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From: qiwuchen55@gmail.com
To: miklos@szeredi.hu
Cc: linux-fsdevel@vger.kernel.org, chenqiwu <chenqiwu@xiaomi.com>
Subject: [PATCH] fuse: fix inode rwsem regression
Date: Sat,  1 Feb 2020 13:49:31 +0800
Message-ID: <1580536171-27838-1-git-send-email-qiwuchen55@gmail.com> (raw)

From: chenqiwu <chenqiwu@xiaomi.com>

Apparently our current rwsem code doesn't like doing the trylock, then
lock for real scheme.  So change our direct write method to just do the
trylock for the RWF_NOWAIT case.
This seems to fix AIM7 regression in some scalable filesystems upto ~25%
in some cases. Claimed in commit 942491c9e6d6 ("xfs: fix AIM7 regression")

Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
---
 fs/fuse/file.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index ce71538..ac16994 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1529,7 +1529,13 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	ssize_t res;
 
 	/* Don't allow parallel writes to the same file */
-	inode_lock(inode);
+	if (iocb->ki_flags & IOCB_NOWAIT) {
+		if (!inode_trylock(inode))
+			return -EAGAIN;
+	} else {
+		inode_lock(inode);
+	}
+
 	res = generic_write_checks(iocb, from);
 	if (res > 0) {
 		if (!is_sync_kiocb(iocb) && iocb->ki_flags & IOCB_DIRECT) {
-- 
1.9.1


             reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-01  5:49 qiwuchen55 [this message]
2020-02-01 15:47 ` Matthew Wilcox
2020-02-01 23:09 ` Bernd Schubert
2020-02-02  2:08   ` chenqiwu
2020-02-02 21:18     ` Bernd Schubert
2020-02-03  3:20       ` chenqiwu
2020-02-13  9:50       ` Miklos Szeredi

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