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Date: Thu, 7 Mar 2019 15:29:24 +0800
From: "Yan, Zheng" <ukernel@...il.com>
To: Luis Henriques <lhenriques@...e.com>
Cc: "Yan, Zheng" <zyan@...hat.com>, Sage Weil <sage@...hat.com>,
Ilya Dryomov <idryomov@...il.com>,
ceph-devel <ceph-devel@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Hendrik Peyerl <hpeyerl@...sline.net>
Subject: Re: [RFC PATCH 2/2] ceph: quota: fix quota subdir mounts
On Thu, Mar 7, 2019 at 2:21 AM Luis Henriques <lhenriques@...e.com> wrote:
>
> "Yan, Zheng" <ukernel@...il.com> writes:
>
> > On Sat, Mar 2, 2019 at 3:13 AM Luis Henriques <lhenriques@...e.com> 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.
> >>
> >
> > This may cause circle reference if somehow an inode owned by snaprealm
> > get moved into mount subdir (other clients do rename). how about
> > holding these inodes in mds_client?
>
> Ok, before proceeded any further I wanted to make sure that what you
> were suggesting was something like the patch below. It simply keeps a
> list of inodes in ceph_mds_client until the filesystem is umounted,
> iput()ing them at that point.
>
yes,
> I'm sure I'm missing another place where the reference should be
> dropped, but I couldn't figure it out yet. It can't be
> ceph_destroy_inode; drop_inode_snap_realm is a possibility, but what if
> the inode becomes visible in the meantime? Well, I'll continue thinking
> about it.
why do you think we need to clean up the references at other place.
what problem you encountered.
Regards
Yan, Zheng
>
> Function get_quota_realm() should have a similar construct to lookup
> inodes. But it's a bit more tricky, because ceph_quota_is_same_realm()
> requires snap_rwsem to be held for the 2 invocations of
> get_quota_realm.
>
> Cheers,
> --
> Luis
>
> From a429a4c167186781bd235a25d72be893baf9e029 Mon Sep 17 00:00:00 2001
> From: Luis Henriques <lhenriques@...e.com>
> Date: Wed, 6 Mar 2019 17:58:04 +0000
> Subject: [PATCH] ceph: quota: fix quota subdir mounts (II)
>
> Signed-off-by: Luis Henriques <lhenriques@...e.com>
> ---
> fs/ceph/mds_client.c | 14 ++++++++++++++
> fs/ceph/mds_client.h | 2 ++
> fs/ceph/quota.c | 34 ++++++++++++++++++++++++++++++----
> fs/ceph/super.h | 2 ++
> 4 files changed, 48 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 163fc74bf221..72c5ce5e4209 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -3656,6 +3656,8 @@ int ceph_mdsc_init(struct ceph_fs_client *fsc)
> mdsc->max_sessions = 0;
> mdsc->stopping = 0;
> atomic64_set(&mdsc->quotarealms_count, 0);
> + INIT_LIST_HEAD(&mdsc->quotarealms_inodes_list);
> + spin_lock_init(&mdsc->quotarealms_inodes_lock);
> mdsc->last_snap_seq = 0;
> init_rwsem(&mdsc->snap_rwsem);
> mdsc->snap_realms = RB_ROOT;
> @@ -3726,9 +3728,21 @@ static void wait_requests(struct ceph_mds_client *mdsc)
> */
> void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc)
> {
> + struct ceph_inode_info *ci;
> +
> dout("pre_umount\n");
> mdsc->stopping = 1;
>
> + spin_lock(&mdsc->quotarealms_inodes_lock);
> + while(!list_empty(&mdsc->quotarealms_inodes_list)) {
> + ci = list_first_entry(&mdsc->quotarealms_inodes_list,
> + struct ceph_inode_info,
> + i_quotarealms_inode_item);
> + list_del(&ci->i_quotarealms_inode_item);
> + iput(&ci->vfs_inode);
> + }
> + spin_unlock(&mdsc->quotarealms_inodes_lock);
> +
> lock_unlock_sessions(mdsc);
> ceph_flush_dirty_caps(mdsc);
> wait_requests(mdsc);
> diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
> index 729da155ebf0..58968fb338ec 100644
> --- a/fs/ceph/mds_client.h
> +++ b/fs/ceph/mds_client.h
> @@ -329,6 +329,8 @@ struct ceph_mds_client {
> int stopping; /* true if shutting down */
>
> atomic64_t quotarealms_count; /* # realms with quota */
> + struct list_head quotarealms_inodes_list;
> + spinlock_t quotarealms_inodes_lock;
>
> /*
> * snap_rwsem will cover cap linkage into snaprealms, and
> diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c
> index 9455d3aef0c3..7d4dec9eea47 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);
> @@ -176,9 +186,25 @@ 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(&mdsc->quotarealms_inodes_lock);
> + list_add(&ceph_inode(in)->i_quotarealms_inode_item,
> + &mdsc->quotarealms_inodes_list);
> + spin_unlock(&mdsc->quotarealms_inodes_lock);
> + spin_lock(&realm->inodes_with_caps_lock);
> + realm->inode = in;
> + 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);
> if (op == QUOTA_CHECK_MAX_FILES_OP) {
> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> index ce51e98b08ec..cc7766aeb73b 100644
> --- a/fs/ceph/super.h
> +++ b/fs/ceph/super.h
> @@ -375,6 +375,8 @@ struct ceph_inode_info {
> struct list_head i_snap_realm_item;
> struct list_head i_snap_flush_item;
>
> + struct list_head i_quotarealms_inode_item;
> +
> struct work_struct i_wb_work; /* writeback work */
> struct work_struct i_pg_inv_work; /* page invalidation work */
>
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