The patch titled
loop: preallocate eight loop devices
has been added to the -mm tree. Its filename is
loop-preallocate-eight-loop-devices.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: loop: preallocate eight loop devices
From: "Ken Chen" <kenchen@xxxxxxxxxx>
The kernel on-demand loop device instantiation breaks several user space
tools as the tools are not ready to cope with the "on-demand feature". Fix
it by instantiate default 8 loop devices and also reinstate max_loop module
parameter.
Signed-off-by: Ken Chen <kenchen@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/loop.c | 68 ++++++++++++++++++++++++++++++-----------
1 files changed, 50 insertions(+), 18 deletions(-)
diff -puN drivers/block/loop.c~loop-preallocate-eight-loop-devices drivers/block/loop.c
--- a/drivers/block/loop.c~loop-preallocate-eight-loop-devices
+++ a/drivers/block/loop.c
@@ -1354,7 +1354,7 @@ static struct block_device_operations lo
*/
static int max_loop;
module_param(max_loop, int, 0);
-MODULE_PARM_DESC(max_loop, "obsolete, loop device is created on-demand");
+MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
MODULE_LICENSE("GPL");
MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
@@ -1462,34 +1462,66 @@ static struct kobject *loop_probe(dev_t
return kobj;
}
-static int __init loop_init(void)
-{
- if (register_blkdev(LOOP_MAJOR, "loop"))
- return -EIO;
- blk_register_region(MKDEV(LOOP_MAJOR, 0), 1UL << MINORBITS,
- THIS_MODULE, loop_probe, NULL, NULL);
-
- if (max_loop) {
- printk(KERN_INFO "loop: the max_loop option is obsolete "
- "and will be removed in March 2008\n");
-
- }
- printk(KERN_INFO "loop: module loaded\n");
- return 0;
-}
-
static void __exit loop_exit(void)
{
+ unsigned long range;
struct loop_device *lo, *next;
+ range = max_loop ? max_loop : 1UL << MINORBITS;
+
list_for_each_entry_safe(lo, next, &loop_devices, lo_list)
loop_del_one(lo);
- blk_unregister_region(MKDEV(LOOP_MAJOR, 0), 1UL << MINORBITS);
+ blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
if (unregister_blkdev(LOOP_MAJOR, "loop"))
printk(KERN_WARNING "loop: cannot unregister blkdev\n");
}
+static int __init loop_init(void)
+{
+ int i, nr;
+ unsigned long range;
+
+ /*
+ * loop module now has a feature to instantiate underlying device
+ * structure on-demand, provided that there is an access dev node.
+ * However, this will not work well with user space tool that doesn't
+ * know about such "feature". In order to not break any existing
+ * tool, we do the following:
+ *
+ * (1) if max_loop is specified, create that many upfront, and this
+ * also becomes a hard limit.
+ * (2) if max_loop is not specified, create 8 loop device on module
+ * load, user can further extend loop device by create dev node
+ * themselves and have kernel automatically instantiate actual
+ * device on-demand.
+ */
+ if (max_loop) {
+ nr = max_loop;
+ range = max_loop;
+ } else {
+ nr = 8;
+ range = 1UL << MINORBITS;
+ }
+
+ if (register_blkdev(LOOP_MAJOR, "loop"))
+ return -EIO;
+ blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
+ THIS_MODULE, loop_probe, NULL, NULL);
+
+ for (i = 0; i < nr; i++) {
+ if (!loop_init_one(i))
+ goto err;
+ }
+
+ printk(KERN_INFO "loop: module loaded\n");
+ return 0;
+err:
+ loop_exit();
+ printk(KERN_INFO "loop: out of memory\n");
+ return -ENOMEM;
+}
+
module_init(loop_init);
module_exit(loop_exit);
_
Patches currently in -mm which might be from kenchen@xxxxxxxxxx are
loop-preallocate-eight-loop-devices.patch
cache-pipe-buf-page-address-for-non-highmem-arch.patch
-
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