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Subject[PATCH AUTOSEL for 4.9 21/54] nfs: Don't take a reference on fl->fl_file for LOCK operation
Date
From: Benjamin Coddington <bcodding@redhat.com>

[ Upstream commit 4b09ec4b14a168bf2c687e1f598140c3c11e9222 ]

I have reports of a crash that look like __fput() was called twice for
a NFSv4.0 file. It seems possible that the state manager could try to
reclaim a lock and take a reference on the fl->fl_file at the same time the
file is being released if, during the close(), a signal interrupts the wait
for outstanding IO while removing locks which then skips the removal
of that lock.

Since 83bfff23e9ed ("nfs4: have do_vfs_lock take an inode pointer") has
removed the need to traverse fl->fl_file->f_inode in nfs4_lock_done(),
taking that reference is no longer necessary.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
---
fs/nfs/nfs4proc.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index a53b8e0c896a..8edfca5d1eb2 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -38,7 +38,6 @@
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/errno.h>
-#include <linux/file.h>
#include <linux/string.h>
#include <linux/ratelimit.h>
#include <linux/printk.h>
@@ -6009,7 +6008,6 @@ static struct nfs4_lockdata *nfs4_alloc_lockdata(struct file_lock *fl,
p->server = server;
atomic_inc(&lsp->ls_count);
p->ctx = get_nfs_open_context(ctx);
- get_file(fl->fl_file);
memcpy(&p->fl, fl, sizeof(p->fl));
return p;
out_free_seqid:
@@ -6122,7 +6120,6 @@ static void nfs4_lock_release(void *calldata)
nfs_free_seqid(data->arg.lock_seqid);
nfs4_put_lock_state(data->lsp);
put_nfs_open_context(data->ctx);
- fput(data->fl.fl_file);
kfree(data);
dprintk("%s: done!\n", __func__);
}
--
2.11.0
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