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mount: improve --move error message on shared trees 

Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Karel Zak 2013-03-25 13:58:53 +01:00
parent dcc15ce5af
commit fcc0413a12
2 changed files with 45 additions and 6 deletions
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5
sys-utils/mount.8
View File

@ -448,6 +448,11 @@ accessed under newdir. The physical location of the files is not changed.
Note that the
.I olddir
has to be a mountpoint.
Note that moving a mount residing under a shared mount is invalid and
unsupported. Use
.B findmnt -o TARGET,PROPAGATION /dir
to see the current propagation flags.
.RE
.B The shared subtrees operations.

46
sys-utils/mount.c
View File

@ -321,6 +321,37 @@ static void selinux_warning(struct libmnt_context *cxt, const char *tgt)
# define selinux_warning(_x, _y)
#endif
/*
* Returns 1 if @dir parent is shared
*/
static int is_shared_tree(struct libmnt_context *cxt, const char *dir)
{
struct libmnt_table *tb = NULL;
struct libmnt_fs *fs;
unsigned long mflags = 0;
char *mnt = NULL, *p;
int rc = 0;
if (!dir)
return 0;
if (mnt_context_get_mtab(cxt, &tb) || !tb)
goto done;
mnt = xstrdup(dir);
p = strrchr(mnt, '/');
if (!p)
goto done;
if (p > mnt)
*p = '\0';
fs = mnt_table_find_mountpoint(tb, mnt, MNT_ITER_BACKWARD);
rc = fs && mnt_fs_is_kernel(fs)
&& mnt_fs_get_propagation(fs, &mflags) == 0
&& (mflags & MS_SHARED);
done:
free(mnt);
return rc;
}
/*
* rc = 0 success
* <0 error (usually -errno or -1)
@ -475,11 +506,11 @@ try_readonly:
break;
}
case ENOENT:
if (lstat(tgt, &st))
if (tgt && lstat(tgt, &st))
warnx(_("mount point %s does not exist"), tgt);
else if (stat(tgt, &st))
else if (tgt && stat(tgt, &st))
warnx(_("mount point %s is a symbolic link to nowhere"), tgt);
else if (stat(src, &st)) {
else if (src && stat(src, &st)) {
if (uflags & MNT_MS_NOFAIL)
return MOUNT_EX_SUCCESS;
@ -493,7 +524,7 @@ try_readonly:
case ENOTDIR:
if (stat(tgt, &st) || ! S_ISDIR(st.st_mode))
warnx(_("mount point %s is not a directory"), tgt);
else if (stat(src, &st) && errno == ENOTDIR) {
else if (src && stat(src, &st) && errno == ENOTDIR) {
if (uflags & MNT_MS_NOFAIL)
return MOUNT_EX_SUCCESS;
@ -510,6 +541,9 @@ try_readonly:
warnx(_("%s not mounted or bad option"), tgt);
else if (rc == -MNT_ERR_APPLYFLAGS)
warnx(_("%s is not mountpoint or bad option"), tgt);
else if ((mflags & MS_MOVE) && is_shared_tree(cxt, src))
warnx(_("bad option. Note that moving a mount residing under a shared\n"
" mount is unsupported."));
else
warnx(_("wrong fs type, bad option, bad superblock on %s,\n"
" missing codepage or helper program, or other error"),
@ -520,9 +554,9 @@ try_readonly:
" (for several filesystems (e.g. nfs, cifs) you might\n"
" need a /sbin/mount.<type> helper program)\n"));
fprintf(stderr, _(
fprintf(stderr, _("\n"
" In some cases useful info is found in syslog - try\n"
" dmesg | tail or so\n"));
" dmesg | tail or so.\n"));
break;
case EMFILE: