1 files changed, 46 insertions, 17 deletions

diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index f25a7339f800..004d3745dc45 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -972,11 +972,39 @@ void dbg_dump_index(struct ubifs_info *c)
 void dbg_save_space_info(struct ubifs_info *c)
 {
         struct ubifs_debug_info *d = c->dbg;
-
-        ubifs_get_lp_stats(c, &d->saved_lst);
+        int freeable_cnt;
 
         spin_lock(&c->space_lock);
+        memcpy(&d->saved_lst, &c->lst, sizeof(struct ubifs_lp_stats));
+
+        /*
+         * We use a dirty hack here and zero out @c->freeable_cnt, because it
+         * affects the free space calculations, and UBIFS might not know about
+         * all freeable eraseblocks. Indeed, we know about freeable eraseblocks
+         * only when we read their lprops, and we do this only lazily, upon the
+         * need. So at any given point of time @c->freeable_cnt might be not
+         * exactly accurate.
+         *
+         * Just one example about the issue we hit when we did not zero
+         * @c->freeable_cnt.
+         * 1. The file-system is mounted R/O, c->freeable_cnt is %0. We save the
+         *    amount of free space in @d->saved_free
+         * 2. We re-mount R/W, which makes UBIFS to read the "lsave"
+         *    information from flash, where we cache LEBs from various
+         *    categories ('ubifs_remount_fs()' -> 'ubifs_lpt_init()'
+         *    -> 'lpt_init_wr()' -> 'read_lsave()' -> 'ubifs_lpt_lookup()'
+         *    -> 'ubifs_get_pnode()' -> 'update_cats()'
+         *    -> 'ubifs_add_to_cat()').
+         * 3. Lsave contains a freeable eraseblock, and @c->freeable_cnt
+         *    becomes %1.
+         * 4. We calculate the amount of free space when the re-mount is
+         *    finished in 'dbg_check_space_info()' and it does not match
+         *    @d->saved_free.
+         */
+        freeable_cnt = c->freeable_cnt;
+        c->freeable_cnt = 0;
         d->saved_free = ubifs_get_free_space_nolock(c);
+        c->freeable_cnt = freeable_cnt;
         spin_unlock(&c->space_lock);
 }
 
@@ -993,12 +1021,15 @@ int dbg_check_space_info(struct ubifs_info *c)
 {
         struct ubifs_debug_info *d = c->dbg;
         struct ubifs_lp_stats lst;
-        long long avail, free;
+        long long free;
+        int freeable_cnt;
 
         spin_lock(&c->space_lock);
-        avail = ubifs_calc_available(c, c->min_idx_lebs);
+        freeable_cnt = c->freeable_cnt;
+        c->freeable_cnt = 0;
+        free = ubifs_get_free_space_nolock(c);
+        c->freeable_cnt = freeable_cnt;
         spin_unlock(&c->space_lock);
-        free = ubifs_get_free_space(c);
 
         if (free != d->saved_free) {
                 ubifs_err("free space changed from %lld to %lld",
@@ -2806,40 +2837,38 @@ int dbg_debugfs_init_fs(struct ubifs_info *c)
         struct ubifs_debug_info *d = c->dbg;
 
         sprintf(d->dfs_dir_name, "ubi%d_%d", c->vi.ubi_num, c->vi.vol_id);
-        d->dfs_dir = debugfs_create_dir(d->dfs_dir_name, dfs_rootdir);
-        if (IS_ERR(d->dfs_dir)) {
-                err = PTR_ERR(d->dfs_dir);
-                ubifs_err("cannot create \"%s\" debugfs directory, error %d\n",
-                          d->dfs_dir_name, err);
+        fname = d->dfs_dir_name;
+        dent = debugfs_create_dir(fname, dfs_rootdir);
+        if (IS_ERR_OR_NULL(dent))
                 goto out;
-        }
+        d->dfs_dir = dent;
 
         fname = "dump_lprops";
         dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, c, &dfs_fops);
-        if (IS_ERR(dent))
+        if (IS_ERR_OR_NULL(dent))
                 goto out_remove;
         d->dfs_dump_lprops = dent;
 
         fname = "dump_budg";
         dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, c, &dfs_fops);
-        if (IS_ERR(dent))
+        if (IS_ERR_OR_NULL(dent))
                 goto out_remove;
         d->dfs_dump_budg = dent;
 
         fname = "dump_tnc";
         dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, c, &dfs_fops);
-        if (IS_ERR(dent))
+        if (IS_ERR_OR_NULL(dent))
                 goto out_remove;
         d->dfs_dump_tnc = dent;
 
         return 0;
 
 out_remove:
-        err = PTR_ERR(dent);
-        ubifs_err("cannot create \"%s\" debugfs directory, error %d\n",
-                  fname, err);
         debugfs_remove_recursive(d->dfs_dir);
 out:
+        err = dent ? PTR_ERR(dent) : -ENODEV;
+        ubifs_err("cannot create \"%s\" debugfs directory, error %d\n",
+                  fname, err);
         return err;
 }