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authorNamhyung Kim <namhyung@gmail.com>2011-05-28 14:44:46 +0200
committerJens Axboe <jaxboe@fusionio.com>2011-05-28 14:44:46 +0200
commit5988ce239682854d4e632fb58bff000700830394 (patch)
tree442b44bb96632b7ed507bc5eeacd10fafc689afd /drivers/block/nbd.c
parent3b2710824e00d238554c13b5add347e6c701ab1a (diff)
nbd: adjust 'max_part' according to part_shift
The 'max_part' parameter determines how many partitions are supported on each nbd device. However the actual number can be changed to the power of 2 minus 1 form during the module initialization as alloc_disk() is called with (1 << part_shift) for some reason. So adjust 'max_part' also at least for consistency with loop and brd. It is exported via sysfs already, and a user should check this value after module loading if [s]he wants to use that number correctly (i.e. fdisk or something). Signed-off-by: Namhyung Kim <namhyung@gmail.com> Cc: Laurent Vivier <Laurent.Vivier@bull.net> Cc: Paul Clements <Paul.Clements@steeleye.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'drivers/block/nbd.c')
-rw-r--r--drivers/block/nbd.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index fdee7567fd15..f533f3375e24 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -754,9 +754,20 @@ static int __init nbd_init(void)
return -ENOMEM;
part_shift = 0;
- if (max_part > 0)
+ if (max_part > 0) {
part_shift = fls(max_part);
+ /*
+ * Adjust max_part according to part_shift as it is exported
+ * to user space so that user can know the max number of
+ * partition kernel should be able to manage.
+ *
+ * Note that -1 is required because partition 0 is reserved
+ * for the whole disk.
+ */
+ max_part = (1UL << part_shift) - 1;
+ }
+
if ((1UL << part_shift) > DISK_MAX_PARTS)
return -EINVAL;