[PATCH 5.13 016/151] cifs: Call close synchronously during unlink/rename/lease break.

Greg Kroah-Hartman
2021-08-16T13:19:59Z

From: Rohith Surabattula <rohiths@microsoft.com>

commit 9e992755be8f2d458a0bcbefd19e493483c1dba2 upstream.

During unlink/rename/lease break, deferred work for close is
scheduled immediately but in an asynchronous manner which might
lead to race with actual(unlink/rename) commands.

This change will schedule close synchronously which will avoid
the race conditions with other commands.

Signed-off-by: Rohith Surabattula <rohiths@microsoft.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Cc: stable@vger.kernel.org # 5.13
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/cifs/cifsglob.h | 5 +++++
fs/cifs/file.c | 35 +++++++++++++++++------------------
fs/cifs/misc.c | 46 ++++++++++++++++++++++++++++++++++------------
3 files changed, 56 insertions(+), 30 deletions(-)

--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1615,6 +1615,11 @@ struct dfs_info3_param {
int ttl;
};

+struct file_list {
+ struct list_head list;
+ struct cifsFileInfo *cfile;
+};
+
/*
* common struct for holding inode info when searching for or updating an
* inode with new info
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -4860,34 +4860,33 @@ void cifs_oplock_break(struct work_struc

oplock_break_ack:
/*
- * 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
- */
- if (!cfile->oplock_break_cancelled) {
- rc = tcon->ses->server->ops->oplock_response(tcon, &cfile->fid,
- cinode);
- cifs_dbg(FYI, "Oplock release rc = %d\n", rc);
- }
- /*
* When oplock break is received and there are no active
* file handles but cached, then schedule deferred close immediately.
* So, new open will not use cached handle.
*/
spin_lock(&CIFS_I(inode)->deferred_lock);
is_deferred = cifs_is_deferred_close(cfile, &dclose);
+ spin_unlock(&CIFS_I(inode)->deferred_lock);
if (is_deferred &&
cfile->deferred_close_scheduled &&
delayed_work_pending(&cfile->deferred)) {
- /*
- * If there is no pending work, mod_delayed_work queues new work.
- * So, Increase the ref count to avoid use-after-free.
- */
- if (!mod_delayed_work(deferredclose_wq, &cfile->deferred, 0))
- cifsFileInfo_get(cfile);
+ if (cancel_delayed_work(&cfile->deferred)) {
+ _cifsFileInfo_put(cfile, false, false);
+ goto oplock_break_done;
+ }
}
- spin_unlock(&CIFS_I(inode)->deferred_lock);
+ /*
+ * 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
+ */
+ if (!cfile->oplock_break_cancelled) {
+ rc = tcon->ses->server->ops->oplock_response(tcon, &cfile->fid,
+ cinode);
+ cifs_dbg(FYI, "Oplock release rc = %d\n", rc);
+ }
+oplock_break_done:
_cifsFileInfo_put(cfile, false /* do not wait for ourself */, false);
cifs_done_oplock_break(cinode);
}
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -735,20 +735,32 @@ void
cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
{
struct cifsFileInfo *cfile = NULL;
+ struct file_list *tmp_list, *tmp_next_list;
+ struct list_head file_head;

if (cifs_inode == NULL)
return;

+ INIT_LIST_HEAD(&file_head);
+ spin_lock(&cifs_inode->open_file_lock);
list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
if (delayed_work_pending(&cfile->deferred)) {
- /*
- * If there is no pending work, mod_delayed_work queues new work.
- * So, Increase the ref count to avoid use-after-free.
- */
- if (!mod_delayed_work(deferredclose_wq, &cfile->deferred, 0))
- cifsFileInfo_get(cfile);
+ if (cancel_delayed_work(&cfile->deferred)) {
+ tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
+ if (tmp_list == NULL)
+ continue;
+ tmp_list->cfile = cfile;
+ list_add_tail(&tmp_list->list, &file_head);
+ }
}
}
+ spin_unlock(&cifs_inode->open_file_lock);
+
+ list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
+ _cifsFileInfo_put(tmp_list->cfile, true, false);
+ list_del(&tmp_list->list);
+ kfree(tmp_list);
+ }
}

void
@@ -756,20 +768,30 @@ cifs_close_all_deferred_files(struct cif
{
struct cifsFileInfo *cfile;
struct list_head *tmp;
+ struct file_list *tmp_list, *tmp_next_list;
+ struct list_head file_head;

+ INIT_LIST_HEAD(&file_head);
spin_lock(&tcon->open_file_lock);
list_for_each(tmp, &tcon->openFileList) {
cfile = list_entry(tmp, struct cifsFileInfo, tlist);
if (delayed_work_pending(&cfile->deferred)) {
- /*
- * If there is no pending work, mod_delayed_work queues new work.
- * So, Increase the ref count to avoid use-after-free.
- */
- if (!mod_delayed_work(deferredclose_wq, &cfile->deferred, 0))
- cifsFileInfo_get(cfile);
+ if (cancel_delayed_work(&cfile->deferred)) {
+ tmp_list = kmalloc(sizeof(struct file_list), GFP_ATOMIC);
+ if (tmp_list == NULL)
+ continue;
+ tmp_list->cfile = cfile;
+ list_add_tail(&tmp_list->list, &file_head);
+ }
}
}
spin_unlock(&tcon->open_file_lock);
+
+ list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
+ _cifsFileInfo_put(tmp_list->cfile, true, false);
+ list_del(&tmp_list->list);
+ kfree(tmp_list);
+ }
}

/* parses DFS refferal V3 structure