126 lines
3 KiB
C
126 lines
3 KiB
C
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/* -*- mode: c; c-basic-offset: 8; -*-
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* vim: noexpandtab sw=8 ts=8 sts=0:
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*
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* locks.c
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*
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* Userspace file locking support
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*
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* Copyright (C) 2007 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include <linux/fs.h>
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#define MLOG_MASK_PREFIX ML_INODE
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#include <cluster/masklog.h>
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#include "ocfs2.h"
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#include "dlmglue.h"
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#include "file.h"
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#include "locks.h"
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static int ocfs2_do_flock(struct file *file, struct inode *inode,
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int cmd, struct file_lock *fl)
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{
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int ret = 0, level = 0, trylock = 0;
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struct ocfs2_file_private *fp = file->private_data;
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struct ocfs2_lock_res *lockres = &fp->fp_flock;
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if (fl->fl_type == F_WRLCK)
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level = 1;
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if (!IS_SETLKW(cmd))
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trylock = 1;
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mutex_lock(&fp->fp_mutex);
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if (lockres->l_flags & OCFS2_LOCK_ATTACHED &&
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lockres->l_level > LKM_NLMODE) {
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int old_level = 0;
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if (lockres->l_level == LKM_EXMODE)
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old_level = 1;
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if (level == old_level)
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goto out;
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/*
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* Converting an existing lock is not guaranteed to be
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* atomic, so we can get away with simply unlocking
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* here and allowing the lock code to try at the new
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* level.
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*/
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flock_lock_file_wait(file,
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&(struct file_lock){.fl_type = F_UNLCK});
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ocfs2_file_unlock(file);
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}
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ret = ocfs2_file_lock(file, level, trylock);
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if (ret) {
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if (ret == -EAGAIN && trylock)
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ret = -EWOULDBLOCK;
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else
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mlog_errno(ret);
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goto out;
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}
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ret = flock_lock_file_wait(file, fl);
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out:
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mutex_unlock(&fp->fp_mutex);
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return ret;
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}
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static int ocfs2_do_funlock(struct file *file, int cmd, struct file_lock *fl)
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{
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int ret;
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struct ocfs2_file_private *fp = file->private_data;
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mutex_lock(&fp->fp_mutex);
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ocfs2_file_unlock(file);
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ret = flock_lock_file_wait(file, fl);
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mutex_unlock(&fp->fp_mutex);
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return ret;
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}
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/*
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* Overall flow of ocfs2_flock() was influenced by gfs2_flock().
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*/
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int ocfs2_flock(struct file *file, int cmd, struct file_lock *fl)
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{
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struct inode *inode = file->f_mapping->host;
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struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
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if (!(fl->fl_flags & FL_FLOCK))
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return -ENOLCK;
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if (__mandatory_lock(inode))
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return -ENOLCK;
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if ((osb->s_mount_opt & OCFS2_MOUNT_LOCALFLOCKS) ||
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ocfs2_mount_local(osb))
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return flock_lock_file_wait(file, fl);
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if (fl->fl_type == F_UNLCK)
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return ocfs2_do_funlock(file, cmd, fl);
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else
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return ocfs2_do_flock(file, inode, cmd, fl);
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}
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