smb3: fix unmount hang in open_shroot
An earlier patch "CIFS: fix deadlock in cached root handling"
did not completely address the deadlock in open_shroot. This
patch addresses the deadlock.
In testing the recent patch:
smb3: improve handling of share deleted (and share recreated)
we were able to reproduce the open_shroot deadlock to one
of the target servers in unmount in a delete share scenario.
Fixes: 7e5a70ad88b1e ("CIFS: fix deadlock in cached root handling")
Suggested-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Reviewed-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
CC: Aurelien Aptel <aaptel@xxxxxxxx>
CC: Stable <stable@xxxxxxxxxxxxxxx>
---
fs/cifs/smb2ops.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 3672ce0bfbaf..150327ebb2b4 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -658,6 +658,15 @@ int open_shroot(unsigned int xid, struct
cifs_tcon *tcon, struct cifs_fid *pfid)
return 0;
}
+ /*
+ * We do not hold the lock for the open because in case
+ * SMB2_open needs to reconnect, it will end up calling
+ * cifs_mark_open_files_invalid() which takes the lock again
+ * thus causing a deadlock
+ */
+
+ mutex_unlock(&tcon->crfid.fid_mutex);
+
if (smb3_encryption_required(tcon))
flags |= CIFS_TRANSFORM_REQ;
@@ -696,14 +705,6 @@ int open_shroot(unsigned int xid, struct
cifs_tcon *tcon, struct cifs_fid *pfid)
smb2_set_related(&rqst[1]);
- /*
- * We do not hold the lock for the open because in case
- * SMB2_open needs to reconnect, it will end up calling
- * cifs_mark_open_files_invalid() which takes the lock again
- * thus causing a deadlock
- */
-
- mutex_unlock(&tcon->crfid.fid_mutex);
rc = compound_send_recv(xid, ses, flags, 2, rqst,
resp_buftype, rsp_iov);
mutex_lock(&tcon->crfid.fid_mutex);
--
Thanks,
Steve
From 1f16bb0483a133882dc2f405dfcc26daa30b9117 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@xxxxxxxxxxxxx>
Date: Thu, 12 Sep 2019 17:52:54 -0500
Subject: [PATCH] smb3: fix unmount hang in open_shroot
An earlier patch "CIFS: fix deadlock in cached root handling"
did not completely address the deadlock in open_shroot. This
patch addresses the deadlock.
In testing the recent patch:
smb3: improve handling of share deleted (and share recreated)
we were able to reproduce the open_shroot deadlock to one
of the target servers in unmount in a delete share scenario.
Fixes: 7e5a70ad88b1e ("CIFS: fix deadlock in cached root handling")
Suggested-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Reviewed-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
CC: Aurelien Aptel <aaptel@xxxxxxxx>
CC: Stable <stable@xxxxxxxxxxxxxxx>
---
fs/cifs/smb2ops.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 3672ce0bfbaf..150327ebb2b4 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -658,6 +658,15 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid *pfid)
return 0;
}
+ /*
+ * We do not hold the lock for the open because in case
+ * SMB2_open needs to reconnect, it will end up calling
+ * cifs_mark_open_files_invalid() which takes the lock again
+ * thus causing a deadlock
+ */
+
+ mutex_unlock(&tcon->crfid.fid_mutex);
+
if (smb3_encryption_required(tcon))
flags |= CIFS_TRANSFORM_REQ;
@@ -696,14 +705,6 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid *pfid)
smb2_set_related(&rqst[1]);
- /*
- * We do not hold the lock for the open because in case
- * SMB2_open needs to reconnect, it will end up calling
- * cifs_mark_open_files_invalid() which takes the lock again
- * thus causing a deadlock
- */
-
- mutex_unlock(&tcon->crfid.fid_mutex);
rc = compound_send_recv(xid, ses, flags, 2, rqst,
resp_buftype, rsp_iov);
mutex_lock(&tcon->crfid.fid_mutex);
--
2.20.1
