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