ceph: clean up readdir caps reservation

Use a global counter for the minimum number of allocated caps instead of
hard coding a check against readdir_max.  This takes into account multiple
client instances, and avoids examining the superblock mount options when a
cap is dropped.

Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 17 insertions, 6 deletions

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index ab9b571dda11..f94b56faba3b 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -128,6 +128,7 @@ static int caps_total_count;        /* total caps allocated */
 static int caps_use_count;          /* in use */
 static int caps_reserve_count;      /* unused, reserved */
 static int caps_avail_count;        /* unused, unreserved */
+static int caps_min_count;          /* keep at least this many (unreserved) */
 
 void __init ceph_caps_init(void)
 {
@@ -149,6 +150,15 @@ void ceph_caps_finalize(void)
         caps_avail_count = 0;
         caps_use_count = 0;
         caps_reserve_count = 0;
+        caps_min_count = 0;
+        spin_unlock(&caps_list_lock);
+}
+
+void ceph_adjust_min_caps(int delta)
+{
+        spin_lock(&caps_list_lock);
+        caps_min_count += delta;
+        BUG_ON(caps_min_count < 0);
         spin_unlock(&caps_list_lock);
 }
 
@@ -265,12 +275,10 @@ static void put_cap(struct ceph_cap *cap,
              caps_reserve_count, caps_avail_count);
         caps_use_count--;
         /*
-         * Keep some preallocated caps around, at least enough to do a
-         * readdir (which needs to preallocate lots of them), to avoid
-         * lots of free/alloc churn.
+         * Keep some preallocated caps around (ceph_min_count), to
+         * avoid lots of free/alloc churn.
          */
-        if (caps_avail_count >= caps_reserve_count +
-            ceph_client(cap->ci->vfs_inode.i_sb)->mount_args->max_readdir) {
+        if (caps_avail_count >= caps_reserve_count + caps_min_count) {
                 caps_total_count--;
                 kmem_cache_free(ceph_cap_cachep, cap);
         } else {
@@ -289,7 +297,8 @@ static void put_cap(struct ceph_cap *cap,
 }
 
 void ceph_reservation_status(struct ceph_client *client,
-                             int *total, int *avail, int *used, int *reserved)
+                             int *total, int *avail, int *used, int *reserved,
+                             int *min)
 {
         if (total)
                 *total = caps_total_count;
@@ -299,6 +308,8 @@ void ceph_reservation_status(struct ceph_client *client,
                 *used = caps_use_count;
         if (reserved)
                 *reserved = caps_reserve_count;
+        if (min)
+                *min = caps_min_count;
 }
 
 /*