From: Hou Tao <houtao1@xxxxxxxxxx>
Hi,
The patch set aims to fix the warning related to an abnormal size
parameter of kmalloc() in virtiofs. Patch #1 fixes it by introducing
use_pages_for_kvec_io option in fuse_conn and enabling it in virtiofs.
Beside the abnormal size parameter for kmalloc, the gfp parameter is
also questionable: GFP_ATOMIC is used even when the allocation occurs
in a kworker context. Patch #2 fixes it by using GFP_NOFS when the
allocation is initiated by the kworker. For more details, please check
the individual patches.
As usual, comments are always welcome.
Change Log:
v4:
* patch 1: add the missed {flush|invalidate}_kernel_vmap_range() and
update commit message accordingly
* patch 2: update commit message to explain why GFP_ATOMIC is
reasonable for the first invocation of
virtio_fs_enqueue_req().
v3: https://lore.kernel.org/linux-fsdevel/20240426143903.1305919-1-houtao@xxxxxxxxxxxxxxx/
* introduce use_pages_for_kvec_io for virtiofs. When the option is
enabled, fuse will use iov_iter_extract_pages() to construct a page
array and pass the pages array instead of a pointer to virtiofs.
The benefit is twofold: the length of the data passed to virtiofs is
limited by max_pages, and there is no memory copy compared with v2.
v2: https://lore.kernel.org/linux-fsdevel/20240228144126.2864064-1-houtao@xxxxxxxxxxxxxxx/
* limit the length of ITER_KVEC dio by max_pages instead of the
newly-introduced max_nopage_rw. Using max_pages make the ITER_KVEC
dio being consistent with other rw operations.
* replace kmalloc-allocated bounce buffer by using a bounce buffer
backed by scattered pages when the length of the bounce buffer for
KVEC_ITER dio is larger than PAG_SIZE, so even on hosts with
fragmented memory, the KVEC_ITER dio can be handled normally by
virtiofs. (Bernd Schubert)
* merge the GFP_NOFS patch [1] into this patch-set and use
memalloc_nofs_{save|restore}+GFP_KERNEL instead of GFP_NOFS
(Benjamin Coddington)
v1: https://lore.kernel.org/linux-fsdevel/20240103105929.1902658-1-houtao@xxxxxxxxxxxxxxx/
[1]: https://lore.kernel.org/linux-fsdevel/20240105105305.4052672-1-houtao@xxxxxxxxxxxxxxx/
Hou Tao (2):
virtiofs: use pages instead of pointer for kernel direct IO
virtiofs: use GFP_NOFS when enqueuing request through kworker
fs/fuse/file.c | 62 +++++++++++++++++++++++++++++++--------------
fs/fuse/fuse_i.h | 6 +++++
fs/fuse/virtio_fs.c | 25 +++++++++++-------
3 files changed, 65 insertions(+), 28 deletions(-)
--
2.29.2
