diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 9 | ||||
| -rw-r--r-- | drivers/block/Kconfig | 15 | ||||
| -rw-r--r-- | drivers/block/loop.c | 27 |
3 files changed, 31 insertions, 20 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 4ca93898fbd3..c32851131646 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1340,9 +1340,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. it is equivalent to "nosmp", which also disables the IO APIC. - max_loop= [LOOP] Maximum number of loopback devices that can - be mounted - Format: <1-256> + max_loop= [LOOP] The number of loop block devices that get + (loop.max_loop) unconditionally pre-created at init time. The default + number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead + of statically allocating a predefined number, loop + devices can be requested on-demand with the + /dev/loop-control interface. mcatest= [IA-64] diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig index 717d6e4e18d3..57212c5235e2 100644 --- a/drivers/block/Kconfig +++ b/drivers/block/Kconfig @@ -256,6 +256,21 @@ config BLK_DEV_LOOP Most users will answer N here. +config BLK_DEV_LOOP_MIN_COUNT + int "Number of loop devices to pre-create at init time" + depends on BLK_DEV_LOOP + default 8 + help + Static number of loop devices to be unconditionally pre-created + at init time. + + This default value can be overwritten on the kernel command + line or with module-parameter loop.max_loop. + + The historic default is 8. If a late 2011 version of losetup(8) + is used, it can be set to 0, since needed loop devices can be + dynamically allocated with the /dev/loop-control interface. + config BLK_DEV_CRYPTOLOOP tristate "Cryptoloop Support" select CRYPTO diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 5c9edf944879..3defc52f060c 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1793,21 +1793,6 @@ static int __init loop_init(void) struct loop_device *lo; int err; - /* - * 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. - */ - err = misc_register(&loop_misc); if (err < 0) return err; @@ -1833,11 +1818,19 @@ static int __init loop_init(void) if (max_loop > 1UL << (MINORBITS - part_shift)) return -EINVAL; + /* + * If max_loop is specified, create that many devices upfront. + * This also becomes a hard limit. If max_loop is not specified, + * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module + * init time. Loop devices can be requested on-demand with the + * /dev/loop-control interface, or be instantiated by accessing + * a 'dead' device node. + */ if (max_loop) { nr = max_loop; range = max_loop << part_shift; } else { - nr = 8; + nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT; range = 1UL << MINORBITS; } @@ -1847,7 +1840,7 @@ static int __init loop_init(void) blk_register_region(MKDEV(LOOP_MAJOR, 0), range, THIS_MODULE, loop_probe, NULL, NULL); - /* pre-create number devices of devices given by config or max_loop */ + /* pre-create number of devices given by config or max_loop */ mutex_lock(&loop_index_mutex); for (i = 0; i < nr; i++) loop_add(&lo, i); |