From: Andiry Xu <jix...@cs.ucsd.edu>

Add notify_change for setattr operations. Truncate the file blocks
if the file is shrunk.

Signed-off-by: Andiry Xu <jix...@cs.ucsd.edu>
---
 fs/nova/inode.c | 180 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/nova/inode.h |   1 +
 fs/nova/namei.c |   2 +
 3 files changed, 183 insertions(+)

diff --git a/fs/nova/inode.c b/fs/nova/inode.c
index 2d3f7a3..2092a55 100644
--- a/fs/nova/inode.c
+++ b/fs/nova/inode.c
@@ -141,6 +141,58 @@ void nova_set_inode_flags(struct inode *inode, struct 
nova_inode *pi,
        inode->i_flags |= S_DAX;
 }
 
+static inline void check_eof_blocks(struct super_block *sb,
+       struct nova_inode *pi, struct inode *inode,
+       struct nova_inode_info_header *sih)
+{
+       if ((pi->i_flags & cpu_to_le32(NOVA_EOFBLOCKS_FL)) &&
+               (inode->i_size + sb->s_blocksize) > (sih->i_blocks
+                       << sb->s_blocksize_bits)) {
+               pi->i_flags &= cpu_to_le32(~NOVA_EOFBLOCKS_FL);
+               nova_persist_inode(pi);
+       }
+}
+
+/*
+ * Free data blocks from inode in the range start <=> end
+ */
+static void nova_truncate_file_blocks(struct inode *inode, loff_t start,
+                                   loff_t end, u64 epoch_id)
+{
+       struct super_block *sb = inode->i_sb;
+       struct nova_inode *pi = nova_get_inode(sb, inode);
+       struct nova_inode_info *si = NOVA_I(inode);
+       struct nova_inode_info_header *sih = &si->header;
+       unsigned int data_bits = blk_type_to_shift[sih->i_blk_type];
+       unsigned long first_blocknr, last_blocknr;
+       int freed = 0;
+
+       inode->i_mtime = inode->i_ctime = current_time(inode);
+
+       nova_dbg_verbose("truncate: pi %p iblocks %lx %llx %llx %llx\n", pi,
+                        sih->i_blocks, start, end, pi->i_size);
+
+       first_blocknr = (start + (1UL << data_bits) - 1) >> data_bits;
+
+       if (end == 0)
+               return;
+       last_blocknr = (end - 1) >> data_bits;
+
+       if (first_blocknr > last_blocknr)
+               return;
+
+       freed = nova_delete_file_tree(sb, sih, first_blocknr,
+                               last_blocknr, true, false, epoch_id);
+
+       inode->i_blocks -= (freed * (1 << (data_bits -
+                               sb->s_blocksize_bits)));
+
+       sih->i_blocks = inode->i_blocks;
+       /* Check for the flag EOFBLOCKS is still valid after the set size */
+       check_eof_blocks(sb, pi, inode, sih);
+
+}
+
 /* copy persistent state to struct inode */
 static int nova_read_inode(struct super_block *sb, struct inode *inode,
        u64 pi_addr)
@@ -963,6 +1015,134 @@ void nova_dirty_inode(struct inode *inode, int flags)
        nova_flush_buffer(&pi->i_atime, sizeof(pi->i_atime), 0);
 }
 
