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