ceph: acquire i_mutex in __ceph_do_pending_vmtruncate

make __ceph_do_pending_vmtruncate() acquire the i_mutex if the caller
does not hold the i_mutex, so ceph_aio_read() can call safely.
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>

fs/ceph/file.c

@@ -653,7 +653,7 @@ static ssize_t ceph_aio_read(struct kiocb *iocb, const struct iovec *iov,
 	dout("aio_read %p %llx.%llx %llu~%u trying to get caps on %p\n",
 	     inode, ceph_vinop(inode), pos, (unsigned)len, inode);
 again:
-	__ceph_do_pending_vmtruncate(inode);
+	__ceph_do_pending_vmtruncate(inode, true);
 	if (fi->fmode & CEPH_FILE_MODE_LAZY)
 		want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO;
 	else
@@ -730,7 +730,7 @@ static ssize_t ceph_aio_write(struct kiocb *iocb, const struct iovec *iov,
 		ret = -ENOSPC;
 		goto out;
 	}
-	__ceph_do_pending_vmtruncate(inode);
+	__ceph_do_pending_vmtruncate(inode, true);
 	dout("aio_write %p %llx.%llx %llu~%u getting caps. i_size %llu\n",
 	     inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
 	     inode->i_size);
@@ -801,7 +801,7 @@ static loff_t ceph_llseek(struct file *file, loff_t offset, int whence)
 	int ret;
 
 	mutex_lock(&inode->i_mutex);
-	__ceph_do_pending_vmtruncate(inode);
+	__ceph_do_pending_vmtruncate(inode, false);
 
 	if (whence == SEEK_END || whence == SEEK_DATA || whence == SEEK_HOLE) {
 		ret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE);

fs/ceph/inode.c

@@ -1453,7 +1453,7 @@ static void ceph_invalidate_work(struct work_struct *work)
 
 
 /*
- * called by trunc_wq; take i_mutex ourselves
+ * called by trunc_wq;
  *
  * We also truncate in a separate thread as well.
  */
@@ -1464,9 +1464,7 @@ static void ceph_vmtruncate_work(struct work_struct *work)
 	struct inode *inode = &ci->vfs_inode;
 
 	dout("vmtruncate_work %p\n", inode);
-	mutex_lock(&inode->i_mutex);
-	__ceph_do_pending_vmtruncate(inode);
-	mutex_unlock(&inode->i_mutex);
+	__ceph_do_pending_vmtruncate(inode, true);
 	iput(inode);
 }
 
@@ -1490,12 +1488,10 @@ void ceph_queue_vmtruncate(struct inode *inode)
 }
 
 /*
- * called with i_mutex held.
- *
  * Make sure any pending truncation is applied before doing anything
  * that may depend on it.
  */
-void __ceph_do_pending_vmtruncate(struct inode *inode)
+void __ceph_do_pending_vmtruncate(struct inode *inode, bool needlock)
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	u64 to;
@@ -1528,7 +1524,11 @@ void __ceph_do_pending_vmtruncate(struct inode *inode)
 	     ci->i_truncate_pending, to);
 	spin_unlock(&ci->i_ceph_lock);
 
+	if (needlock)
+		mutex_lock(&inode->i_mutex);
 	truncate_inode_pages(inode->i_mapping, to);
+	if (needlock)
+		mutex_unlock(&inode->i_mutex);
 
 	spin_lock(&ci->i_ceph_lock);
 	if (to == ci->i_truncate_size) {
@@ -1581,7 +1581,7 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 	if (ceph_snap(inode) != CEPH_NOSNAP)
 		return -EROFS;
 
-	__ceph_do_pending_vmtruncate(inode);
+	__ceph_do_pending_vmtruncate(inode, false);
 
 	err = inode_change_ok(inode, attr);
 	if (err != 0)
@@ -1763,7 +1763,7 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 	     ceph_cap_string(dirtied), mask);
 
 	ceph_mdsc_put_request(req);
-	__ceph_do_pending_vmtruncate(inode);
+	__ceph_do_pending_vmtruncate(inode, false);
 	return err;
 out:
 	spin_unlock(&ci->i_ceph_lock);

fs/ceph/super.h

@@ -694,7 +694,7 @@ extern int ceph_readdir_prepopulate(struct ceph_mds_request *req,
 extern int ceph_inode_holds_cap(struct inode *inode, int mask);
 
 extern int ceph_inode_set_size(struct inode *inode, loff_t size);
-extern void __ceph_do_pending_vmtruncate(struct inode *inode);
+extern void __ceph_do_pending_vmtruncate(struct inode *inode, bool needlock);
 extern void ceph_queue_vmtruncate(struct inode *inode);
 
 extern void ceph_queue_invalidate(struct inode *inode);