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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>
This commit is contained in:
Rob Evers 2014-12-16 11:01:20 -05:00 committed by Christoph Hellwig
parent 2a904e5dd9
commit acd6d73826
1 changed files with 11 additions and 30 deletions
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41
drivers/scsi/scsi_scan.c
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@ -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"));