From: Miklos Szeredi <miklos@szeredi.hu>
To: Vasily Averin <vvs@virtuozzo.com>
Cc: linux-fsdevel@vger.kernel.org, Maxim Patlasov <maximvp@gmail.com>,
Kirill Tkhai <ktkhai@virtuozzo.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] fuse_writepages_fill: simplified "if-else if" constuction
Date: Tue, 14 Jul 2020 14:24:33 +0200 [thread overview]
Message-ID: <CAJfpegv_7nvWoigY-eCX0ny+phWYOz3kEZvYsuGb=u65yMLGHg@mail.gmail.com> (raw)
In-Reply-To: <446f0df5-798d-ab3a-e773-39d9f202c092@virtuozzo.com>
[-- Attachment #1: Type: text/plain, Size: 545 bytes --]
On Thu, Jun 25, 2020 at 11:30 AM Vasily Averin <vvs@virtuozzo.com> wrote:
>
> fuse_writepages_fill uses following construction:
> if (wpa && ap->num_pages &&
> (A || B || C)) {
> action;
> } else if (wpa && D) {
> if (E) {
> the same action;
> }
> }
>
> - ap->num_pages check is always true and can be removed
> - "if" and "else if" calls the same action and can be merged.
Makes sense. Attached patch goes further and moves checking the
conditions to a separate helper for clarity.
Thanks,
Miklos
[-- Attachment #2: fuse-clean-up-writepage-sending.patch --]
[-- Type: text/x-patch, Size: 3058 bytes --]
From: Miklos Szeredi <mszeredi@redhat.com>
Subject: fuse: clean up condition for writepage sending
fuse_writepages_fill uses following construction:
if (wpa && ap->num_pages &&
(A || B || C)) {
action;
} else if (wpa && D) {
if (E) {
the same action;
}
}
- ap->num_pages check is always true and can be removed
- "if" and "else if" calls the same action and can be merged.
Move checking A, B, C, D, E conditions to a helper, add comments.
Original-patch-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
fs/fuse/file.c | 51 +++++++++++++++++++++++++++++++++------------------
1 file changed, 33 insertions(+), 18 deletions(-)
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2015,6 +2015,38 @@ static bool fuse_writepage_add(struct fu
return false;
}
+static bool fuse_writepage_need_send(struct fuse_conn *fc, struct page *page,
+ struct fuse_args_pages *ap,
+ struct fuse_fill_wb_data *data)
+{
+ /*
+ * Being under writeback is unlikely but possible. For example direct
+ * read to an mmaped fuse file will set the page dirty twice; once when
+ * the pages are faulted with get_user_pages(), and then after the read
+ * completed.
+ */
+ if (fuse_page_is_writeback(data->inode, page->index))
+ return true;
+
+ /* Reached max pages */
+ if (ap->num_pages == fc->max_pages)
+ return true;
+
+ /* Reached max write bytes */
+ if ((ap->num_pages + 1) * PAGE_SIZE > fc->max_write)
+ return true;
+
+ /* Discontinuity */
+ if (data->orig_pages[ap->num_pages - 1]->index + 1 != page->index)
+ return true;
+
+ /* Need to grow the pages array? If so, did the expansion fail? */
+ if (ap->num_pages == data->max_pages && !fuse_pages_realloc(data))
+ return true;
+
+ return false;
+}
+
static int fuse_writepages_fill(struct page *page,
struct writeback_control *wbc, void *_data)
{
@@ -2025,7 +2057,6 @@ static int fuse_writepages_fill(struct p
struct fuse_inode *fi = get_fuse_inode(inode);
struct fuse_conn *fc = get_fuse_conn(inode);
struct page *tmp_page;
- bool is_writeback;
int err;
if (!data->ff) {
@@ -2035,25 +2066,9 @@ static int fuse_writepages_fill(struct p
goto out_unlock;
}
- /*
- * Being under writeback is unlikely but possible. For example direct
- * read to an mmaped fuse file will set the page dirty twice; once when
- * the pages are faulted with get_user_pages(), and then after the read
- * completed.
- */
- is_writeback = fuse_page_is_writeback(inode, page->index);
-
- if (wpa && ap->num_pages &&
- (is_writeback || ap->num_pages == fc->max_pages ||
- (ap->num_pages + 1) * PAGE_SIZE > fc->max_write ||
- data->orig_pages[ap->num_pages - 1]->index + 1 != page->index)) {
+ if (wpa && fuse_writepage_need_send(fc, page, ap, data)) {
fuse_writepages_send(data);
data->wpa = NULL;
- } else if (wpa && ap->num_pages == data->max_pages) {
- if (!fuse_pages_realloc(data)) {
- fuse_writepages_send(data);
- data->wpa = NULL;
- }
}
err = -ENOMEM;
next prev parent reply other threads:[~2020-07-14 12:24 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <2733b41a-b4c6-be94-0118-a1a8d6f26eec@virtuozzo.com>
2020-06-25 9:02 ` [PATCH] fuse_writepages_fill() optimization to avoid WARN_ON in tree_insert Vasily Averin
2020-06-27 10:31 ` Sedat Dilek
2020-06-29 21:11 ` Vivek Goyal
2020-07-11 4:01 ` Miklos Szeredi
2020-07-13 8:02 ` Vasily Averin
2020-07-13 16:14 ` Miklos Szeredi
2020-07-14 6:18 ` Vasily Averin
2020-07-14 12:40 ` Sedat Dilek
2020-07-14 12:52 ` Miklos Szeredi
2020-07-14 12:57 ` Sedat Dilek
2020-07-15 7:48 ` Sedat Dilek
2020-06-25 9:30 ` [PATCH] fuse_writepages_fill: simplified "if-else if" constuction Vasily Averin
2020-07-14 12:24 ` Miklos Szeredi [this message]
2020-07-14 18:53 ` Vasily Averin
2020-06-25 9:39 ` [PATCH] fuse_writepages ignores errors from fuse_writepages_fill Vasily Averin
2020-07-14 12:44 ` Miklos Szeredi
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