fs/ceph/snap.c
> @@ -988,3 +988,157 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc,
> up_write(&mdsc->snap_rwsem);
> return;
> }
> +
> +struct ceph_snapid_map* ceph_get_snapid_map(struct ceph_mds_client *mdsc,
> + u64 snap)
> +{
> + struct ceph_snapid_map *sm, *exist;
> + struct rb_node **p, *parent;
> + int ret;
> +
> + exist = NULL;
> + spin_lock(&mdsc->snapid_map_lock);
> + p = &mdsc->snapid_map_tree.rb_node;
> + while (*p) {
> + exist = rb_entry(*p, struct ceph_snapid_map, node);
> + if (snap > exist->snap) {
> + p = &(*p)->rb_left;
> + } else if (snap < exist->snap) {
> + p = &(*p)->rb_right;
> + } else {
> + if (atomic_inc_return(&exist->ref) == 1)
> + list_del_init(&exist->lru);
> + break;
> + }
> + exist = NULL;
> + }
> + spin_unlock(&mdsc->snapid_map_lock);
> + if (exist) {
> + dout("found snapid map %llx -> %x\n", exist->snap, exist->dev);
> + return exist;
> + }
> +
> + sm = kmalloc(sizeof(*sm), GFP_NOFS);
> + if (!sm)
> + return NULL;
> +
> + ret = get_anon_bdev(&sm->dev);
> + if (ret < 0) {
> + kfree(sm);
> + return NULL;
> + }
> +
> + INIT_LIST_HEAD(&sm->lru);
> + atomic_set(&sm->ref, 1);
> + sm->snap = snap;
> +
> + exist = NULL;
> + parent = NULL;
> + p = &mdsc->snapid_map_tree.rb_node;
> + spin_lock(&mdsc->snapid_map_lock);
> + while (*p) {
> + parent = *p;
> + exist = rb_entry(*p, struct ceph_snapid_map, node);
> + if (snap > exist->snap)
> + p = &(*p)->rb_left;
> + else if (snap < exist->snap)
> + p = &(*p)->rb_right;
> + else
> + break;
> + exist = NULL;
> + }
> + if (exist) {
> + if (atomic_inc_return(&exist->ref) == 1)
> + list_del_init(&exist->lru);
> + } else {
> + rb_link_node(&sm->node, parent, p);
> + rb_insert_color(&sm->node, &mdsc->snapid_map_tree);
> + }
> + spin_unlock(&mdsc->snapid_map_lock);
> + if (exist) {
> + free_anon_bdev(sm->dev);
> + kfree(sm);
> + dout("found snapid map %llx -> %x\n", exist->snap, exist->dev);
> + return exist;
> + }
> +
> + dout("create snapid map %llx -> %x\n", sm->snap, sm->dev);
> + return sm;
> +}
> +
> +void ceph_put_snapid_map(struct ceph_mds_client* mdsc,
> + struct ceph_snapid_map *sm)
> +{
> + if (!sm)
> + return;
> + if (!atomic_dec_and_lock(&sm->ref, &mdsc->snapid_map_lock)) {
> + if (!RB_EMPTY_NODE(&sm->node)) {
> + sm->last_used = jiffies;
> + list_add_tail(&sm->lru, &mdsc->snapid_map_lru);
> + spin_unlock(&mdsc->snapid_map_lock);
> + } else {
> + /* already cleaned up by
> + * ceph_cleanup_snapid_map() */
> + spin_unlock(&mdsc->snapid_map_lock);
> + kfree(sm);
> + }
> + }
> +}
> +
> +void ceph_trim_snapid_map(struct ceph_mds_client *mdsc)
> +{
> + struct ceph_snapid_map *sm;
> + unsigned long now;
> + LIST_HEAD(to_free);
> +
> + /* unused map expires after 5 minutes */
> + static unsigned timeout = 5 * 60 * HZ;
> +
No need for static constant here. This could just be something like:
#define CEPH_SNAPID_MAP_TIMEOUT (5 * 60 * HZ)
...particularly if you don't care about being able to set this at
runtime.
