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ceph: ceph_kick_flushing_caps needs the s_mutex

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The mdsc->cap_dirty_lock is not held while walking the list in
ceph_kick_flushing_caps, which is not safe.

ceph_early_kick_flushing_caps does something similar, but the
s_mutex is held while it's called and I think that guards against
changes to the list.

Ensure we hold the s_mutex when calling ceph_kick_flushing_caps,
and add some clarifying comments.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Jeff Layton 2020-04-03 13:09:07 -04:00 committed by Ilya Dryomov
parent d67c72e6cc
commit 829ad4db95
4 changed files with 12 additions and 3 deletions
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2
fs/ceph/caps.c
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@ -2518,6 +2518,8 @@ void ceph_kick_flushing_caps(struct ceph_mds_client *mdsc,
struct ceph_cap *cap;
u64 oldest_flush_tid;
lockdep_assert_held(&session->s_mutex);
dout("kick_flushing_caps mds%d\n", session->s_mds);
spin_lock(&mdsc->cap_dirty_lock);

2
fs/ceph/mds_client.c
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@ -4024,7 +4024,9 @@ static void check_new_map(struct ceph_mds_client *mdsc,
oldstate != CEPH_MDS_STATE_STARTING)
pr_info("mds%d recovery completed\n", s->s_mds);
kick_requests(mdsc, i);
mutex_lock(&s->s_mutex);
ceph_kick_flushing_caps(mdsc, s);
mutex_unlock(&s->s_mutex);
wake_up_session_caps(s, RECONNECT);
}
}

4
fs/ceph/mds_client.h
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@ -199,8 +199,10 @@ struct ceph_mds_session {
struct list_head s_cap_releases; /* waiting cap_release messages */
struct work_struct s_cap_release_work;
/* both protected by s_mdsc->cap_dirty_lock */
/* See ceph_inode_info->i_dirty_item. */
struct list_head s_cap_dirty; /* inodes w/ dirty caps */
/* See ceph_inode_info->i_flushing_item. */
struct list_head s_cap_flushing; /* inodes w/ flushing caps */
unsigned long s_renew_requested; /* last time we sent a renew req */

7
fs/ceph/super.h
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@ -362,8 +362,11 @@ struct ceph_inode_info {
struct list_head i_dirty_item;
/*
* Link to session's s_cap_flushing list. Protected by
* mdsc->cap_dirty_lock.
* Link to session's s_cap_flushing list. Protected in a similar
* fashion to i_dirty_item, but also by the s_mutex for changes. The
* s_cap_flushing list can be walked while holding either the s_mutex
* or msdc->cap_dirty_lock. List presence can also be checked while
* holding the i_ceph_lock for this inode.
*/
struct list_head i_flushing_item;