libmount: export locking errors as MNT_EX_FILEIO

The mount man page assumes locking errors mapped to MNT_EX_FILEIO (16)
return code. Unfortunately, this is internally not exported as a
special error code, so it's returned as a generic (errno based)
stuff. This patch fixes this issue.

Note that we still use locking for example for utab or when enabled
/etc/mtab (disabled by default).

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

4 files changed, 37 insertions, 10 deletions

diff --git a/libmount/src/context_mount.c b/libmount/src/context_mount.c
index 65f7dbfd0..e84947f00 100644
--- a/libmount/src/context_mount.c
+++ b/libmount/src/context_mount.c
@@ -1379,6 +1379,10 @@ int mnt_context_get_mount_excode(
 			if (buf)
 				snprintf(buf, bufsz, _("overlapping loop device exists for %s"), src);
 			return MNT_EX_FAIL;
+		case -MNT_ERR_LOCK:
+			if (buf)
+				snprintf(buf, bufsz, _("locking failed"));
+			return MNT_EX_FILEIO;
 		default:
 			return mnt_context_get_generic_excode(rc, buf, bufsz, _("mount failed: %m"));
 		}
@@ -1388,7 +1392,12 @@ int mnt_context_get_mount_excode(
 		 * mount(2) syscall success, but something else failed
 		 * (probably error in mtab processing).
 		 */
-		if (rc < 0)
+		if (rc == -MNT_ERR_LOCK) {
+			if (buf)
+				snprintf(buf, bufsz, _("filesystem was mounted, but failed to update userspace mount table"));
+			return MNT_EX_FILEIO;
+
+		} else if (rc < 0)
 			return mnt_context_get_generic_excode(rc, buf, bufsz,
 				_("filesystem was mounted, but any subsequent operation failed: %m"));
 
diff --git a/libmount/src/context_umount.c b/libmount/src/context_umount.c
index f2c304f4a..a8124629f 100644
--- a/libmount/src/context_umount.c
+++ b/libmount/src/context_umount.c
@@ -1063,6 +1063,10 @@ int mnt_context_get_umount_excode(
 			if (buf)
 				snprintf(buf, bufsz, _("not mounted"));
 			return MNT_EX_USAGE;
+		} else if (rc == -MNT_ERR_LOCK) {
+			if (buf)
+				snprintf(buf, bufsz, _("locking failed"));
+			return MNT_EX_FILEIO;
 		}
 		return mnt_context_get_generic_excode(rc, buf, bufsz,
 					_("umount failed: %m"));
@@ -1072,7 +1076,12 @@ int mnt_context_get_umount_excode(
 		 * umount(2) syscall success, but something else failed
 		 * (probably error in mtab processing).
 		 */
-		if (rc < 0)
+		if (rc == -MNT_ERR_LOCK) {
+			if (buf)
+				snprintf(buf, bufsz, _("filesystem was unmounted, but failed to update userspace mount table"));
+			return MNT_EX_FILEIO;
+
+		} else if (rc < 0)
 			return mnt_context_get_generic_excode(rc, buf, bufsz,
 				_("filesystem was unmounted, but any subsequent operation failed: %m"));
 
diff --git a/libmount/src/libmount.h.in b/libmount/src/libmount.h.in
index 123145fc4..463b8ddcc 100644
--- a/libmount/src/libmount.h.in
+++ b/libmount/src/libmount.h.in
@@ -184,6 +184,12 @@ enum {
  * detected overlapping loop device that cannot be re-used
  */
 #define MNT_ERR_LOOPOVERLAP 5007
+/**
+ * MNT_ERR_LOCK:
+ *
+ * failed to lock mtab/utab or so.
+ */
+#define MNT_ERR_LOCK         5008
 
 
 /*
@@ -230,7 +236,7 @@ enum {
 /**
  * MNT_EX_FILEIO:
  *
- * [u]mount(8) exit code: problems writing, locking, ... mtab/fstab
+ * [u]mount(8) exit code: problems writing, locking, ... mtab/utab
  */
 #define MNT_EX_FILEIO	16
 
diff --git a/libmount/src/tab_update.c b/libmount/src/tab_update.c
index 52e1dd444..e95713301 100644
--- a/libmount/src/tab_update.c
+++ b/libmount/src/tab_update.c
@@ -696,7 +696,7 @@ static int update_add_entry(struct libmnt_update *upd, struct libmnt_lock *lc)
 	if (lc)
 		rc = mnt_lock_file(lc);
 	if (rc)
-		return rc;
+		return -MNT_ERR_LOCK;
 
 	tb = __mnt_new_table_from_file(upd->filename,
 			upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB);
@@ -722,7 +722,7 @@ static int update_remove_entry(struct libmnt_update *upd, struct libmnt_lock *lc
 	if (lc)
 		rc = mnt_lock_file(lc);
 	if (rc)
-		return rc;
+		return -MNT_ERR_LOCK;
 
 	tb = __mnt_new_table_from_file(upd->filename,
 			upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB);
@@ -751,7 +751,7 @@ static int update_modify_target(struct libmnt_update *upd, struct libmnt_lock *l
 	if (lc)
 		rc = mnt_lock_file(lc);
 	if (rc)
-		return rc;
+		return -MNT_ERR_LOCK;
 
 	tb = __mnt_new_table_from_file(upd->filename,
 			upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB);
@@ -788,7 +788,7 @@ static int update_modify_options(struct libmnt_update *upd, struct libmnt_lock *
 	if (lc)
 		rc = mnt_lock_file(lc);
 	if (rc)
-		return rc;
+		return -MNT_ERR_LOCK;
 
 	tb = __mnt_new_table_from_file(upd->filename,
 			upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB);
@@ -885,10 +885,13 @@ int mnt_update_already_done(struct libmnt_update *upd, struct libmnt_lock *lc)
 	}
 	if (lc && upd->userspace_only)
 		mnt_lock_use_simplelock(lc, TRUE);	/* use flock */
-	if (lc)
+	if (lc) {
 		rc = mnt_lock_file(lc);
-	if (rc)
-		goto done;
+		if (rc) {
+			rc = -MNT_ERR_LOCK;
+			goto done;
+		}
+	}
 
 	tb = __mnt_new_table_from_file(upd->filename,
 			upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB);