ceph: handle cap import atomically
cap import messages are processed by both handle_cap_import() and
handle_cap_grant(). These two functions are not executed in the same
atomic context, so they can races with cap release.
The fix is make handle_cap_import() not release the i_ceph_lock when
it returns. Let handle_cap_grant() release the lock after it finishes
its job.
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 73a42f5..9f2c99c 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2379,23 +2379,20 @@
* actually be a revocation if it specifies a smaller cap set.)
*
* caller holds s_mutex and i_ceph_lock, we drop both.
- *
- * return value:
- * 0 - ok
- * 1 - check_caps on auth cap only (writeback)
- * 2 - check_caps (ack revoke)
*/
-static void handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
+static void handle_cap_grant(struct ceph_mds_client *mdsc,
+ struct inode *inode, struct ceph_mds_caps *grant,
+ void *snaptrace, int snaptrace_len,
+ struct ceph_buffer *xattr_buf,
struct ceph_mds_session *session,
- struct ceph_cap *cap,
- struct ceph_buffer *xattr_buf)
- __releases(ci->i_ceph_lock)
+ struct ceph_cap *cap, int issued)
+ __releases(ci->i_ceph_lock)
{
struct ceph_inode_info *ci = ceph_inode(inode);
int mds = session->s_mds;
int seq = le32_to_cpu(grant->seq);
int newcaps = le32_to_cpu(grant->caps);
- int issued, implemented, used, wanted, dirty;
+ int used, wanted, dirty;
u64 size = le64_to_cpu(grant->size);
u64 max_size = le64_to_cpu(grant->max_size);
struct timespec mtime, atime, ctime;
@@ -2449,10 +2446,6 @@
}
/* side effects now are allowed */
-
- issued = __ceph_caps_issued(ci, &implemented);
- issued |= implemented | __ceph_caps_dirty(ci);
-
cap->cap_gen = session->s_cap_gen;
cap->seq = seq;
@@ -2585,6 +2578,17 @@
spin_unlock(&ci->i_ceph_lock);
+ if (le32_to_cpu(grant->op) == CEPH_CAP_OP_IMPORT) {
+ down_write(&mdsc->snap_rwsem);
+ ceph_update_snap_trace(mdsc, snaptrace,
+ snaptrace + snaptrace_len, false);
+ downgrade_write(&mdsc->snap_rwsem);
+ kick_flushing_inode_caps(mdsc, session, inode);
+ up_read(&mdsc->snap_rwsem);
+ if (newcaps & ~issued)
+ wake = 1;
+ }
+
if (queue_trunc) {
ceph_queue_vmtruncate(inode);
ceph_queue_revalidate(inode);
@@ -2886,21 +2890,22 @@
}
/*
- * Handle cap IMPORT. If there are temp bits from an older EXPORT,
- * clean them up.
+ * Handle cap IMPORT.
*
- * caller holds s_mutex.
