Commit 9e992755 authored by Rohith Surabattula's avatar Rohith Surabattula Committed by Steve French
Browse files

cifs: Call close synchronously during unlink/rename/lease break. 



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: default avatarRohith Surabattula <rohiths@microsoft.com>
Reviewed-by: default avatarShyam Prasad N <sprasad@microsoft.com>
Cc: stable@vger.kernel.org # 5.13
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 41535701

fs/cifs/cifsglob.h

+5 −0
Original line number Diff line number Diff line
@@ -1611,6 +1611,11 @@ 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

fs/cifs/file.c

+17 −18
Original line number Diff line number Diff line
@@ -4847,17 +4847,6 @@ void cifs_oplock_break(struct work_struct *work) 
		cifs_dbg(VFS, "Push locks rc = %d\n", rc);



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.
@@ -4865,17 +4854,27 @@ void cifs_oplock_break(struct work_struct *work) 
	 */

	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 (cancel_delayed_work(&cfile->deferred)) {

			_cifsFileInfo_put(cfile, false, false);

			goto oplock_break_done;

		}

	}

	/*

		 * If there is no pending work, mod_delayed_work queues new work.

		 * So, Increase the ref count to avoid use-after-free.

	 * 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 (!mod_delayed_work(deferredclose_wq, &cfile->deferred, 0))

			cifsFileInfo_get(cfile);

	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);

	}

	spin_unlock(&CIFS_I(inode)->deferred_lock);

oplock_break_done:

	_cifsFileInfo_put(cfile, false /* do not wait for ourself */, false);

	cifs_done_oplock_break(cinode);

}

fs/cifs/misc.c

+34 −12
Original line number Diff line number Diff line
@@ -723,41 +723,63 @@ 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

cifs_close_all_deferred_files(struct cifs_tcon *tcon)

{

	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