[PATCH 2/2] ext4: Fix fsync(2) for nojournal mode

[PATCH 2/2] ext4: Fix fsync(2) for nojournal mode

[Jan Kara]

When inode metadata is changed, we sometimes just call
ext4_mark_inode_dirty() to track modified metadata. This copies inode
metadata into block buffer which is enough when we are journalling
metadata. However when we are running in nojournal mode we currently
fail to write the dirtied inode buffer during fsync(2) because the inode
is not marked as dirty. Use explicit ext4_write_inode() call to make
sure the inode table buffer is written to the disk. This is a band aid
solution but proper solution requires a much larger rewrite including
changes in metadata bh tracking infrastructure.

Reported-by: Free Ekanayaka <free.ekanayaka@gmail.com>
Link: https://lore.kernel.org/all/87il8nhxdm.fsf@x1.mail-host-address-is-not-set/
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/fsync.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
index e476c6de3074..bd8f230fa507 100644
--- a/fs/ext4/fsync.c
+++ b/fs/ext4/fsync.c
@@ -83,11 +83,23 @@ static int ext4_fsync_nojournal(struct file *file, loff_t start, loff_t end,
 				int datasync, bool *needs_barrier)
 {
 	struct inode *inode = file->f_inode;
+	struct writeback_control wbc = {
+		.sync_mode = WB_SYNC_ALL,
+		.nr_to_write = 0,
+	};
 	int ret;
 
 	ret = generic_buffers_fsync_noflush(file, start, end, datasync);
-	if (!ret)
-		ret = ext4_sync_parent(inode);
+	if (ret)
+		return ret;
+
+	/* Force writeout of inode table buffer to disk */
+	ret = ext4_write_inode(inode, &wbc);
+	if (ret)
+		return ret;
+
+	ret = ext4_sync_parent(inode);
+
 	if (test_opt(inode->i_sb, BARRIER))
 		*needs_barrier = true;
 
-- 
2.51.0

Re: [PATCH 2/2] ext4: Fix fsync(2) for nojournal mode

[Zhang Yi]

On 2/17/2026 12:48 AM, Jan Kara wrote:
> When inode metadata is changed, we sometimes just call
> ext4_mark_inode_dirty() to track modified metadata. This copies inode
> metadata into block buffer which is enough when we are journalling
> metadata. However when we are running in nojournal mode we currently
> fail to write the dirtied inode buffer during fsync(2) because the inode
> is not marked as dirty.

Please let me understand this. You mean that because some places we
directly call ext4_mark_inode_dirty() to mark the inode as dirty, instead
of using the generic mark_inode_dirty(), this results in the inode missing
the I_DIRTY_INODE flag. Consequently, generic_buffers_fsync_noflush()->
sync_inode_metadata() does not write the inode, leading to the metadata
not being updated on disk after fsync(2), right?

Reviewed-by: Zhang Yi <yi.zhang@huawei.com>

> Use explicit ext4_write_inode() call to make
> sure the inode table buffer is written to the disk. This is a band aid
> solution but proper solution requires a much larger rewrite including
> changes in metadata bh tracking infrastructure.
> 
> Reported-by: Free Ekanayaka <free.ekanayaka@gmail.com>
> Link: https://lore.kernel.org/all/87il8nhxdm.fsf@x1.mail-host-address-is-not-set/
> CC: stable@vger.kernel.org
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
>  fs/ext4/fsync.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
> index e476c6de3074..bd8f230fa507 100644
> --- a/fs/ext4/fsync.c
> +++ b/fs/ext4/fsync.c
> @@ -83,11 +83,23 @@ static int ext4_fsync_nojournal(struct file *file, loff_t start, loff_t end,
>  				int datasync, bool *needs_barrier)
>  {
>  	struct inode *inode = file->f_inode;
> +	struct writeback_control wbc = {
> +		.sync_mode = WB_SYNC_ALL,
> +		.nr_to_write = 0,
> +	};
>  	int ret;
>  
>  	ret = generic_buffers_fsync_noflush(file, start, end, datasync);
> -	if (!ret)
> -		ret = ext4_sync_parent(inode);
> +	if (ret)
> +		return ret;
> +
> +	/* Force writeout of inode table buffer to disk */
> +	ret = ext4_write_inode(inode, &wbc);
> +	if (ret)
> +		return ret;
> +
> +	ret = ext4_sync_parent(inode);
> +
>  	if (test_opt(inode->i_sb, BARRIER))
>  		*needs_barrier = true;
>  

Re: [PATCH 2/2] ext4: Fix fsync(2) for nojournal mode

[Jan Kara]

On Thu 26-02-26 19:56:34, Zhang Yi wrote:
> On 2/17/2026 12:48 AM, Jan Kara wrote:
> > When inode metadata is changed, we sometimes just call
> > ext4_mark_inode_dirty() to track modified metadata. This copies inode
> > metadata into block buffer which is enough when we are journalling
> > metadata. However when we are running in nojournal mode we currently
> > fail to write the dirtied inode buffer during fsync(2) because the inode
> > is not marked as dirty.
> 
> Please let me understand this. You mean that because some places we
> directly call ext4_mark_inode_dirty() to mark the inode as dirty, instead
> of using the generic mark_inode_dirty(), this results in the inode missing
> the I_DIRTY_INODE flag. Consequently, generic_buffers_fsync_noflush()->
> sync_inode_metadata() does not write the inode, leading to the metadata
> not being updated on disk after fsync(2), right?

Correct.

> Reviewed-by: Zhang Yi <yi.zhang@huawei.com>

Thanks for review!

								Honza

> > Use explicit ext4_write_inode() call to make
> > sure the inode table buffer is written to the disk. This is a band aid
> > solution but proper solution requires a much larger rewrite including
> > changes in metadata bh tracking infrastructure.
> > 
> > Reported-by: Free Ekanayaka <free.ekanayaka@gmail.com>
> > Link: https://lore.kernel.org/all/87il8nhxdm.fsf@x1.mail-host-address-is-not-set/
> > CC: stable@vger.kernel.org
> > Signed-off-by: Jan Kara <jack@suse.cz>
> > ---
> >  fs/ext4/fsync.c | 16 ++++++++++++++--
> >  1 file changed, 14 insertions(+), 2 deletions(-)
> > 
> > diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
> > index e476c6de3074..bd8f230fa507 100644
> > --- a/fs/ext4/fsync.c
> > +++ b/fs/ext4/fsync.c
> > @@ -83,11 +83,23 @@ static int ext4_fsync_nojournal(struct file *file, loff_t start, loff_t end,
> >  				int datasync, bool *needs_barrier)
> >  {
> >  	struct inode *inode = file->f_inode;
> > +	struct writeback_control wbc = {
> > +		.sync_mode = WB_SYNC_ALL,
> > +		.nr_to_write = 0,
> > +	};
> >  	int ret;
> >  
> >  	ret = generic_buffers_fsync_noflush(file, start, end, datasync);
> > -	if (!ret)
> > -		ret = ext4_sync_parent(inode);
> > +	if (ret)
> > +		return ret;
> > +
> > +	/* Force writeout of inode table buffer to disk */
> > +	ret = ext4_write_inode(inode, &wbc);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = ext4_sync_parent(inode);
> > +
> >  	if (test_opt(inode->i_sb, BARRIER))
> >  		*needs_barrier = true;
> >  
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR