[Cluster-devel] [GFS2] Fix glock dumping oops

[Kevin Anderson <kanderso@redhat.com>]

What bugzilla does this address?

Kevin

On Tue, 2007-07-24 at 14:11 +0100, Steven Whitehouse wrote:
> Hi,
> 
> This fixes an oops which was occurring during glock dumping due to the
> seq file code not taking a reference to the glock. Also this fixes a
> memory leak which occurred in certain cases, in turn preventing the
> filesystem from unmounting.
> 
> Steve.
> 
> ----------------------------------------------------------------------
> diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
> index d403fd7..e4bc8ae 100644
> --- a/fs/gfs2/glock.c
> +++ b/fs/gfs2/glock.c
> @@ -46,7 +46,6 @@ struct glock_iter {
>  	int hash;                     /* hash bucket index         */
>  	struct gfs2_sbd *sdp;         /* incore superblock         */
>  	struct gfs2_glock *gl;        /* current glock struct      */
> -	struct hlist_head *hb_list;   /* current hash bucket ptr   */
>  	struct seq_file *seq;         /* sequence file for debugfs */
>  	char string[512];             /* scratch space             */
>  };
> @@ -1990,47 +1989,38 @@ int __init gfs2_glock_init(void)
>  
>  static int gfs2_glock_iter_next(struct glock_iter *gi)
>  {
> +	struct gfs2_glock *gl;
> +
>  	read_lock(gl_lock_addr(gi->hash));
> -	while (1) {
> -		if (!gi->hb_list) {  /* If we don't have a hash bucket yet */
> -			gi->hb_list = &gl_hash_table[gi->hash].hb_list;
> -			if (hlist_empty(gi->hb_list)) {
> -				read_unlock(gl_lock_addr(gi->hash));
> -				gi->hash++;
> -				read_lock(gl_lock_addr(gi->hash));
> -				gi->hb_list = NULL;
> -				if (gi->hash >= GFS2_GL_HASH_SIZE) {
> -					read_unlock(gl_lock_addr(gi->hash));
> -					return 1;
> -				}
> -				else
> -					continue;
> -			}
> -			if (!hlist_empty(gi->hb_list)) {
> -				gi->gl = list_entry(gi->hb_list->first,
> -						    struct gfs2_glock,
> -						    gl_list);
> -			}
> -		} else {
> -			if (gi->gl->gl_list.next == NULL) {
> -				read_unlock(gl_lock_addr(gi->hash));
> -				gi->hash++;
> -				read_lock(gl_lock_addr(gi->hash));
> -				gi->hb_list = NULL;
> -				continue;
> -			}
> -			gi->gl = list_entry(gi->gl->gl_list.next,
> -					    struct gfs2_glock, gl_list);
> -		}
> +	gl = gi->gl;
> +	if (gl) {
> +		gi->gl = hlist_entry(gl->gl_list.next, struct gfs2_glock,
> +				     gl_list);
>  		if (gi->gl)
> -			break;
> +			gfs2_glock_hold(gi->gl);
>  	}
>  	read_unlock(gl_lock_addr(gi->hash));
> +	if (gl)
> +		gfs2_glock_put(gl);
> +
> +	while(gi->gl == NULL) {
> +		gi->hash++;
> +		if (gi->hash >= GFS2_GL_HASH_SIZE)
> +			return 1;
> +		read_lock(gl_lock_addr(gi->hash));
> +		gi->gl = hlist_entry(gl_hash_table[gi->hash].hb_list.first,
> +				     struct gfs2_glock, gl_list);
> +		if (gi->gl)
> +			gfs2_glock_hold(gi->gl);
> +		read_unlock(gl_lock_addr(gi->hash));
> +	}
>  	return 0;
>  }
>  
>  static void gfs2_glock_iter_free(struct glock_iter *gi)
>  {
> +	if (gi->gl)
> +		gfs2_glock_put(gi->gl);
>  	kfree(gi);
>  }
>  
> @@ -2044,12 +2034,17 @@ static struct glock_iter *gfs2_glock_iter_init(struct gfs2_sbd *sdp)
>  
>  	gi->sdp = sdp;
>  	gi->hash = 0;
> -	gi->gl = NULL;
> -	gi->hb_list = NULL;
>  	gi->seq = NULL;
>  	memset(gi->string, 0, sizeof(gi->string));
>  
> -	if (gfs2_glock_iter_next(gi)) {
> +	read_lock(gl_lock_addr(gi->hash));
> +	gi->gl = hlist_entry(gl_hash_table[gi->hash].hb_list.first,
> +			     struct gfs2_glock, gl_list);
> +	if (gi->gl)
> +		gfs2_glock_hold(gi->gl);
> +	read_unlock(gl_lock_addr(gi->hash));
> +
> +	if (!gi->gl && gfs2_glock_iter_next(gi)) {
>  		gfs2_glock_iter_free(gi);
>  		return NULL;
>  	}
> @@ -2066,7 +2061,7 @@ static void *gfs2_glock_seq_start(struct seq_file *file, loff_t *pos)
>  	if (!gi)
>  		return NULL;
>  
> -	while (n--) {
> +	while(n--) {
>  		if (gfs2_glock_iter_next(gi)) {
>  			gfs2_glock_iter_free(gi);
>  			return NULL;
> @@ -2093,7 +2088,9 @@ static void *gfs2_glock_seq_next(struct seq_file *file, void *iter_ptr,
>  
>  static void gfs2_glock_seq_stop(struct seq_file *file, void *iter_ptr)
>  {
> -	/* nothing for now */
> +	struct glock_iter *gi = iter_ptr;
> +	if (gi)
> +		gfs2_glock_iter_free(gi);
>  }
>  
>  static int gfs2_glock_seq_show(struct seq_file *file, void *iter_ptr)
> 
> 
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