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Message-Id: <20070323151956.1ac6a47b.dada1@cosmosbay.com>
Date: Fri, 23 Mar 2007 15:19:56 +0100
From: Eric Dumazet <dada1@...mosbay.com>
To: Tomas M <tomas@...x.org>
Cc: linux-kernel@...r.kernel.org
Subject: Re: [patch] [bugfix] loop.c
On Fri, 23 Mar 2007 15:04:54 +0100
Tomas M <tomas@...x.org> wrote:
> I posted this yesterday but it seems people didn't understand the real
> goal of my patch. So I will explain once more again:
>
> This is a bugfix for loop.c block driver, as it currently allocates more
> memory then it needs, without any further use.
Well... changing the Changelog wont help I'm afraid.
I cooked the following patch (untested), feel free to test it.
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 6b5b642..3f4b68c 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -65,6 +65,7 @@ #include <linux/init.h>
#include <linux/smp_lock.h>
#include <linux/swap.h>
#include <linux/slab.h>
+#include <linux/vmalloc.h>
#include <linux/loop.h>
#include <linux/compat.h>
#include <linux/suspend.h>
@@ -78,8 +79,8 @@ #include <linux/kthread.h>
#include <asm/uaccess.h>
static int max_loop = 8;
-static struct loop_device *loop_dev;
-static struct gendisk **disks;
+static struct loop_device **loop_dev;
+static int loop_dev_vmalloced;
/*
* Transfer functions
@@ -183,7 +184,7 @@ figure_loop_size(struct loop_device *lo)
if (unlikely((loff_t)x != size))
return -EFBIG;
- set_capacity(disks[lo->lo_number], x);
+ set_capacity(lo->lo_disk, x);
return 0;
}
@@ -812,7 +813,7 @@ static int loop_set_fd(struct loop_devic
lo->lo_queue->queuedata = lo;
lo->lo_queue->unplug_fn = loop_unplug;
- set_capacity(disks[lo->lo_number], size);
+ set_capacity(lo->lo_disk, size);
bd_set_size(bdev, size << 9);
set_blocksize(bdev, lo_blocksize);
@@ -832,7 +833,7 @@ out_clr:
lo->lo_device = NULL;
lo->lo_backing_file = NULL;
lo->lo_flags = 0;
- set_capacity(disks[lo->lo_number], 0);
+ set_capacity(lo->lo_disk, 0);
invalidate_bdev(bdev, 0);
bd_set_size(bdev, 0);
mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
@@ -918,7 +919,7 @@ static int loop_clr_fd(struct loop_devic
memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
memset(lo->lo_file_name, 0, LO_NAME_SIZE);
invalidate_bdev(bdev, 0);
- set_capacity(disks[lo->lo_number], 0);
+ set_capacity(lo->lo_disk, 0);
bd_set_size(bdev, 0);
mapping_set_gfp_mask(filp->f_mapping, gfp);
lo->lo_state = Lo_unbound;
@@ -1358,7 +1359,7 @@ #endif
* And now the modules code and kernel interface.
*/
module_param(max_loop, int, 0);
-MODULE_PARM_DESC(max_loop, "Maximum number of loop devices (1-256)");
+MODULE_PARM_DESC(max_loop, "Maximum number of loop devices (1-16384)");
MODULE_LICENSE("GPL");
MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
@@ -1377,13 +1378,15 @@ int loop_unregister_transfer(int number)
unsigned int n = number;
struct loop_device *lo;
struct loop_func_table *xfer;
+ int i;
if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
return -EINVAL;
xfer_funcs[n] = NULL;
- for (lo = &loop_dev[0]; lo < &loop_dev[max_loop]; lo++) {
+ for (i = 0; i < max_loop; i++) {
+ lo = loop_dev[i];
mutex_lock(&lo->lo_ctl_mutex);
if (lo->lo_encryption == xfer)
@@ -1400,70 +1403,74 @@ EXPORT_SYMBOL(loop_unregister_transfer);
static int __init loop_init(void)
{
- int i;
+ struct gendisk *disk;
+ struct loop_device *lo;
+ int i, nba = 0, nbl = 0;
- if (max_loop < 1 || max_loop > 256) {
