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ceph: do not touch_caps while iterating over caps list 

Avoid confusing iterate_session_caps(), flag the session while we are
iterating so that __touch_cap does not rearrange items on the list.

All other modifiers of session->s_caps do so under the protection of
s_mutex.

Signed-off-by: Sage Weil <sage@newdream.net>
This commit is contained in:
Sage Weil 2009-12-21 20:40:34 -08:00
parent 7067f797b8
commit 5dacf09121
3 changed files with 19 additions and 7 deletions
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11
fs/ceph/caps.c
View File

@ -697,10 +697,15 @@ static void __touch_cap(struct ceph_cap *cap)
{
struct ceph_mds_session *s = cap->session;
dout("__touch_cap %p cap %p mds%d\n", &cap->ci->vfs_inode, cap,
s->s_mds);
spin_lock(&s->s_cap_lock);
list_move_tail(&cap->session_caps, &s->s_caps);
if (!s->s_iterating_caps) {
dout("__touch_cap %p cap %p mds%d\n", &cap->ci->vfs_inode, cap,
s->s_mds);
list_move_tail(&cap->session_caps, &s->s_caps);
} else {
dout("__touch_cap %p cap %p mds%d NOP, iterating over caps\n",
&cap->ci->vfs_inode, cap, s->s_mds);
}
spin_unlock(&s->s_cap_lock);
}

14
fs/ceph/mds_client.c
View File

@ -337,10 +337,12 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
s->s_renew_seq = 0;
INIT_LIST_HEAD(&s->s_caps);
s->s_nr_caps = 0;
s->s_trim_caps = 0;
atomic_set(&s->s_ref, 1);
INIT_LIST_HEAD(&s->s_waiting);
INIT_LIST_HEAD(&s->s_unsafe);
s->s_num_cap_releases = 0;
s->s_iterating_caps = false;
INIT_LIST_HEAD(&s->s_cap_releases);
INIT_LIST_HEAD(&s->s_cap_releases_done);
INIT_LIST_HEAD(&s->s_cap_flushing);
@ -699,6 +701,7 @@ static int iterate_session_caps(struct ceph_mds_session *session,
dout("iterate_session_caps %p mds%d\n", session, session->s_mds);
spin_lock(&session->s_cap_lock);
session->s_iterating_caps = true;
list_for_each_entry_safe(cap, ncap, &session->s_caps, session_caps) {
inode = igrab(&cap->ci->vfs_inode);
if (!inode)
@ -706,13 +709,15 @@ static int iterate_session_caps(struct ceph_mds_session *session,
spin_unlock(&session->s_cap_lock);
ret = cb(inode, cap, arg);
iput(inode);
if (ret < 0)
return ret;
spin_lock(&session->s_cap_lock);
if (ret < 0)
goto out;
}
ret = 0;
out:
session->s_iterating_caps = false;
spin_unlock(&session->s_cap_lock);
return 0;
return ret;
}
static int remove_session_caps_cb(struct inode *inode, struct ceph_cap *cap,
@ -935,6 +940,7 @@ static int trim_caps(struct ceph_mds_client *mdsc,
dout("trim_caps mds%d done: %d / %d, trimmed %d\n",
session->s_mds, session->s_nr_caps, max_caps,
trim_caps - session->s_trim_caps);
session->s_trim_caps = 0;
}
return 0;
}

1
fs/ceph/mds_client.h
View File

@ -114,6 +114,7 @@ struct ceph_mds_session {
int s_num_cap_releases;
struct list_head s_cap_releases; /* waiting cap_release messages */
struct list_head s_cap_releases_done; /* ready to send */
bool s_iterating_caps;
/* protected by mutex */
struct list_head s_cap_flushing; /* inodes w/ flushing caps */