ceph: use i_ceph_lock instead of i_lock

We have been using i_lock to protect all kinds of data structures in the
ceph_inode_info struct, including lists of inodes that we need to iterate
over while avoiding races with inode destruction.  That requires grabbing
a reference to the inode with the list lock protected, but igrab() now
takes i_lock to check the inode flags.

Changing the list lock ordering would be a painful process.

However, using a ceph-specific i_ceph_lock in the ceph inode instead of
i_lock is a simple mechanical change and avoids the ordering constraints
imposed by igrab().

Reported-by: Amon Ott <a.ott@m-privacy.de>
Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 8 insertions, 8 deletions

diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index e26437191333..a559c80f127a 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -446,7 +446,7 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci)
                 return;
         }
 
-        spin_lock(&inode->i_lock);
+        spin_lock(&ci->i_ceph_lock);
         used = __ceph_caps_used(ci);
         dirty = __ceph_caps_dirty(ci);
 
@@ -528,7 +528,7 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci)
                 kfree(capsnap);
         }
 
-        spin_unlock(&inode->i_lock);
+        spin_unlock(&ci->i_ceph_lock);
 }
 
 /*
@@ -537,7 +537,7 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci)
  *
  * If capsnap can now be flushed, add to snap_flush list, and return 1.
  *
- * Caller must hold i_lock.
+ * Caller must hold i_ceph_lock.
  */
 int __ceph_finish_cap_snap(struct ceph_inode_info *ci,
                             struct ceph_cap_snap *capsnap)
@@ -739,9 +739,9 @@ static void flush_snaps(struct ceph_mds_client *mdsc)
                 inode = &ci->vfs_inode;
                 ihold(inode);
                 spin_unlock(&mdsc->snap_flush_lock);
-                spin_lock(&inode->i_lock);
+                spin_lock(&ci->i_ceph_lock);
                 __ceph_flush_snaps(ci, &session, 0);
-                spin_unlock(&inode->i_lock);
+                spin_unlock(&ci->i_ceph_lock);
                 iput(inode);
                 spin_lock(&mdsc->snap_flush_lock);
         }
@@ -847,7 +847,7 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc,
                                 continue;
                         ci = ceph_inode(inode);
 
-                        spin_lock(&inode->i_lock);
+                        spin_lock(&ci->i_ceph_lock);
                         if (!ci->i_snap_realm)
                                 goto skip_inode;
                         /*
@@ -876,7 +876,7 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc,
                         oldrealm = ci->i_snap_realm;
                         ci->i_snap_realm = realm;
                         spin_unlock(&realm->inodes_with_caps_lock);
-                        spin_unlock(&inode->i_lock);
+                        spin_unlock(&ci->i_ceph_lock);
 
                         ceph_get_snap_realm(mdsc, realm);
                         ceph_put_snap_realm(mdsc, oldrealm);
@@ -885,7 +885,7 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc,
                         continue;
 
 skip_inode:
-                        spin_unlock(&inode->i_lock);
+                        spin_unlock(&ci->i_ceph_lock);
                         iput(inode);
                 }