[PATCH] libata: implement ata_dev_revalidate()

ata_dev_revalidate() re-reads IDENTIFY PAGE of the given device and
makes sure it's the same device as the configured one.  Once it's
verified that it's the same device, @dev is configured according to
newly read IDENTIFY PAGE.  Note that revalidation currently doesn't
invoke transfer mode reconfiguration.

Criteria for 'same device'

* same class (of course)
* same model string
* same serial string
* if ATA, same n_sectors (to catch geometry parameter changes)

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 115 insertions, 0 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index d65aa86ddbb2..5d0adfa4610a 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -2345,6 +2345,120 @@ int ata_drive_probe_reset(struct ata_port *ap, ata_probeinit_fn_t probeinit,
         return rc;
 }
 
+/**
+ *      ata_dev_same_device - Determine whether new ID matches configured device
+ *      @ap: port on which the device to compare against resides
+ *      @dev: device to compare against
+ *      @new_class: class of the new device
+ *      @new_id: IDENTIFY page of the new device
+ *
+ *      Compare @new_class and @new_id against @dev and determine
+ *      whether @dev is the device indicated by @new_class and
+ *      @new_id.
+ *
+ *      LOCKING:
+ *      None.
+ *
+ *      RETURNS:
+ *      1 if @dev matches @new_class and @new_id, 0 otherwise.
+ */
+static int ata_dev_same_device(struct ata_port *ap, struct ata_device *dev,
+                               unsigned int new_class, const u16 *new_id)
+{
+        const u16 *old_id = dev->id;
+        unsigned char model[2][41], serial[2][21];
+        u64 new_n_sectors;
+
+        if (dev->class != new_class) {
+                printk(KERN_INFO
+                       "ata%u: dev %u class mismatch %d != %d\n",
+                       ap->id, dev->devno, dev->class, new_class);
+                return 0;
+        }
+
+        ata_id_c_string(old_id, model[0], ATA_ID_PROD_OFS, sizeof(model[0]));
+        ata_id_c_string(new_id, model[1], ATA_ID_PROD_OFS, sizeof(model[1]));
+        ata_id_c_string(old_id, serial[0], ATA_ID_SERNO_OFS, sizeof(serial[0]));
+        ata_id_c_string(new_id, serial[1], ATA_ID_SERNO_OFS, sizeof(serial[1]));
+        new_n_sectors = ata_id_n_sectors(new_id);
+
+        if (strcmp(model[0], model[1])) {
+                printk(KERN_INFO
+                       "ata%u: dev %u model number mismatch '%s' != '%s'\n",
+                       ap->id, dev->devno, model[0], model[1]);
+                return 0;
+        }
+
+        if (strcmp(serial[0], serial[1])) {
+                printk(KERN_INFO
+                       "ata%u: dev %u serial number mismatch '%s' != '%s'\n",
+                       ap->id, dev->devno, serial[0], serial[1]);
+                return 0;
+        }
+
+        if (dev->class == ATA_DEV_ATA && dev->n_sectors != new_n_sectors) {
+                printk(KERN_INFO
+                       "ata%u: dev %u n_sectors mismatch %llu != %llu\n",
+                       ap->id, dev->devno, (unsigned long long)dev->n_sectors,
+                       (unsigned long long)new_n_sectors);
+                return 0;
+        }
+
+        return 1;
+}
+
+/**
+ *      ata_dev_revalidate - Revalidate ATA device
+ *      @ap: port on which the device to revalidate resides
+ *      @dev: device to revalidate
+ *      @post_reset: is this revalidation after reset?
+ *
+ *      Re-read IDENTIFY page and make sure @dev is still attached to
+ *      the port.
+ *
+ *      LOCKING:
+ *      Kernel thread context (may sleep)
+ *
+ *      RETURNS:
+ *      0 on success, negative errno otherwise
+ */
+int ata_dev_revalidate(struct ata_port *ap, struct ata_device *dev,
+                       int post_reset)
+{
+        unsigned int class;
+        u16 *id;
+        int rc;
+
+        if (!ata_dev_present(dev))
+                return -ENODEV;
+
+        class = dev->class;
+        id = NULL;
+
+        /* allocate & read ID data */
+        rc = ata_dev_read_id(ap, dev, &class, post_reset, &id);
+        if (rc)
+                goto fail;
+
+        /* is the device still there? */
+        if (!ata_dev_same_device(ap, dev, class, id)) {
+                rc = -ENODEV;
+                goto fail;
+        }
+
+        kfree(dev->id);
+        dev->id = id;
+
+        /* configure device according to the new ID */
+        return ata_dev_configure(ap, dev, 0);
+
+ fail:
+        printk(KERN_ERR "ata%u: dev %u revalidation failed (errno=%d)\n",
+               ap->id, dev->devno, rc);
+        kfree(id);
+        return rc;
+}
+
 static void ata_pr_blacklisted(const struct ata_port *ap,
                                const struct ata_device *dev)
 {
@@ -4964,6 +5078,7 @@ EXPORT_SYMBOL_GPL(sata_std_hardreset);
 EXPORT_SYMBOL_GPL(ata_std_postreset);
 EXPORT_SYMBOL_GPL(ata_std_probe_reset);
 EXPORT_SYMBOL_GPL(ata_drive_probe_reset);
+EXPORT_SYMBOL_GPL(ata_dev_revalidate);
 EXPORT_SYMBOL_GPL(ata_port_disable);
 EXPORT_SYMBOL_GPL(ata_ratelimit);
 EXPORT_SYMBOL_GPL(ata_busy_sleep);