[PATCH 1/6] block: export blkdev_reread_part()

Ming Lei
2015-04-05T07:24:43Z

This patch exports blkdev_reread_part() for block drivers, also
introduce blkdev_reread_part_no_lock().

For some drivers, such as loop, reread partition can be run
from release path, and the bd_mutex has been held already before
calling ioctl_by_bdev(bdev, BLKRRPART, 0), so this patch introduces
blkdev_reread_part_no_lock() too for this requirment.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
---
block/ioctl.c | 14 ++++++++++----
include/linux/fs.h | 9 +++++++++
2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/block/ioctl.c b/block/ioctl.c
index 7d8befd..7dce19a 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -150,7 +150,11 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
}
}

-static int blkdev_reread_part(struct block_device *bdev)
+/*
+ * This is exported as API for block driver, can be called
+ * with requiring bd_mutex or not.
+ */
+int __blkdev_reread_part(struct block_device *bdev, bool lock)
{
struct gendisk *disk = bdev->bd_disk;
int res;
@@ -159,12 +163,14 @@ static int blkdev_reread_part(struct block_device *bdev)
return -EINVAL;
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
- if (!mutex_trylock(&bdev->bd_mutex))
+ if (lock && !mutex_trylock(&bdev->bd_mutex))
return -EBUSY;
res = rescan_partitions(disk, bdev);
- mutex_unlock(&bdev->bd_mutex);
+ if (lock)
+ mutex_unlock(&bdev->bd_mutex);
return res;
}
+EXPORT_SYMBOL(__blkdev_reread_part);

static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
uint64_t len, int secure)
@@ -407,7 +413,7 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
ret = blkpg_ioctl(bdev, (struct blkpg_ioctl_arg __user *) arg);
break;
case BLKRRPART:
- ret = blkdev_reread_part(bdev);
+ ret = __blkdev_reread_part(bdev, true);
break;
case BLKGETSIZE:
size = i_size_read(bdev->bd_inode);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 368e349..948bf75 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2275,6 +2275,15 @@ extern struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
extern struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode,
void *holder);
extern void blkdev_put(struct block_device *bdev, fmode_t mode);
+extern int __blkdev_reread_part(struct block_device *bdev, bool lock);
+static inline int blkdev_reread_part(struct block_device *bdev)
+{
+ return __blkdev_reread_part(bdev, true);
+}
+static inline int blkdev_reread_part_nolock(struct block_device *bdev)
+{
+ return __blkdev_reread_part(bdev, false);
+}
#ifdef CONFIG_SYSFS
extern int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk);
extern void bd_unlink_disk_holder(struct block_device *bdev,
--
1.7.9.5