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Commit ddf25aea authored by Andreas Gruenbacher's avatar Andreas Gruenbacher Committed by Greg Kroah-Hartman
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gfs2: Fix debugfs glocks dump 



commit 10201655b085df8e000822e496e5d4016a167a36 upstream.

The switch to rhashtables (commit 88ffbf3e) broke the debugfs glock
dump (/sys/kernel/debug/gfs2/<device>/glocks) for dumps bigger than a
single buffer: the right function for restarting an rhashtable iteration
from the beginning of the hash table is rhashtable_walk_enter;
rhashtable_walk_stop + rhashtable_walk_start will just resume from the
current position.

The upstream commit doesn't directly apply to 4.4.y because 4.4.y
doesn't have rhashtable_walk_enter and the following mainline commits:

  92ecd73a887c4a2b94daf5fc35179d75d1c4ef95  
    gfs2: Deduplicate gfs2_{glocks,glstats}_open
  cc37a62785a584f4875788689f3fd1fa6e4eb291  
    gfs2: Replace rhashtable_walk_init with rhashtable_walk_enter

Other than rhashtable_walk_enter, rhashtable_walk_init can fail.  To
handle the failure case in gfs2_glock_seq_stop, we check if
rhashtable_walk_init has initialized iter->walker; if it has not, we
must not call rhashtable_walk_stop or rhashtable_walk_exit.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: default avatarBob Peterson <rpeterso@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d25fea06

fs/gfs2/glock.c

+9 −12
Original line number Diff line number Diff line
@@ -1814,13 +1814,10 @@ static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos) 
{

	struct gfs2_glock_iter *gi = seq->private;

	loff_t n = *pos;

	int ret;



	if (gi->last_pos <= *pos)

		n = (*pos - gi->last_pos);



	ret = rhashtable_walk_start(&gi->hti);

	if (ret)

	if (rhashtable_walk_init(&gl_hash_table, &gi->hti) != 0)

		return NULL;

	if (rhashtable_walk_start(&gi->hti) != 0)

		return NULL;



	do {
@@ -1828,6 +1825,7 @@ static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos) 
	} while (gi->gl && n--);



	gi->last_pos = *pos;



	return gi->gl;

}
@@ -1839,6 +1837,7 @@ static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr, 
	(*pos)++;

	gi->last_pos = *pos;

	gfs2_glock_iter_next(gi);



	return gi->gl;

}
@@ -1847,7 +1846,10 @@ static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr) 
	struct gfs2_glock_iter *gi = seq->private;



	gi->gl = NULL;

	if (gi->hti.walker) {

		rhashtable_walk_stop(&gi->hti);

		rhashtable_walk_exit(&gi->hti);

	}

}



static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
@@ -1910,12 +1912,10 @@ static int gfs2_glocks_open(struct inode *inode, struct file *file) 
		struct gfs2_glock_iter *gi = seq->private;



		gi->sdp = inode->i_private;

		gi->last_pos = 0;

		seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);

		if (seq->buf)

			seq->size = GFS2_SEQ_GOODSIZE;

		gi->gl = NULL;

		ret = rhashtable_walk_init(&gl_hash_table, &gi->hti);

	}

	return ret;

}
@@ -1926,7 +1926,6 @@ static int gfs2_glocks_release(struct inode *inode, struct file *file) 
	struct gfs2_glock_iter *gi = seq->private;



	gi->gl = NULL;

	rhashtable_walk_exit(&gi->hti);

	return seq_release_private(inode, file);

}
@@ -1938,12 +1937,10 @@ static int gfs2_glstats_open(struct inode *inode, struct file *file) 
		struct seq_file *seq = file->private_data;

		struct gfs2_glock_iter *gi = seq->private;

		gi->sdp = inode->i_private;

		gi->last_pos = 0;

		seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);

		if (seq->buf)

			seq->size = GFS2_SEQ_GOODSIZE;

		gi->gl = NULL;

		ret = rhashtable_walk_init(&gl_hash_table, &gi->hti);

	}

	return ret;

}