linux-ext4 - Re: [PATCH] ext4: Remove redundant check under lock scope

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Message-ID: <87mw2ki6ur.fsf@openvz.org>
Date:	Tue, 07 Apr 2015 13:13:32 +0300
From:	Dmitry Monakhov <dmonlist@...il.com>
To:	Davide Italiano <dccitaliano@...il.com>, linux-ext4@...r.kernel.org
Cc:	Davide Italiano <dccitaliano@...il.com>
Subject: Re: [PATCH] ext4: Remove redundant check under lock scope

Davide Italiano <dccitaliano@...il.com> writes:

> ext4_zero_range() and ext4_collapse_range() duplicate
> the check in ext4_fallocate(). The checks are made with
> inode lock held when there's no need for that. Remove them,
> reducing the scope of the lock.
NAK. Other task can convert indirect<=>extent via
ioctl(, EXT4_IOC_SETFLAGS, flags)
  ->ext4_ext_migrate()
  ->ext4_int_migrate()
So we _must_ recheck EXT4_INODE_EXTENTS after we grab i_mutex.
>
> Signed-off-by: Davide Italiano <dccitaliano@...il.com>
> ---
>  fs/ext4/extents.c | 16 ----------------
>  1 file changed, 16 deletions(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index bed4308..9e6fa09 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4810,15 +4810,6 @@ static long ext4_zero_range(struct file *file, loff_t offset,
>  		flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
>  
>  	mutex_lock(&inode->i_mutex);
> -
> -	/*
> -	 * Indirect files do not support unwritten extnets
> -	 */
> -	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
> -		ret = -EOPNOTSUPP;
> -		goto out_mutex;
> -	}
> -
>  	if (!(mode & FALLOC_FL_KEEP_SIZE) &&
>  	     offset + len > i_size_read(inode)) {
>  		new_size = offset + len;
> @@ -5445,13 +5436,6 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
>  		ret = -EINVAL;
>  		goto out_mutex;
>  	}
> -
> -	/* Currently just for extent based files */
> -	if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
> -		ret = -EOPNOTSUPP;
> -		goto out_mutex;
> -	}
> -
>  	truncate_pagecache(inode, ioffset);
>  
>  	/* Wait for existing dio to complete */
> -- 
> 2.3.4
>
> --
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