From: Jeff Layton <jlayton-vpEMnDpepFuMZCB2o+C8xQ@public.gmane.org>
To: bfields-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org
Cc: linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Al Viro <viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
Subject: [PATCH v6 02/19] fs: have flush_delayed_fput flush the workqueue job
Date: Tue, 20 Oct 2015 13:33:35 -0400 [thread overview]
Message-ID: <1445362432-18869-3-git-send-email-jeff.layton@primarydata.com> (raw)
In-Reply-To: <1445362432-18869-1-git-send-email-jeff.layton-7I+n7zu2hftEKMMhf/gKZA@public.gmane.org>
I think there's a potential race in flush_delayed_fput. A kthread does
an fput() and that file gets added to the list and the delayed work is
scheduled. More than 1 jiffy passes, and the workqueue thread picks up
the work and starts running it. Then the kthread calls
flush_delayed_work. It sees that the list is empty and returns
immediately, even though the __fput for its file may not have run yet.
Close this by making flush_delayed_fput use flush_delayed_work instead,
which should immediately schedule the work to run if it's not already,
and block until the workqueue job completes.
Cc: Al Viro <viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
Signed-off-by: Jeff Layton <jeff.layton-7I+n7zu2hftEKMMhf/gKZA@public.gmane.org>
---
fs/file_table.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/file_table.c b/fs/file_table.c
index ad17e05ebf95..52cc6803c07a 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -244,6 +244,8 @@ static void ____fput(struct callback_head *work)
__fput(container_of(work, struct file, f_u.fu_rcuhead));
}
+static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput);
+
/*
* If kernel thread really needs to have the final fput() it has done
* to complete, call this. The only user right now is the boot - we
@@ -256,11 +258,9 @@ static void ____fput(struct callback_head *work)
*/
void flush_delayed_fput(void)
{
- delayed_fput(NULL);
+ flush_delayed_work(&delayed_fput_work);
}
-static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput);
-
void fput(struct file *file)
{
if (atomic_long_dec_and_test(&file->f_count)) {
--
2.4.3
--
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WARNING: multiple messages have this Message-ID (diff)
From: Jeff Layton <jlayton@poochiereds.net>
To: bfields@fieldses.org
Cc: linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Al Viro <viro@ZenIV.linux.org.uk>
Subject: [PATCH v6 02/19] fs: have flush_delayed_fput flush the workqueue job
Date: Tue, 20 Oct 2015 13:33:35 -0400 [thread overview]
Message-ID: <1445362432-18869-3-git-send-email-jeff.layton@primarydata.com> (raw)
In-Reply-To: <1445362432-18869-1-git-send-email-jeff.layton@primarydata.com>
I think there's a potential race in flush_delayed_fput. A kthread does
an fput() and that file gets added to the list and the delayed work is
scheduled. More than 1 jiffy passes, and the workqueue thread picks up
the work and starts running it. Then the kthread calls
flush_delayed_work. It sees that the list is empty and returns
immediately, even though the __fput for its file may not have run yet.
Close this by making flush_delayed_fput use flush_delayed_work instead,
which should immediately schedule the work to run if it's not already,
and block until the workqueue job completes.
