On 08/20/2015 04:35 AM, Richard Weinberger wrote:
Currently UBIFS does not support direct IO, but some applications
blindly use the O_DIRECT flag.
Instead of failing upon open() we can do better and fall back
to buffered IO.
Hmmmm, to be honest, I am not sure we have to do it as Dave
suggested. I think that's just a work-around for current fstests.
IMHO, perform a buffered IO when user request direct IO without
any warning sounds not a good idea. Maybe adding a warning would
make it better.
I think we need more discussion about AIO&DIO in ubifs, and actually
I have a plan for it. But I have not listed the all cons and pros of
it so far.
Artem, what's your opinion?
Yang
Cc: Dongsheng Yang <yangds.fnst@xxxxxxxxxxxxxx>
Cc: dedekind1@xxxxxxxxx
Suggested-by: Dave Chinner <david@xxxxxxxxxxxxx>
Signed-off-by: Richard Weinberger <richard@xxxxxx>
---
fs/ubifs/file.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index a3dfe2a..a61fe86 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -1540,6 +1540,15 @@ static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma)
return 0;
}
+/*
+ * For now fall back to buffered IO.
+ */
+static ssize_t ubifs_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
+ loff_t offset)
+{
+ return 0;
+}
+
const struct address_space_operations ubifs_file_address_operations = {
.readpage = ubifs_readpage,
.writepage = ubifs_writepage,
@@ -1548,6 +1557,7 @@ const struct address_space_operations ubifs_file_address_operations = {
.invalidatepage = ubifs_invalidatepage,
.set_page_dirty = ubifs_set_page_dirty,
.releasepage = ubifs_releasepage,
+ .direct_IO = ubifs_direct_IO,
};
const struct inode_operations ubifs_file_inode_operations = {
--
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