linux-kernel - [PATCH 5/5] fuse: enable close

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Message-ID: <20140925120659.540.9507.stgit@dhcp-10-30-22-200.sw.ru>
Date:	Thu, 25 Sep 2014 16:07:08 +0400
From:	Maxim Patlasov <MPatlasov@...allels.com>
To:	miklos@...redi.hu
Cc:	fuse-devel@...ts.sourceforge.net, avati@...ster.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 5/5] fuse: enable close_wait synchronous release

The patch enables the feature by passing 'true' to fuse_file_put in
fuse_release_common.

Previously, this was safe only in special cases when we sure that
multi-threaded userspace won't deadlock if we'll synchronously send
FUSE_RELEASE in the context of read-ahead or write-back callback. Now, it's
always safe because callbacks don't send requests to userspace anymore.

The feature can be made privileged by means of DISABLE_SYNC_RELEASE mount
option implemented by the previous patch.

Signed-off-by: Maxim Patlasov <mpatlasov@...allels.com>
---
 fs/fuse/file.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index c4599c8..858280f 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -334,7 +334,8 @@ void fuse_release_common(struct file *file, int opcode)
 	 * synchronous RELEASE is allowed (and desirable) in this case
 	 * because the server can be trusted not to screw up.
 	 */
-	fuse_file_put(ff, ff->fc->destroy_req != NULL);
+	fuse_file_put(ff, ff->fc->destroy_req != NULL ||
+			  must_release_synchronously(ff));
 }
 
 static int fuse_open(struct inode *inode, struct file *file)

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