From: Ronnie Sahlberg lsahlber@redhat.com
[ Upstream commit 487317c99477d00f22370625d53be3239febabbe ]
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: Ronnie Sahlberg lsahlber@redhat.com Signed-off-by: Steve French stfrench@microsoft.com Reviewed-by: Pavel Shilovsky pshilov@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/cifs/cifsfs.c | 1 + fs/cifs/cifsglob.h | 5 +++++ fs/cifs/file.c | 8 ++++++-- 3 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c index fb32f3d6925e8..64e3888f30e6d 100644 --- a/fs/cifs/cifsfs.c +++ b/fs/cifs/cifsfs.c @@ -292,6 +292,7 @@ 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);
/* diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index 0ee0072c1f362..57af9bac0045a 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -1287,6 +1287,7 @@ 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 */ @@ -1687,10 +1688,14 @@ 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 diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 933013543edab..8703b5f26f452 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -336,10 +336,12 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file, list_add(&cfile->tlist, &tcon->openFileList);
/* 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) @@ -411,7 +413,9 @@ 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);
if (list_empty(&cifsi->openFileList)) { @@ -1929,10 +1933,10 @@ struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *cifs_inode, if (!rc) return inv_file; else { - 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;