[PATCH] ext4: don't fail remount if journalling mode didn't change

[PATCH] ext4: don't fail remount if journalling mode didn't change

[Lukas Czerner]

Switching to the new mount api introduced inconsistency in how the
journalling mode mount option (data=) is handled during a remount.

Ext4 always prevented changing the journalling mode during the remount,
however the new code always fails the remount when the journalling mode
is specified, even if it remains unchanged. Fix it.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reported-by: Heiner Kallweit <hkallweit1@gmail.com>
Fixes: cebe85d570cf ("ext4: switch to the new mount api")
---
 fs/ext4/super.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index b72d989b77fb..dd9de4bf414d 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2148,19 +2148,22 @@ static int unnote_qf_name(struct fs_context *fc, int qtype)
 #endif
 
 #define EXT4_SET_CTX(name)						\
-static inline void ctx_set_##name(struct ext4_fs_context *ctx, int flag)\
+static inline void ctx_set_##name(struct ext4_fs_context *ctx,		\
+				  unsigned long flag)			\
 {									\
 	ctx->mask_s_##name |= flag;					\
 	ctx->vals_s_##name |= flag;					\
 }									\
-static inline void ctx_clear_##name(struct ext4_fs_context *ctx, int flag)\
+static inline void ctx_clear_##name(struct ext4_fs_context *ctx,	\
+				    unsigned long flag)			\
 {									\
 	ctx->mask_s_##name |= flag;					\
 	ctx->vals_s_##name &= ~flag;					\
 }									\
-static inline bool ctx_test_##name(struct ext4_fs_context *ctx, int flag)\
+static inline unsigned long						\
+ctx_test_##name(struct ext4_fs_context *ctx, unsigned long flag)	\
 {									\
-	return ((ctx->vals_s_##name & flag) != 0);			\
+	return (ctx->vals_s_##name & flag);				\
 }									\
 
 EXT4_SET_CTX(flags);
@@ -2821,7 +2824,8 @@ static int ext4_check_opt_consistency(struct fs_context *fc,
 				 "Remounting file system with no journal "
 				 "so ignoring journalled data option");
 			ctx_clear_mount_opt(ctx, EXT4_MOUNT_DATA_FLAGS);
-		} else if (ctx->mask_s_mount_opt & EXT4_MOUNT_DATA_FLAGS) {
+		} else if (ctx_test_mount_opt(ctx, EXT4_MOUNT_DATA_FLAGS) !=
+			   test_opt(sb, DATA_FLAGS)) {
 			ext4_msg(NULL, KERN_ERR, "Cannot change data mode "
 				 "on remount");
 			return -EINVAL;
-- 
2.31.1

Re: [PATCH] ext4: don't fail remount if journalling mode didn't change

[Theodore Ts'o]

On Mon, 20 Dec 2021 16:26:57 +0100, Lukas Czerner wrote:
> Switching to the new mount api introduced inconsistency in how the
> journalling mode mount option (data=) is handled during a remount.
> 
> Ext4 always prevented changing the journalling mode during the remount,
> however the new code always fails the remount when the journalling mode
> is specified, even if it remains unchanged. Fix it.
> 
> [...]

Applied, thanks!

[1/1] ext4: don't fail remount if journalling mode didn't change
      commit: 4c2467287779f744cdd70c8ec70903034d6584f0

Best regards,
-- 
Theodore Ts'o <tytso@mit.edu>