ceph: defer flushing the capsnap if the Fb is used

If the Fb cap is used it means the current inode is flushing the
dirty data to OSD, just defer flushing the capsnap.

URL: https://tracker.ceph.com/issues/48640
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index abbf48fc62303bc323c5d0ec49ab31a5305639af..570731c4d019d406b9ce90fafe00cb54f02c55c2 100644 (file)
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -3047,6 +3047,7 @@ static void __ceph_put_cap_refs(struct ceph_inode_info *ci, int had,
 {
        struct inode *inode = &ci->vfs_inode;
        int last = 0, put = 0, flushsnaps = 0, wake = 0;
+       bool check_flushsnaps = false;
 
        spin_lock(&ci->i_ceph_lock);
        if (had & CEPH_CAP_PIN)
@@ -3063,26 +3064,17 @@ static void __ceph_put_cap_refs(struct ceph_inode_info *ci, int had,
        if (had & CEPH_CAP_FILE_BUFFER) {
                if (--ci->i_wb_ref == 0) {
                        last++;
+                       /* put the ref held by ceph_take_cap_refs() */
                        put++;
+                       check_flushsnaps = true;
                }
                dout("put_cap_refs %p wb %d -> %d (?)\n",
                     inode, ci->i_wb_ref+1, ci->i_wb_ref);
        }
-       if (had & CEPH_CAP_FILE_WR)
+       if (had & CEPH_CAP_FILE_WR) {
                if (--ci->i_wr_ref == 0) {
                        last++;
-                       if (__ceph_have_pending_cap_snap(ci)) {
-                               struct ceph_cap_snap *capsnap =
-                                       list_last_entry(&ci->i_cap_snaps,
-                                                       struct ceph_cap_snap,
-                                                       ci_item);
-                               capsnap->writing = 0;
-                               if (ceph_try_drop_cap_snap(ci, capsnap))
-                                       put++;
-                               else if (__ceph_finish_cap_snap(ci, capsnap))
-                                       flushsnaps = 1;
-                               wake = 1;
-                       }
+                       check_flushsnaps = true;
                        if (ci->i_wrbuffer_ref_head == 0 &&
                            ci->i_dirty_caps == 0 &&
                            ci->i_flushing_caps == 0) {
@@ -3094,6 +3086,21 @@ static void __ceph_put_cap_refs(struct ceph_inode_info *ci, int had,
                        if (!__ceph_is_any_real_caps(ci) && ci->i_snap_realm)
                                drop_inode_snap_realm(ci);
                }
+       }
+       if (check_flushsnaps && __ceph_have_pending_cap_snap(ci)) {
+               struct ceph_cap_snap *capsnap =
+                       list_last_entry(&ci->i_cap_snaps,
+                                       struct ceph_cap_snap,
+                                       ci_item);
+
+               capsnap->writing = 0;
+               if (ceph_try_drop_cap_snap(ci, capsnap))
+                       /* put the ref held by ceph_queue_cap_snap() */
+                       put++;
+               else if (__ceph_finish_cap_snap(ci, capsnap))
+                       flushsnaps = 1;
+               wake = 1;
+       }
        spin_unlock(&ci->i_ceph_lock);
 
        dout("put_cap_refs %p had %s%s%s\n", inode, ceph_cap_string(had),

diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index b611f829cb611590f2baaf36ec799a2fabb0ad66..0728b01d4d431f0d4f6860975146b59d46727cbb 100644 (file)
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -623,6 +623,16 @@ int __ceph_finish_cap_snap(struct ceph_inode_info *ci,
                return 0;
        }
 
+       /* Fb cap still in use, delay it */
+       if (ci->i_wb_ref) {
+               dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu "
+                    "used WRBUFFER, delaying\n", inode, capsnap,
+                    capsnap->context, capsnap->context->seq,
+                    ceph_cap_string(capsnap->dirty), capsnap->size);
+               capsnap->writing = 1;
+               return 0;
+       }
+
        ci->i_ceph_flags |= CEPH_I_FLUSH_SNAPS;
        dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu\n",
             inode, capsnap, capsnap->context,