linux-ext4 - Re: [PATCH 1/2] ext4: use handle to mark fc as ineligible in __track_dentry

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Message-ID: <20240919214749.s2imkiffjfc5ziqe@quack3>
Date: Thu, 19 Sep 2024 23:47:49 +0200
From: Jan Kara <jack@...e.cz>
To: "Luis Henriques (SUSE)" <luis.henriques@...ux.dev>
Cc: Theodore Ts'o <tytso@....edu>, Andreas Dilger <adilger@...ger.ca>,
	Jan Kara <jack@...e.cz>,
	Harshad Shirwadkar <harshadshirwadkar@...il.com>,
	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] ext4: use handle to mark fc as ineligible in
 __track_dentry_update()

On Thu 19-09-24 10:38:47, Luis Henriques (SUSE) wrote:
> Calling ext4_fc_mark_ineligible() with a NULL handle is racy and may result
> in a fast-commit being done before the filesystem is effectively marked as
> ineligible.  This patch fixes the calls to this function in
> __track_dentry_update() by adding an extra parameter to the callback used in
> ext4_fc_track_template().
> 
> Suggested-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Luis Henriques (SUSE) <luis.henriques@...ux.dev>

This looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/ext4/fast_commit.c | 19 +++++++++++--------
>  1 file changed, 11 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
> index 3926a05eceee..c330efd771d1 100644
> --- a/fs/ext4/fast_commit.c
> +++ b/fs/ext4/fast_commit.c
> @@ -372,7 +372,7 @@ void ext4_fc_mark_ineligible(struct super_block *sb, int reason, handle_t *handl
>   */
>  static int ext4_fc_track_template(
>  	handle_t *handle, struct inode *inode,
> -	int (*__fc_track_fn)(struct inode *, void *, bool),
> +	int (*__fc_track_fn)(handle_t *handle, struct inode *, void *, bool),
>  	void *args, int enqueue)
>  {
>  	bool update = false;
> @@ -389,7 +389,7 @@ static int ext4_fc_track_template(
>  		ext4_fc_reset_inode(inode);
>  		ei->i_sync_tid = tid;
>  	}
> -	ret = __fc_track_fn(inode, args, update);
> +	ret = __fc_track_fn(handle, inode, args, update);
>  	mutex_unlock(&ei->i_fc_lock);
>  
>  	if (!enqueue)
> @@ -413,7 +413,8 @@ struct __track_dentry_update_args {
>  };
>  
>  /* __track_fn for directory entry updates. Called with ei->i_fc_lock. */
> -static int __track_dentry_update(struct inode *inode, void *arg, bool update)
> +static int __track_dentry_update(handle_t *handle, struct inode *inode,
> +				 void *arg, bool update)
>  {
>  	struct ext4_fc_dentry_update *node;
>  	struct ext4_inode_info *ei = EXT4_I(inode);
> @@ -428,14 +429,14 @@ static int __track_dentry_update(struct inode *inode, void *arg, bool update)
>  
>  	if (IS_ENCRYPTED(dir)) {
>  		ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_ENCRYPTED_FILENAME,
> -					NULL);
> +					handle);
>  		mutex_lock(&ei->i_fc_lock);
>  		return -EOPNOTSUPP;
>  	}
>  
>  	node = kmem_cache_alloc(ext4_fc_dentry_cachep, GFP_NOFS);
>  	if (!node) {
> -		ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM, NULL);
> +		ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM, handle);
>  		mutex_lock(&ei->i_fc_lock);
>  		return -ENOMEM;
>  	}
> @@ -447,7 +448,7 @@ static int __track_dentry_update(struct inode *inode, void *arg, bool update)
>  		node->fcd_name.name = kmalloc(dentry->d_name.len, GFP_NOFS);
>  		if (!node->fcd_name.name) {
>  			kmem_cache_free(ext4_fc_dentry_cachep, node);
> -			ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM, NULL);
> +			ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM, handle);
>  			mutex_lock(&ei->i_fc_lock);
>  			return -ENOMEM;
>  		}
> @@ -569,7 +570,8 @@ void ext4_fc_track_create(handle_t *handle, struct dentry *dentry)
>  }
>  
>  /* __track_fn for inode tracking */
> -static int __track_inode(struct inode *inode, void *arg, bool update)
> +static int __track_inode(handle_t *handle, struct inode *inode, void *arg,
> +			 bool update)
>  {
>  	if (update)
>  		return -EEXIST;
> @@ -607,7 +609,8 @@ struct __track_range_args {
>  };
>  
>  /* __track_fn for tracking data updates */
> -static int __track_range(struct inode *inode, void *arg, bool update)
> +static int __track_range(handle_t *handle, struct inode *inode, void *arg,
> +			 bool update)
>  {
>  	struct ext4_inode_info *ei = EXT4_I(inode);
>  	ext4_lblk_t oldstart;
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR