GFS2: Fix remount argument parsing

The following patch fixes an issue relating to remount and argument
parsing. After this fix is applied, remount becomes atomic in that
it either succeeds changing the mount to the new state, or it fails
and leaves it in the old state. Previously it was possible for the
parsing of options to fail part way though and for the fs to be left
in a state where some of the new arguments had been applied, but some
had not.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 19 insertions, 92 deletions

diff --git a/fs/gfs2/mount.c b/fs/gfs2/mount.c
index 3cb0a44ba02..3524ae81189 100644
--- a/fs/gfs2/mount.c
+++ b/fs/gfs2/mount.c
@@ -17,7 +17,7 @@
 
 #include "gfs2.h"
 #include "incore.h"
-#include "mount.h"
+#include "super.h"
 #include "sys.h"
 #include "util.h"
 
@@ -77,101 +77,46 @@ static const match_table_t tokens = {
  * Return: errno
  */
 
-int gfs2_mount_args(struct gfs2_sbd *sdp, char *data_arg, int remount)
+int gfs2_mount_args(struct gfs2_sbd *sdp, struct gfs2_args *args, char *options)
 {
-	struct gfs2_args *args = &sdp->sd_args;
-	char *data = data_arg;
-	char *options, *o, *v;
-	int error = 0;
-
-	if (!remount) {
-		/*  Set some defaults  */
-		args->ar_quota = GFS2_QUOTA_DEFAULT;
-		args->ar_data = GFS2_DATA_DEFAULT;
-	}
+	char *o;
+	int token;
+	substring_t tmp[MAX_OPT_ARGS];
 
 	/* Split the options into tokens with the "," character and
 	   process them */
 
-	for (options = data; (o = strsep(&options, ",")); ) {
-		int token;
-		substring_t tmp[MAX_OPT_ARGS];
-
-		if (!*o)
+	while (1) {
+		o = strsep(&options, ",");
+		if (o == NULL)
+			break;
+		if (*o == '\0')
 			continue;
 
 		token = match_token(o, tokens, tmp);
 		switch (token) {
 		case Opt_lockproto:
-			v = match_strdup(&tmp[0]);
-			if (!v) {
-				fs_info(sdp, "no memory for lockproto\n");
-				error = -ENOMEM;
-				goto out_error;
-			}
-
-			if (remount && strcmp(v, args->ar_lockproto)) {
-				kfree(v);
-				goto cant_remount;
-			}
-			
-			strncpy(args->ar_lockproto, v, GFS2_LOCKNAME_LEN);
-			args->ar_lockproto[GFS2_LOCKNAME_LEN - 1] = 0;
-			kfree(v);
+			match_strlcpy(args->ar_lockproto, &tmp[0],
+				      GFS2_LOCKNAME_LEN);
 			break;
 		case Opt_locktable:
-			v = match_strdup(&tmp[0]);
-			if (!v) {
-				fs_info(sdp, "no memory for locktable\n");
-				error = -ENOMEM;
-				goto out_error;
-			}
-
-			if (remount && strcmp(v, args->ar_locktable)) {
-				kfree(v);
-				goto cant_remount;
-			}
-
-			strncpy(args->ar_locktable, v, GFS2_LOCKNAME_LEN);
-			args->ar_locktable[GFS2_LOCKNAME_LEN - 1]  = 0;
-			kfree(v);
+			match_strlcpy(args->ar_locktable, &tmp[0],
+				      GFS2_LOCKNAME_LEN);
 			break;
 		case Opt_hostdata:
-			v = match_strdup(&tmp[0]);
-			if (!v) {
-				fs_info(sdp, "no memory for hostdata\n");
-				error = -ENOMEM;
-				goto out_error;
-			}
-
-			if (remount && strcmp(v, args->ar_hostdata)) {
-				kfree(v);
-				goto cant_remount;
-			}
-
-			strncpy(args->ar_hostdata, v, GFS2_LOCKNAME_LEN);
-			args->ar_hostdata[GFS2_LOCKNAME_LEN - 1] = 0;
-			kfree(v);
+			match_strlcpy(args->ar_hostdata, &tmp[0],
+				      GFS2_LOCKNAME_LEN);
 			break;
 		case Opt_spectator:
-			if (remount && !args->ar_spectator)
-				goto cant_remount;
 			args->ar_spectator = 1;
-			sdp->sd_vfs->s_flags |= MS_RDONLY;
 			break;
 		case Opt_ignore_local_fs:
-			if (remount && !args->ar_ignore_local_fs)
-				goto cant_remount;
 			args->ar_ignore_local_fs = 1;
 			break;
 		case Opt_localflocks:
-			if (remount && !args->ar_localflocks)
-				goto cant_remount;
 			args->ar_localflocks = 1;
 			break;
 		case Opt_localcaching:
-			if (remount && !args->ar_localcaching)
-				goto cant_remount;
 			args->ar_localcaching = 1;
 			break;
 		case Opt_debug:
@@ -181,17 +126,13 @@ int gfs2_mount_args(struct gfs2_sbd *sdp, char *data_arg, int remount)
 			args->ar_debug = 0;
 			break;
 		case Opt_upgrade:
-			if (remount && !args->ar_upgrade)
-				goto cant_remount;
 			args->ar_upgrade = 1;
 			break;
 		case Opt_acl:
 			args->ar_posix_acl = 1;
-			sdp->sd_vfs->s_flags |= MS_POSIXACL;
 			break;
 		case Opt_noacl:
 			args->ar_posix_acl = 0;
-			sdp->sd_vfs->s_flags &= ~MS_POSIXACL;
 			break;
 		case Opt_quota_off:
 			args->ar_quota = GFS2_QUOTA_OFF;
@@ -215,29 +156,15 @@ int gfs2_mount_args(struct gfs2_sbd *sdp, char *data_arg, int remount)
 			args->ar_data = GFS2_DATA_ORDERED;
 			break;
 		case Opt_meta:
-			if (remount && args->ar_meta != 1)
-				goto cant_remount;
 			args->ar_meta = 1;
 			break;
 		case Opt_err:
 		default:
-			fs_info(sdp, "unknown option: %s\n", o);
-			error = -EINVAL;
-			goto out_error;
+			fs_info(sdp, "invalid mount option: %s\n", o);
+			return -EINVAL;
 		}
 	}
 
-out_error:
-	if (error)
-		fs_info(sdp, "invalid mount option(s)\n");
-
-	if (data != data_arg)
-		kfree(data);
-
-	return error;
-
-cant_remount:
-	fs_info(sdp, "can't remount with option %s\n", o);
-	return -EINVAL;
+	return 0;
 }