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Date:   Tue, 29 Jan 2019 18:23:05 -0700
From:   Andreas Dilger <adilger@...ger.ca>
To:     "Theodore Y. Ts'o" <tytso@....edu>
Cc:     Nikolay Borisov <nborisov@...e.com>,
        Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] ext4: Replace opencoded i_writecount usage with
 inode_is_open_for_write

On Dec 11, 2018, at 1:23 AM, Nikolay Borisov <nborisov@...e.com> wrote:
> 
> There is a function which clearly conveys the objective of checking
> i_writecount. Additionally the usage in ext4_mb_initialize_context was
> wrong, since a node would have wrongfully been reported as writable if
> i_writecount had a negative value (MMAP_DENY_WRITE).
> 
> Reviewed-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Nikolay Borisov <nborisov@...e.com>

Reviewed-by: Andreas Dilger <adilger@...ger.ca>

> ---
> fs/ext4/inode.c   | 2 +-
> fs/ext4/mballoc.c | 7 +++----
> 2 files changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 22a9d8159720..04e5bc0b5c8d 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -391,7 +391,7 @@ void ext4_da_update_reserve_space(struct inode *inode,
> 	 * inode's preallocations.
> 	 */
> 	if ((ei->i_reserved_data_blocks == 0) &&
> -	    (atomic_read(&inode->i_writecount) == 0))
> +	    !inode_is_open_for_write(inode))
> 		ext4_discard_preallocations(inode);
> }
> 
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index e2248083cdca..6fb76d408093 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -4176,9 +4176,8 @@ static void ext4_mb_group_or_file(struct ext4_allocation_context *ac)
> 	isize = (i_size_read(ac->ac_inode) + ac->ac_sb->s_blocksize - 1)
> 		>> bsbits;
> 
> -	if ((size == isize) &&
> -	    !ext4_fs_is_busy(sbi) &&
> -	    (atomic_read(&ac->ac_inode->i_writecount) == 0)) {
> +	if ((size == isize) && !ext4_fs_is_busy(sbi) &&
> +	    !inode_is_open_for_write(ac->ac_inode)) {
> 		ac->ac_flags |= EXT4_MB_HINT_NOPREALLOC;
> 		return;
> 	}
> @@ -4258,7 +4257,7 @@ ext4_mb_initialize_context(struct ext4_allocation_context *ac,
> 			(unsigned) ar->goal, ac->ac_flags, ac->ac_2order,
> 			(unsigned) ar->lleft, (unsigned) ar->pleft,
> 			(unsigned) ar->lright, (unsigned) ar->pright,
> -			atomic_read(&ar->inode->i_writecount) ? "" : "non-");
> +			inode_is_open_for_write(ar->inode) ? "" : "non-");
> 	return 0;
> 
> }
> --
> 2.17.1
> 


Cheers, Andreas






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