cifs: convert oplock breaks to use slow_work facility (try #4)
This is the fourth respin of the patch to convert oplock breaks to
use the slow_work facility.
A customer of ours was testing a backport of one of the earlier
patchsets, and hit a "Busy inodes after umount..." problem. An oplock
break job had raced with a umount, and the superblock got torn down and
its memory reused. When the oplock break job tried to dereference the
inode->i_sb, the kernel oopsed.
This patchset has the oplock break job hold an inode and vfsmount
reference until the oplock break completes. With this, there should be
no need to take a tcon reference (the vfsmount implicitly holds one
already).
Currently, when an oplock break comes in there's a chance that the
oplock break job won't occur if the allocation of the oplock_q_entry
fails. There are also some rather nasty races in the allocation and
handling these structs.
Rather than allocating oplock queue entries when an oplock break comes
in, add a few extra fields to the cifsFileInfo struct. Get rid of the
dedicated cifs_oplock_thread as well and queue the oplock break job to
the slow_work thread pool.
This approach also has the advantage that the oplock break jobs can
potentially run in parallel rather than be serialized like they are
today.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 3610e99..89142b3 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -64,9 +64,6 @@
unsigned int extended_security = CIFSSEC_DEF;
/* unsigned int ntlmv2_support = 0; */
unsigned int sign_CIFS_PDUs = 1;
-extern struct task_struct *oplockThread; /* remove sparse warning */
-struct task_struct *oplockThread = NULL;
-/* extern struct task_struct * dnotifyThread; remove sparse warning */
static const struct super_operations cifs_super_ops;
unsigned int CIFSMaxBufSize = CIFS_MAX_MSGSIZE;
module_param(CIFSMaxBufSize, int, 0);
@@ -973,89 +970,12 @@
kmem_cache_destroy(cifs_oplock_cachep);
}
-static int cifs_oplock_thread(void *dummyarg)
-{
- struct oplock_q_entry *oplock_item;
- struct cifsTconInfo *pTcon;
- struct inode *inode;
- __u16 netfid;
- int rc, waitrc = 0;
-
- set_freezable();
- do {
- if (try_to_freeze())
- continue;
-
- spin_lock(&cifs_oplock_lock);
- if (list_empty(&cifs_oplock_list)) {
- spin_unlock(&cifs_oplock_lock);
- set_current_state(TASK_INTERRUPTIBLE);
- schedule_timeout(39*HZ);
- } else {
- oplock_item = list_entry(cifs_oplock_list.next,
- struct oplock_q_entry, qhead);
- cFYI(1, ("found oplock item to write out"));
- pTcon = oplock_item->tcon;
- inode = oplock_item->pinode;
- netfid = oplock_item->netfid;
- spin_unlock(&cifs_oplock_lock);
- DeleteOplockQEntry(oplock_item);
- /* 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);*/
- if (S_ISREG(inode->i_mode)) {
-#ifdef CONFIG_CIFS_EXPERIMENTAL
- if (CIFS_I(inode)->clientCanCacheAll == 0)
- break_lease(inode, FMODE_READ);
- else if (CIFS_I(inode)->clientCanCacheRead == 0)
- break_lease(inode, FMODE_WRITE);
-#endif
- rc = filemap_fdatawrite(inode->i_mapping);
- if (CIFS_I(inode)->clientCanCacheRead == 0) {
- waitrc = filemap_fdatawait(
- inode->i_mapping);
- invalidate_remote_inode(inode);
- }
- if (rc == 0)
- rc = waitrc;
- } else
- rc = 0;
- /* mutex_unlock(&inode->i_mutex);*/
- if (rc)
- CIFS_I(inode)->write_behind_rc = rc;
- cFYI(1, ("Oplock flush inode %p rc %d",
- inode, rc));
-
- /* releasing stale oplock after recent reconnect
- of smb session using a now incorrect file
- handle is not a data integrity issue but do
- not bother sending an oplock release if session
- to server still is disconnected since oplock
- already released by the server in that case */
- if (!pTcon->need_reconnect) {
- rc = CIFSSMBLock(0, pTcon, netfid,
- 0 /* len */ , 0 /* offset */, 0,
- 0, LOCKING_ANDX_OPLOCK_RELEASE,
- false /* wait flag */);
- cFYI(1, ("Oplock release rc = %d", rc));
- }
- set_current_state(TASK_INTERRUPTIBLE);
- schedule_timeout(1); /* yield in case q were corrupt */
- }
- } while (!kthread_should_stop());
-
- return 0;
-}
-
static int __init
init_cifs(void)
{
int rc = 0;
cifs_proc_init();
INIT_LIST_HEAD(&cifs_tcp_ses_list);
- INIT_LIST_HEAD(&cifs_oplock_list);
#ifdef CONFIG_CIFS_EXPERIMENTAL
INIT_LIST_HEAD(&GlobalDnotifyReqList);
INIT_LIST_HEAD(&GlobalDnotifyRsp_Q);
@@ -1084,7 +1004,6 @@
rwlock_init(&GlobalSMBSeslock);
rwlock_init(&cifs_tcp_ses_lock);
spin_lock_init(&GlobalMid_Lock);
- spin_lock_init(&cifs_oplock_lock);
if (cifs_max_pending < 2) {
cifs_max_pending = 2;
@@ -1119,18 +1038,15 @@
if (rc)
goto out_unregister_key_type;
#endif
- oplockThread = kthread_run(cifs_oplock_thread, NULL, "cifsoplockd");
- if (IS_ERR(oplockThread)) {
- rc = PTR_ERR(oplockThread);
- cERROR(1, ("error %d create oplock thread", rc));
- goto out_unregister_dfs_key_type;
- }
+ rc = slow_work_register_user();
+ if (rc)
+ goto out_unregister_resolver_key;
return 0;
- out_unregister_dfs_key_type:
-#ifdef CONFIG_CIFS_DFS_UPCALL
+ out_unregister_resolver_key:
unregister_key_type(&key_type_dns_resolver);
+#ifdef CONFIG_CIFS_DFS_UPCALL
out_unregister_key_type:
#endif
#ifdef CONFIG_CIFS_UPCALL
@@ -1165,7 +1081,6 @@
cifs_destroy_inodecache();
cifs_destroy_mids();
cifs_destroy_request_bufs();
- kthread_stop(oplockThread);
}
MODULE_AUTHOR("Steve French <sfrench@us.ibm.com>");