ceph: take snap_rwsem when accessing snap realm's cached_context

[firefly-linux-kernel-4.4.55.git] / fs / ceph / inode.c

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 1a68c0e38a52d86c7973a182392a7a4650a05d28..1c991df276c96e093f88cb9cf795df4fb82edfbf 100644 (file)
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1727,6 +1727,7 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
        int mask = 0;
        int err = 0;
        int inode_dirty_flags = 0;
+       bool lock_snap_rwsem = false;
 
        if (ceph_snap(inode) != CEPH_NOSNAP)
                return -EROFS;
@@ -1742,6 +1743,18 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 
        spin_lock(&ci->i_ceph_lock);
        issued = __ceph_caps_issued(ci, NULL);
+
+       if (!ci->i_head_snapc &&
+           (issued & (CEPH_CAP_ANY_EXCL | CEPH_CAP_FILE_WR))) {
+               lock_snap_rwsem = true;
+               if (!down_read_trylock(&mdsc->snap_rwsem)) {
+                       spin_unlock(&ci->i_ceph_lock);
+                       down_read(&mdsc->snap_rwsem);
+                       spin_lock(&ci->i_ceph_lock);
+                       issued = __ceph_caps_issued(ci, NULL);
+               }
+       }
+
        dout("setattr %p issued %s\n", inode, ceph_cap_string(issued));
 
        if (ia_valid & ATTR_UID) {
@@ -1890,6 +1903,8 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 
        release &= issued;
        spin_unlock(&ci->i_ceph_lock);
+       if (lock_snap_rwsem)
+               up_read(&mdsc->snap_rwsem);
 
        if (inode_dirty_flags)
                __mark_inode_dirty(inode, inode_dirty_flags);