fs/ocfs2/locks.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * locks.c
0004  *
0005  * Userspace file locking support
0006  *
0007  * Copyright (C) 2007 Oracle.  All rights reserved.
0008  */
0009
0010 #include <linux/fs.h>
0011 #include <linux/fcntl.h>
0012
0013 #include <cluster/masklog.h>
0014
0015 #include "ocfs2.h"
0016
0017 #include "dlmglue.h"
0018 #include "file.h"
0019 #include "inode.h"
0020 #include "locks.h"
0021
0022 static int ocfs2_do_flock(struct file *file, struct inode *inode,
0023               int cmd, struct file_lock *fl)
0024 {
0025     int ret = 0, level = 0, trylock = 0;
0026     struct ocfs2_file_private *fp = file->private_data;
0027     struct ocfs2_lock_res *lockres = &fp->fp_flock;
0028
0029     if (fl->fl_type == F_WRLCK)
0030         level = 1;
0031     if (!IS_SETLKW(cmd))
0032         trylock = 1;
0033
0034     mutex_lock(&fp->fp_mutex);
0035
0036     if (lockres->l_flags & OCFS2_LOCK_ATTACHED &&
0037         lockres->l_level > LKM_NLMODE) {
0038         int old_level = 0;
0039         struct file_lock request;
0040
0041         if (lockres->l_level == LKM_EXMODE)
0042             old_level = 1;
0043
0044         if (level == old_level)
0045             goto out;
0046
0047         /*
0048          * Converting an existing lock is not guaranteed to be
0049          * atomic, so we can get away with simply unlocking
0050          * here and allowing the lock code to try at the new
0051          * level.
0052          */
0053
0054         locks_init_lock(&request);
0055         request.fl_type = F_UNLCK;
0056         request.fl_flags = FL_FLOCK;
0057         locks_lock_file_wait(file, &request);
0058
0059         ocfs2_file_unlock(file);
0060     }
0061
0062     ret = ocfs2_file_lock(file, level, trylock);
0063     if (ret) {
0064         if (ret == -EAGAIN && trylock)
0065             ret = -EWOULDBLOCK;
0066         else
0067             mlog_errno(ret);
0068         goto out;
0069     }
0070
0071     ret = locks_lock_file_wait(file, fl);
0072     if (ret)
0073         ocfs2_file_unlock(file);
0074
0075 out:
0076     mutex_unlock(&fp->fp_mutex);
0077
0078     return ret;
0079 }
0080
0081 static int ocfs2_do_funlock(struct file *file, int cmd, struct file_lock *fl)
0082 {
0083     int ret;
0084     struct ocfs2_file_private *fp = file->private_data;
0085
0086     mutex_lock(&fp->fp_mutex);
0087     ocfs2_file_unlock(file);
0088     ret = locks_lock_file_wait(file, fl);
0089     mutex_unlock(&fp->fp_mutex);
0090
0091     return ret;
0092 }
0093
0094 /*
0095  * Overall flow of ocfs2_flock() was influenced by gfs2_flock().
0096  */
0097 int ocfs2_flock(struct file *file, int cmd, struct file_lock *fl)
0098 {
0099     struct inode *inode = file->f_mapping->host;
0100     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
0101
0102     if (!(fl->fl_flags & FL_FLOCK))
0103         return -ENOLCK;
0104
0105     if ((osb->s_mount_opt & OCFS2_MOUNT_LOCALFLOCKS) ||
0106         ocfs2_mount_local(osb))
0107         return locks_lock_file_wait(file, fl);
0108
0109     if (fl->fl_type == F_UNLCK)
0110         return ocfs2_do_funlock(file, cmd, fl);
0111     else
0112         return ocfs2_do_flock(file, inode, cmd, fl);
0113 }
0114
0115 int ocfs2_lock(struct file *file, int cmd, struct file_lock *fl)
0116 {
0117     struct inode *inode = file->f_mapping->host;
0118     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
0119
0120     if (!(fl->fl_flags & FL_POSIX))
0121         return -ENOLCK;
0122
0123     return ocfs2_plock(osb->cconn, OCFS2_I(inode)->ip_blkno, file, cmd, fl);
0124 }