fs/ocfs2/locks.c

   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 }