UBIFS: improve space checking debugging feature

This patch improves the 'dbg_check_space_info()' function which checks
whether the amount of space before re-mounting and after re-mounting
is the same (remounting from R/O to R/W modes and vice-versa).

The problem is that 'dbg_check_space_info()' does not save the budgeting
information before re-mounting, so when an error is reported, we do not
know why the amount of free space changed.

This patches makes the following changes:

1. Teaches 'dbg_dump_budg()' function to accept a 'struct ubifs_budg_info'
   argument and print out the this argument. This way we may ask it to
   print any saved budgeting info, no only the current one.
2. Accordingly changes all the callers of 'dbg_dump_budg()' to comply with
   the changed interface.
3. Introduce a 'saved_bi' (saved budgeting info) field to
   'struct ubifs_debug_info' and save the budgeting info before re-mounting
   there.
4. Change 'dbg_check_space_info()' and make it print both old and new
   budgeting information.
5. Additionally, save 'c->igx_gc_cnt' and print it if and error happens. This
   value contributes to the amount of free space, so we have to print it.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 29 insertions, 13 deletions

diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 8e8bba93733..546ad575b66 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -602,7 +602,7 @@ void dbg_dump_lstats(const struct ubifs_lp_stats *lst)
 	spin_unlock(&dbg_lock);
 }
 
-void dbg_dump_budg(struct ubifs_info *c)
+void dbg_dump_budg(struct ubifs_info *c, const struct ubifs_budg_info *bi)
 {
 	int i;
 	struct rb_node *rb;
@@ -614,20 +614,29 @@ void dbg_dump_budg(struct ubifs_info *c)
 	spin_lock(&dbg_lock);
 	printk(KERN_DEBUG "(pid %d) Budgeting info: data budget sum %lld, "
 	       "total budget sum %lld\n", current->pid,
-	       c->bi.data_growth + c->bi.dd_growth,
-	       c->bi.data_growth + c->bi.dd_growth + c->bi.idx_growth);
+	       bi->data_growth + bi->dd_growth,
+	       bi->data_growth + bi->dd_growth + bi->idx_growth);
 	printk(KERN_DEBUG "\tbudg_data_growth %lld, budg_dd_growth %lld, "
-	       "budg_idx_growth %lld\n", c->bi.data_growth, c->bi.dd_growth,
-	       c->bi.idx_growth);
+	       "budg_idx_growth %lld\n", bi->data_growth, bi->dd_growth,
+	       bi->idx_growth);
 	printk(KERN_DEBUG "\tmin_idx_lebs %d, old_idx_sz %llu, "
-	       "uncommitted_idx %lld\n", c->bi.min_idx_lebs, c->bi.old_idx_sz,
-	       c->bi.uncommitted_idx);
+	       "uncommitted_idx %lld\n", bi->min_idx_lebs, bi->old_idx_sz,
+	       bi->uncommitted_idx);
 	printk(KERN_DEBUG "\tpage_budget %d, inode_budget %d, dent_budget %d\n",
-	       c->bi.page_budget, c->bi.inode_budget, c->bi.dent_budget);
+	       bi->page_budget, bi->inode_budget, bi->dent_budget);
 	printk(KERN_DEBUG "\tnospace %u, nospace_rp %u\n",
-	       c->bi.nospace, c->bi.nospace_rp);
+	       bi->nospace, bi->nospace_rp);
 	printk(KERN_DEBUG "\tdark_wm %d, dead_wm %d, max_idx_node_sz %d\n",
 	       c->dark_wm, c->dead_wm, c->max_idx_node_sz);
+
+	if (bi != &c->bi)
+		/*
+		 * If we are dumping saved budgeting data, do not print
+		 * additional information which is about the current state, not
+		 * the old one which corresponded to the saved budgeting data.
+		 */
+		goto out_unlock;
+
 	printk(KERN_DEBUG "\tfreeable_cnt %d, calc_idx_sz %lld, idx_gc_cnt %d\n",
 	       c->freeable_cnt, c->calc_idx_sz, c->idx_gc_cnt);
 	printk(KERN_DEBUG "\tdirty_pg_cnt %ld, dirty_zn_cnt %ld, "
@@ -636,6 +645,7 @@ void dbg_dump_budg(struct ubifs_info *c)
 	       atomic_long_read(&c->clean_zn_cnt));
 	printk(KERN_DEBUG "\tgc_lnum %d, ihead_lnum %d\n",
 	       c->gc_lnum, c->ihead_lnum);
+
 	/* If we are in R/O mode, journal heads do not exist */
 	if (c->jheads)
 		for (i = 0; i < c->jhead_cnt; i++)
@@ -660,6 +670,7 @@ void dbg_dump_budg(struct ubifs_info *c)
 	printk(KERN_DEBUG "Budgeting predictions:\n");
 	printk(KERN_DEBUG "\tavailable: %lld, outstanding %lld, free %lld\n",
 	       available, outstanding, free);
+out_unlock:
 	spin_unlock(&dbg_lock);
 	spin_unlock(&c->space_lock);
 }
@@ -983,6 +994,8 @@ void dbg_save_space_info(struct ubifs_info *c)
 
 	spin_lock(&c->space_lock);
 	memcpy(&d->saved_lst, &c->lst, sizeof(struct ubifs_lp_stats));
+	memcpy(&d->saved_bi, &c->bi, sizeof(struct ubifs_budg_info));
+	d->saved_idx_gc_cnt = c->idx_gc_cnt;
 
 	/*
 	 * We use a dirty hack here and zero out @c->freeable_cnt, because it
@@ -1049,11 +1062,14 @@ int dbg_check_space_info(struct ubifs_info *c)
 out:
 	ubifs_msg("saved lprops statistics dump");
 	dbg_dump_lstats(&d->saved_lst);
-	ubifs_get_lp_stats(c, &lst);
-
+	ubifs_msg("saved budgeting info dump");
+	dbg_dump_budg(c, &d->saved_bi);
+	ubifs_msg("saved idx_gc_cnt %d", d->saved_idx_gc_cnt);
 	ubifs_msg("current lprops statistics dump");
+	ubifs_get_lp_stats(c, &lst);
 	dbg_dump_lstats(&lst);
-	dbg_dump_budg(c);
+	ubifs_msg("current budgeting info dump");
+	dbg_dump_budg(c, &c->bi);
 	dump_stack();
 	return -EINVAL;
 }
@@ -2801,7 +2817,7 @@ static ssize_t write_debugfs_file(struct file *file, const char __user *buf,
 	if (file->f_path.dentry == d->dfs_dump_lprops)
 		dbg_dump_lprops(c);
 	else if (file->f_path.dentry == d->dfs_dump_budg)
-		dbg_dump_budg(c);
+		dbg_dump_budg(c, &c->bi);
 	else if (file->f_path.dentry == d->dfs_dump_tnc) {
 		mutex_lock(&c->tnc_mutex);
 		dbg_dump_tnc(c);