[Ocfs2-devel] [PATCH 2/4] ocfs2: take ip_alloc_sem in ocfs2_dio_get_block & ocfs2_dio_end_io_write

[Junxiao Bi <junxiao.bi@oracle.com>]

On 11/20/2015 04:23 PM, Ryan Ding wrote:
> Take ip_alloc_sem to prevent concurrent access to extent tree, which may cause
> the extent tree in an unstable state.
> 
> Signed-off-by: Ryan Ding <ryan.ding@oracle.com>
Looks good.

Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
> ---
>  fs/ocfs2/aops.c |   23 +++++++++++++++++------
>  1 files changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
> index cc604a2..d571509 100644
> --- a/fs/ocfs2/aops.c
> +++ b/fs/ocfs2/aops.c
> @@ -2151,6 +2151,7 @@ static int ocfs2_dio_get_block(struct inode *inode, sector_t iblock,
>  			       struct buffer_head *bh_result, int create)
>  {
>  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
> +	struct ocfs2_inode_info *oi = OCFS2_I(inode);
>  	struct ocfs2_write_ctxt *wc;
>  	struct ocfs2_write_cluster_desc *desc = NULL;
>  	struct ocfs2_dio_write_ctxt *dwc = NULL;
> @@ -2166,9 +2167,12 @@ static int ocfs2_dio_get_block(struct inode *inode, sector_t iblock,
>  	mlog(0, "get block of %lu at %llu:%u req %u\n",
>  			inode->i_ino, pos, len, total_len);
>  
> +	down_read(&oi->ip_alloc_sem);
>  	/* This is the fast path for re-write. */
>  	ret = ocfs2_get_block(inode, iblock, bh_result, create);
>  
> +	up_read(&oi->ip_alloc_sem);
> +
>  	if (buffer_mapped(bh_result) &&
>  	    !buffer_new(bh_result) &&
>  	    ret == 0)
> @@ -2206,6 +2210,8 @@ static int ocfs2_dio_get_block(struct inode *inode, sector_t iblock,
>  		goto out;
>  	}
>  
> +	down_write(&oi->ip_alloc_sem);
> +
>  	if (first_get_block) {
>  		if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
>  			ret = ocfs2_zero_tail(inode, di_bh, pos);
> @@ -2259,6 +2265,7 @@ static int ocfs2_dio_get_block(struct inode *inode, sector_t iblock,
>  	BUG_ON(ret != len);
>  	ret = 0;
>  unlock:
> +	up_write(&oi->ip_alloc_sem);
>  	ocfs2_inode_unlock(inode, 1);
>  	brelse(di_bh);
>  out:
> @@ -2275,6 +2282,7 @@ static void ocfs2_dio_end_io_write(struct inode *inode,
>  	struct ocfs2_cached_dealloc_ctxt dealloc;
>  	struct ocfs2_extent_tree et;
>  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
> +	struct ocfs2_inode_info *oi = OCFS2_I(inode);
>  	struct ocfs2_unwritten_extent *ue = NULL;
>  	struct buffer_head *di_bh = NULL;
>  	struct ocfs2_dinode *di;
> @@ -2293,12 +2301,6 @@ static void ocfs2_dio_end_io_write(struct inode *inode,
>  	    !dwc->dw_orphaned)
>  		goto out;
>  
> -	ret = ocfs2_inode_lock(inode, &di_bh, 1);
> -	if (ret < 0) {
> -		mlog_errno(ret);
> -		goto out;
> -	}
> -
>  	/* ocfs2_file_write_iter will get i_mutex, so we need not lock if we
>  	 * are in that context. */
>  	if (dwc->dw_writer_pid != task_pid_nr(current)) {
> @@ -2306,6 +2308,14 @@ static void ocfs2_dio_end_io_write(struct inode *inode,
>  		locked = 1;
>  	}
>  
> +	ret = ocfs2_inode_lock(inode, &di_bh, 1);
> +	if (ret < 0) {
> +		mlog_errno(ret);
> +		goto out;
> +	}
> +
> +	down_write(&oi->ip_alloc_sem);
> +
>  	/* Delete orphan before acquire i_mutex. */
>  	if (dwc->dw_orphaned) {
>  		BUG_ON(dwc->dw_writer_pid != task_pid_nr(current));
> @@ -2359,6 +2369,7 @@ static void ocfs2_dio_end_io_write(struct inode *inode,
>  commit:
>  	ocfs2_commit_trans(osb, handle);
>  unlock:
> +	up_write(&oi->ip_alloc_sem);
>  	ocfs2_inode_unlock(inode, 1);
>  	brelse(di_bh);
>  out:
>