linux-ext4 - Re: [PATCH v2] fs: Convert open-coded "is inode open for write" check

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Message-Id: <C2F1A10B-9035-409F-AF7C-EDCF9C1648C3@dilger.ca>
Date:   Mon, 10 Dec 2018 13:18:25 -0700
From:   Andreas Dilger <adilger@...ger.ca>
To:     Nikolay Borisov <nborisov@...e.com>
Cc:     linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Jan Kara <jack@...e.cz>, linux-integrity@...r.kernel.org,
        Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        Amir Goldstein <amir73il@...il.com>, jmorris@...ei.org,
        jlayton@...nel.org, "Theodore Y. Ts'o" <tytso@....edu>,
        Ext4 Developers List <linux-ext4@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v2] fs: Convert open-coded "is inode open for write" check

On Dec 10, 2018, at 6:25 AM, Nikolay Borisov <nborisov@...e.com> wrote:
> 
> There is a generic helper inode_is_open_for_write that could be used
> when checking i_writecount. Use it instead of opencoding
> if (i_writecount > 0) check.
> 
> Signed-off-by: Nikolay Borisov <nborisov@...e.com>
> ---
> 
> Changes v2:
> * This time actually compile-tested it, doh...
> 
> 
> fs/ext4/inode.c                    | 2 +-
> fs/ext4/mballoc.c                  | 7 +++----
> fs/locks.c                         | 2 +-
> fs/notify/fanotify/fanotify_user.c | 2 +-
> security/integrity/ima/ima_main.c  | 2 +-
> 5 files changed, 7 insertions(+), 8 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..b811a9cb896e 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)) {

If you will note the other cases in this patch, the "&&" operator should go
at the end of the previous line, instead of the start of the continued line.

Cheers, Andreas

> 		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;
> 
> }
> diff --git a/fs/locks.c b/fs/locks.c
> index 2ecb4db8c840..16ea7d89a67d 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -1646,7 +1646,7 @@ check_conflicting_open(const struct dentry *dentry, const long arg, int flags)
> 	if (flags & FL_LAYOUT)
> 		return 0;
> 
> -	if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
> +	if ((arg == F_RDLCK) && inode_is_open_for_write(inode))
> 		return -EAGAIN;
> 
> 	if ((arg == F_WRLCK) && ((d_count(dentry) > 1) ||
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index e03be5071362..98b0769e4cf2 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -669,7 +669,7 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group,
> 	 */
> 	if ((flags & FAN_MARK_IGNORED_MASK) &&
> 	    !(flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
> -	    (atomic_read(&inode->i_writecount) > 0))
> +	    inode_is_open_for_write(inode))
> 		return 0;
> 
> 	return fanotify_add_mark(group, &inode->i_fsnotify_marks,
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 1b88d58e1325..05fbf8a2fa42 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -103,7 +103,7 @@ static void ima_rdwr_violation_check(struct file *file,
> 	} else {
> 		if (must_measure)
> 			set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
> -		if ((atomic_read(&inode->i_writecount) > 0) && must_measure)
> +		if (inode_is_open_for_write(inode) && must_measure)
> 			send_writers = true;
> 	}
> 
> --
> 2.17.1
> 


Cheers, Andreas






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