[PATCH] libata-eh: implement dev->ering

This patch implements ata_ering and uses it to define dev->ering.

ata_ering is a ring buffer which records libata errors - whether a
command was for normar IO request, err_mask and timestamp.  Errors are
recorded per-device in dev->ering.  This will be used by EH to
determine recovery actions.

Signed-off-by: Tejun Heo <htejun@gmail.com>

1 files changed, 45 insertions, 0 deletions

diff --git a/drivers/scsi/libata-eh.c b/drivers/scsi/libata-eh.c
index 0803231f657..71ad18b7cff 100644
--- a/drivers/scsi/libata-eh.c
+++ b/drivers/scsi/libata-eh.c
@@ -46,6 +46,51 @@
 
 static void __ata_port_freeze(struct ata_port *ap);
 
+static void ata_ering_record(struct ata_ering *ering, int is_io,
+                             unsigned int err_mask)
+{
+        struct ata_ering_entry *ent;
+
+        WARN_ON(!err_mask);
+
+        ering->cursor++;
+        ering->cursor %= ATA_ERING_SIZE;
+
+        ent = &ering->ring[ering->cursor];
+        ent->is_io = is_io;
+        ent->err_mask = err_mask;
+        ent->timestamp = get_jiffies_64();
+}
+
+static struct ata_ering_entry * ata_ering_top(struct ata_ering *ering)
+{
+        struct ata_ering_entry *ent = &ering->ring[ering->cursor];
+        if (!ent->err_mask)
+                return NULL;
+        return ent;
+}
+
+static int ata_ering_map(struct ata_ering *ering,
+                         int (*map_fn)(struct ata_ering_entry *, void *),
+                         void *arg)
+{
+        int idx, rc = 0;
+        struct ata_ering_entry *ent;
+
+        idx = ering->cursor;
+        do {
+                ent = &ering->ring[idx];
+                if (!ent->err_mask)
+                        break;
+                rc = map_fn(ent, arg);
+                if (rc)
+                        break;
+                idx = (idx - 1 + ATA_ERING_SIZE) % ATA_ERING_SIZE;
+        } while (idx != ering->cursor);
+
+        return rc;
+}
+
 /**
  *      ata_scsi_timed_out - SCSI layer time out callback
  *      @cmd: timed out SCSI command