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authorRonnie Sahlberg <lsahlber@redhat.com>2019-06-05 10:38:38 +1000
committerSteve French <stfrench@microsoft.com>2019-06-13 14:21:09 -0500
commit487317c99477d00f22370625d53be3239febabbe (patch)
treea6da1276cdc7abd0870f9eda758115c8912f930e /fs/cifs
parent0ff2b018b02f89da26a616e0148582321a00fd99 (diff)
downloadlinux-487317c99477d00f22370625d53be3239febabbe.tar.bz2
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>
Diffstat (limited to 'fs/cifs')
-rw-r--r--fs/cifs/cifsfs.c1
-rw-r--r--fs/cifs/cifsglob.h5
-rw-r--r--fs/cifs/file.c8
3 files changed, 12 insertions, 2 deletions
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index f5fcd6360056..65d9771e49f9 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -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);
/*
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 334ff5f9c3f3..4777b3c4a92c 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -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
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 06e27ac6d82c..97090693d182 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -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 @@ refind_writable:
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;