+ * caller holds s_mutex. acquires i_ceph_lock
*/
static void handle_cap_import(struct ceph_mds_client *mdsc,
struct inode *inode, struct ceph_mds_caps *im,
struct ceph_mds_cap_peer *ph,
struct ceph_mds_session *session,
- void *snaptrace, int snaptrace_len)
+ struct ceph_cap **target_cap, int *old_issued)
+ __acquires(ci->i_ceph_lock)
{
struct ceph_inode_info *ci = ceph_inode(inode);
- struct ceph_cap *cap, *new_cap = NULL;
+ struct ceph_cap *cap, *ocap, *new_cap = NULL;
int mds = session->s_mds;
- unsigned issued = le32_to_cpu(im->caps);
+ int issued;
+ unsigned caps = le32_to_cpu(im->caps);
unsigned wanted = le32_to_cpu(im->wanted);
unsigned seq = le32_to_cpu(im->seq);
unsigned mseq = le32_to_cpu(im->migrate_seq);
@@ -2929,44 +2934,43 @@
new_cap = ceph_get_cap(mdsc, NULL);
goto retry;
}
+ cap = new_cap;
+ } else {
+ if (new_cap) {
+ ceph_put_cap(mdsc, new_cap);
+ new_cap = NULL;
+ }
}
- ceph_add_cap(inode, session, cap_id, -1, issued, wanted, seq, mseq,
+ __ceph_caps_issued(ci, &issued);
+ issued |= __ceph_caps_dirty(ci);
+
+ ceph_add_cap(inode, session, cap_id, -1, caps, wanted, seq, mseq,
realmino, CEPH_CAP_FLAG_AUTH, &new_cap);
- cap = peer >= 0 ? __get_cap_for_mds(ci, peer) : NULL;
- if (cap && cap->cap_id == p_cap_id) {
+ ocap = peer >= 0 ? __get_cap_for_mds(ci, peer) : NULL;
+ if (ocap && ocap->cap_id == p_cap_id) {
dout(" remove export cap %p mds%d flags %d\n",
- cap, peer, ph->flags);
+ ocap, peer, ph->flags);
if ((ph->flags & CEPH_CAP_FLAG_AUTH) &&
- (cap->seq != le32_to_cpu(ph->seq) ||
- cap->mseq != le32_to_cpu(ph->mseq))) {
+ (ocap->seq != le32_to_cpu(ph->seq) ||
+ ocap->mseq != le32_to_cpu(ph->mseq))) {
pr_err("handle_cap_import: mismatched seq/mseq: "
"ino (%llx.%llx) mds%d seq %d mseq %d "
"importer mds%d has peer seq %d mseq %d\n",
- ceph_vinop(inode), peer, cap->seq,
- cap->mseq, mds, le32_to_cpu(ph->seq),
+ ceph_vinop(inode), peer, ocap->seq,
+ ocap->mseq, mds, le32_to_cpu(ph->seq),
le32_to_cpu(ph->mseq));
}
- __ceph_remove_cap(cap, (ph->flags & CEPH_CAP_FLAG_RELEASE));
+ __ceph_remove_cap(ocap, (ph->flags & CEPH_CAP_FLAG_RELEASE));
}
/* make sure we re-request max_size, if necessary */
ci->i_wanted_max_size = 0;
ci->i_requested_max_size = 0;
- spin_unlock(&ci->i_ceph_lock);
- wake_up_all(&ci->i_cap_wq);
-
- down_write(&mdsc->snap_rwsem);
- ceph_update_snap_trace(mdsc, snaptrace, snaptrace+snaptrace_len,
- false);
- downgrade_write(&mdsc->snap_rwsem);
- kick_flushing_inode_caps(mdsc, session, inode);
- up_read(&mdsc->snap_rwsem);
-
- if (new_cap)
- ceph_put_cap(mdsc, new_cap);
+ *old_issued = issued;
+ *target_cap = cap;
}
/*
@@ -2986,7 +2990,7 @@
struct ceph_mds_caps *h;
struct ceph_mds_cap_peer *peer = NULL;
int mds = session->s_mds;
- int op;
+ int op, issued;
u32 seq, mseq;
struct ceph_vino vino;
u64 cap_id;
@@ -3078,7 +3082,10 @@
case CEPH_CAP_OP_IMPORT:
handle_cap_import(mdsc, inode, h, peer, session,
- snaptrace, snaptrace_len);
+ &cap, &issued);
+ handle_cap_grant(mdsc, inode, h, snaptrace, snaptrace_len,
+ msg->middle, session, cap, issued);
+ goto done_unlocked;
}
/* the rest require a cap */
@@ -3095,8 +3102,10 @@
switch (op) {
case CEPH_CAP_OP_REVOKE:
case CEPH_CAP_OP_GRANT:
- case CEPH_CAP_OP_IMPORT:
- handle_cap_grant(inode, h, session, cap, msg->middle);
+ __ceph_caps_issued(ci, &issued);
+ issued |= __ceph_caps_dirty(ci);
+ handle_cap_grant(mdsc, inode, h, NULL, 0, msg->middle,
+ session, cap, issued);
goto done_unlocked;
case CEPH_CAP_OP_FLUSH_ACK: