On 12/06/2024 22:10, Darrick J. Wong wrote:
On Fri, Jun 07, 2024 at 02:38:58PM +0000, John Garry wrote:
Add a generic helper for FSes to validate that an atomic write is
appropriately sized (along with the other checks).
Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
---
include/linux/fs.h | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 069cbab62700..e13d34f8c24e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3645,4 +3645,16 @@ bool generic_atomic_write_valid(loff_t pos, struct iov_iter *iter)
return true;
}
+static inline
+bool generic_atomic_write_valid_size(loff_t pos, struct iov_iter *iter,
+ unsigned int unit_min, unsigned int unit_max)
+{
+ size_t len = iov_iter_count(iter);
+
+ if (len < unit_min || len > unit_max)
+ return false;
+
+ return generic_atomic_write_valid(pos, iter);
+}
Now that I look back at "fs: Initial atomic write support" I wonder why
not pass the iocb and the iov_iter instead of pos and the iov_iter?
The original user of generic_atomic_write_valid()
[blkdev_dio_unaligned() or blkdev_dio_invalid() with the rename] used
these same args, so I just went with that.
And can these be collapsed into a single generic_atomic_write_checks()
function?
bdev file operations would then need to use
generic_atomic_write_valid_size(), and there is no unit_min and unit_max
size there, apart from bdev awu min and max. And if I checked them, we
would be duplicating checks (of awu min and max) in the block layer.
Cheers,
John
