1 files changed, 25 insertions, 18 deletions

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 0c1681806867..0dd0b81e64f7 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -858,6 +858,8 @@ static int __ceph_is_any_caps(struct ceph_inode_info *ci)
 }
 
 /*
+ * Remove a cap.  Take steps to deal with a racing iterate_session_caps.
+ *
  * caller should hold i_lock.
  * caller will not hold session s_mutex if called from destroy_inode.
  */
@@ -865,16 +867,12 @@ void __ceph_remove_cap(struct ceph_cap *cap)
 {
         struct ceph_mds_session *session = cap->session;
         struct ceph_inode_info *ci = cap->ci;
-        struct ceph_mds_client *mdsc = &ceph_client(ci->vfs_inode.i_sb)->mdsc;
+        struct ceph_mds_client *mdsc =
+                &ceph_sb_to_client(ci->vfs_inode.i_sb)->mdsc;
+        int removed = 0;
 
         dout("__ceph_remove_cap %p from %p\n", cap, &ci->vfs_inode);
 
-        /* remove from inode list */
-        rb_erase(&cap->ci_node, &ci->i_caps);
-        cap->ci = NULL;
-        if (ci->i_auth_cap == cap)
-                ci->i_auth_cap = NULL;
-
         /* remove from session list */
         spin_lock(&session->s_cap_lock);
         if (session->s_cap_iterator == cap) {
@@ -885,10 +883,18 @@ void __ceph_remove_cap(struct ceph_cap *cap)
                 list_del_init(&cap->session_caps);
                 session->s_nr_caps--;
                 cap->session = NULL;
+                removed = 1;
         }
+        /* protect backpointer with s_cap_lock: see iterate_session_caps */
+        cap->ci = NULL;
         spin_unlock(&session->s_cap_lock);
 
-        if (cap->session == NULL)
+        /* remove from inode list */
+        rb_erase(&cap->ci_node, &ci->i_caps);
+        if (ci->i_auth_cap == cap)
+                ci->i_auth_cap = NULL;
+
+        if (removed)
                 ceph_put_cap(cap);
 
         if (!__ceph_is_any_caps(ci) && ci->i_snap_realm) {
@@ -932,9 +938,9 @@ static int send_cap_msg(struct ceph_mds_session *session,
              seq, issue_seq, mseq, follows, size, max_size,
              xattr_version, xattrs_buf ? (int)xattrs_buf->vec.iov_len : 0);
 
-        msg = ceph_msg_new(CEPH_MSG_CLIENT_CAPS, sizeof(*fc), 0, 0, NULL);
-        if (IS_ERR(msg))
-                return PTR_ERR(msg);
+        msg = ceph_msg_new(CEPH_MSG_CLIENT_CAPS, sizeof(*fc), GFP_NOFS);
+        if (!msg)
+                return -ENOMEM;
 
         msg->hdr.tid = cpu_to_le64(flush_tid);
 
@@ -1293,7 +1299,8 @@ static void ceph_flush_snaps(struct ceph_inode_info *ci)
  */
 void __ceph_mark_dirty_caps(struct ceph_inode_info *ci, int mask)
 {
-        struct ceph_mds_client *mdsc = &ceph_client(ci->vfs_inode.i_sb)->mdsc;
+        struct ceph_mds_client *mdsc =
+                &ceph_sb_to_client(ci->vfs_inode.i_sb)->mdsc;
         struct inode *inode = &ci->vfs_inode;
         int was = ci->i_dirty_caps;
         int dirty = 0;
@@ -1331,7 +1338,7 @@ void __ceph_mark_dirty_caps(struct ceph_inode_info *ci, int mask)
 static int __mark_caps_flushing(struct inode *inode,
                                  struct ceph_mds_session *session)
 {
-        struct ceph_mds_client *mdsc = &ceph_client(inode->i_sb)->mdsc;
+        struct ceph_mds_client *mdsc = &ceph_sb_to_client(inode->i_sb)->mdsc;
         struct ceph_inode_info *ci = ceph_inode(inode);
         int flushing;
 
@@ -1658,7 +1665,7 @@ ack:
 static int try_flush_caps(struct inode *inode, struct ceph_mds_session *session,
                           unsigned *flush_tid)
 {
-        struct ceph_mds_client *mdsc = &ceph_client(inode->i_sb)->mdsc;
+        struct ceph_mds_client *mdsc = &ceph_sb_to_client(inode->i_sb)->mdsc;
         struct ceph_inode_info *ci = ceph_inode(inode);
         int unlock_session = session ? 0 : 1;
         int flushing = 0;
@@ -1711,10 +1718,9 @@ out_unlocked:
 static int caps_are_flushed(struct inode *inode, unsigned tid)
 {
         struct ceph_inode_info *ci = ceph_inode(inode);
-        int dirty, i, ret = 1;
+        int i, ret = 1;
 
         spin_lock(&inode->i_lock);
-        dirty = __ceph_caps_dirty(ci);
         for (i = 0; i < CEPH_CAP_BITS; i++)
                 if ((ci->i_flushing_caps & (1 << i)) &&
                     ci->i_cap_flush_tid[i] <= tid) {
@@ -1824,7 +1830,8 @@ int ceph_write_inode(struct inode *inode, struct writeback_control *wbc)
                         err = wait_event_interruptible(ci->i_cap_wq,
                                        caps_are_flushed(inode, flush_tid));
         } else {
-                struct ceph_mds_client *mdsc = &ceph_client(inode->i_sb)->mdsc;
+                struct ceph_mds_client *mdsc =
+                        &ceph_sb_to_client(inode->i_sb)->mdsc;
 
                 spin_lock(&inode->i_lock);
                 if (__ceph_caps_dirty(ci))
@@ -2406,7 +2413,7 @@ static void handle_cap_flush_ack(struct inode *inode, u64 flush_tid,
         __releases(inode->i_lock)
 {
         struct ceph_inode_info *ci = ceph_inode(inode);
-        struct ceph_mds_client *mdsc = &ceph_client(inode->i_sb)->mdsc;
+        struct ceph_mds_client *mdsc = &ceph_sb_to_client(inode->i_sb)->mdsc;
         unsigned seq = le32_to_cpu(m->seq);
         int dirty = le32_to_cpu(m->dirty);
         int cleaned = 0;