[RFC v2 75/83] File operation: read/write iter.

Andiry Xu
2018-03-10T18:24:39Z

They use the iomap framework to do read/write. Due to software overheads
they are slower than dax read/write.

Signed-off-by: Andiry Xu <jix024@cs.ucsd.edu>
---
fs/nova/file.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 65 insertions(+)

diff --git a/fs/nova/file.c b/fs/nova/file.c
index 0ae0333..7e90415 100644
--- a/fs/nova/file.c
+++ b/fs/nova/file.c
@@ -260,6 +260,69 @@ static long nova_fallocate(struct file *file, int mode, loff_t offset,
return ret;
}

+static ssize_t nova_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ struct inode *inode = iocb->ki_filp->f_mapping->host;
+ ssize_t ret;
+ timing_t read_iter_time;
+
+ if (!iov_iter_count(to))
+ return 0;
+
+ NOVA_START_TIMING(read_iter_t, read_iter_time);
+
+ inode_lock_shared(inode);
+ ret = dax_iomap_rw(iocb, to, &nova_iomap_ops);
+ inode_unlock_shared(inode);
+
+ file_accessed(iocb->ki_filp);
+ NOVA_END_TIMING(read_iter_t, read_iter_time);
+ return ret;
+}
+
+static ssize_t nova_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file->f_mapping->host;
+ struct nova_inode_info *si = NOVA_I(inode);
+ struct nova_inode_info_header *sih = &si->header;
+ loff_t offset;
+ size_t count;
+ ssize_t ret;
+ timing_t write_iter_time;
+
+ NOVA_START_TIMING(write_iter_t, write_iter_time);
+ inode_lock(inode);
+ ret = generic_write_checks(iocb, from);
+ if (ret <= 0)
+ goto out_unlock;
+
+ ret = file_remove_privs(file);
+ if (ret)
+ goto out_unlock;
+
+ ret = file_update_time(file);
+ if (ret)
+ goto out_unlock;
+
+ count = iov_iter_count(from);
+ offset = iocb->ki_pos;
+
+ ret = dax_iomap_rw(iocb, from, &nova_iomap_ops);
+ if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
+ i_size_write(inode, iocb->ki_pos);
+ sih->i_size = iocb->ki_pos;
+ mark_inode_dirty(inode);
+ }
+
+out_unlock:
+ inode_unlock(inode);
+ if (ret > 0)
+ ret = generic_write_sync(iocb, ret);
+ NOVA_END_TIMING(write_iter_t, write_iter_time);
+ return ret;
+}
+
static ssize_t
do_dax_mapping_read(struct file *filp, char __user *buf,
size_t len, loff_t *ppos)
@@ -645,6 +708,8 @@ const struct file_operations nova_dax_file_operations = {
.llseek = nova_llseek,
.read = nova_dax_file_read,
.write = nova_dax_file_write,
+ .read_iter = nova_dax_read_iter,
+ .write_iter = nova_dax_write_iter,
.mmap = nova_dax_file_mmap,
.open = nova_open,
.fsync = nova_fsync,
--
2.7.4