[PATCH 4/5] cifs: take reference to inode for oplock breaks

When an oplock break comes in, cifs needs to do things like write out
dirty data for it. It doesn't hold a reference to that inode in this
case however. Get an active reference to the inode when an oplock break
comes in. If we don't get a reference, we still need to create an oplock
queue entry so that the oplock release call gets done, but we'll want to
skip writeback in that case.

Signed-off-by: Jeff Layton <[email protected]>
---
 fs/cifs/cifsfs.c |   26 ++++++++++----------------
 fs/cifs/misc.c   |    4 +++-
 2 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 2fcc722..647c5bc 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -993,13 +993,8 @@ static int cifs_oplock_thread(void *dummyarg)
 			cFYI(1, ("found oplock item to write out"));
 			tcon = oplock->tcon;
 			inode = oplock->pinode;
-			/* can not grab inode sem here since it would
-				deadlock when oplock received on delete
-				since vfs_unlink holds the i_mutex across
-				the call */
-			/* mutex_lock(&inode->i_mutex);*/
-			cifsi = CIFS_I(inode);
-			if (S_ISREG(inode->i_mode)) {
+			if (inode && S_ISREG(inode->i_mode)) {
+				cifsi = CIFS_I(inode);
 #ifdef CONFIG_CIFS_EXPERIMENTAL
 				if (cifsi->clientCanCacheAll == 0)
 					break_lease(inode, FMODE_READ);
@@ -1010,17 +1005,16 @@ static int cifs_oplock_thread(void *dummyarg)
 				if (cifsi->clientCanCacheRead == 0) {
 					waitrc = filemap_fdatawait(
 							      inode->i_mapping);
+					if (rc == 0)
+						rc = waitrc;
 					invalidate_remote_inode(inode);
 				}
-				if (rc == 0)
-					rc = waitrc;
-			} else
-				rc = 0;
-			/* mutex_unlock(&inode->i_mutex);*/
-			if (rc)
-				cifsi->write_behind_rc = rc;
-			cFYI(1, ("Oplock flush inode %p rc %d",
-				inode, rc));
+				if (rc)
+					cifsi->write_behind_rc = rc;
+				cFYI(1, ("Oplock flush inode %p rc %d",
+					 inode, rc));
+			}
+			iput(inode);
 
 			/*
 			 * releasing stale oplock after recent reconnect
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 7221af9..3bf3a52 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -502,6 +502,7 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv,
 	struct cifsInodeInfo *pCifsInode;
 	struct cifsFileInfo *netfile;
 	struct oplock_q_entry *oplock;
+	struct inode *inode;
 
 	cFYI(1, ("Checking for oplock break or dnotify response"));
 	if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
@@ -600,6 +601,7 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv,
 				pCifsInode->clientCanCacheAll = false;
 				if (pSMB->OplockLevel == 0)
 					pCifsInode->clientCanCacheRead = false;
+				inode = igrab(netfile->pInode);
 
 				if (!oplock) {
 					cERROR(1, ("Unable to allocate "
@@ -608,7 +610,7 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv,
 				}
 
 				oplock->tcon = tcon;
-				oplock->pinode = netfile->pInode;
+				oplock->pinode = inode;
 				oplock->netfid = netfile->netfid;
 				spin_lock(&cifs_oplock_lock);
 				list_add_tail(&oplock->qhead,
-- 
1.6.0.6