ceph: don't invalidate page cache when inode is no longer used

ceph_check_caps() invalidate page cache when inode is not used
by any open file. This behaviour is not friendly for workload
that repeatly read files.

Signed-off-by: Yan, Zheng <zyan@redhat.com>

2 files changed, 10 insertions, 4 deletions

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 27b566874bc1..349315332040 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -1655,9 +1655,8 @@ retry_locked:
             !S_ISDIR(inode->i_mode) &&          /* ignore readdir cache */
             ci->i_wrbuffer_ref == 0 &&          /* no dirty pages... */
             inode->i_data.nrpages &&            /* have cached pages */
-            (file_wanted == 0 ||                /* no open files */
-             (revoking & (CEPH_CAP_FILE_CACHE|
-                          CEPH_CAP_FILE_LAZYIO))) && /*  or revoking cache */
+            (revoking & (CEPH_CAP_FILE_CACHE|
+                         CEPH_CAP_FILE_LAZYIO)) && /*  or revoking cache */
             !tried_invalidate) {
                 dout("check_caps trying to invalidate on %p\n", inode);
                 if (try_nonblocking_invalidate(inode) < 0) {
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index fe2c982764e7..a7a967abb49e 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1430,6 +1430,13 @@ static int trim_caps_cb(struct inode *inode, struct ceph_cap *cap, void *arg)
                 if ((used | wanted) & CEPH_CAP_ANY_WR)
                         goto out;
         }
+        /* The inode has cached pages, but it's no longer used.
+         * we can safely drop it */
+        if (wanted == 0 && used == CEPH_CAP_FILE_CACHE &&
+            !(oissued & CEPH_CAP_FILE_CACHE)) {
+          used = 0;
+          oissued = 0;
+        }
         if ((used | wanted) & ~oissued & mine)
                 goto out;   /* we need these caps */
 
@@ -1438,7 +1445,7 @@ static int trim_caps_cb(struct inode *inode, struct ceph_cap *cap, void *arg)
                 /* we aren't the only cap.. just remove us */
                 __ceph_remove_cap(cap, true);
         } else {
-                /* try to drop referring dentries */
+                /* try dropping referring dentries */
                 spin_unlock(&ci->i_ceph_lock);
                 d_prune_aliases(inode);
                 dout("trim_caps_cb %p cap %p  pruned, count now %d\n",