From: Karel Zak <kzak@redhat.com>
Date: Fri, 27 Mar 2020 10:10:26 +0000 (+0100)
Subject: libmount: (umount) FS lookup refactoring
X-Git-Tag: v2.36-rc1~164
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4ce77c625a2e87c021a87d306a66ec1f3942d430;p=thirdparty%2Futil-linux.git

libmount: (umount) FS lookup refactoring

Let's split lookup to more function to make it easy to add another
lookup method.

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

diff --git a/libmount/src/context_umount.c b/libmount/src/context_umount.c
index db6c432d06..642212fda0 100644
--- a/libmount/src/context_umount.c
+++ b/libmount/src/context_umount.c
@@ -226,28 +226,16 @@ static int has_utab_entry(struct libmnt_context *cxt, const char *target)
 
 	if (!cache)
 		free(cn);
-
 	return rc;
 }
 
-/* this is umount replacement to mnt_context_apply_fstab(), use
- * mnt_context_tab_applied() to check result.
- */
-static int lookup_umount_fs(struct libmnt_context *cxt)
+/* returns: 1 not found; <0 on error; 1 success */
+static int lookup_umount_fs_by_statfs(struct libmnt_context *cxt, const char *tgt)
 {
-	const char *tgt;
 	struct stat st;
-	struct libmnt_fs *fs = NULL;
-	int rc = 0;
-
-	assert(cxt);
-	assert(cxt->fs);
+	const char *type;
 
-	tgt = mnt_fs_get_target(cxt->fs);
-	if (!tgt) {
-		DBG(CXT, ul_debugobj(cxt, "umount: undefined target"));
-		return -EINVAL;
-	}
+	DBG(CXT, ul_debugobj(cxt, " lookup by statfs"));
 
 	/*
 	 * Let's try to avoid mountinfo usage at all to minimize performance
@@ -261,53 +249,56 @@ static int lookup_umount_fs(struct libmnt_context *cxt)
 	 * umounts as target is probably unreachable NFS, also for --detach-loop
 	 * as this additionally needs to know the name of the loop device).
 	 */
-	if (!mnt_context_is_restricted(cxt)
-	    && *tgt == '/'
-	    && !(cxt->flags & MNT_FL_HELPER)
-	    && !mnt_context_mtab_writable(cxt)
-	    && !mnt_context_is_force(cxt)
-	    && !mnt_context_is_lazy(cxt)
-	    && !mnt_context_is_nocanonicalize(cxt)
-	    && !mnt_context_is_loopdel(cxt)
-	    && mnt_stat_mountpoint(tgt, &st) == 0 && S_ISDIR(st.st_mode)
-	    && !has_utab_entry(cxt, tgt)) {
-
-		const char *type = mnt_fs_get_fstype(cxt->fs);
-
-		DBG(CXT, ul_debugobj(cxt, "umount: disable mtab"));
-
-		/* !mnt_context_mtab_writable(cxt) && has_utab_entry() verified that there
-		 * is no stuff in utab, so disable all mtab/utab related actions */
-		mnt_context_disable_mtab(cxt, TRUE);
-
-		if (!type) {
-			struct statfs vfs;
-
-			DBG(CXT, ul_debugobj(cxt, "umount: trying statfs()"));
-			if (statfs(tgt, &vfs) == 0)
-				type = mnt_statfs_get_fstype(&vfs);
-			if (type) {
-				rc = mnt_fs_set_fstype(cxt->fs, type);
-				if (rc)
-					return rc;
-			}
-		}
+	if (mnt_context_is_restricted(cxt)
+	    || *tgt != '/'
+	    || (cxt->flags & MNT_FL_HELPER)
+	    || mnt_context_mtab_writable(cxt)
+	    || mnt_context_is_force(cxt)
+	    || mnt_context_is_lazy(cxt)
+	    || mnt_context_is_nocanonicalize(cxt)
+	    || mnt_context_is_loopdel(cxt)
+	    || mnt_stat_mountpoint(tgt, &st) != 0 || !S_ISDIR(st.st_mode)
+	    || has_utab_entry(cxt, tgt))
+		return 1; /* not found */
+
+	type = mnt_fs_get_fstype(cxt->fs);
+
+	DBG(CXT, ul_debugobj(cxt, "  umount: disabling mtab"));
+	mnt_context_disable_mtab(cxt, TRUE);
+
+	if (!type) {
+		struct statfs vfs;
+
+		DBG(CXT, ul_debugobj(cxt, "  trying statfs()"));
+		if (statfs(tgt, &vfs) == 0)
+			type = mnt_statfs_get_fstype(&vfs);
 		if (type) {
-			DBG(CXT, ul_debugobj(cxt,
-				"umount: mountinfo unnecessary [type=%s]", type));
-			return 0;
+			int rc = mnt_fs_set_fstype(cxt->fs, type);
+			if (rc)
+				return rc;
 		}
 	}
+	if (type) {
+		DBG(CXT, ul_debugobj(cxt,
+			"  mountinfo unnecessary [type=%s]", type));
+		return 0;
+	}
+
+	return 1; /* not found */
+}
+
+/* returns: 1 not found; <0 on error; 1 success */
+static int lookup_umount_fs_by_mountinfo(struct libmnt_context *cxt, const char *tgt)
+{
+	struct libmnt_fs *fs = NULL;
+	int rc;
+
+	DBG(CXT, ul_debugobj(cxt, " lookup by mountinfo"));
 
