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Subject[PATCH] Nfs lost locks
From
Date
The NFS client is prone to loose locks on filesystems when the locking
process is killed with a signal. This has been discussed on the nfs
mailing list in these threads:

http://sourceforge.net/mailarchive/forum.php?thread_id=3213117&forum_id=4930

http://marc.theaimsgroup.com/?l=linux-nfs&m=107074045907620&w=2

Marcelo, if the above links are not sufficient, please email back for
more details.

The enclosed patch is from Trond, and it fixes the problem.

Phil.
diff -ruN linux-2.4.25.orig/fs/nfs/file.c linux-2.4.25/fs/nfs/file.c
--- linux-2.4.25.orig/fs/nfs/file.c Mon Aug 25 04:44:43 2003
+++ linux-2.4.25/fs/nfs/file.c Wed Feb 18 13:32:05 2004
@@ -241,6 +241,93 @@
goto out;
}

+static int
+do_getlk(struct inode *inode, int cmd, struct file_lock *fl)
+{
+ int status;
+
+ lock_kernel();
+ status = nlmclnt_proc(inode, cmd, fl);
+ unlock_kernel();
+ return status;
+}
+
+static int
+do_unlk(struct inode *inode, int cmd, struct file_lock *fl)
+{
+ sigset_t oldset;
+ int status;
+
+ rpc_clnt_sigmask(NFS_CLIENT(inode), &oldset);
+ /*
+ * Flush all pending writes before doing anything
+ * with locks..
+ */
+ filemap_fdatasync(inode->i_mapping);
+ down(&inode->i_sem);
+ nfs_wb_all(inode);
+ up(&inode->i_sem);
+ filemap_fdatawait(inode->i_mapping);
+
+ /* NOTE: special case
+ * If we're signalled while cleaning up locks on process exit, we
+ * still need to complete the unlock.
+ */
+ lock_kernel();
+ status = nlmclnt_proc(inode, cmd, fl);
+ unlock_kernel();
+ rpc_clnt_sigunmask(NFS_CLIENT(inode), &oldset);
+ return status;
+}
+
+static int
+do_setlk(struct file *filp, int cmd, struct file_lock *fl)
+{
+ struct inode * inode = filp->f_dentry->d_inode;
+ int status;
+
+ /*
+ * Flush all pending writes before doing anything
+ * with locks..
+ */
+ status = filemap_fdatasync(inode->i_mapping);
+ if (status == 0) {
+ down(&inode->i_sem);
+ status = nfs_wb_all(inode);
+ up(&inode->i_sem);
+ if (status == 0)
+ status = filemap_fdatawait(inode->i_mapping);
+ }
+ if (status < 0)
+ return status;
+
+ lock_kernel();
+ status = nlmclnt_proc(inode, cmd, fl);
+ /* If we were signalled we still need to ensure that
+ * we clean up any state on the server. We therefore
+ * record the lock call as having succeeded in order to
+ * ensure that locks_remove_posix() cleans it out when
+ * the process exits.
+ */
+ if (status == -EINTR || status == -ERESTARTSYS)
+ posix_lock_file(filp, fl, 0);
+ unlock_kernel();
+ if (status < 0)
+ return status;
+
+ /*
+ * Make sure we clear the cache whenever we try to get the lock.
+ * This makes locking act as a cache coherency point.
+ */
+ filemap_fdatasync(inode->i_mapping);
+ down(&inode->i_sem);
+ nfs_wb_all(inode); /* we may have slept */
+ up(&inode->i_sem);
+ filemap_fdatawait(inode->i_mapping);
+ nfs_zap_caches(inode);
+ return 0;
+}
+
/*
* Lock a (portion of) a file
*/
@@ -248,8 +335,6 @@
nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
{
struct inode * inode = filp->f_dentry->d_inode;
- int status = 0;
- int status2;

dprintk("NFS: nfs_lock(f=%4x/%ld, t=%x, fl=%x, r=%Ld:%Ld)\n",
inode->i_dev, inode->i_ino,
@@ -266,8 +351,8 @@
/* Fake OK code if mounted without NLM support */
if (NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM) {
if (IS_GETLK(cmd))
- status = LOCK_USE_CLNT;
- goto out_ok;
+ return LOCK_USE_CLNT;
+ return 0;
}

/*
@@ -280,42 +365,9 @@
if (!fl->fl_owner || (fl->fl_flags & (FL_POSIX|FL_BROKEN)) != FL_POSIX)
return -ENOLCK;

- /*
- * Flush all pending writes before doing anything
- * with locks..
- */
- status = filemap_fdatasync(inode->i_mapping);
- down(&inode->i_sem);
- status2 = nfs_wb_all(inode);
- if (status2 && !status)
- status = status2;
- up(&inode->i_sem);
- status2 = filemap_fdatawait(inode->i_mapping);
- if (status2 && !status)
- status = status2;
- if (status < 0)
- return status;
-
- lock_kernel();
- status = nlmclnt_proc(inode, cmd, fl);
- unlock_kernel();
- if (status < 0)
- return status;
-
- status = 0;
-
- /*
- * Make sure we clear the cache whenever we try to get the lock.
- * This makes locking act as a cache coherency point.
- */
- out_ok:
- if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
- filemap_fdatasync(inode->i_mapping);
- down(&inode->i_sem);
- nfs_wb_all(inode); /* we may have slept */
- up(&inode->i_sem);
- filemap_fdatawait(inode->i_mapping);
- nfs_zap_caches(inode);
- }
- return status;
+ if (IS_GETLK(cmd))
+ return do_getlk(inode, cmd, fl);
+ if (fl->fl_type == F_UNLCK)
+ return do_unlk(inode, cmd, fl);
+ return do_setlk(filp, cmd, fl);
}
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