[SCSI] sd: update index allocation and use ida instead of idr

Update index allocation as follows.

* sd_index_idr is used only for ID allocation and mapping
  functionality is not used.  Use more memory efficient ida instead.

* idr and ida have their own locks inside them and don't need them for
  operation.  Drop it.

* index wasn't freed if probing failed after index allocation.  fix
  it.

* ida allocation should be repeated if it fails with -EAGAIN.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 14 insertions, 13 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 0c63947d8a9d..99dddcae7851 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -99,8 +99,7 @@ static void scsi_disk_release(struct device *cdev);
 static void sd_print_sense_hdr(struct scsi_disk *, struct scsi_sense_hdr *);
 static void sd_print_result(struct scsi_disk *, int);
 
-static DEFINE_IDR(sd_index_idr);
-static DEFINE_SPINLOCK(sd_index_lock);
+static DEFINE_IDA(sd_index_ida);
 
 /* This semaphore is used to mediate the 0->1 reference get in the
  * face of object destruction (i.e. we can't allow a get on an
@@ -1643,18 +1642,20 @@ static int sd_probe(struct device *dev)
         if (!gd)
                 goto out_free;
 
-        if (!idr_pre_get(&sd_index_idr, GFP_KERNEL))
-                goto out_put;
+        do {
+                if (!ida_pre_get(&sd_index_ida, GFP_KERNEL))
+                        goto out_put;
 
-        spin_lock(&sd_index_lock);
-        error = idr_get_new(&sd_index_idr, NULL, &index);
-        spin_unlock(&sd_index_lock);
+                error = ida_get_new(&sd_index_ida, &index);
+        } while (error == -EAGAIN);
 
-        if (index >= SD_MAX_DISKS)
-                error = -EBUSY;
         if (error)
                 goto out_put;
 
+        error = -EBUSY;
+        if (index >= SD_MAX_DISKS)
+                goto out_free_index;
+
         sdkp->device = sdp;
         sdkp->driver = &sd_template;
         sdkp->disk = gd;
@@ -1675,7 +1676,7 @@ static int sd_probe(struct device *dev)
         strncpy(sdkp->dev.bus_id, sdp->sdev_gendev.bus_id, BUS_ID_SIZE);
 
         if (device_add(&sdkp->dev))
-                goto out_put;
+                goto out_free_index;
 
         get_device(&sdp->sdev_gendev);
 
@@ -1717,6 +1718,8 @@ static int sd_probe(struct device *dev)
 
         return 0;
 
+ out_free_index:
+        ida_remove(&sd_index_ida, index);
  out_put:
         put_disk(gd);
  out_free:
@@ -1766,9 +1769,7 @@ static void scsi_disk_release(struct device *dev)
         struct scsi_disk *sdkp = to_scsi_disk(dev);
         struct gendisk *disk = sdkp->disk;
         
-        spin_lock(&sd_index_lock);
-        idr_remove(&sd_index_idr, sdkp->index);
-        spin_unlock(&sd_index_lock);
+        ida_remove(&sd_index_ida, sdkp->index);
 
         disk->private_data = NULL;
         put_disk(disk);