[RFC v2 71/83] Symlink support.

Andiry Xu
2018-03-10T18:25:51Z

NOVA alloates two blocks for symlink inode: One for inode log,
and the other one is a data block, storing symname.

Signed-off-by: Andiry Xu <jix024@cs.ucsd.edu>
---
fs/nova/Makefile | 2 +-
fs/nova/inode.c | 2 +
fs/nova/namei.c | 70 ++++++++++++++++++++++++++++
fs/nova/nova.h | 5 ++
fs/nova/symlink.c | 133 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 211 insertions(+), 1 deletion(-)
create mode 100644 fs/nova/symlink.c

diff --git a/fs/nova/Makefile b/fs/nova/Makefile
index 7f851f2..7bf6403 100644
--- a/fs/nova/Makefile
+++ b/fs/nova/Makefile
@@ -5,4 +5,4 @@
obj-$(CONFIG_NOVA_FS) += nova.o

nova-y := balloc.o bbuild.o dax.o dir.o file.o inode.o journal.o log.o namei.o\
- rebuild.o stats.o super.o
+ rebuild.o stats.o super.o symlink.o
diff --git a/fs/nova/inode.c b/fs/nova/inode.c
index a6d74cb..21be31a 100644
--- a/fs/nova/inode.c
+++ b/fs/nova/inode.c
@@ -285,6 +285,7 @@ static int nova_read_inode(struct super_block *sb, struct inode *inode,
inode->i_fop = &nova_dir_operations;
break;
case S_IFLNK:
+ inode->i_op = &nova_symlink_inode_operations;
break;
default:
inode->i_op = &nova_special_inode_operations;
@@ -983,6 +984,7 @@ struct inode *nova_new_vfs_inode(enum nova_new_inode_type type,
inode->i_op = &nova_special_inode_operations;
break;
case TYPE_SYMLINK:
+ inode->i_op = &nova_symlink_inode_operations;
inode->i_mapping->a_ops = &nova_aops_dax;
break;
case TYPE_MKDIR:
diff --git a/fs/nova/namei.c b/fs/nova/namei.c
index 7a81672..58f6a72 100644
--- a/fs/nova/namei.c
+++ b/fs/nova/namei.c
@@ -207,6 +207,75 @@ static int nova_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
return err;
}

+static int nova_symlink(struct inode *dir, struct dentry *dentry,
+ const char *symname)
+{
+ struct super_block *sb = dir->i_sb;
+ int err = -ENAMETOOLONG;
+ unsigned int len = strlen(symname);
+ struct inode *inode;
+ struct nova_inode_info *si;
+ struct nova_inode_info_header *sih;
+ u64 pi_addr = 0;
+ struct nova_inode *pidir, *pi;
+ struct nova_inode_update update;
+ u64 ino;
+ u64 epoch_id;
+ timing_t symlink_time;
+
+ NOVA_START_TIMING(symlink_t, symlink_time);
+ if (len + 1 > sb->s_blocksize)
+ goto out;
+
+ pidir = nova_get_inode(sb, dir);
+ if (!pidir)
+ goto out_fail;
+
+ epoch_id = nova_get_epoch_id(sb);
+ ino = nova_new_nova_inode(sb, &pi_addr);
+ if (ino == 0)
+ goto out_fail;
+
+ nova_dbgv("%s: name %s, symname %s\n", __func__,
+ dentry->d_name.name, symname);
+ nova_dbgv("%s: inode %llu, dir %lu\n", __func__, ino, dir->i_ino);
+
+ update.tail = 0;
+ err = nova_add_dentry(dentry, ino, 0, &update, epoch_id);
+ if (err)
+ goto out_fail;
+
+ inode = nova_new_vfs_inode(TYPE_SYMLINK, dir, pi_addr, ino,
+ S_IFLNK|0777, len, 0,
+ &dentry->d_name, epoch_id);
+ if (IS_ERR(inode)) {
+ err = PTR_ERR(inode);
+ goto out_fail;
+ }
+
+ pi = nova_get_inode(sb, inode);
+
+ si = NOVA_I(inode);
+ sih = &si->header;
+
+ err = nova_block_symlink(sb, pi, inode, symname, len, epoch_id);
+ if (err)
+ goto out_fail;
+
+ d_instantiate(dentry, inode);
+ unlock_new_inode(inode);
+
+ nova_lite_transaction_for_new_inode(sb, pi, pidir, inode, dir,
+ &update);
+out:
+ NOVA_END_TIMING(symlink_t, symlink_time);
+ return err;
+
+out_fail:
+ nova_err(sb, "%s return %d\n", __func__, err);
+ goto out;
+}
+
static void nova_lite_transaction_for_time_and_link(struct super_block *sb,
struct nova_inode *pi, struct nova_inode *pidir, struct inode *inode,
struct inode *dir, struct nova_inode_update *update,
@@ -764,6 +833,7 @@ const struct inode_operations nova_dir_inode_operations = {
.lookup = nova_lookup,
.link = nova_link,
.unlink = nova_unlink,
+ .symlink = nova_symlink,
.mkdir = nova_mkdir,
.rmdir = nova_rmdir,
.mknod = nova_mknod,
diff --git a/fs/nova/nova.h b/fs/nova/nova.h
index 40c70da..6392bb3 100644
--- a/fs/nova/nova.h
+++ b/fs/nova/nova.h
@@ -518,6 +518,11 @@ int nova_rebuild_dir_inode_tree(struct super_block *sb,
int nova_rebuild_inode(struct super_block *sb, struct nova_inode_info *si,
u64 ino, u64 pi_addr, int rebuild_dir);

