1 /* -*- mode: c; c-basic-offset: 8; -*- 2 * vim: noexpandtab sw=8 ts=8 sts=0: 3 * 4 * locks.c 5 * 6 * Userspace file locking support 7 * 8 * Copyright (C) 2007 Oracle. All rights reserved. 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public 12 * License as published by the Free Software Foundation; either 13 * version 2 of the License, or (at your option) any later version. 14 * 15 * This program is distributed in the hope that it will be useful, 16 * but WITHOUT ANY WARRANTY; without even the implied warranty of 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 18 * General Public License for more details. 19 * 20 * You should have received a copy of the GNU General Public 21 * License along with this program; if not, write to the 22 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, 23 * Boston, MA 021110-1307, USA. 24 */ 25 26 #include <linux/fs.h> 27 #include <linux/fcntl.h> 28 29 #include <cluster/masklog.h> 30 31 #include "ocfs2.h" 32 33 #include "dlmglue.h" 34 #include "file.h" 35 #include "inode.h" 36 #include "locks.h" 37 38 static int ocfs2_do_flock(struct file *file, struct inode *inode, 39 int cmd, struct file_lock *fl) 40 { 41 int ret = 0, level = 0, trylock = 0; 42 struct ocfs2_file_private *fp = file->private_data; 43 struct ocfs2_lock_res *lockres = &fp->fp_flock; 44 45 if (fl->fl_type == F_WRLCK) 46 level = 1; 47 if (!IS_SETLKW(cmd)) 48 trylock = 1; 49 50 mutex_lock(&fp->fp_mutex); 51 52 if (lockres->l_flags & OCFS2_LOCK_ATTACHED && 53 lockres->l_level > LKM_NLMODE) { 54 int old_level = 0; 55 56 if (lockres->l_level == LKM_EXMODE) 57 old_level = 1; 58 59 if (level == old_level) 60 goto out; 61 62 /* 63 * Converting an existing lock is not guaranteed to be 64 * atomic, so we can get away with simply unlocking 65 * here and allowing the lock code to try at the new 66 * level. 67 */ 68 69 locks_lock_file_wait(file, 70 &(struct file_lock) { 71 .fl_type = F_UNLCK, 72 .fl_flags = FL_FLOCK 73 }); 74 75 ocfs2_file_unlock(file); 76 } 77 78 ret = ocfs2_file_lock(file, level, trylock); 79 if (ret) { 80 if (ret == -EAGAIN && trylock) 81 ret = -EWOULDBLOCK; 82 else 83 mlog_errno(ret); 84 goto out; 85 } 86 87 ret = locks_lock_file_wait(file, fl); 88 if (ret) 89 ocfs2_file_unlock(file); 90 91 out: 92 mutex_unlock(&fp->fp_mutex); 93 94 return ret; 95 } 96 97 static int ocfs2_do_funlock(struct file *file, int cmd, struct file_lock *fl) 98 { 99 int ret; 100 struct ocfs2_file_private *fp = file->private_data; 101 102 mutex_lock(&fp->fp_mutex); 103 ocfs2_file_unlock(file); 104 ret = locks_lock_file_wait(file, fl); 105 mutex_unlock(&fp->fp_mutex); 106 107 return ret; 108 } 109 110 /* 111 * Overall flow of ocfs2_flock() was influenced by gfs2_flock(). 112 */ 113 int ocfs2_flock(struct file *file, int cmd, struct file_lock *fl) 114 { 115 struct inode *inode = file->f_mapping->host; 116 struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); 117 118 if (!(fl->fl_flags & FL_FLOCK)) 119 return -ENOLCK; 120 if (__mandatory_lock(inode)) 121 return -ENOLCK; 122 123 if ((osb->s_mount_opt & OCFS2_MOUNT_LOCALFLOCKS) || 124 ocfs2_mount_local(osb)) 125 return locks_lock_file_wait(file, fl); 126 127 if (fl->fl_type == F_UNLCK) 128 return ocfs2_do_funlock(file, cmd, fl); 129 else 130 return ocfs2_do_flock(file, inode, cmd, fl); 131 } 132 133 int ocfs2_lock(struct file *file, int cmd, struct file_lock *fl) 134 { 135 struct inode *inode = file->f_mapping->host; 136 struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); 137 138 if (!(fl->fl_flags & FL_POSIX)) 139 return -ENOLCK; 140 if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK) 141 return -ENOLCK; 142 143 return ocfs2_plock(osb->cconn, OCFS2_I(inode)->ip_blkno, file, cmd, fl); 144 } 145