- printk(KERN_WARNING "loop: invalid max_loop (must be between"
- " 1 and 256), using default (8)\n");
+ if (max_loop < 1) {
+ printk(KERN_WARNING "loop: invalid max_loop (must be > 1)"
+ ", using default (8)\n");
max_loop = 8;
}
if (register_blkdev(LOOP_MAJOR, "loop"))
return -EIO;
- loop_dev = kmalloc(max_loop * sizeof(struct loop_device), GFP_KERNEL);
- if (!loop_dev)
- goto out_mem1;
- memset(loop_dev, 0, max_loop * sizeof(struct loop_device));
-
- disks = kmalloc(max_loop * sizeof(struct gendisk *), GFP_KERNEL);
- if (!disks)
- goto out_mem2;
-
- for (i = 0; i < max_loop; i++) {
- disks[i] = alloc_disk(1);
- if (!disks[i])
- goto out_mem3;
+ loop_dev = kmalloc(max_loop * sizeof(struct loop_device *), GFP_KERNEL);
+ if (!loop_dev) {
+ loop_dev = vmalloc(max_loop * sizeof(struct loop_device *));
+ if (!loop_dev)
+ goto out_mem;
+ loop_dev_vmalloced = 1;
}
- for (i = 0; i < max_loop; i++) {
- struct loop_device *lo = &loop_dev[i];
- struct gendisk *disk = disks[i];
+ while (nbl < max_loop) {
+ lo = kzalloc(sizeof(struct loop_device), GFP_KERNEL);
+ if (!lo)
+ goto out_mem;
+ disk = alloc_disk(1);
+ lo->lo_disk = disk;
+ loop_dev[nbl++] = lo;
+ if (!disk)
+ goto out_mem;
+ }
- memset(lo, 0, sizeof(*lo));
+ for (; nba < max_loop; nba++) {
+ lo = loop_dev[nba];
lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
if (!lo->lo_queue)
- goto out_mem4;
+ goto out_mem;
+ disk = lo->lo_disk;
mutex_init(&lo->lo_ctl_mutex);
- lo->lo_number = i;
+ lo->lo_number = nba;
lo->lo_thread = NULL;
init_waitqueue_head(&lo->lo_event);
spin_lock_init(&lo->lo_lock);
disk->major = LOOP_MAJOR;
- disk->first_minor = i;
+ disk->first_minor = nba;
disk->fops = &lo_fops;
- sprintf(disk->disk_name, "loop%d", i);
+ sprintf(disk->disk_name, "loop%d", nba);
disk->private_data = lo;
disk->queue = lo->lo_queue;
}
/* We cannot fail after we call this, so another loop!*/
for (i = 0; i < max_loop; i++)
- add_disk(disks[i]);
+ add_disk(loop_dev[i]->lo_disk);
printk(KERN_INFO "loop: loaded (max %d devices)\n", max_loop);
return 0;
-out_mem4:
- while (i--)
- blk_cleanup_queue(loop_dev[i].lo_queue);
- i = max_loop;
-out_mem3:
- while (i--)
- put_disk(disks[i]);
- kfree(disks);
-out_mem2:
- kfree(loop_dev);
-out_mem1:
+out_mem:
+ while (nba--)
+ blk_cleanup_queue(loop_dev[nba]->lo_queue);
+ while (nbl--) {
+ put_disk(loop_dev[nbl]->lo_disk);
+ kfree(loop_dev[nbl]);
+ }
+ if (loop_dev_vmalloced)
+ vfree(loop_dev);
+ else
+ kfree(loop_dev);
unregister_blkdev(LOOP_MAJOR, "loop");
printk(KERN_ERR "loop: ran out of memory\n");
return -ENOMEM;
@@ -1472,17 +1479,22 @@ out_mem1:
static void loop_exit(void)
{
int i;
+ struct loop_device *lo;
for (i = 0; i < max_loop; i++) {
- del_gendisk(disks[i]);
- blk_cleanup_queue(loop_dev[i].lo_queue);
- put_disk(disks[i]);
+ lo = loop_dev[i];
+ del_gendisk(lo->lo_disk);
+ blk_cleanup_queue(lo->lo_queue);
+ put_disk(lo->lo_disk);
+ kfree(lo);
}
if (unregister_blkdev(LOOP_MAJOR, "loop"))
printk(KERN_WARNING "loop: cannot unregister blkdev\n");
- kfree(disks);
- kfree(loop_dev);
+ if (loop_dev_vmalloced)
+ vfree(loop_dev);
+ else
+ kfree(loop_dev);
}
module_init(loop_init);
diff --git a/include/linux/loop.h b/include/linux/loop.h
index 191a595..fef7c5e 100644
--- a/include/linux/loop.h
+++ b/include/linux/loop.h
@@ -29,6 +29,7 @@ enum {
struct loop_func_table;
struct loop_device {
+ struct gendisk *lo_disk;
int lo_number;
int lo_refcnt;
loff_t lo_offset;
-
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