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SubjectRe: [RFC PATCH 2/2] ceph: quota: fix quota subdir mounts
Date
Jeff Layton <jlayton@redhat.com> writes:

> On Fri, 2019-03-01 at 17:57 +0000, Luis Henriques wrote:
>> The CephFS kernel client doesn't enforce quotas that are set in a
>> directory that isn't visible in the mount point. For example, given the
>> path '/dir1/dir2', if quotas are set in 'dir1' and the mount is done in with
>>
>> mount -t ceph <server>:<port>:/dir1/ /mnt
>>
>> then the client can't access the 'dir1' inode from the quota realm dir2
>> belongs to.
>>
>> This patch fixes this by simply doing an MDS LOOKUPINO Op and grabbing a
>> reference to it (so that it doesn't disappear again). This also requires an
>> extra field in ceph_snap_realm so that we know we have to release that
>> reference when destroying the realm.
>>
>> Links: https://tracker.ceph.com/issues/3848
>
> This bug looks unrelated to the patch description. Are you sure it's
> correct?

Ups! Looks like I truncated the bug number. Sorry about that, here's
the correct link:

https://tracker.ceph.com/issues/38482

Cheers,
--
Luis


>> Reported-by: Hendrik Peyerl <hpeyerl@plusline.net>
>> Signed-off-by: Luis Henriques <lhenriques@suse.com>
>> ---
>> fs/ceph/caps.c | 2 +-
>> fs/ceph/quota.c | 30 +++++++++++++++++++++++++++---
>> fs/ceph/snap.c | 3 +++
>> fs/ceph/super.h | 2 ++
>> 4 files changed, 33 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
>> index bba28a5034ba..e79994ff53d6 100644
>> --- a/fs/ceph/caps.c
>> +++ b/fs/ceph/caps.c
>> @@ -1035,7 +1035,7 @@ static void drop_inode_snap_realm(struct ceph_inode_info *ci)
>> list_del_init(&ci->i_snap_realm_item);
>> ci->i_snap_realm_counter++;
>> ci->i_snap_realm = NULL;
>> - if (realm->ino == ci->i_vino.ino)
>> + if ((realm->ino == ci->i_vino.ino) && !realm->own_inode)
>> realm->inode = NULL;
>> spin_unlock(&realm->inodes_with_caps_lock);
>> ceph_put_snap_realm(ceph_sb_to_client(ci->vfs_inode.i_sb)->mdsc,
>> diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c
>> index 9455d3aef0c3..f6b972d222e4 100644
>> --- a/fs/ceph/quota.c
>> +++ b/fs/ceph/quota.c
>> @@ -22,7 +22,16 @@ void ceph_adjust_quota_realms_count(struct inode *inode, bool inc)
>> static inline bool ceph_has_realms_with_quotas(struct inode *inode)
>> {
>> struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
>> - return atomic64_read(&mdsc->quotarealms_count) > 0;
>> + struct super_block *sb = mdsc->fsc->sb;
>> +
>> + if (atomic64_read(&mdsc->quotarealms_count) > 0)
>> + return true;
>> + /* if root is the real CephFS root, we don't have quota realms */
>> + if (sb->s_root->d_inode &&
>> + (sb->s_root->d_inode->i_ino == CEPH_INO_ROOT))
>> + return false;
>> + /* otherwise, we can't know for sure */
>> + return true;
>> }
>>
>> void ceph_handle_quota(struct ceph_mds_client *mdsc,
>> @@ -166,6 +175,7 @@ static bool check_quota_exceeded(struct inode *inode, enum quota_check_op op,
>> return false;
>>
>> down_read(&mdsc->snap_rwsem);
>> +restart:
>> realm = ceph_inode(inode)->i_snap_realm;
>> if (realm)
>> ceph_get_snap_realm(mdsc, realm);
>> @@ -176,8 +186,22 @@ static bool check_quota_exceeded(struct inode *inode, enum quota_check_op op,
>> spin_lock(&realm->inodes_with_caps_lock);
>> in = realm->inode ? igrab(realm->inode) : NULL;
>> spin_unlock(&realm->inodes_with_caps_lock);
>> - if (!in)
>> - break;
>> + if (!in) {
>> + up_read(&mdsc->snap_rwsem);
>> + in = ceph_lookup_inode(inode->i_sb, realm->ino);
>> + down_read(&mdsc->snap_rwsem);
>> + if (IS_ERR(in)) {
>> + pr_warn("Can't lookup inode %llx (err: %ld)\n",
>> + realm->ino, PTR_ERR(in));
>> + break;
>> + }
>> + spin_lock(&realm->inodes_with_caps_lock);
>> + realm->inode = in;
>> + realm->own_inode = true;
>> + spin_unlock(&realm->inodes_with_caps_lock);
>> + ceph_put_snap_realm(mdsc, realm);
>> + goto restart;
>> + }
>>
>> ci = ceph_inode(in);
>> spin_lock(&ci->i_ceph_lock);
>> diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
>> index f74193da0e09..c84ed8e8526a 100644
>> --- a/fs/ceph/snap.c
>> +++ b/fs/ceph/snap.c
>> @@ -117,6 +117,7 @@ static struct ceph_snap_realm *ceph_create_snap_realm(
>>
>> atomic_set(&realm->nref, 1); /* for caller */
>> realm->ino = ino;
>> + realm->own_inode = false;
>> INIT_LIST_HEAD(&realm->children);
>> INIT_LIST_HEAD(&realm->child_item);
>> INIT_LIST_HEAD(&realm->empty_item);
>> @@ -184,6 +185,8 @@ static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
>> kfree(realm->prior_parent_snaps);
>> kfree(realm->snaps);
>> ceph_put_snap_context(realm->cached_context);
>> + if (realm->own_inode && realm->inode)
>> + iput(realm->inode);
>> kfree(realm);
>> }
>>
>> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
>> index ce51e98b08ec..3f0d74d2150f 100644
>> --- a/fs/ceph/super.h
>> +++ b/fs/ceph/super.h
>> @@ -764,6 +764,8 @@ struct ceph_snap_realm {
>> atomic_t nref;
>> struct rb_node node;
>>
>> + bool own_inode; /* true if we hold a ref to the inode */
>> +
>> u64 created, seq;
>> u64 parent_ino;
>> u64 parent_since; /* snapid when our current parent became so */

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