scsi: retry report-luns when reported LU count requres more memory

Update scsi_report_lun_scan to initially always report up to 511 LUs,
as the previous default max_report_luns did.  Retry in a loop if not
enough memory is available for the number of LUs reported.  Parameter
max_report_luns is removed as it is no longer used.

Signed-off-by: Rob Evers <revers@redhat.com>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index b7948d20c23b0798d0832208bece95a0b4a4f762..0deb385ad4d66e0449187a61ebac94e958a2bf5b 100644 (file)
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -99,20 +99,6 @@ char scsi_scan_type[6] = SCSI_SCAN_TYPE_DEFAULT;
 module_param_string(scan, scsi_scan_type, sizeof(scsi_scan_type), S_IRUGO);
 MODULE_PARM_DESC(scan, "sync, async or none");
 
-/*
- * max_scsi_report_luns: the maximum number of LUNS that will be
- * returned from the REPORT LUNS command. 8 times this value must
- * be allocated. In theory this could be up to an 8 byte value, but
- * in practice, the maximum number of LUNs suppored by any device
- * is about 16k.
- */
-static unsigned int max_scsi_report_luns = 511;
-
-module_param_named(max_report_luns, max_scsi_report_luns, uint, S_IRUGO|S_IWUSR);
-MODULE_PARM_DESC(max_report_luns,
-                "REPORT LUNS maximum number of LUNS received (should be"
-                " between 1 and 16384)");
-
 static unsigned int scsi_inq_timeout = SCSI_TIMEOUT/HZ + 18;
 
 module_param_named(inq_timeout, scsi_inq_timeout, uint, S_IRUGO|S_IWUSR);
@@ -1407,15 +1393,11 @@ static int scsi_report_lun_scan(struct scsi_target *starget, int bflags,
 
        /*
         * Allocate enough to hold the header (the same size as one scsi_lun)
-        * plus the max number of luns we are requesting.
-        *
-        * Reallocating and trying again (with the exact amount we need)
-        * would be nice, but then we need to somehow limit the size
-        * allocated based on the available memory and the limits of
-        * kmalloc - we don't want a kmalloc() failure of a huge value to
-        * prevent us from finding any LUNs on this target.
+        * plus the number of luns we are requesting.  511 was the default
+        * value of the now removed max_report_luns parameter.
         */
-       length = (max_scsi_report_luns + 1) * sizeof(struct scsi_lun);
+       length = (511 + 1) * sizeof(struct scsi_lun);
+retry:
        lun_data = kmalloc(length, GFP_KERNEL |
                           (sdev->host->unchecked_isa_dma ? __GFP_DMA : 0));
        if (!lun_data) {
@@ -1481,17 +1463,16 @@ static int scsi_report_lun_scan(struct scsi_target *starget, int bflags,
        /*
         * Get the length from the first four bytes of lun_data.
         */
+       if (get_unaligned_be32(lun_data->scsi_lun) +
+           sizeof(struct scsi_lun) > length) {
+               length = get_unaligned_be32(lun_data->scsi_lun) +
+                        sizeof(struct scsi_lun);
+               kfree(lun_data);
+               goto retry;
+       }
        length = get_unaligned_be32(lun_data->scsi_lun);
 
        num_luns = (length / sizeof(struct scsi_lun));
-       if (num_luns > max_scsi_report_luns) {
-               sdev_printk(KERN_WARNING, sdev,
-                           "Only %d (max_scsi_report_luns)"
-                           " of %d luns reported, try increasing"
-                           " max_scsi_report_luns.\n",
-                           max_scsi_report_luns, num_luns);
-               num_luns = max_scsi_report_luns;
-       }
 
        SCSI_LOG_SCAN_BUS(3, sdev_printk (KERN_INFO, sdev,
                "scsi scan: REPORT LUN scan\n"));