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[SCSI] sg: fixes for large page_size

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This sg driver patch addresses the problem with larger
page sizes reported by Brian King in this post:
http://marc.theaimsgroup.com/?l=linux-scsi&m=115867718623631&w=2
Some other related matters are also addressed. Some of these
prevent oopses when the SG_SCATTER_SZ or scatter_elem_sz are
set to inappropriate values.

The scatter_elem_sz has been tested up to 4 MB which should
make the largest data transfer with one SCSI command, 32 MB
less one block, achievable with a relatively small number
of elements in the scatter gather list.

ChangeLog:
    - add scatter_elem_sz boot time parameter and sysfs module
      parameter that is initialized to SG_SCATTER_SZ
    - the driver will then adjust scatter_elem_sz to be the
      max(given(scatter_elem_sz), PAGE_SIZE)
      It will also round it up, if necessary, to be a power
      of two
    - clean up sg.h header, correct bad urls and some statements
      that are no longer valid
    - make the def_reserved_size sysfs module attribute writable

Signed-off-by: Douglas Gilbert <dougg@torque.net>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This commit is contained in:
Douglas Gilbert
2006-09-20 18:20:49 -04:00
committed by James Bottomley
parent 8aee918a1c
commit 6460e75a10
2 changed files with 60 additions and 52 deletions
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53
drivers/scsi/sg.c
View File

@@ -60,7 +60,7 @@ static int sg_version_num = 30534; /* 2 digits for each component */
#ifdef CONFIG_SCSI_PROC_FS
#include <linux/proc_fs.h>
static char *sg_version_date = "20060818";
static char *sg_version_date = "20060920";
static int sg_proc_init(void);
static void sg_proc_cleanup(void);
@@ -94,6 +94,9 @@ int sg_big_buff = SG_DEF_RESERVED_SIZE;
static int def_reserved_size = -1; /* picks up init parameter */
static int sg_allow_dio = SG_ALLOW_DIO_DEF;
static int scatter_elem_sz = SG_SCATTER_SZ;
static int scatter_elem_sz_prev = SG_SCATTER_SZ;
#define SG_SECTOR_SZ 512
#define SG_SECTOR_MSK (SG_SECTOR_SZ - 1)
@@ -1537,11 +1540,9 @@ sg_remove(struct class_device *cl_dev, struct class_interface *cl_intf)
msleep(10); /* dirty detach so delay device destruction */
}
/* Set 'perm' (4th argument) to 0 to disable module_param's definition
* of sysfs parameters (which module_param doesn't yet support).
* Sysfs parameters defined explicitly below.
*/
module_param_named(def_reserved_size, def_reserved_size, int, S_IRUGO);
module_param_named(scatter_elem_sz, scatter_elem_sz, int, S_IRUGO | S_IWUSR);
module_param_named(def_reserved_size, def_reserved_size, int,
S_IRUGO | S_IWUSR);
module_param_named(allow_dio, sg_allow_dio, int, S_IRUGO | S_IWUSR);
MODULE_AUTHOR("Douglas Gilbert");
@@ -1550,6 +1551,8 @@ MODULE_LICENSE("GPL");
MODULE_VERSION(SG_VERSION_STR);
MODULE_ALIAS_CHARDEV_MAJOR(SCSI_GENERIC_MAJOR);
MODULE_PARM_DESC(scatter_elem_sz, "scatter gather element "
"size (default: max(SG_SCATTER_SZ, PAGE_SIZE))");
MODULE_PARM_DESC(def_reserved_size, "size of buffer reserved for each fd");
MODULE_PARM_DESC(allow_dio, "allow direct I/O (default: 0 (disallow))");
@@ -1558,8 +1561,14 @@ init_sg(void)
{
int rc;
if (scatter_elem_sz < PAGE_SIZE) {
scatter_elem_sz = PAGE_SIZE;
scatter_elem_sz_prev = scatter_elem_sz;
}
if (def_reserved_size >= 0)
sg_big_buff = def_reserved_size;
else
def_reserved_size = sg_big_buff;
rc = register_chrdev_region(MKDEV(SCSI_GENERIC_MAJOR, 0),
SG_MAX_DEVS, "sg");
@@ -1842,15 +1851,30 @@ sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size)
if (mx_sc_elems < 0)
return mx_sc_elems; /* most likely -ENOMEM */
num = scatter_elem_sz;
if (unlikely(num != scatter_elem_sz_prev)) {
if (num < PAGE_SIZE) {
scatter_elem_sz = PAGE_SIZE;
scatter_elem_sz_prev = PAGE_SIZE;
} else
scatter_elem_sz_prev = num;
}
for (k = 0, sg = schp->buffer, rem_sz = blk_size;
(rem_sz > 0) && (k < mx_sc_elems);
++k, rem_sz -= ret_sz, ++sg) {
num = (rem_sz > SG_SCATTER_SZ) ? SG_SCATTER_SZ : rem_sz;
num = (rem_sz > scatter_elem_sz_prev) ?
scatter_elem_sz_prev : rem_sz;
p = sg_page_malloc(num, sfp->low_dma, &ret_sz);
if (!p)
return -ENOMEM;
if (num == scatter_elem_sz_prev) {
if (unlikely(ret_sz > scatter_elem_sz_prev)) {
scatter_elem_sz = ret_sz;
scatter_elem_sz_prev = ret_sz;
}
}
sg->page = p;
sg->length = ret_sz;
@@ -2341,6 +2365,9 @@ sg_add_sfp(Sg_device * sdp, int dev)
}
write_unlock_irqrestore(&sg_dev_arr_lock, iflags);
SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp: sfp=0x%p\n", sfp));
if (unlikely(sg_big_buff != def_reserved_size))
sg_big_buff = def_reserved_size;
sg_build_reserve(sfp, sg_big_buff);
SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp: bufflen=%d, k_use_sg=%d\n",
sfp->reserve.bufflen, sfp->reserve.k_use_sg));
@@ -2437,16 +2464,16 @@ sg_res_in_use(Sg_fd * sfp)
return srp ? 1 : 0;
}
/* If retSzp==NULL want exact size or fail */
/* The size fetched (value output via retSzp) set when non-NULL return */
static struct page *
sg_page_malloc(int rqSz, int lowDma, int *retSzp)
{
struct page *resp = NULL;
gfp_t page_mask;
int order, a_size;
int resSz = rqSz;
int resSz;
if (rqSz <= 0)
if ((rqSz <= 0) || (NULL == retSzp))
return resp;
if (lowDma)
@@ -2456,8 +2483,9 @@ sg_page_malloc(int rqSz, int lowDma, int *retSzp)
for (order = 0, a_size = PAGE_SIZE; a_size < rqSz;
order++, a_size <<= 1) ;
resSz = a_size; /* rounded up if necessary */
resp = alloc_pages(page_mask, order);
while ((!resp) && order && retSzp) {
while ((!resp) && order) {
--order;
a_size >>= 1; /* divide by 2, until PAGE_SIZE */
resp = alloc_pages(page_mask, order); /* try half */
@@ -2466,8 +2494,7 @@ sg_page_malloc(int rqSz, int lowDma, int *retSzp)
if (resp) {
if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
memset(page_address(resp), 0, resSz);
if (retSzp)
*retSzp = resSz;
*retSzp = resSz;
}
return resp;
}