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Prevent duplicate mnttab cache entries

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Under Linux its possible to mount the same filesystem multiple
times in the namespace.  This can be done either with bind mounts
or simply with multiple mount points.  Unfortunately, the mnttab
cache code is implemented using an AVL tree which does not support
duplicate entries.  To avoid this issue this patch updates the
code to check for a duplicate entry before adding a new one.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Michael Martin <mgmartin.mgm@gmail.com>
Closes #2041
This commit is contained in:
Brian Behlendorf 2014-01-13 13:02:59 -08:00
parent fd23720ae1
commit 741304503a
1 changed files with 13 additions and 0 deletions
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13
lib/libzfs/libzfs_dataset.c
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@ -640,14 +640,27 @@ libzfs_mnttab_update(libzfs_handle_t *hdl)
while (getmntent(hdl->libzfs_mnttab, &entry) == 0) {
mnttab_node_t *mtn;
avl_index_t where;
if (strcmp(entry.mnt_fstype, MNTTYPE_ZFS) != 0)
continue;
mtn = zfs_alloc(hdl, sizeof (mnttab_node_t));
mtn->mtn_mt.mnt_special = zfs_strdup(hdl, entry.mnt_special);
mtn->mtn_mt.mnt_mountp = zfs_strdup(hdl, entry.mnt_mountp);
mtn->mtn_mt.mnt_fstype = zfs_strdup(hdl, entry.mnt_fstype);
mtn->mtn_mt.mnt_mntopts = zfs_strdup(hdl, entry.mnt_mntopts);
/* Exclude duplicate mounts */
if (avl_find(&hdl->libzfs_mnttab_cache, mtn, &where) != NULL) {
free(mtn->mtn_mt.mnt_special);
free(mtn->mtn_mt.mnt_mountp);
free(mtn->mtn_mt.mnt_fstype);
free(mtn->mtn_mt.mnt_mntopts);
free(mtn);
continue;
}
avl_add(&hdl->libzfs_mnttab_cache, mtn);
}