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 v5 03/20] fs: add a kerneldoc header to fput
Date: Mon, 5 Oct 2015 07:02:25 -0400 [thread overview]
Message-ID: <1444042962-6947-4-git-send-email-jeff.layton@primarydata.com> (raw)
In-Reply-To: <1444042962-6947-1-git-send-email-jeff.layton@primarydata.com>
...and move its EXPORT_SYMBOL just below the function.
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
---
fs/file_table.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/fs/file_table.c b/fs/file_table.c
index 52cc6803c07a..8cfeaee6323f 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -261,6 +261,25 @@ void flush_delayed_fput(void)
flush_delayed_work(&delayed_fput_work);
}
+/**
+ * fput - put a struct file reference
+ * @file: file of which to put the reference
+ *
+ * This function decrements the reference count for the struct file reference,
+ * and queues it up for destruction if the count goes to zero. In the case of
+ * most tasks we queue it to the task_work infrastructure, which will be run
+ * just before the task returns back to userspace. kthreads however never
+ * return to userspace, so for those we add them to a global list and schedule
+ * a delayed workqueue job to do the final cleanup work.
+ *
+ * Why not just do it synchronously? __fput can involve taking locks of all
+ * sorts, and doing it synchronously means that the callers must take extra care
+ * not to deadlock. That can be very difficult to ensure, so by deferring it
+ * until just before return to userland or to the workqueue, we sidestep that
+ * nastiness. Also, __fput can be quite stack intensive, so doing a final fput
+ * has the possibility of blowing up if we don't take steps to ensure that we
+ * have enough stack space to make it work.
+ */
void fput(struct file *file)
{
if (atomic_long_dec_and_test(&file->f_count)) {
@@ -281,6 +300,7 @@ void fput(struct file *file)
schedule_delayed_work(&delayed_fput_work, 1);
}
}
+EXPORT_SYMBOL(fput);
/*
* synchronous analog of fput(); for kernel threads that might be needed
@@ -299,7 +319,6 @@ void __fput_sync(struct file *file)
}
}
-EXPORT_SYMBOL(fput);
void put_filp(struct file *file)
{
--
2.4.3
next prev parent reply other threads:[~2015-10-05 11:02 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-05 11:02 [PATCH v5 00/20] nfsd: open file caching Jeff Layton
2015-10-05 11:02 ` [PATCH v5 01/20] list_lru: add list_lru_rotate Jeff Layton
[not found] ` <1444042962-6947-2-git-send-email-jeff.layton-7I+n7zu2hftEKMMhf/gKZA@public.gmane.org>
2015-10-05 21:47 ` Dave Chinner
2015-10-06 11:43 ` Jeff Layton
[not found] ` <20151006074341.0e2f796e-9yPaYZwiELC+kQycOl6kW4xkIHaj4LzF@public.gmane.org>
2015-10-07 1:09 ` Dave Chinner
2015-10-05 11:02 ` [PATCH v5 02/20] fs: have flush_delayed_fput flush the workqueue job Jeff Layton
2015-10-05 11:02 ` Jeff Layton [this message]
2015-10-05 11:02 ` [PATCH v5 04/20] fs: add fput_queue Jeff Layton
2015-10-05 11:02 ` [PATCH v5 07/20] locks: create a new notifier chain for lease attempts Jeff Layton
2015-10-05 11:02 ` [PATCH v5 09/20] sunrpc: add a new cache_detail operation for when a cache is flushed Jeff Layton
2015-10-05 11:02 ` [PATCH v5 10/20] nfsd: add a new struct file caching facility to nfsd Jeff Layton
2015-10-05 11:02 ` [PATCH v5 11/20] nfsd: keep some rudimentary stats on nfsd_file cache Jeff Layton
[not found] ` <1444042962-6947-1-git-send-email-jeff.layton-7I+n7zu2hftEKMMhf/gKZA@public.gmane.org>
2015-10-05 11:02 ` [PATCH v5 05/20] fs: export flush_delayed_fput Jeff Layton
2015-10-05 11:02 ` [PATCH v5 06/20] fsnotify: export several symbols Jeff Layton
2015-10-05 11:02 ` [PATCH v5 08/20] nfsd: move include of state.h from trace.c to trace.h Jeff Layton
2015-10-05 11:02 ` [PATCH v5 12/20] nfsd: allow filecache open to skip fh_verify check Jeff Layton
2015-10-05 11:02 ` [PATCH v5 13/20] nfsd: hook up nfsd_write to the new nfsd_file cache Jeff Layton
2015-10-05 11:02 ` [PATCH v5 14/20] nfsd: hook up nfsd_read to the " Jeff Layton
2015-10-05 11:02 ` [PATCH v5 18/20] nfsd: convert fi_deleg_file and ls_file fields to nfsd_file Jeff Layton
2015-10-08 16:42 ` [PATCH v5 00/20] nfsd: open file caching J. Bruce Fields
2015-10-08 16:55 ` Jeff Layton
[not found] ` <20151008125529.3f30308e-08S845evdOaAjSkqwZiSMmfYqLom42DlXqFh9Ls21Oc@public.gmane.org>
2015-10-08 18:04 ` J. Bruce Fields
[not found] ` <20151008180400.GB496-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org>
2015-10-10 11:19 ` Jeff Layton
2015-10-10 13:48 ` J. Bruce Fields
2015-10-05 11:02 ` [PATCH v5 15/20] nfsd: hook nfsd_commit up to the nfsd_file cache Jeff Layton
2015-10-05 11:02 ` [PATCH v5 16/20] nfsd: convert nfs4_file->fi_fds array to use nfsd_files Jeff Layton
2015-10-05 11:02 ` [PATCH v5 17/20] nfsd: have nfsd_test_lock use the nfsd_file cache Jeff Layton
2015-10-05 11:02 ` [PATCH v5 19/20] nfsd: hook up nfs4_preprocess_stateid_op to " Jeff Layton
2015-10-05 11:02 ` [PATCH v5 20/20] nfsd: rip out the raparms cache Jeff Layton
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