 	rc = mnt_context_find_umount_fs(cxt, tgt, &fs);
-	if (rc < 0)
+	if (rc != 0)
 		return rc;
 
-	if (rc == 1 || !fs) {
-		DBG(CXT, ul_debugobj(cxt, "umount: cannot find '%s' in mtab", tgt));
-		return 0;	/* this is correct! */
-	}
-
 	if (fs != cxt->fs) {
 		/* copy from mtab to our FS description
 		 */
@@ -315,14 +306,47 @@ static int lookup_umount_fs(struct libmnt_context *cxt)
 		mnt_fs_set_target(cxt->fs, NULL);
 
 		if (!mnt_copy_fs(cxt->fs, fs)) {
-			DBG(CXT, ul_debugobj(cxt, "umount: failed to copy FS"));
+			DBG(CXT, ul_debugobj(cxt, "  failed to copy FS"));
 			return -errno;
 		}
-		DBG(CXT, ul_debugobj(cxt, "umount: mtab applied"));
+		DBG(CXT, ul_debugobj(cxt, "  mtab applied"));
 	}
 
 	cxt->flags |= MNT_FL_TAB_APPLIED;
-	return rc;
+	return 0;
+}
+
+/* this is umount replacement to mnt_context_apply_fstab(), use
+ * mnt_context_tab_applied() to check result.
+ */
+static int lookup_umount_fs(struct libmnt_context *cxt)
+{
+	const char *tgt;
+	int rc = 0;
+
+	assert(cxt);
+	assert(cxt->fs);
+
+	DBG(CXT, ul_debugobj(cxt, "umount: lookup FS"));
+
+	tgt = mnt_fs_get_target(cxt->fs);
+	if (!tgt) {
+		DBG(CXT, ul_debugobj(cxt, " undefined target"));
+		return -EINVAL;
+	}
+
+	/* try get fs type by statfs() */
+	rc = lookup_umount_fs_by_statfs(cxt, tgt);
+	if (rc <= 0)
+		return rc;
+
+	/* get complete fs from fs entry from mountinfo */
+	rc = lookup_umount_fs_by_mountinfo(cxt, tgt);
+	if (rc <= 0)
+		return rc;
+
+	DBG(CXT, ul_debugobj(cxt, " cannot find '%s'", tgt));
+	return 0;	/* this is correct! */
 }
 
 /* check if @devname is loopdev and if the device is associated