libmount: save current FS setting as template

This commit adds new functions to save and reuse the current FS
setting (mount options from command line, etc) after context reset.
It's usable for example in "mount --all" when we use the same context
for more times for more mount operations.

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

diff --git a/libmount/src/context.c b/libmount/src/context.c
index fd6cfc8369daa87dcffe69ddcd673247da7356da..f925bfaf05c1d3dc393937292e8bef7855fbbea8 100644 (file)
--- a/libmount/src/context.c
+++ b/libmount/src/context.c
@@ -99,6 +99,8 @@ void mnt_free_context(struct libmnt_context *cxt)
 
        mnt_unref_table(cxt->fstab);
        mnt_unref_cache(cxt->cache);
+       mnt_unref_fs(cxt->fs);
+       mnt_unref_fs(cxt->fs_template);
 
        mnt_context_clear_loopdev(cxt);
        mnt_free_lock(cxt->lock);
@@ -191,9 +193,75 @@ int mnt_reset_context(struct libmnt_context *cxt)
        cxt->flags |= (fl & MNT_FL_NOSWAPMATCH);
        cxt->flags |= (fl & MNT_FL_TABPATHS_CHECKED);
 
+       mnt_context_apply_template(cxt);
+
+       return 0;
+}
+
+/*
+ * Saves the current context FS setting (mount options, etc) to make it usable after
+ * mnt_reset_context() or by mnt_context_apply_template(). This is usable for
+ * example for mnt_context_next_mount() where for the next mount operation we
+ * need to restore to the original context setting.
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_save_template(struct libmnt_context *cxt)
+{
+       struct libmnt_fs *fs = NULL;
+
+       if (!cxt)
+               return -EINVAL;
+
+       DBG(CXT, ul_debugobj(cxt, "save FS as template"));
+
+       if (cxt->fs) {
+               fs = mnt_copy_fs(NULL, cxt->fs);
+               if (!fs)
+                       return -ENOMEM;
+       }
+
+       mnt_unref_fs(cxt->fs_template);
+       cxt->fs_template = fs;
+
        return 0;
 }
 
+/*
+ * Restores context FS setting from previously saved template (see
+ * mnt_context_save_template()).
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_context_apply_template(struct libmnt_context *cxt)
+{
+       struct libmnt_fs *fs = NULL;
+       int rc = 0;
+
+       if (!cxt)
+               return -EINVAL;
+
+       if (cxt->fs_template) {
+               DBG(CXT, ul_debugobj(cxt, "copy FS from template"));
+               fs = mnt_copy_fs(NULL, cxt->fs_template);
+               if (!fs)
+                       return -ENOMEM;
+               rc = mnt_context_set_fs(cxt, fs);
+               mnt_unref_fs(fs);
+       } else {
+               DBG(CXT, ul_debugobj(cxt, "no FS template, reset only"));
+               mnt_unref_fs(cxt->fs);
+               cxt->fs = NULL;
+       }
+
+       return rc;
+}
+
+int mnt_context_has_template(struct libmnt_context *cxt)
+{
+       return cxt && cxt->fs_template ? 1 : 0;
+}
+
 struct libmnt_context *mnt_copy_context(struct libmnt_context *o)
 {
        struct libmnt_context *n;
@@ -823,6 +891,7 @@ int mnt_context_set_fs(struct libmnt_context *cxt, struct libmnt_fs *fs)
        if (!cxt)
                return -EINVAL;
 
+       DBG(CXT, ul_debugobj(cxt, "setting new FS"));
        mnt_ref_fs(fs);                 /* new */
        mnt_unref_fs(cxt->fs);          /* old */
        cxt->fs = fs;

diff --git a/libmount/src/mountP.h b/libmount/src/mountP.h
index 4ba1308796359c4e5bb7538f7d46274ace47c543..cba6ff92fc959a55e7c18034949e85e848fb4e04 100644 (file)
--- a/libmount/src/mountP.h
+++ b/libmount/src/mountP.h
@@ -295,6 +295,7 @@ struct libmnt_context
        char    *optstr_pattern;        /* for mnt_match_options() */
 
        struct libmnt_fs *fs;           /* filesystem description (type, mountpoint, device, ...) */
+       struct libmnt_fs *fs_template;  /* used for @fs on mnt_reset_context() */
 
        struct libmnt_table *fstab;     /* fstab (or mtab for some remounts) entries */
        struct libmnt_table *mtab;      /* mtab entries */
@@ -456,6 +457,10 @@ extern int mnt_context_get_generic_excode(int rc, char *buf, size_t bufsz, char
 extern int mnt_context_get_mount_excode(struct libmnt_context *cxt, int mntrc, char *buf, size_t bufsz);
 extern int mnt_context_get_umount_excode(struct libmnt_context *cxt, int mntrc, char *buf, size_t bufsz);
 
+extern int mnt_context_has_template(struct libmnt_context *cxt);
+extern int mnt_context_apply_template(struct libmnt_context *cxt);
+extern int mnt_context_save_template(struct libmnt_context *cxt);
+
 /* tab_update.c */
 extern int mnt_update_set_filename(struct libmnt_update *upd,
                                   const char *filename, int userspace_only);