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 #define MLOG_MASK_PREFIX ML_INODE 30 #include <cluster/masklog.h> 31 32 #include "ocfs2.h" 33 34 #include "dlmglue.h" 35 #include "file.h" 36 #include "inode.h" 37 #include "locks.h" 38 39 static int ocfs2_do_flock(struct file *file, struct inode *inode, 40 int cmd, struct file_lock *fl) 41 { 42 int ret = 0, level = 0, trylock = 0; 43 struct ocfs2_file_private *fp = file->private_data; 44 struct ocfs2_lock_res *lockres = &fp->fp_flock; 45 46 if (fl->fl_type == F_WRLCK) 47 level = 1; 48 if (!IS_SETLKW(cmd)) 49 trylock = 1; 50 51 mutex_lock(&fp->fp_mutex); 52 53 if (lockres->l_flags & OCFS2_LOCK_ATTACHED && 54 lockres->l_level > LKM_NLMODE) { 55 int old_level = 0; 56 57 if (lockres->l_level == LKM_EXMODE) 58 old_level = 1; 59 60 if (level == old_level) 61 goto out; 62 63 /* 64 * Converting an existing lock is not guaranteed to be 65 * atomic, so we can get away with simply unlocking 66 * here and allowing the lock code to try at the new 67 * level. 68 */ 69 70 flock_lock_file_wait(file, 71 &(struct file_lock){.fl_type = F_UNLCK}); 72 73 ocfs2_file_unlock(file); 74 } 75 76 ret = ocfs2_file_lock(file, level, trylock); 77 if (ret) { 78 if (ret == -EAGAIN && trylock) 79 ret = -EWOULDBLOCK; 80 else 81 mlog_errno(ret); 82 goto out; 83 } 84 85 ret = flock_lock_file_wait(file, fl); 86 87 out: 88 mutex_unlock(&fp->fp_mutex); 89 90 return ret; 91 } 92 93 static int ocfs2_do_funlock(struct file *file, int cmd, struct file_lock *fl) 94 { 95 int ret; 96 struct ocfs2_file_private *fp = file->private_data; 97 98 mutex_lock(&fp->fp_mutex); 99 ocfs2_file_unlock(file); 100 ret = flock_lock_file_wait(file, fl); 101 mutex_unlock(&fp->fp_mutex); 102 103 return ret; 104 } 105 106 /* 107 * Overall flow of ocfs2_flock() was influenced by gfs2_flock(). 108 */ 109 int ocfs2_flock(struct file *file, int cmd, struct file_lock *fl) 110 { 111 struct inode *inode = file->f_mapping->host; 112 struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); 113 114 if (!(fl->fl_flags & FL_FLOCK)) 115 return -ENOLCK; 116 if (__mandatory_lock(inode)) 117 return -ENOLCK; 118 119 if ((osb->s_mount_opt & OCFS2_MOUNT_LOCALFLOCKS) || 120 ocfs2_mount_local(osb)) 121 return flock_lock_file_wait(file, fl); 122 123 if (fl->fl_type == F_UNLCK) 124 return ocfs2_do_funlock(file, cmd, fl); 125 else 126 return ocfs2_do_flock(file, inode, cmd, fl); 127 } 128 129 int ocfs2_lock(struct file *file, int cmd, struct file_lock *fl) 130 { 131 struct inode *inode = file->f_mapping->host; 132 struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); 133 134 if (!(fl->fl_flags & FL_POSIX)) 135 return -ENOLCK; 136 if (__mandatory_lock(inode)) 137 return -ENOLCK; 138 139 return ocfs2_plock(osb->cconn, OCFS2_I(inode)->ip_blkno, file, cmd, fl); 140 } 141