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-rw-r--r--fs/gfs2/glock.c90
1 files changed, 67 insertions, 23 deletions
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 3ad8fd36f8d..cf351554673 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -30,6 +30,7 @@
#include <linux/rculist_bl.h>
#include <linux/bit_spinlock.h>
#include <linux/percpu.h>
+#include <linux/list_sort.h>
#include "gfs2.h"
#include "incore.h"
@@ -1376,50 +1377,93 @@ void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
gfs2_glock_put(gl);
}
+static int glock_cmp(void *priv, struct list_head *a, struct list_head *b)
+{
+ struct gfs2_glock *gla, *glb;
+
+ gla = list_entry(a, struct gfs2_glock, gl_lru);
+ glb = list_entry(b, struct gfs2_glock, gl_lru);
+
+ if (gla->gl_name.ln_number > glb->gl_name.ln_number)
+ return 1;
+ if (gla->gl_name.ln_number < glb->gl_name.ln_number)
+ return -1;
+
+ return 0;
+}
+
+/**
+ * gfs2_dispose_glock_lru - Demote a list of glocks
+ * @list: The list to dispose of
+ *
+ * Disposing of glocks may involve disk accesses, so that here we sort
+ * the glocks by number (i.e. disk location of the inodes) so that if
+ * there are any such accesses, they'll be sent in order (mostly).
+ *
+ * Must be called under the lru_lock, but may drop and retake this
+ * lock. While the lru_lock is dropped, entries may vanish from the
+ * list, but no new entries will appear on the list (since it is
+ * private)
+ */
+
+static void gfs2_dispose_glock_lru(struct list_head *list)
+__releases(&lru_lock)
+__acquires(&lru_lock)
+{
+ struct gfs2_glock *gl;
+
+ list_sort(NULL, list, glock_cmp);
+
+ while(!list_empty(list)) {
+ gl = list_entry(list->next, struct gfs2_glock, gl_lru);
+ list_del_init(&gl->gl_lru);
+ clear_bit(GLF_LRU, &gl->gl_flags);
+ gfs2_glock_hold(gl);
+ spin_unlock(&lru_lock);
+ spin_lock(&gl->gl_spin);
+ if (demote_ok(gl))
+ handle_callback(gl, LM_ST_UNLOCKED, 0);
+ WARN_ON(!test_and_clear_bit(GLF_LOCK, &gl->gl_flags));
+ smp_mb__after_clear_bit();
+ if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
+ gfs2_glock_put_nolock(gl);
+ spin_unlock(&gl->gl_spin);
+ spin_lock(&lru_lock);
+ }
+}
+
/**
* gfs2_scan_glock_lru - Scan the LRU looking for locks to demote
* @nr: The number of entries to scan
*
+ * This function selects the entries on the LRU which are able to
+ * be demoted, and then kicks off the process by calling
+ * gfs2_dispose_glock_lru() above.
*/
static void gfs2_scan_glock_lru(int nr)
{
struct gfs2_glock *gl;
- int may_demote;
- int nr_skipped = 0;
LIST_HEAD(skipped);
+ LIST_HEAD(dispose);
spin_lock(&lru_lock);
while(nr && !list_empty(&lru_list)) {
gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
- list_del_init(&gl->gl_lru);
- clear_bit(GLF_LRU, &gl->gl_flags);
- atomic_dec(&lru_count);
/* Test for being demotable */
if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
- gfs2_glock_hold(gl);
- spin_unlock(&lru_lock);
- spin_lock(&gl->gl_spin);
- may_demote = demote_ok(gl);
- if (may_demote) {
- handle_callback(gl, LM_ST_UNLOCKED, 0);
- nr--;
- }
- clear_bit(GLF_LOCK, &gl->gl_flags);
- smp_mb__after_clear_bit();
- if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
- gfs2_glock_put_nolock(gl);
- spin_unlock(&gl->gl_spin);
- spin_lock(&lru_lock);
+ list_move(&gl->gl_lru, &dispose);
+ atomic_dec(&lru_count);
+ nr--;
continue;
}
- nr_skipped++;
- list_add(&gl->gl_lru, &skipped);
- set_bit(GLF_LRU, &gl->gl_flags);
+
+ list_move(&gl->gl_lru, &skipped);
}
list_splice(&skipped, &lru_list);
- atomic_add(nr_skipped, &lru_count);
+ if (!list_empty(&dispose))
+ gfs2_dispose_glock_lru(&dispose);
spin_unlock(&lru_lock);
}