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authorJan Kara <jack@suse.cz>2017-03-23 01:37:00 +0100
committerJens Axboe <axboe@fb.com>2017-03-22 20:11:33 -0600
commitf759741d9d913eb57784a94b9bca78b376fc26a9 (patch)
tree19832434e2c4c1db34bceee048f422b910300686 /fs/block_dev.c
parentb1c51afc00f164457e126dcfc946fdd563948d26 (diff)
downloadlinux-f759741d9d913eb57784a94b9bca78b376fc26a9.tar.bz2
block: Fix oops in locked_inode_to_wb_and_lock_list()
When block device is closed, we call inode_detach_wb() in __blkdev_put() which sets inode->i_wb to NULL. That is contrary to expectations that inode->i_wb stays valid once set during the whole inode's lifetime and leads to oops in wb_get() in locked_inode_to_wb_and_lock_list() because inode_to_wb() returned NULL. The reason why we called inode_detach_wb() is not valid anymore though. BDI is guaranteed to stay along until we call bdi_put() from bdev_evict_inode() so we can postpone calling inode_detach_wb() to that moment. Also add a warning to catch if someone uses inode_detach_wb() in a dangerous way. Reported-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'fs/block_dev.c')
-rw-r--r--fs/block_dev.c8
1 files changed, 2 insertions, 6 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 53e2389ae4d4..f2d59f143ef4 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -885,6 +885,8 @@ static void bdev_evict_inode(struct inode *inode)
spin_lock(&bdev_lock);
list_del_init(&bdev->bd_list);
spin_unlock(&bdev_lock);
+ /* Detach inode from wb early as bdi_put() may free bdi->wb */
+ inode_detach_wb(inode);
if (bdev->bd_bdi != &noop_backing_dev_info) {
bdi_put(bdev->bd_bdi);
bdev->bd_bdi = &noop_backing_dev_info;
@@ -1875,12 +1877,6 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
kill_bdev(bdev);
bdev_write_inode(bdev);
- /*
- * Detaching bdev inode from its wb in __destroy_inode()
- * is too late: the queue which embeds its bdi (along with
- * root wb) can be gone as soon as we put_disk() below.
- */
- inode_detach_wb(bdev->bd_inode);
}
if (bdev->bd_contains == bdev) {
if (disk->fops->release)