[PATCH v3] f2fs: Fix deadlock in shutdown ioctl

Sahitya Tummala
2018-05-18T06:22:06Z

f2fs_ioc_shutdown() ioctl gets stuck in the below path
when issued with F2FS_GOING_DOWN_FULLSYNC option.

__switch_to+0x90/0xc4
percpu_down_write+0x8c/0xc0
freeze_super+0xec/0x1e4
freeze_bdev+0xc4/0xcc
f2fs_ioctl+0xc0c/0x1ce0
f2fs_compat_ioctl+0x98/0x1f0

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
---
fs/f2fs/file.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 6b94f19..5d99fd1 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1851,9 +1851,11 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
if (get_user(in, (__u32 __user *)arg))
return -EFAULT;

- ret = mnt_want_write_file(filp);
- if (ret)
- return ret;
+ if (in != F2FS_GOING_DOWN_FULLSYNC) {
+ ret = mnt_want_write_file(filp);
+ if (ret)
+ return ret;
+ }

switch (in) {
case F2FS_GOING_DOWN_FULLSYNC:
@@ -1894,7 +1896,8 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)

f2fs_update_time(sbi, REQ_TIME);
out:
- mnt_drop_write_file(filp);
+ if (in != F2FS_GOING_DOWN_FULLSYNC)
+ mnt_drop_write_file(filp);
return ret;
}

--
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Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.