[PATCH 03/24] GFS2: Fix bug-trap in ail flush code

From: Steven Whitehouse
Date: Mon Oct 24 2011 - 08:47:33 EST

The assert was being tested under the wrong lock, a
legacy of the original code. Also, if it does trigger,
the resulting information was not always a lot of help.

This moves the patch under the correct lock and also
prints out more useful information in tacking down the
source of the problem.

Signed-off-by: Steven Whitehouse <swhiteho@xxxxxxxxxx>

diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c
index da21eca..99df483 100644
--- a/fs/gfs2/glops.c
+++ b/fs/gfs2/glops.c
@@ -28,6 +28,17 @@
#include "trans.h"
#include "dir.h"

+static void gfs2_ail_error(struct gfs2_glock *gl, const struct buffer_head *bh)
+ fs_err(gl->gl_sbd, "AIL buffer %p: blocknr %llu state 0x%08lx mapping %p page state 0x%lx\n",
+ bh, (unsigned long long)bh->b_blocknr, bh->b_state,
+ bh->b_page->mapping, bh->b_page->flags);
+ fs_err(gl->gl_sbd, "AIL glock %u:%llu mapping %p\n",
+ gl->gl_name.ln_type, gl->gl_name.ln_number,
+ gfs2_glock2aspace(gl));
+ gfs2_lm_withdraw(gl->gl_sbd, "AIL error\n");
* __gfs2_ail_flush - remove all buffers for a given lock from the AIL
* @gl: the glock
@@ -41,20 +52,24 @@ static void __gfs2_ail_flush(struct gfs2_glock *gl)
struct list_head *head = &gl->gl_ail_list;
struct gfs2_bufdata *bd;
struct buffer_head *bh;
+ sector_t blocknr;

while (!list_empty(head)) {
bd = list_entry(head->next, struct gfs2_bufdata,
bh = bd->bd_bh;
- gfs2_remove_from_ail(bd);
- bd->bd_bh = NULL;
+ blocknr = bh->b_blocknr;
+ if (buffer_busy(bh))
+ gfs2_ail_error(gl, bh);
bh->b_private = NULL;
+ gfs2_remove_from_ail(bd); /* drops ref on bh */

- bd->bd_blkno = bh->b_blocknr;
+ bd->bd_bh = NULL;
+ bd->bd_blkno = blocknr;
- gfs2_assert_withdraw(sdp, !buffer_busy(bh));
gfs2_trans_add_revoke(sdp, bd);


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