ext4: convert DAX reads to iomap infrastructure
Implement basic iomap_begin function that handles reading and use it for
DAX reads.
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 9facb4d..1f25c64 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -31,6 +31,42 @@
#include "xattr.h"
#include "acl.h"
+#ifdef CONFIG_FS_DAX
+static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+ ssize_t ret;
+
+ inode_lock_shared(inode);
+ /*
+ * Recheck under inode lock - at this point we are sure it cannot
+ * change anymore
+ */
+ if (!IS_DAX(inode)) {
+ inode_unlock_shared(inode);
+ /* Fallback to buffered IO in case we cannot support DAX */
+ return generic_file_read_iter(iocb, to);
+ }
+ ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
+ inode_unlock_shared(inode);
+
+ file_accessed(iocb->ki_filp);
+ return ret;
+}
+#endif
+
+static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ if (!iov_iter_count(to))
+ return 0; /* skip atime */
+
+#ifdef CONFIG_FS_DAX
+ if (IS_DAX(file_inode(iocb->ki_filp)))
+ return ext4_dax_read_iter(iocb, to);
+#endif
+ return generic_file_read_iter(iocb, to);
+}
+
/*
* Called when an inode is released. Note that this is different
* from ext4_file_open: open gets called at every open, but release
@@ -690,7 +726,7 @@ loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
const struct file_operations ext4_file_operations = {
.llseek = ext4_llseek,
- .read_iter = generic_file_read_iter,
+ .read_iter = ext4_file_read_iter,
.write_iter = ext4_file_write_iter,
.unlocked_ioctl = ext4_ioctl,
#ifdef CONFIG_COMPAT