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 28 #define MLOG_MASK_PREFIX ML_INODE 29 #include <cluster/masklog.h> 30 31 #include "ocfs2.h" 32 33 #include "dlmglue.h" 34 #include "file.h" 35 #include "locks.h" 36 37 static int ocfs2_do_flock(struct file *file, struct inode *inode, 38 int cmd, struct file_lock *fl) 39 { 40 int ret = 0, level = 0, trylock = 0; 41 struct ocfs2_file_private *fp = file->private_data; 42 struct ocfs2_lock_res *lockres = &fp->fp_flock; 43 44 if (fl->fl_type == F_WRLCK) 45 level = 1; 46 if (!IS_SETLKW(cmd)) 47 trylock = 1; 48 49 mutex_lock(&fp->fp_mutex); 50 51 if (lockres->l_flags & OCFS2_LOCK_ATTACHED && 52 lockres->l_level > LKM_NLMODE) { 53 int old_level = 0; 54 55 if (lockres->l_level == LKM_EXMODE) 56 old_level = 1; 57 58 if (level == old_level) 59 goto out; 60 61 /* 62 * Converting an existing lock is not guaranteed to be 63 * atomic, so we can get away with simply unlocking 64 * here and allowing the lock code to try at the new 65 * level. 66 */ 67 68 flock_lock_file_wait(file, 69 &(struct file_lock){.fl_type = F_UNLCK}); 70 71 ocfs2_file_unlock(file); 72 } 73 74 ret = ocfs2_file_lock(file, level, trylock); 75 if (ret) { 76 if (ret == -EAGAIN && trylock) 77 ret = -EWOULDBLOCK; 78 else 79 mlog_errno(ret); 80 goto out; 81 } 82 83 ret = flock_lock_file_wait(file, fl); 84 85 out: 86 mutex_unlock(&fp->fp_mutex); 87 88 return ret; 89 } 90 91 static int ocfs2_do_funlock(struct file *file, int cmd, struct file_lock *fl) 92 { 93 int ret; 94 struct ocfs2_file_private *fp = file->private_data; 95 96 mutex_lock(&fp->fp_mutex); 97 ocfs2_file_unlock(file); 98 ret = flock_lock_file_wait(file, fl); 99 mutex_unlock(&fp->fp_mutex); 100 101 return ret; 102 } 103 104 /* 105 * Overall flow of ocfs2_flock() was influenced by gfs2_flock(). 106 */ 107 int ocfs2_flock(struct file *file, int cmd, struct file_lock *fl) 108 { 109 struct inode *inode = file->f_mapping->host; 110 struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); 111 112 if (!(fl->fl_flags & FL_FLOCK)) 113 return -ENOLCK; 114 if (__mandatory_lock(inode)) 115 return -ENOLCK; 116 117 if ((osb->s_mount_opt & OCFS2_MOUNT_LOCALFLOCKS) || 118 ocfs2_mount_local(osb)) 119 return flock_lock_file_wait(file, fl); 120 121 if (fl->fl_type == F_UNLCK) 122 return ocfs2_do_funlock(file, cmd, fl); 123 else 124 return ocfs2_do_flock(file, inode, cmd, fl); 125 } 126