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Commit 487317c9 authored by Ronnie Sahlberg's avatar Ronnie Sahlberg Committed by Steve French
Browse files

cifs: add spinlock for the openFileList to cifsInodeInfo 



We can not depend on the tcon->open_file_lock here since in multiuser mode
we may have the same file/inode open via multiple different tcons.

The current code is race prone and will crash if one user deletes a file
at the same time a different user opens/create the file.

To avoid this we need to have a spinlock attached to the inode and not the tcon.

RHBZ:  1580165

CC: Stable <stable@vger.kernel.org>
Signed-off-by: default avatarRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
Reviewed-by: default avatarPavel Shilovsky <pshilov@microsoft.com>
parent 0ff2b018

fs/cifs/cifsfs.c

+1 −0
Original line number Diff line number Diff line
@@ -303,6 +303,7 @@ cifs_alloc_inode(struct super_block *sb) 
	cifs_inode->uniqueid = 0;

	cifs_inode->createtime = 0;

	cifs_inode->epoch = 0;

	spin_lock_init(&cifs_inode->open_file_lock);

	generate_random_uuid(cifs_inode->lease_key);



	/*

fs/cifs/cifsglob.h

+5 −0
Original line number Diff line number Diff line
@@ -1377,6 +1377,7 @@ struct cifsInodeInfo { 
	struct rw_semaphore lock_sem;	/* protect the fields above */

	/* BB add in lists for dirty pages i.e. write caching info for oplock */

	struct list_head openFileList;

	spinlock_t	open_file_lock;	/* protects openFileList */

	__u32 cifsAttrs; /* e.g. DOS archive bit, sparse, compressed, system */

	unsigned int oplock;		/* oplock/lease level we have */

	unsigned int epoch;		/* used to track lease state changes */
@@ -1780,10 +1781,14 @@ require use of the stronger protocol */ 
 *  tcp_ses_lock protects:

 *	list operations on tcp and SMB session lists

 *  tcon->open_file_lock protects the list of open files hanging off the tcon

 *  inode->open_file_lock protects the openFileList hanging off the inode

 *  cfile->file_info_lock protects counters and fields in cifs file struct

 *  f_owner.lock protects certain per file struct operations

 *  mapping->page_lock protects certain per page operations

 *

 *  Note that the cifs_tcon.open_file_lock should be taken before

 *  not after the cifsInodeInfo.open_file_lock

 *

 *  Semaphores

 *  ----------

 *  sesSem     operations on smb session

fs/cifs/file.c

+6 −2
Original line number Diff line number Diff line
@@ -338,10 +338,12 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file, 
	atomic_inc(&tcon->num_local_opens);



	/* if readable file instance put first in list*/

	spin_lock(&cinode->open_file_lock);

	if (file->f_mode & FMODE_READ)

		list_add(&cfile->flist, &cinode->openFileList);

	else

		list_add_tail(&cfile->flist, &cinode->openFileList);

	spin_unlock(&cinode->open_file_lock);

	spin_unlock(&tcon->open_file_lock);



	if (fid->purge_cache)
@@ -413,7 +415,9 @@ void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_handler) 
	cifs_add_pending_open_locked(&fid, cifs_file->tlink, &open);



	/* remove it from the lists */

	spin_lock(&cifsi->open_file_lock);

	list_del(&cifs_file->flist);

	spin_unlock(&cifsi->open_file_lock);

	list_del(&cifs_file->tlist);

	atomic_dec(&tcon->num_local_opens);
@@ -1950,9 +1954,9 @@ cifs_get_writable_file(struct cifsInodeInfo *cifs_inode, bool fsuid_only, 
			return 0;

		}



		spin_lock(&tcon->open_file_lock);

		spin_lock(&cifs_inode->open_file_lock);

		list_move_tail(&inv_file->flist, &cifs_inode->openFileList);

		spin_unlock(&tcon->open_file_lock);

		spin_unlock(&cifs_inode->open_file_lock);

		cifsFileInfo_put(inv_file);

		++refind;

		inv_file = NULL;