+/* symlink.c */
+int nova_block_symlink(struct super_block *sb, struct nova_inode *pi,
+ struct inode *inode, const char *symname, int len, u64 epoch_id);
+extern const struct inode_operations nova_symlink_inode_operations;
+
/* stats.c */
void nova_get_timing_stats(void);
void nova_get_IO_stats(void);
diff --git a/fs/nova/symlink.c b/fs/nova/symlink.c
new file mode 100644
index 0000000..dbd57c5
--- /dev/null
+++ b/fs/nova/symlink.c
@@ -0,0 +1,133 @@
+/*
+ * BRIEF DESCRIPTION
+ *
+ * Symlink operations
+ *
+ * Copyright 2015-2016 Regents of the University of California,
+ * UCSD Non-Volatile Systems Lab, Andiry Xu <jix024@cs.ucsd.edu>
+ * Copyright 2012-2013 Intel Corporation
+ * Copyright 2009-2011 Marco Stornelli <marco.stornelli@gmail.com>
+ * Copyright 2003 Sony Corporation
+ * Copyright 2003 Matsushita Electric Industrial Co., Ltd.
+ * 2003-2004 (c) MontaVista Software, Inc. , Steve Longerbeam
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/version.h>
+#include "nova.h"
+#include "inode.h"
+
+int nova_block_symlink(struct super_block *sb, struct nova_inode *pi,
+ struct inode *inode, const char *symname, int len, u64 epoch_id)
+{
+ struct nova_file_write_item entry_item;
+ struct nova_inode_info *si = NOVA_I(inode);
+ struct nova_inode_info_header *sih = &si->header;
+ struct nova_inode_update update;
+ unsigned long name_blocknr = 0;
+ int allocated;
+ u64 block;
+ char *blockp;
+ u32 time;
+ int ret;
+
+ update.tail = sih->log_tail;
+
+ allocated = nova_new_data_blocks(sb, sih, &name_blocknr, 0, 1,
+ ALLOC_INIT_ZERO, ANY_CPU, ALLOC_FROM_TAIL);
+ if (allocated != 1 || name_blocknr == 0) {
+ ret = allocated;
+ return ret;
+ }
+
+ /* First copy name to name block */
+ block = nova_get_block_off(sb, name_blocknr, NOVA_BLOCK_TYPE_4K);
+ blockp = (char *)nova_get_block(sb, block);
+
+ memcpy_to_pmem_nocache(blockp, symname, len);
+ blockp[len] = '\0';
+
+ /* Apply a write entry to the log page */
+ time = current_time(inode).tv_sec;
+ nova_init_file_write_item(sb, sih, &entry_item, epoch_id, 0, 1,
+ name_blocknr, time, len + 1);
+
+ sih_lock(sih);
+ ret = nova_append_file_write_entry(sb, pi, inode, &entry_item, &update);
+ if (ret) {
+ nova_dbg("%s: append file write entry failed %d\n",
+ __func__, ret);
+ nova_free_data_blocks(sb, sih, name_blocknr, 1);
+ return ret;
+ }
+
+ nova_update_inode(sb, inode, pi, &update);
+ sih->trans_id++;
+ sih_unlock(sih);
+
+ return 0;
+}
+
+/* FIXME: Temporary workaround */
+static int nova_readlink_copy(char __user *buffer, int buflen, const char *link)
+{
+ int len = PTR_ERR(link);
+
+ if (IS_ERR(link))
+ goto out;
+
+ len = strlen(link);
+ if (len > (unsigned int) buflen)
+ len = buflen;
+ if (copy_to_user(buffer, link, len))
+ len = -EFAULT;
+out:
+ return len;
+}
+
+static int nova_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+{
+ struct nova_file_write_entry *entry;
+ struct inode *inode = dentry->d_inode;
+ struct super_block *sb = inode->i_sb;
+ struct nova_inode_info *si = NOVA_I(inode);
+ struct nova_inode_info_header *sih = &si->header;
+ char *blockp;
+
+ entry = (struct nova_file_write_entry *)nova_get_block(sb,
+ sih->log_head);
+
+ blockp = (char *)nova_get_block(sb, BLOCK_OFF(entry->block));
+
+ return nova_readlink_copy(buffer, buflen, blockp);
+}
+
+static const char *nova_get_link(struct dentry *dentry, struct inode *inode,
+ struct delayed_call *done)
+{
+ struct nova_file_write_entry *entry;
+ struct super_block *sb = inode->i_sb;
+ struct nova_inode_info *si = NOVA_I(inode);
+ struct nova_inode_info_header *sih = &si->header;
+ char *blockp;
+
+ entry = (struct nova_file_write_entry *)nova_get_block(sb,
+ sih->log_head);
+
+ blockp = (char *)nova_get_block(sb, BLOCK_OFF(entry->block));
+
+ return blockp;
+}
+
+const struct inode_operations nova_symlink_inode_operations = {
+ .readlink = nova_readlink,
+ .get_link = nova_get_link,
+ .setattr = nova_notify_change,
+};
--
2.7.4