[Devel] [PATCH RHEL7 COMMIT] ext4: Attach write_iter and read_iter

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-1127.8.2.vz7.161.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1127.8.2.vz7.161.1
------>
commit ecfce8dcb499853ed89ea4ccb1ceaf1244e53aba
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Mon May 25 17:52:37 2020 +0300

    ext4: Attach write_iter and read_iter
    
    Now all ext4 direct_IO code is prepared to work with iov_iter,
    so we allow to use it for submitting bvec from kernel.
    
    See aio_write_iter() and aio_read_iter() for the details,
    where from it comes.
    
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    
    =====================
    Patchset description:
    [00/30] fs,direct_IO: Switch to iov_iter and allow bio_vec for ext4
    
    This patchset transforms direct_IO callbacks, blockdev_direct_IO
    and its underlining functions to iov_iter, and introduces complete
    support of iov_iter for ext4.
    
    Supported iov_iter subtypes for ext4 is iovec and bio_vec. The first
    is for traditional user-submitted aio, while bio_vec is the type,
    which is important for us, since we use it in ploop.
    
    bio_vec operates with pages instead of user addresses (like iovec
    does), so it requires specific callbacks in do_blockdev_direct_IO()
    and in the functions it calls.
    
    The patchset reworks do_blockdev_direct_IO() in the same manner
    as in mainstrean. The most of rest patches are prepared manually,
    since we have significant differences to ms (RHEL7 patches, our
    direct IO patches for FUSE; all they have changed many functions).
    At the end, kaio engine (resulting in direct_IO) became possible
    to be enabled for ext4.
    
    https://jira.sw.ru/browse/PSBM-99793
---
 fs/ext4/file.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 32b17c61b52b3..83f8aaaeda9d9 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -583,6 +583,8 @@ const struct file_operations_extend  ext4_file_operations = {
 		.splice_read	= generic_file_splice_read,
 		.splice_write	= generic_file_splice_write,
 		.fallocate	= ext4_fallocate,
+		.read_iter	= generic_file_read_iter,
+		.write_iter	= ext4_file_write_iter,
 	},
 	.mmap_supported_flags = MAP_SYNC,
 };