[PATCH 38/47] staging/lustre/lloop: avoid panic during blockdev_info

[Oleg Drokin]

From: Bob Glossman <bob.glossman@xxxxxxxxx>

Change the LL_IOC_LLOOP_INFO ioctl in the lustre lloop
device driver to return an error instead of causing
panics with LASSERT().

Signed-off-by: Bob Glossman <bob.glossman@xxxxxxxxx>
Reviewed-on: http://review.whamcloud.com/9888
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4863
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@xxxxxxxxx>
Reviewed-by: Andreas Dilger <andreas.dilger@xxxxxxxxx>
Signed-off-by: Oleg Drokin <oleg.drokin@xxxxxxxxx>
---
 drivers/staging/lustre/lustre/llite/lloop.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/lustre/lustre/llite/lloop.c b/drivers/staging/lustre/lustre/llite/lloop.c
index f78eda2..437adaf 100644
--- a/drivers/staging/lustre/lustre/llite/lloop.c
+++ b/drivers/staging/lustre/lustre/llite/lloop.c
@@ -624,7 +624,10 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode,
 	case LL_IOC_LLOOP_INFO: {
 		struct lu_fid fid;
 
-		LASSERT(lo->lo_backing_file != NULL);
+		if (lo->lo_backing_file == NULL) {
+			err = -ENOENT;
+			break;
+		}
 		if (inode == NULL)
 			inode = lo->lo_backing_file->f_dentry->d_inode;
 		if (lo->lo_state == LLOOP_BOUND)
-- 
1.8.5.3

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