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authorDongli Zhang <dongli.zhang@oracle.com>2019-02-22 17:10:20 +0300
committerJens Axboe <axboe@kernel.dk>2019-02-23 01:51:22 +0300
commit758a58d0bc67457f1215321a536226654a830eeb (patch)
treeee6f9031129c6b323adfd13c79c96b9863f7c73c /drivers/block/loop.c
parent40853d6fc619a6fd3d3177c3973a2eac9b598a80 (diff)
downloadlinux-758a58d0bc67457f1215321a536226654a830eeb.tar.xz
loop: set GENHD_FL_NO_PART_SCAN after blkdev_reread_part()
Commit 0da03cab87e6 ("loop: Fix deadlock when calling blkdev_reread_part()") moves blkdev_reread_part() out of the loop_ctl_mutex. However, GENHD_FL_NO_PART_SCAN is set before __blkdev_reread_part(). As a result, __blkdev_reread_part() will fail the check of GENHD_FL_NO_PART_SCAN and will not rescan the loop device to delete all partitions. Below are steps to reproduce the issue: step1 # dd if=/dev/zero of=tmp.raw bs=1M count=100 step2 # losetup -P /dev/loop0 tmp.raw step3 # parted /dev/loop0 mklabel gpt step4 # parted -a none -s /dev/loop0 mkpart primary 64s 1 step5 # losetup -d /dev/loop0 Step5 will not be able to delete /dev/loop0p1 (introduced by step4) and there is below kernel warning message: [ 464.414043] __loop_clr_fd: partition scan of loop0 failed (rc=-22) This patch sets GENHD_FL_NO_PART_SCAN after blkdev_reread_part(). Fixes: 0da03cab87e6 ("loop: Fix deadlock when calling blkdev_reread_part()") Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/block/loop.c')
-rw-r--r--drivers/block/loop.c21
1 files changed, 17 insertions, 4 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index e25df5ea9792..1e6edd568214 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1089,16 +1089,12 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
}
mapping_set_gfp_mask(filp->f_mapping, gfp);
- lo->lo_state = Lo_unbound;
/* This is safe: open() is still holding a reference. */
module_put(THIS_MODULE);
blk_mq_unfreeze_queue(lo->lo_queue);
partscan = lo->lo_flags & LO_FLAGS_PARTSCAN && bdev;
lo_number = lo->lo_number;
- lo->lo_flags = 0;
- if (!part_shift)
- lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
loop_unprepare_queue(lo);
out_unlock:
mutex_unlock(&loop_ctl_mutex);
@@ -1121,6 +1117,23 @@ out_unlock:
/* Device is gone, no point in returning error */
err = 0;
}
+
+ /*
+ * lo->lo_state is set to Lo_unbound here after above partscan has
+ * finished.
+ *
+ * There cannot be anybody else entering __loop_clr_fd() as
+ * lo->lo_backing_file is already cleared and Lo_rundown state
+ * protects us from all the other places trying to change the 'lo'
+ * device.
+ */
+ mutex_lock(&loop_ctl_mutex);
+ lo->lo_flags = 0;
+ if (!part_shift)
+ lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
+ lo->lo_state = Lo_unbound;
+ mutex_unlock(&loop_ctl_mutex);
+
/*
* Need not hold loop_ctl_mutex to fput backing file.
* Calling fput holding loop_ctl_mutex triggers a circular