linux-kernel - [34-longterm 164/209] NFS: Fix fcntl F

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Message-Id: <1302803767-9715-51-git-send-email-paul.gortmaker@windriver.com>
Date:	Thu, 14 Apr 2011 13:55:22 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	stable@...nel.org, linux-kernel@...r.kernel.org
Cc:	stable-review@...nel.org, Sergey Vlasov <vsu@...linux.ru>,
	Trond Myklebust <Trond.Myklebust@...app.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 164/209] NFS: Fix fcntl F_GETLK not reporting some conflicts

From: Sergey Vlasov <vsu@...linux.ru>

  =====================================================================
  | This is a commit scheduled for the next v2.6.34 longterm release. |
  | If you see a problem with using this for longterm, please comment.|
  =====================================================================

commit 21ac19d484a8ffb66f64487846c8d53afef04d2b upstream.

The commit 129a84de2347002f09721cda3155ccfd19fade40 (locks: fix F_GETLK
regression (failure to find conflicts)) fixed the posix_test_lock()
function by itself, however, its usage in NFS changed by the commit
9d6a8c5c213e34c475e72b245a8eb709258e968c (locks: give posix_test_lock
same interface as ->lock) remained broken - subsequent NFS-specific
locking code received F_UNLCK instead of the user-specified lock type.
To fix the problem, fl->fl_type needs to be saved before the
posix_test_lock() call and restored if no local conflicts were reported.

Reference: https://bugzilla.kernel.org/show_bug.cgi?id=23892
Tested-by: Alexander Morozov <amorozov@...rsoft.ru>
Signed-off-by: Sergey Vlasov <vsu@...linux.ru>
Signed-off-by: Trond Myklebust <Trond.Myklebust@...app.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 fs/nfs/file.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 8fc1c55..7f7df1d 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -693,6 +693,7 @@ static int do_getlk(struct file *filp, int cmd, struct file_lock *fl)
 {
 	struct inode *inode = filp->f_mapping->host;
 	int status = 0;
+	unsigned int saved_type = fl->fl_type;

 	/* Try local locking first */
 	posix_test_lock(filp, fl);
@@ -700,6 +701,7 @@ static int do_getlk(struct file *filp, int cmd, struct file_lock *fl)
 		/* found a conflict */
 		goto out;
 	}
+	fl->fl_type = saved_type;

 	if (nfs_have_delegation(inode, FMODE_READ))
 		goto out_noconflict;
-- 
1.7.4.4

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