+/*
+ * Zero the tail page. Used in resize request
+ * to avoid to keep data in case the file grows again.
+ */
+static void nova_clear_last_page_tail(struct super_block *sb,
+       struct inode *inode, loff_t newsize)
+{
+       struct nova_sb_info *sbi = NOVA_SB(sb);
+       struct nova_inode_info *si = NOVA_I(inode);
+       struct nova_inode_info_header *sih = &si->header;
+       unsigned long offset = newsize & (sb->s_blocksize - 1);
+       unsigned long pgoff, length;
+       u64 nvmm;
+       char *nvmm_addr;
+
+       if (offset == 0 || newsize > inode->i_size)
+               return;
+
+       length = sb->s_blocksize - offset;
+       pgoff = newsize >> sb->s_blocksize_bits;
+
+       nvmm = nova_find_nvmm_block(sb, sih, NULL, pgoff);
+       if (nvmm == 0)
+               return;
+
+       nvmm_addr = (char *)nova_get_block(sb, nvmm);
+       memcpy_to_pmem_nocache(nvmm_addr + offset, sbi->zeroed_page, length);
+}
+
+static void nova_setsize(struct inode *inode, loff_t oldsize, loff_t newsize,
+       u64 epoch_id)
+{
+       struct super_block *sb = inode->i_sb;
+       struct nova_inode_info *si = NOVA_I(inode);
+       struct nova_inode_info_header *sih = &si->header;
+       timing_t setsize_time;
+
+       /* We only support truncate regular file */
+       if (!(S_ISREG(inode->i_mode))) {
+               nova_err(inode->i_sb, "%s:wrong file mode %x\n", inode->i_mode);
+               return;
+       }
+
+       NOVA_START_TIMING(setsize_t, setsize_time);
+
+       inode_dio_wait(inode);
+
+       nova_dbgv("%s: inode %lu, old size %llu, new size %llu\n",
+               __func__, inode->i_ino, oldsize, newsize);
+
+       sih_lock(sih);
+       if (newsize != oldsize) {
+               nova_clear_last_page_tail(sb, inode, newsize);
+               i_size_write(inode, newsize);
+               sih->i_size = newsize;
+       }
+
+       /* FIXME: we should make sure that there is nobody reading the inode
+        * before truncating it. Also we need to munmap the truncated range
+        * from application address space, if mmapped.
+        */
+       /* synchronize_rcu(); */
+
+       /* FIXME: Do we need to clear truncated DAX pages? */
+//     dax_truncate_page(inode, newsize, nova_dax_get_block);
+
+       truncate_pagecache(inode, newsize);
+       nova_truncate_file_blocks(inode, newsize, oldsize, epoch_id);
+       sih_unlock(sih);
+       NOVA_END_TIMING(setsize_t, setsize_time);
+}
+
+int nova_notify_change(struct dentry *dentry, struct iattr *attr)
+{
+       struct inode *inode = dentry->d_inode;
+       struct nova_inode_info *si = NOVA_I(inode);
+       struct nova_inode_info_header *sih = &si->header;
+       struct super_block *sb = inode->i_sb;
+       struct nova_inode *pi = nova_get_inode(sb, inode);
+       int ret;
+       unsigned int ia_valid = attr->ia_valid, attr_mask;
+       loff_t oldsize = inode->i_size;
+       u64 epoch_id;
+       timing_t setattr_time;
+
+       NOVA_START_TIMING(setattr_t, setattr_time);
+       if (!pi) {
+               ret = -EACCES;
+               goto out;
+       }
+
+       ret = setattr_prepare(dentry, attr);
+       if (ret)
+               goto out;
+
+       /* Update inode with attr except for size */
+       setattr_copy(inode, attr);
+
+       epoch_id = nova_get_epoch_id(sb);
+
+       attr_mask = ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_SIZE | ATTR_ATIME
+                       | ATTR_MTIME | ATTR_CTIME;
+
+       ia_valid = ia_valid & attr_mask;
+
+       if (ia_valid == 0)
+               goto out;
+
+       ret = nova_handle_setattr_operation(sb, inode, pi, ia_valid,
+                                       attr, epoch_id);
+       if (ret)
+               goto out;
+
+       /* Only after log entry is committed, we can truncate size */
+       if ((ia_valid & ATTR_SIZE) && (attr->ia_size != oldsize ||
+                       pi->i_flags & cpu_to_le32(NOVA_EOFBLOCKS_FL))) {
+//             nova_set_blocksize_hint(sb, inode, pi, attr->ia_size);
+
+               /* now we can freely truncate the inode */
+               nova_setsize(inode, oldsize, attr->ia_size, epoch_id);
+       }
+
+       sih->trans_id++;
+out:
+       NOVA_END_TIMING(setattr_t, setattr_time);
+       return ret;
+}
+
 static ssize_t nova_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 {
        /* DAX does not support direct IO */
diff --git a/fs/nova/inode.h b/fs/nova/inode.h
index 42690e6..4ddf8c2 100644
--- a/fs/nova/inode.h
+++ b/fs/nova/inode.h
@@ -267,5 +267,6 @@ int nova_delete_file_tree(struct super_block *sb,
 extern void nova_evict_inode(struct inode *inode);
 extern int nova_write_inode(struct inode *inode, struct writeback_control 
*wbc);
 extern void nova_dirty_inode(struct inode *inode, int flags);
+extern int nova_notify_change(struct dentry *dentry, struct iattr *attr);
 
 #endif
diff --git a/fs/nova/namei.c b/fs/nova/namei.c
index bb50c0a..1966bff 100644
--- a/fs/nova/namei.c
+++ b/fs/nova/namei.c
@@ -768,4 +768,6 @@ const struct inode_operations nova_dir_inode_operations = {
        .rmdir          = nova_rmdir,
        .mknod          = nova_mknod,
        .rename         = nova_rename,
+       .setattr        = nova_notify_change,
+       .get_acl        = NULL,
 };
-- 
2.7.4

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