Merge tag 'asoc-fix-v4.2-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/brooni...

[cascardo/linux.git] / fs / ceph / snap.c

diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index 5bfdab9..233d906 100644 (file)
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -436,6 +436,14 @@ static int dup_array(u64 **dst, __le64 *src, u32 num)
        return 0;
 }
 
+static bool has_new_snaps(struct ceph_snap_context *o,
+                         struct ceph_snap_context *n)
+{
+       if (n->num_snaps == 0)
+               return false;
+       /* snaps are in descending order */
+       return n->snaps[0] > o->seq;
+}
 
 /*
  * When a snapshot is applied, the size/mtime inode metadata is queued
@@ -455,7 +463,7 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci)
 {
        struct inode *inode = &ci->vfs_inode;
        struct ceph_cap_snap *capsnap;
-       struct ceph_snap_context *old_snapc;
+       struct ceph_snap_context *old_snapc, *new_snapc;
        int used, dirty;
 
        capsnap = kzalloc(sizeof(*capsnap), GFP_NOFS);
@@ -469,6 +477,7 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci)
        dirty = __ceph_caps_dirty(ci);
 
        old_snapc = ci->i_head_snapc;
+       new_snapc = ci->i_snap_realm->cached_context;
 
        /*
         * If there is a write in progress, treat that as a dirty Fw,
@@ -486,20 +495,37 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci)
                dout("queue_cap_snap %p already pending\n", inode);
                goto update_snapc;
        }
-       if (ci->i_snap_realm->cached_context == ceph_empty_snapc) {
-               dout("queue_cap_snap %p empty snapc\n", inode);
-               goto update_snapc;
-       }
-       if (!(dirty & (CEPH_CAP_AUTH_EXCL|CEPH_CAP_XATTR_EXCL|
-                      CEPH_CAP_FILE_EXCL|CEPH_CAP_FILE_WR))) {
+       if (ci->i_wrbuffer_ref_head == 0 &&
+           !(dirty & (CEPH_CAP_ANY_EXCL|CEPH_CAP_FILE_WR))) {
                dout("queue_cap_snap %p nothing dirty|writing\n", inode);
                goto update_snapc;
        }
 
        BUG_ON(!old_snapc);
 
-       dout("queue_cap_snap %p cap_snap %p queuing under %p %s\n",
-            inode, capsnap, old_snapc, ceph_cap_string(dirty));
+       /*
+        * There is no need to send FLUSHSNAP message to MDS if there is
+        * no new snapshot. But when there is dirty pages or on-going
+        * writes, we still need to create cap_snap. cap_snap is needed
+        * by the write path and page writeback path.
+        *
+        * also see ceph_try_drop_cap_snap()
+        */
+       if (has_new_snaps(old_snapc, new_snapc)) {
+               if (dirty & (CEPH_CAP_ANY_EXCL|CEPH_CAP_FILE_WR))
+                       capsnap->need_flush = true;
+       } else {
+               if (!(used & CEPH_CAP_FILE_WR) &&
+                   ci->i_wrbuffer_ref_head == 0) {
+                       dout("queue_cap_snap %p "
+                            "no new_snap|dirty_page|writing\n", inode);
+                       goto update_snapc;
+               }
+       }
+
+       dout("queue_cap_snap %p cap_snap %p queuing under %p %s %s\n",
+            inode, capsnap, old_snapc, ceph_cap_string(dirty),
+            capsnap->need_flush ? "" : "no_flush");
        ihold(inode);
 
        atomic_set(&capsnap->nref, 1);
@@ -549,9 +575,8 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci)
 
 update_snapc:
        if (ci->i_head_snapc) {
-               ci->i_head_snapc = ceph_get_snap_context(
-                               ci->i_snap_realm->cached_context);
-               dout(" new snapc is %p\n", ci->i_head_snapc);
+               ci->i_head_snapc = ceph_get_snap_context(new_snapc);
+               dout(" new snapc is %p\n", new_snapc);
        }
        spin_unlock(&ci->i_ceph_lock);
 
@@ -705,6 +730,8 @@ more:
 
                /* queue realm for cap_snap creation */
                list_add(&realm->dirty_item, &dirty_realms);
+               if (realm->seq > mdsc->last_snap_seq)
+                       mdsc->last_snap_seq = realm->seq;
 
                invalidate = 1;
        } else if (!realm->cached_context) {