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Do not flock() block devices. The kernel recently started to guard

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against opening a block device twice and flock requires that we
keep the device open.  Hence, the same mount would attempt to open
for locking and then VOP_OPEN for kernel access and run into
problems.  This makes it possible to rump_foofs block devices again,
i.e. take the same command line arguments as regular mounts.
Noticed by apb.
This commit is contained in:
pooka 2009-02-11 14:35:58 +00:00
parent 028f3ea750
commit d5aab2d6c4
1 changed files with 22 additions and 4 deletions
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26
lib/libukfs/ukfs.c
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@ -1,4 +1,4 @@
/* $NetBSD: ukfs.c,v 1.21 2009/01/23 19:36:01 pooka Exp $ */
/* $NetBSD: ukfs.c,v 1.22 2009/02/11 14:35:58 pooka Exp $ */
/*
* Copyright (c) 2007, 2008 Antti Kantee. All Rights Reserved.
@ -163,6 +163,7 @@ struct ukfs *
ukfs_mount(const char *vfsname, const char *devpath, const char *mountpath,
int mntflags, void *arg, size_t alen)
{
struct stat sb;
struct ukfs *fs = NULL;
struct vfsops *vfsops;
struct mount *mp = NULL;
@ -190,14 +191,31 @@ ukfs_mount(const char *vfsname, const char *devpath, const char *mountpath,
rdonly = mntflags & MNT_RDONLY;
devfd = open(devpath, rdonly ? O_RDONLY : O_RDWR);
if (devfd != -1) {
if (flock(devfd, LOCK_NB | (rdonly ? LOCK_SH:LOCK_EX)) == -1) {
warnx("ukfs_mount: cannot get %s lock on device",
rdonly ? "shared" : "exclusive");
if (fstat(devfd, &sb) == -1) {
close(devfd);
devfd = -1;
rv = errno;
goto out;
}
/*
* We do this only for non-block device since the
* (NetBSD) kernel allows block device open only once.
*/
if (!S_ISBLK(sb.st_mode)) {
if (flock(devfd, LOCK_NB | (rdonly ? LOCK_SH:LOCK_EX))
== -1) {
warnx("ukfs_mount: cannot get %s lock on "
"device", rdonly ? "shared" : "exclusive");
close(devfd);
devfd = -1;
rv = errno;
goto out;
}
} else {
close(devfd);
devfd = -1;
}
}
fs = malloc(sizeof(struct ukfs));