fs/9p: add 9P2000.L unlinkat operation

unlinkat - Remove a directory entry

size[4] Tunlinkat tag[2] dirfid[4] name[s] flag[4]
size[4] Runlinkat tag[2]

older Tremove have the below request format

size[4] Tremove tag[2] fid[4]

The remove message is used to remove a directory entry either file or directory
The remove opreation is actually a directory opertation and should ideally have
dirfid, if not we cannot represent the fid on server with anything other than
name. We will have to derive the directory name from fid in the Tremove request.

NOTE: The operation doesn't clunk the unlink fid.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

fs/9p/vfs_inode.c

@@ -534,38 +534,50 @@ v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
 /**
  * v9fs_remove - helper function to remove files and directories
  * @dir: directory inode that is being deleted
- * @file:  dentry that is being deleted
+ * @dentry:  dentry that is being deleted
  * @rmdir: removing a directory
  *
  */
 
-static int v9fs_remove(struct inode *dir, struct dentry *file, int rmdir)
+static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
 {
-	int retval;
-	struct p9_fid *v9fid;
-	struct inode *file_inode;
-
-	P9_DPRINTK(P9_DEBUG_VFS, "inode: %p dentry: %p rmdir: %d\n", dir, file,
-		rmdir);
+	struct inode *inode;
+	int retval = -EOPNOTSUPP;
+	struct p9_fid *v9fid, *dfid;
+	struct v9fs_session_info *v9ses;
 
-	file_inode = file->d_inode;
-	v9fid = v9fs_fid_clone(file);
-	if (IS_ERR(v9fid))
-		return PTR_ERR(v9fid);
+	P9_DPRINTK(P9_DEBUG_VFS, "inode: %p dentry: %p rmdir: %x\n",
+		   dir, dentry, flags);
 
-	retval = p9_client_remove(v9fid);
+	v9ses = v9fs_inode2v9ses(dir);
+	inode = dentry->d_inode;
+	dfid = v9fs_fid_lookup(dentry->d_parent);
+	if (IS_ERR(dfid)) {
+		retval = PTR_ERR(dfid);
+		P9_DPRINTK(P9_DEBUG_VFS, "fid lookup failed %d\n", retval);
+		return retval;
+	}
+	if (v9fs_proto_dotl(v9ses))
+		retval = p9_client_unlinkat(dfid, dentry->d_name.name, flags);
+	if (retval == -EOPNOTSUPP) {
+		/* Try the one based on path */
+		v9fid = v9fs_fid_clone(dentry);
+		if (IS_ERR(v9fid))
+			return PTR_ERR(v9fid);
+		retval = p9_client_remove(v9fid);
+	}
 	if (!retval) {
 		/*
 		 * directories on unlink should have zero
 		 * link count
 		 */
-		if (rmdir) {
-			clear_nlink(file_inode);
+		if (flags & AT_REMOVEDIR) {
+			clear_nlink(inode);
 			drop_nlink(dir);
 		} else
-			drop_nlink(file_inode);
+			drop_nlink(inode);
 
-		v9fs_invalidate_inode_attr(file_inode);
+		v9fs_invalidate_inode_attr(inode);
 		v9fs_invalidate_inode_attr(dir);
 	}
 	return retval;
@@ -856,7 +868,7 @@ int v9fs_vfs_unlink(struct inode *i, struct dentry *d)
 
 int v9fs_vfs_rmdir(struct inode *i, struct dentry *d)
 {
-	return v9fs_remove(i, d, 1);
+	return v9fs_remove(i, d, AT_REMOVEDIR);
 }
 
 /**

include/net/9p/9p.h

@@ -183,6 +183,8 @@ enum p9_msg_t {
 	P9_RMKDIR,
 	P9_TRENAMEAT = 74,
 	P9_RRENAMEAT,
+	P9_TUNLINKAT = 76,
+	P9_RUNLINKAT,
 	P9_TVERSION = 100,
 	P9_RVERSION,
 	P9_TAUTH = 102,

include/net/9p/client.h

@@ -234,6 +234,7 @@ int p9_client_create_dotl(struct p9_fid *ofid, char *name, u32 flags, u32 mode,
 int p9_client_clunk(struct p9_fid *fid);
 int p9_client_fsync(struct p9_fid *fid, int datasync);
 int p9_client_remove(struct p9_fid *fid);
+int p9_client_unlinkat(struct p9_fid *dfid, const char *name, int flags);
 int p9_client_read(struct p9_fid *fid, char *data, char __user *udata,
 							u64 offset, u32 count);
 int p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,

net/9p/client.c

@@ -1303,6 +1303,29 @@ error:
 }
 EXPORT_SYMBOL(p9_client_remove);
 
+int p9_client_unlinkat(struct p9_fid *dfid, const char *name, int flags)
+{
+	int err = 0;
+	struct p9_req_t *req;
+	struct p9_client *clnt;
+
+	P9_DPRINTK(P9_DEBUG_9P, ">>> TUNLINKAT fid %d %s %d\n",
+		   dfid->fid, name, flags);
+
+	clnt = dfid->clnt;
+	req = p9_client_rpc(clnt, P9_TUNLINKAT, "dsd", dfid->fid, name, flags);
+	if (IS_ERR(req)) {
+		err = PTR_ERR(req);
+		goto error;
+	}
+	P9_DPRINTK(P9_DEBUG_9P, "<<< RUNLINKAT fid %d %s\n", dfid->fid, name);
+
+	p9_free_req(clnt, req);
+error:
+	return err;
+}
+EXPORT_SYMBOL(p9_client_unlinkat);
+
 int
 p9_client_read(struct p9_fid *fid, char *data, char __user *udata, u64 offset,
 								u32 count)