libmount: fix mnt_context_next_remount()

The current implementation works, but the remount operation is done in
the cloned context and the original context (and calling application)
has no information about the final status/errors. This is mistake.

This new implementation works like mnt_context_next_mount(), it means
the same context (as used by application) is reused for all remounts.
The original setting is restored by mnt_context_apply_template().

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libmount/src/context_mount.c b/libmount/src/context_mount.c
index 6ce33ac1f2e745bf990772afa536d66fad3fb5f7..ae72929330deeb39a95bb6383eb9fbe31f2fc4a8 100644 (file)
--- a/libmount/src/context_mount.c
+++ b/libmount/src/context_mount.c
@@ -1281,7 +1281,6 @@ int mnt_context_next_mount(struct libmnt_context *cxt,
 {
        struct libmnt_table *fstab, *mtab;
        const char *o, *tgt;
-       char *pattern;
        int rc, mounted = 0;
 
        if (ignored)
@@ -1366,7 +1365,7 @@ int mnt_context_next_mount(struct libmnt_context *cxt,
                 * mount operation -t means "-t <type>". We have to zeroize the pattern
                 * to avoid misinterpretation.
                 */
-               pattern = cxt->fstype_pattern;
+               char *pattern = cxt->fstype_pattern;
                cxt->fstype_pattern = NULL;
 
                rc = mnt_context_mount(cxt);
@@ -1405,6 +1404,11 @@ int mnt_context_next_mount(struct libmnt_context *cxt,
  * mnt_context_next_remount() function returns zero, but the @ignored is
  * non-zero.
  *
+ * IMPORTANT -- the mount operation is performed in the current context.
+ * The context is reset before the next mount (see mnt_reset_context()).
+ * The context setting related to the filesystem (e.g. mount options,
+ * etc.) are protected.
+
  * If mount(2) syscall or mount.type helper failed, then the
  * mnt_context_next_mount() function returns zero, but the @mntrc is non-zero.
  * Use also mnt_context_get_status() to check if the filesystem was
@@ -1424,7 +1428,6 @@ int mnt_context_next_remount(struct libmnt_context *cxt,
                           int *mntrc,
                           int *ignored)
 {
-       struct libmnt_context *remount_cxt = NULL;
        struct libmnt_table *mtab;
        const char *tgt;
        int rc;
@@ -1467,30 +1470,34 @@ int mnt_context_next_remount(struct libmnt_context *cxt,
                return 0;
        }
 
-       /* make sure fstab is already read to avoid fstab parsing in cloned context */
-       mnt_context_get_fstab(cxt, NULL);
+       if (!mnt_context_has_template(cxt))
+               mnt_context_save_template(cxt);
 
-       /* clone context */
-       remount_cxt = mnt_copy_context(cxt);
-       if (!remount_cxt)
-               return -ENOMEM;
+       /* restore original, but protect mtab */
+       cxt->mtab = NULL;
+       mnt_reset_context(cxt);
+       cxt->mtab = mtab;
 
-       rc = mnt_context_set_target(remount_cxt, tgt);
+       rc = mnt_context_set_target(cxt, tgt);
        if (!rc) {
                /*
                 * "-t <pattern>" is used to filter out fstab entries, but for ordinary
                 * mount operation -t means "-t <type>". We have to zeroize the pattern
                 * to avoid misinterpretation.
                 */
-               remount_cxt->fstype_pattern = NULL;
-               rc = mnt_context_mount(remount_cxt);
+               char *pattern = cxt->fstype_pattern;
+               cxt->fstype_pattern = NULL;
+
+               rc = mnt_context_mount(cxt);
+
+               cxt->fstype_pattern = pattern;
 
                if (mntrc)
                        *mntrc = rc;
+               rc = 0;
        }
 
-       mnt_free_context(remount_cxt);
-       return 0;
+       return rc;
 }
 
 /*