afs: Fix deadlock between writeback and truncate

[sfrench/cifs-2.6.git] / fs / afs / inode.c

diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 1d13d2e882ada5af1118262e755da806eac4d89e..0fe8844b4bee2f942ba64925fb14f09738ba425b 100644 (file)
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -810,14 +810,32 @@ void afs_evict_inode(struct inode *inode)
 
 static void afs_setattr_success(struct afs_operation *op)
 {
-       struct inode *inode = &op->file[0].vnode->vfs_inode;
+       struct afs_vnode_param *vp = &op->file[0];
+       struct inode *inode = &vp->vnode->vfs_inode;
+       loff_t old_i_size = i_size_read(inode);
+
+       op->setattr.old_i_size = old_i_size;
+       afs_vnode_commit_status(op, vp);
+       /* inode->i_size has now been changed. */
+
+       if (op->setattr.attr->ia_valid & ATTR_SIZE) {
+               loff_t size = op->setattr.attr->ia_size;
+               if (size > old_i_size)
+                       pagecache_isize_extended(inode, old_i_size, size);
+       }
+}
+
+static void afs_setattr_edit_file(struct afs_operation *op)
+{
+       struct afs_vnode_param *vp = &op->file[0];
+       struct inode *inode = &vp->vnode->vfs_inode;
 
-       afs_vnode_commit_status(op, &op->file[0]);
        if (op->setattr.attr->ia_valid & ATTR_SIZE) {
-               loff_t i_size = inode->i_size, size = op->setattr.attr->ia_size;
-               if (size > i_size)
-                       pagecache_isize_extended(inode, i_size, size);
-               truncate_pagecache(inode, size);
+               loff_t size = op->setattr.attr->ia_size;
+               loff_t i_size = op->setattr.old_i_size;
+
+               if (size < i_size)
+                       truncate_pagecache(inode, size);
        }
 }
 
@@ -825,6 +843,7 @@ static const struct afs_operation_ops afs_setattr_operation = {
        .issue_afs_rpc  = afs_fs_setattr,
        .issue_yfs_rpc  = yfs_fs_setattr,
        .success        = afs_setattr_success,
+       .edit_dir       = afs_setattr_edit_file,
 };
 
 /*
@@ -863,11 +882,16 @@ int afs_setattr(struct dentry *dentry, struct iattr *attr)
        if (S_ISREG(vnode->vfs_inode.i_mode))
                filemap_write_and_wait(vnode->vfs_inode.i_mapping);
 
+       /* Prevent any new writebacks from starting whilst we do this. */
+       down_write(&vnode->validate_lock);
+
        op = afs_alloc_operation(((attr->ia_valid & ATTR_FILE) ?
                                  afs_file_key(attr->ia_file) : NULL),
                                 vnode->volume);
-       if (IS_ERR(op))
-               return PTR_ERR(op);
+       if (IS_ERR(op)) {
+               ret = PTR_ERR(op);
+               goto out_unlock;
+       }
 
        afs_op_set_vnode(op, 0, vnode);
        op->setattr.attr = attr;
@@ -880,5 +904,10 @@ int afs_setattr(struct dentry *dentry, struct iattr *attr)
        op->file[0].update_ctime = 1;
 
        op->ops = &afs_setattr_operation;
-       return afs_do_sync_operation(op);
+       ret = afs_do_sync_operation(op);
+
+out_unlock:
+       up_write(&vnode->validate_lock);
+       _leave(" = %d", ret);
+       return ret;
 }