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 flock_lock_file_wait(file, 70 &(struct file_lock){.fl_type = F_UNLCK}); 71 72 ocfs2_file_unlock(file); 73 } 74 75 ret = ocfs2_file_lock(file, level, trylock); 76 if (ret) { 77 if (ret == -EAGAIN && trylock) 78 ret = -EWOULDBLOCK; 79 else 80 mlog_errno(ret); 81 goto out; 82 } 83 84 ret = flock_lock_file_wait(file, fl); 85 86 out: 87 mutex_unlock(&fp->fp_mutex); 88 89 return ret; 90 } 91 92 static int ocfs2_do_funlock(struct file *file, int cmd, struct file_lock *fl) 93 { 94 int ret; 95 struct ocfs2_file_private *fp = file->private_data; 96 97 mutex_lock(&fp->fp_mutex); 98 ocfs2_file_unlock(file); 99 ret = flock_lock_file_wait(file, fl); 100 mutex_unlock(&fp->fp_mutex); 101 102 return ret; 103 } 104 105 /* 106 * Overall flow of ocfs2_flock() was influenced by gfs2_flock(). 107 */ 108 int ocfs2_flock(struct file *file, int cmd, struct file_lock *fl) 109 { 110 struct inode *inode = file->f_mapping->host; 111 struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); 112 113 if (!(fl->fl_flags & FL_FLOCK)) 114 return -ENOLCK; 115 if (__mandatory_lock(inode)) 116 return -ENOLCK; 117 118 if ((osb->s_mount_opt & OCFS2_MOUNT_LOCALFLOCKS) || 119 ocfs2_mount_local(osb)) 120 return flock_lock_file_wait(file, fl); 121 122 if (fl->fl_type == F_UNLCK) 123 return ocfs2_do_funlock(file, cmd, fl); 124 else 125 return ocfs2_do_flock(file, inode, cmd, fl); 126 } 127 128 int ocfs2_lock(struct file *file, int cmd, struct file_lock *fl) 129 { 130 struct inode *inode = file->f_mapping->host; 131 struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); 132 133 if (!(fl->fl_flags & FL_POSIX)) 134 return -ENOLCK; 135 if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK) 136 return -ENOLCK; 137 138 return ocfs2_plock(osb->cconn, OCFS2_I(inode)->ip_blkno, file, cmd, fl); 139 } 140