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
---
fs/file_table.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/file_table.c b/fs/file_table.c
index ad17e05ebf95..52cc6803c07a 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -244,6 +244,8 @@ static void ____fput(struct callback_head *work)
__fput(container_of(work, struct file, f_u.fu_rcuhead));
}
+static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput);
+
/*
* If kernel thread really needs to have the final fput() it has done
* to complete, call this. The only user right now is the boot - we
@@ -256,11 +258,9 @@ static void ____fput(struct callback_head *work)
*/
void flush_delayed_fput(void)
{
- delayed_fput(NULL);
+ flush_delayed_work(&delayed_fput_work);
}
-static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput);
-
void fput(struct file *file)
{
if (atomic_long_dec_and_test(&file->f_count)) {
--
2.4.3
next prev parent reply other threads:[~2015-10-20 17:33 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-20 17:33 [PATCH v6 00/19] nfsd: open file caching Jeff Layton
2015-10-20 17:33 ` Jeff Layton
2015-10-20 17:33 ` [PATCH v6 03/19] fs: add a kerneldoc header to fput Jeff Layton
2015-10-20 17:33 ` [PATCH v6 04/19] fs: rename "delayed_fput" infrastructure to "fput_global" Jeff Layton
2015-10-20 17:33 ` [PATCH v6 06/19] fsnotify: export several symbols Jeff Layton
2015-10-20 17:33 ` [PATCH v6 07/19] locks: create a new notifier chain for lease attempts Jeff Layton
2015-10-20 17:33 ` [PATCH v6 15/19] nfsd: convert nfs4_file->fi_fds array to use nfsd_files Jeff Layton
2015-10-20 17:33 ` [PATCH v6 19/19] nfsd: rip out the raparms cache Jeff Layton
[not found] ` <1445362432-18869-1-git-send-email-jeff.layton-7I+n7zu2hftEKMMhf/gKZA@public.gmane.org>
2015-10-20 17:33 ` [PATCH v6 01/19] nfsd: move include of state.h from trace.c to trace.h Jeff Layton
2015-10-20 17:33 ` Jeff Layton
[not found] ` <1445362432-18869-2-git-send-email-jeff.layton-7I+n7zu2hftEKMMhf/gKZA@public.gmane.org>
2015-10-21 15:51 ` J. Bruce Fields
2015-10-21 15:51 ` J. Bruce Fields
2015-10-20 17:33 ` Jeff Layton [this message]
2015-10-20 17:33 ` [PATCH v6 02/19] fs: have flush_delayed_fput flush the workqueue job Jeff Layton
2015-10-20 17:33 ` [PATCH v6 05/19] fs: add fput_global Jeff Layton
2015-10-20 17:33 ` Jeff Layton
2015-10-20 17:33 ` [PATCH v6 08/19] sunrpc: add a new cache_detail operation for when a cache is flushed Jeff Layton
2015-10-20 17:33 ` Jeff Layton
2015-10-20 17:33 ` [PATCH v6 09/19] nfsd: add a new struct file caching facility to nfsd Jeff Layton
2015-10-20 17:33 ` Jeff Layton
2015-10-20 17:33 ` [PATCH v6 10/19] nfsd: keep some rudimentary stats on nfsd_file cache Jeff Layton
2015-10-20 17:33 ` Jeff Layton
2015-10-20 17:33 ` [PATCH v6 11/19] nfsd: allow filecache open to skip fh_verify check Jeff Layton
2015-10-20 17:33 ` Jeff Layton
2015-10-20 17:33 ` [PATCH v6 12/19] nfsd: hook up nfsd_write to the new nfsd_file cache Jeff Layton
2015-10-20 17:33 ` Jeff Layton
2015-10-20 17:33 ` [PATCH v6 13/19] nfsd: hook up nfsd_read to the " Jeff Layton
2015-10-20 17:33 ` Jeff Layton
2015-10-20 17:33 ` [PATCH v6 14/19] nfsd: hook nfsd_commit up " Jeff Layton
2015-10-20 17:33 ` Jeff Layton
2015-10-20 17:33 ` [PATCH v6 16/19] nfsd: have nfsd_test_lock use " Jeff Layton
2015-10-20 17:33 ` Jeff Layton
2015-10-20 17:33 ` [PATCH v6 17/19] nfsd: convert fi_deleg_file and ls_file fields to nfsd_file Jeff Layton
2015-10-20 17:33 ` Jeff Layton
2015-10-20 17:33 ` [PATCH v6 18/19] nfsd: hook up nfs4_preprocess_stateid_op to the nfsd_file cache Jeff Layton
2015-10-20 17:33 ` Jeff Layton
2015-10-21 15:57 ` [PATCH v6 00/19] nfsd: open file caching J. Bruce Fields
2015-10-21 15:57 ` J. Bruce Fields
2015-10-22 21:19 ` J. Bruce Fields
2015-10-22 21:19 ` J. Bruce Fields
2015-10-23 0:21 ` Jeff Layton
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