1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* -*- mode: c; c-basic-offset: 8; -*- 3 * vim: noexpandtab sw=8 ts=8 sts=0: 4 * 5 * locks.c 6 * 7 * Userspace file locking support 8 * 9 * Copyright (C) 2007 Oracle. All rights reserved. 10 */ 11 12 #include <linux/fs.h> 13 #include <linux/fcntl.h> 14 15 #include <cluster/masklog.h> 16 17 #include "ocfs2.h" 18 19 #include "dlmglue.h" 20 #include "file.h" 21 #include "inode.h" 22 #include "locks.h" 23 24 static int ocfs2_do_flock(struct file *file, struct inode *inode, 25 int cmd, struct file_lock *fl) 26 { 27 int ret = 0, level = 0, trylock = 0; 28 struct ocfs2_file_private *fp = file->private_data; 29 struct ocfs2_lock_res *lockres = &fp->fp_flock; 30 31 if (fl->fl_type == F_WRLCK) 32 level = 1; 33 if (!IS_SETLKW(cmd)) 34 trylock = 1; 35 36 mutex_lock(&fp->fp_mutex); 37 38 if (lockres->l_flags & OCFS2_LOCK_ATTACHED && 39 lockres->l_level > LKM_NLMODE) { 40 int old_level = 0; 41 struct file_lock request; 42 43 if (lockres->l_level == LKM_EXMODE) 44 old_level = 1; 45 46 if (level == old_level) 47 goto out; 48 49 /* 50 * Converting an existing lock is not guaranteed to be 51 * atomic, so we can get away with simply unlocking 52 * here and allowing the lock code to try at the new 53 * level. 54 */ 55 56 locks_init_lock(&request); 57 request.fl_type = F_UNLCK; 58 request.fl_flags = FL_FLOCK; 59 locks_lock_file_wait(file, &request); 60 61 ocfs2_file_unlock(file); 62 } 63 64 ret = ocfs2_file_lock(file, level, trylock); 65 if (ret) { 66 if (ret == -EAGAIN && trylock) 67 ret = -EWOULDBLOCK; 68 else 69 mlog_errno(ret); 70 goto out; 71 } 72 73 ret = locks_lock_file_wait(file, fl); 74 if (ret) 75 ocfs2_file_unlock(file); 76 77 out: 78 mutex_unlock(&fp->fp_mutex); 79 80 return ret; 81 } 82 83 static int ocfs2_do_funlock(struct file *file, int cmd, struct file_lock *fl) 84 { 85 int ret; 86 struct ocfs2_file_private *fp = file->private_data; 87 88 mutex_lock(&fp->fp_mutex); 89 ocfs2_file_unlock(file); 90 ret = locks_lock_file_wait(file, fl); 91 mutex_unlock(&fp->fp_mutex); 92 93 return ret; 94 } 95 96 /* 97 * Overall flow of ocfs2_flock() was influenced by gfs2_flock(). 98 */ 99 int ocfs2_flock(struct file *file, int cmd, struct file_lock *fl) 100 { 101 struct inode *inode = file->f_mapping->host; 102 struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); 103 104 if (!(fl->fl_flags & FL_FLOCK)) 105 return -ENOLCK; 106 if (__mandatory_lock(inode)) 107 return -ENOLCK; 108 109 if ((osb->s_mount_opt & OCFS2_MOUNT_LOCALFLOCKS) || 110 ocfs2_mount_local(osb)) 111 return locks_lock_file_wait(file, fl); 112 113 if (fl->fl_type == F_UNLCK) 114 return ocfs2_do_funlock(file, cmd, fl); 115 else 116 return ocfs2_do_flock(file, inode, cmd, fl); 117 } 118 119 int ocfs2_lock(struct file *file, int cmd, struct file_lock *fl) 120 { 121 struct inode *inode = file->f_mapping->host; 122 struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); 123 124 if (!(fl->fl_flags & FL_POSIX)) 125 return -ENOLCK; 126 if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK) 127 return -ENOLCK; 128 129 return ocfs2_plock(osb->cconn, OCFS2_I(inode)->ip_blkno, file, cmd, fl); 130 } 131