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Subject[PATCH 2/4] fs: add a kerneldoc header to fput
Date
...and move its EXPORT_SYMBOL just below the function.

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
---
fs/file_table.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/fs/file_table.c b/fs/file_table.c
index f4833af62eae..d63f4a399d39 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -260,6 +260,21 @@ 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 work of putting them.
+ *
+ * Why not just do it synchronously? __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)) {
@@ -280,6 +295,7 @@ 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
@@ -298,7 +314,6 @@ void __fput_sync(struct file *file)
}
}

-EXPORT_SYMBOL(fput);

void put_filp(struct file *file)
{
--
2.4.3


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