> + spin_lock(&mdsc->snapid_map_lock);
> + now = jiffies;
> +
> + while (!list_empty(&mdsc->snapid_map_lru)) {
> + sm = list_first_entry(&mdsc->snapid_map_lru,
> + struct ceph_snapid_map, lru);
> + if (time_after(sm->last_used + timeout, now))
> + break;
> +
> + rb_erase(&sm->node, &mdsc->snapid_map_tree);
> + list_move(&sm->lru, &to_free);
> + }
> + spin_unlock(&mdsc->snapid_map_lock);
> +
> + while (!list_empty(&to_free)) {
> + sm = list_first_entry(&to_free, struct ceph_snapid_map, lru);
> + list_del(&sm->lru);
> + dout("trim snapid map %llx -> %x\n", sm->snap, sm->dev);
> + free_anon_bdev(sm->dev);
> + kfree(sm);
> + }
> +}
> +
> +void ceph_cleanup_snapid_map(struct ceph_mds_client *mdsc)
> +{
> + struct ceph_snapid_map *sm;
> + struct rb_node *p;
> + LIST_HEAD(to_free);
> +
> + spin_lock(&mdsc->snapid_map_lock);
> + while ((p = rb_first(&mdsc->snapid_map_tree))) {
> + sm = rb_entry(p, struct ceph_snapid_map, node);
> + rb_erase(p, &mdsc->snapid_map_tree);
> + RB_CLEAR_NODE(p);
> + list_move(&sm->lru, &to_free);
> + }
> + spin_unlock(&mdsc->snapid_map_lock);
> +
> + while (!list_empty(&to_free)) {
> + sm = list_first_entry(&to_free, struct ceph_snapid_map, lru);
> + list_del(&sm->lru);
> + free_anon_bdev(sm->dev);
> + if (WARN_ON_ONCE(atomic_read(&sm->ref))) {
> + pr_err("snapid map %llx -> %x still in use\n",
> + sm->snap, sm->dev);
> + }
> + }
> +}
> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> index 79a265ba9200..7a74b5652a0c 100644
> --- a/fs/ceph/super.h
> +++ b/fs/ceph/super.h
> @@ -370,7 +370,10 @@ struct ceph_inode_info {
> struct list_head i_unsafe_iops; /* uncommitted mds inode ops */
> spinlock_t i_unsafe_lock;
>
> - struct ceph_snap_realm *i_snap_realm; /* snap realm (if caps) */
> + union {
> + struct ceph_snap_realm *i_snap_realm; /* snap realm (if caps) */
> + struct ceph_snapid_map *i_snapid_map; /* snapid -> dev_t */
> + };
> int i_snap_realm_counter; /* snap realm (if caps) */
> struct list_head i_snap_realm_item;
> struct list_head i_snap_flush_item;
> @@ -837,6 +840,14 @@ extern int __ceph_finish_cap_snap(struct ceph_inode_info *ci,
> struct ceph_cap_snap *capsnap);
> extern void ceph_cleanup_empty_realms(struct ceph_mds_client *mdsc);
>
> +extern struct ceph_snapid_map *ceph_get_snapid_map(struct ceph_mds_client *mdsc,
> + u64 snap);
> +extern void ceph_put_snapid_map(struct ceph_mds_client* mdsc,
> + struct ceph_snapid_map *sm);
> +extern void ceph_trim_snapid_map(struct ceph_mds_client *mdsc);
> +extern void ceph_cleanup_snapid_map(struct ceph_mds_client *mdsc);
> +
> +
> /*
> * a cap_snap is "pending" if it is still awaiting an in-progress
> * sync write (that may/may not still update size, mtime, etc.).
I think this looks reasonable overall. It's definitely less confusing
for userland than showing two different dentries as having the same
ino/dev tuple without them being hardlinked (particularly if they are
directories).
Acked-by: Jeff Layton <jlayton@xxxxxxxxxx>
