[Cluster-devel] [GFS2 PATCH] GFS2: Check rs_free with rd_rsspin protection

[Cluster-devel] [GFS2 PATCH] GFS2: Check rs_free with rd_rsspin protection

[Bob Peterson]

Hi,

For the last process to close a file opened for write, function
gfs2_rsqa_delete was deleting the file's inode's block reservation
out of the rgrp reservations tree. Then it was checking to make sure
rs_free was 0, but it was performing the check outside the protection
of rd_rsspin spin_lock. The rd_rsspin spin_lock protection is needed
to prevent a race between the process freeing the reservation and
another who is allocating a new set of blocks inside the same rgrp
for the same inode, thus changing its value.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>

Regards,

Bob Peterson
Red Hat File Systems
---
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index fba38ca..86ccc015 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -658,6 +658,7 @@ void gfs2_rs_deltree(struct gfs2_blkreserv *rs)
 	if (rgd) {
 		spin_lock(&rgd->rd_rsspin);
 		__rs_deltree(rs);
+		BUG_ON(rs->rs_free);
 		spin_unlock(&rgd->rd_rsspin);
 	}
 }
@@ -671,10 +672,8 @@ void gfs2_rs_deltree(struct gfs2_blkreserv *rs)
 void gfs2_rsqa_delete(struct gfs2_inode *ip, atomic_t *wcount)
 {
 	down_write(&ip->i_rw_mutex);
-	if ((wcount == NULL) || (atomic_read(wcount) <= 1)) {
+	if ((wcount == NULL) || (atomic_read(wcount) <= 1))
 		gfs2_rs_deltree(&ip->i_res);
-		BUG_ON(ip->i_res.rs_free);
-	}
 	up_write(&ip->i_rw_mutex);
 	gfs2_qa_delete(ip, wcount);
 }

[Cluster-devel] [GFS2 PATCH] GFS2: Check rs_free with rd_rsspin protection

[Steven Whitehouse]

Hi,

Acked-by: Steven Whitehouse <swhiteho@redhat.com>

Steve.

On 06/07/16 16:52, Bob Peterson wrote:
> Hi,
>
> For the last process to close a file opened for write, function
> gfs2_rsqa_delete was deleting the file's inode's block reservation
> out of the rgrp reservations tree. Then it was checking to make sure
> rs_free was 0, but it was performing the check outside the protection
> of rd_rsspin spin_lock. The rd_rsspin spin_lock protection is needed
> to prevent a race between the process freeing the reservation and
> another who is allocating a new set of blocks inside the same rgrp
> for the same inode, thus changing its value.
>
> Signed-off-by: Bob Peterson <rpeterso@redhat.com>
>
> Regards,
>
> Bob Peterson
> Red Hat File Systems
> ---
> diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
> index fba38ca..86ccc015 100644
> --- a/fs/gfs2/rgrp.c
> +++ b/fs/gfs2/rgrp.c
> @@ -658,6 +658,7 @@ void gfs2_rs_deltree(struct gfs2_blkreserv *rs)
>   	if (rgd) {
>   		spin_lock(&rgd->rd_rsspin);
>   		__rs_deltree(rs);
> +		BUG_ON(rs->rs_free);
>   		spin_unlock(&rgd->rd_rsspin);
>   	}
>   }
> @@ -671,10 +672,8 @@ void gfs2_rs_deltree(struct gfs2_blkreserv *rs)
>   void gfs2_rsqa_delete(struct gfs2_inode *ip, atomic_t *wcount)
>   {
>   	down_write(&ip->i_rw_mutex);
> -	if ((wcount == NULL) || (atomic_read(wcount) <= 1)) {
> +	if ((wcount == NULL) || (atomic_read(wcount) <= 1))
>   		gfs2_rs_deltree(&ip->i_res);
> -		BUG_ON(ip->i_res.rs_free);
> -	}
>   	up_write(&ip->i_rw_mutex);
>   	gfs2_qa_delete(ip, wcount);
>   }
>