[RFC v2 73/83] Dax: Add iomap operations.

Andiry Xu
2018-03-10T18:25:24Z

The key of iomap is dax_get_blocks(). It first takes the read lock
and lookup the block; if the block is missing, it takes write lock,
check again and allocate the new block if needed.

Signed-off-by: Andiry Xu <jix024@cs.ucsd.edu>
---
fs/nova/dax.c | 184 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/nova/nova.h | 3 +
2 files changed, 187 insertions(+)

diff --git a/fs/nova/dax.c b/fs/nova/dax.c
index 8624ce4..e639b23 100644
--- a/fs/nova/dax.c
+++ b/fs/nova/dax.c
@@ -731,3 +731,187 @@ ssize_t nova_inplace_file_write(struct file *filp,

return ret;
}
+
+/*
+ * return > 0, # of blocks mapped or allocated.
+ * return = 0, if plain lookup failed.
+ * return < 0, error case.
+ */
+static int nova_dax_get_blocks(struct inode *inode, sector_t iblock,
+ unsigned long max_blocks, u32 *bno, bool *new, bool *boundary,
+ int create)
+{
+ struct super_block *sb = inode->i_sb;
+ struct nova_inode *pi;
+ struct nova_inode_info *si = NOVA_I(inode);
+ struct nova_inode_info_header *sih = &si->header;
+ struct nova_file_write_entry *entry = NULL;
+ struct nova_file_write_item entry_item;
+ struct list_head item_head;
+ struct nova_inode_update update;
+ u32 time;
+ unsigned long nvmm = 0;
+ unsigned long blocknr = 0;
+ u64 epoch_id;
+ int num_blocks = 0;
+ int inplace = 0;
+ int allocated = 0;
+ int locked = 0;
+ int check_next;
+ int ret = 0;
+ timing_t get_block_time;
+
+
+ if (max_blocks == 0)
+ return 0;
+
+ NOVA_START_TIMING(dax_get_block_t, get_block_time);
+ INIT_LIST_HEAD(&item_head);
+
+ nova_dbgv("%s: pgoff %lu, num %lu, create %d\n",
+ __func__, iblock, max_blocks, create);
+
+ epoch_id = nova_get_epoch_id(sb);
+
+ check_next = 0;
+ sih_lock_shared(sih);
+
+again:
+ num_blocks = nova_check_existing_entry(sb, inode, max_blocks,
+ iblock, &entry, check_next,
+ epoch_id, &inplace);
+
+ if (entry) {
+ if (create == 0 || inplace) {
+ nvmm = get_nvmm(sb, sih, entry, iblock);
+ nova_dbgv("%s: found pgoff %lu, block %lu\n",
+ __func__, iblock, nvmm);
+ goto out;
+ }
+ }
+
+ if (create == 0) {
+ num_blocks = 0;
+ goto out1;
+ }
+
+ if (locked == 0) {
+ sih_unlock_shared(sih);
+ sih_lock(sih);
+ locked = 1;
+ /* Check again incase someone has done it for us */
+ check_next = 1;
+ goto again;
+ }
+
+ pi = nova_get_inode(sb, inode);
+ inode->i_ctime = inode->i_mtime = current_time(inode);
+ time = current_time(inode).tv_sec;
+ update.tail = sih->log_tail;
+
+ /* Return initialized blocks to the user */
+ allocated = nova_new_data_blocks(sb, sih, &blocknr, iblock,
+ num_blocks, ALLOC_INIT_ZERO, ANY_CPU,
+ ALLOC_FROM_HEAD);
+ if (allocated <= 0) {
+ nova_dbgv("%s alloc blocks failed %d\n", __func__,
+ allocated);
+ ret = allocated;
+ goto out;
+ }
+
+ num_blocks = allocated;
+ /* FIXME: how to handle file size? */
+ nova_init_file_write_item(sb, sih, &entry_item,
+ epoch_id, iblock, num_blocks,
+ blocknr, time, inode->i_size);
+
+ list_add_tail(&entry_item.list, &item_head);
+
+ nvmm = blocknr;
+
+ ret = nova_commit_writes_to_log(sb, pi, inode,
+ &item_head, num_blocks, 0);
+ if (ret < 0) {
+ nova_err(sb, "commit to log failed\n");
+ goto out;
+ }
+
+ NOVA_STATS_ADD(dax_new_blocks, 1);
+
+ *new = true;
+// set_buffer_new(bh);
+out:
+ if (ret < 0) {
+ nova_cleanup_incomplete_write(sb, sih, &item_head, 0);
+ num_blocks = ret;
+ goto out1;
+ }
+
+ *bno = nvmm;
+// if (num_blocks > 1)
+// bh->b_size = sb->s_blocksize * num_blocks;
+
+out1:
+ if (locked)
+ sih_unlock(sih);
+ else
+ sih_unlock_shared(sih);
+
+ NOVA_END_TIMING(dax_get_block_t, get_block_time);
+ return num_blocks;
+}
+
+static int nova_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
+ unsigned int flags, struct iomap *iomap)
+{
+ struct nova_sb_info *sbi = NOVA_SB(inode->i_sb);
+ unsigned int blkbits = inode->i_blkbits;
+ unsigned long first_block = offset >> blkbits;
+ unsigned long max_blocks = (length + (1 << blkbits) - 1) >> blkbits;
+ bool new = false, boundary = false;
+ u32 bno;
+ int ret;
+
+ ret = nova_dax_get_blocks(inode, first_block, max_blocks, &bno, &new,
+ &boundary, flags & IOMAP_WRITE);
+ if (ret < 0) {
+ nova_dbgv("%s: nova_dax_get_blocks failed %d", __func__, ret);
+ return ret;
+ }
+
+ iomap->flags = 0;
+ iomap->bdev = inode->i_sb->s_bdev;
+ iomap->dax_dev = sbi->s_dax_dev;
+ iomap->offset = (u64)first_block << blkbits;
+
+ if (ret == 0) {
+ iomap->type = IOMAP_HOLE;
+ iomap->addr = IOMAP_NULL_ADDR;
+ iomap->length = 1 << blkbits;
+ } else {
+ iomap->type = IOMAP_MAPPED;
+ iomap->addr = (u64)bno << blkbits;
+ iomap->length = (u64)ret << blkbits;
+ iomap->flags |= IOMAP_F_MERGED;
+ }
+
+ if (new)
+ iomap->flags |= IOMAP_F_NEW;
+ return 0;
+}
+
+static int nova_iomap_end(struct inode *inode, loff_t offset, loff_t length,
+ ssize_t written, unsigned int flags, struct iomap *iomap)
+{
+ if (iomap->type == IOMAP_MAPPED &&
+ written < length &&
+ (flags & IOMAP_WRITE))
+ truncate_pagecache(inode, inode->i_size);
+ return 0;
+}
+
+const struct iomap_ops nova_iomap_ops = {
+ .iomap_begin = nova_iomap_begin,
+ .iomap_end = nova_iomap_end,
+};
diff --git a/fs/nova/nova.h b/fs/nova/nova.h
index ab9e8f3..0d62c47 100644
--- a/fs/nova/nova.h
+++ b/fs/nova/nova.h
@@ -487,6 +487,9 @@ ssize_t nova_inplace_file_write(struct file *filp, const char __user *buf,
ssize_t do_nova_inplace_file_write(struct file *filp, const char __user *buf,
size_t len, loff_t *ppos);

+extern const struct iomap_ops nova_iomap_ops;
+
+
/* dir.c */
extern const struct file_operations nova_dir_operations;
int nova_insert_dir_radix_tree(struct super_block *sb,
--
2.7.4