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authorKay Sievers <kay.sievers@vrfy.org>2011-08-23 20:12:04 +0200
committerJens Axboe <jaxboe@fusionio.com>2011-08-23 20:12:04 +0200
commite03c8dd14915fabc101aa495828d58598dc5af98 (patch)
tree8aba1d519848c3f7684ac5673c95f56aa6ff1d57
parente8b177cedc39b092e423b8cbc687dbf096a1de47 (diff)
downloadop-kernel-dev-e03c8dd14915fabc101aa495828d58598dc5af98.zip
op-kernel-dev-e03c8dd14915fabc101aa495828d58598dc5af98.tar.gz
loop: always allow userspace partitions and optionally support automatic scanning
Automatic partition scanning can be requested individually per loop device during its setup by setting LO_FLAGS_PARTSCAN. By default, no partition tables are scanned. Userspace can now always add and remove partitions from all loop devices, regardless if the in-kernel partition scanner is enabled or not. The needed partition minor numbers are allocated from the extended minors space, the main loop device numbers will continue to match the loop minors, regardless of the number of partitions used. # grep . /sys/class/block/loop1/loop/* /sys/block/loop1/loop/autoclear:0 /sys/block/loop1/loop/backing_file:/home/kay/data/stuff/part.img /sys/block/loop1/loop/offset:0 /sys/block/loop1/loop/partscan:1 /sys/block/loop1/loop/sizelimit:0 # ls -l /dev/loop* brw-rw---- 1 root disk 7, 0 Aug 14 20:22 /dev/loop0 brw-rw---- 1 root disk 7, 1 Aug 14 20:23 /dev/loop1 brw-rw---- 1 root disk 259, 0 Aug 14 20:23 /dev/loop1p1 brw-rw---- 1 root disk 259, 1 Aug 14 20:23 /dev/loop1p2 brw-rw---- 1 root disk 7, 99 Aug 14 20:23 /dev/loop99 brw-rw---- 1 root disk 259, 2 Aug 14 20:23 /dev/loop99p1 brw-rw---- 1 root disk 259, 3 Aug 14 20:23 /dev/loop99p2 crw------T 1 root root 10, 237 Aug 14 20:22 /dev/loop-control Cc: Karel Zak <kzak@redhat.com> Cc: Davidlohr Bueso <dave@gnu.org> Acked-By: Tejun Heo <tj@kernel.org> Signed-off-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
-rw-r--r--drivers/block/loop.c49
-rw-r--r--include/linux/loop.h1
2 files changed, 46 insertions, 4 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 936cac3..b336433 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -724,7 +724,7 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
goto out_putf;
fput(old_file);
- if (max_part > 0)
+ if (lo->lo_flags & LO_FLAGS_PARTSCAN)
ioctl_by_bdev(bdev, BLKRRPART, 0);
return 0;
@@ -808,16 +808,25 @@ static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
return sprintf(buf, "%s\n", autoclear ? "1" : "0");
}
+static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
+{
+ int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
+
+ return sprintf(buf, "%s\n", partscan ? "1" : "0");
+}
+
LOOP_ATTR_RO(backing_file);
LOOP_ATTR_RO(offset);
LOOP_ATTR_RO(sizelimit);
LOOP_ATTR_RO(autoclear);
+LOOP_ATTR_RO(partscan);
static struct attribute *loop_attrs[] = {
&loop_attr_backing_file.attr,
&loop_attr_offset.attr,
&loop_attr_sizelimit.attr,
&loop_attr_autoclear.attr,
+ &loop_attr_partscan.attr,
NULL,
};
@@ -979,7 +988,9 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
}
lo->lo_state = Lo_bound;
wake_up_process(lo->lo_thread);
- if (max_part > 0)
+ if (part_shift)
+ lo->lo_flags |= LO_FLAGS_PARTSCAN;
+ if (lo->lo_flags & LO_FLAGS_PARTSCAN)
ioctl_by_bdev(bdev, BLKRRPART, 0);
return 0;
@@ -1070,7 +1081,6 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
lo->lo_offset = 0;
lo->lo_sizelimit = 0;
lo->lo_encrypt_key_size = 0;
- lo->lo_flags = 0;
lo->lo_thread = NULL;
memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
@@ -1088,8 +1098,11 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
lo->lo_state = Lo_unbound;
/* This is safe: open() is still holding a reference. */
module_put(THIS_MODULE);
- if (max_part > 0 && bdev)
+ if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
ioctl_by_bdev(bdev, BLKRRPART, 0);
+ lo->lo_flags = 0;
+ if (!part_shift)
+ lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
mutex_unlock(&lo->lo_ctl_mutex);
/*
* Need not hold lo_ctl_mutex to fput backing file.
@@ -1159,6 +1172,13 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
(info->lo_flags & LO_FLAGS_AUTOCLEAR))
lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
+ if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
+ !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
+ lo->lo_flags |= LO_FLAGS_PARTSCAN;
+ lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
+ ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
+ }
+
lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
lo->lo_init[0] = info->lo_init[0];
lo->lo_init[1] = info->lo_init[1];
@@ -1654,6 +1674,27 @@ static struct loop_device *loop_alloc(int i)
if (!disk)
goto out_free_queue;
+ /*
+ * Disable partition scanning by default. The in-kernel partition
+ * scanning can be requested individually per-device during its
+ * setup. Userspace can always add and remove partitions from all
+ * devices. The needed partition minors are allocated from the
+ * extended minor space, the main loop device numbers will continue
+ * to match the loop minors, regardless of the number of partitions
+ * used.
+ *
+ * If max_part is given, partition scanning is globally enabled for
+ * all loop devices. The minors for the main loop devices will be
+ * multiples of max_part.
+ *
+ * Note: Global-for-all-devices, set-only-at-init, read-only module
+ * parameteters like 'max_loop' and 'max_part' make things needlessly
+ * complicated, are too static, inflexible and may surprise
+ * userspace tools. Parameters like this in general should be avoided.
+ */
+ if (!part_shift)
+ disk->flags |= GENHD_FL_NO_PART_SCAN;
+ disk->flags |= GENHD_FL_EXT_DEVT;
mutex_init(&lo->lo_ctl_mutex);
lo->lo_number = i;
lo->lo_thread = NULL;
diff --git a/include/linux/loop.h b/include/linux/loop.h
index 66c194e..4367fc5 100644
--- a/include/linux/loop.h
+++ b/include/linux/loop.h
@@ -76,6 +76,7 @@ enum {
LO_FLAGS_READ_ONLY = 1,
LO_FLAGS_USE_AOPS = 2,
LO_FLAGS_AUTOCLEAR = 4,
+ LO_FLAGS_PARTSCAN = 8,
};
#include <asm/posix_types.h> /* for __kernel_old_dev_t */
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