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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: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
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parent
0ff2b018b0
commit
487317c994
3 changed files with 12 additions and 2 deletions
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@ -303,6 +303,7 @@ cifs_alloc_inode(struct super_block *sb)
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cifs_inode->uniqueid = 0;
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cifs_inode->createtime = 0;
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cifs_inode->epoch = 0;
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spin_lock_init(&cifs_inode->open_file_lock);
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generate_random_uuid(cifs_inode->lease_key);
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/*
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@ -1377,6 +1377,7 @@ struct cifsInodeInfo {
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struct rw_semaphore lock_sem; /* protect the fields above */
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/* BB add in lists for dirty pages i.e. write caching info for oplock */
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struct list_head openFileList;
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spinlock_t open_file_lock; /* protects openFileList */
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__u32 cifsAttrs; /* e.g. DOS archive bit, sparse, compressed, system */
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unsigned int oplock; /* oplock/lease level we have */
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unsigned int epoch; /* used to track lease state changes */
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@ -1780,10 +1781,14 @@ require use of the stronger protocol */
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* tcp_ses_lock protects:
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* list operations on tcp and SMB session lists
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* tcon->open_file_lock protects the list of open files hanging off the tcon
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* inode->open_file_lock protects the openFileList hanging off the inode
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* cfile->file_info_lock protects counters and fields in cifs file struct
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* f_owner.lock protects certain per file struct operations
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* mapping->page_lock protects certain per page operations
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*
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* Note that the cifs_tcon.open_file_lock should be taken before
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* not after the cifsInodeInfo.open_file_lock
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*
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* Semaphores
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* ----------
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* sesSem operations on smb session
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@ -338,10 +338,12 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
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atomic_inc(&tcon->num_local_opens);
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/* if readable file instance put first in list*/
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spin_lock(&cinode->open_file_lock);
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if (file->f_mode & FMODE_READ)
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list_add(&cfile->flist, &cinode->openFileList);
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else
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list_add_tail(&cfile->flist, &cinode->openFileList);
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spin_unlock(&cinode->open_file_lock);
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spin_unlock(&tcon->open_file_lock);
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if (fid->purge_cache)
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@ -413,7 +415,9 @@ void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_handler)
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cifs_add_pending_open_locked(&fid, cifs_file->tlink, &open);
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/* remove it from the lists */
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spin_lock(&cifsi->open_file_lock);
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list_del(&cifs_file->flist);
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spin_unlock(&cifsi->open_file_lock);
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list_del(&cifs_file->tlist);
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atomic_dec(&tcon->num_local_opens);
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@ -1950,9 +1954,9 @@ cifs_get_writable_file(struct cifsInodeInfo *cifs_inode, bool fsuid_only,
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return 0;
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}
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spin_lock(&tcon->open_file_lock);
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spin_lock(&cifs_inode->open_file_lock);
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list_move_tail(&inv_file->flist, &cifs_inode->openFileList);
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spin_unlock(&tcon->open_file_lock);
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spin_unlock(&cifs_inode->open_file_lock);
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cifsFileInfo_put(inv_file);
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++refind;
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inv_file = NULL;
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