UBIFS: always clean up GC LEB space

When we mount UBIFS, GC LEB may contain out-of-date information,
and UBIFS should update lprops and set free space for thei LEB.
Currently UBIFS does this only if mounted R/W. But for R/O mount
we have to do the same, because otherwise we will have incorrect
FS free space reported to user-space.

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

1 files changed, 33 insertions, 14 deletions

diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 5c814a71f33a..336073e4c391 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -397,6 +397,7 @@ static int ubifs_statfs(struct dentry *dentry, struct kstatfs *buf)
         buf->f_namelen = UBIFS_MAX_NLEN;
         buf->f_fsid.val[0] = le32_to_cpu(uuid[0]) ^ le32_to_cpu(uuid[2]);
         buf->f_fsid.val[1] = le32_to_cpu(uuid[1]) ^ le32_to_cpu(uuid[3]);
+        ubifs_assert(buf->f_bfree <= c->block_cnt);
         return 0;
 }
 
@@ -735,12 +736,12 @@ static void init_constants_master(struct ubifs_info *c)
  * take_gc_lnum - reserve GC LEB.
  * @c: UBIFS file-system description object
  *
- * This function ensures that the LEB reserved for garbage collection is
- * unmapped and is marked as "taken" in lprops. We also have to set free space
- * to LEB size and dirty space to zero, because lprops may contain out-of-date
- * information if the file-system was un-mounted before it has been committed.
- * This function returns zero in case of success and a negative error code in
- * case of failure.
+ * This function ensures that the LEB reserved for garbage collection is marked
+ * as "taken" in lprops. We also have to set free space to LEB size and dirty
+ * space to zero, because lprops may contain out-of-date information if the
+ * file-system was un-mounted before it has been committed. This function
+ * returns zero in case of success and a negative error code in case of
+ * failure.
  */
 static int take_gc_lnum(struct ubifs_info *c)
 {
@@ -751,10 +752,6 @@ static int take_gc_lnum(struct ubifs_info *c)
                 return -EINVAL;
         }
 
-        err = ubifs_leb_unmap(c, c->gc_lnum);
-        if (err)
-                return err;
-
         /* And we have to tell lprops that this LEB is taken */
         err = ubifs_change_one_lp(c, c->gc_lnum, c->leb_size, 0,
                                   LPROPS_TAKEN, 0, 0);
@@ -1280,10 +1277,19 @@ static int mount_ubifs(struct ubifs_info *c)
                         if (err)
                                 goto out_orphans;
                         err = ubifs_rcvry_gc_commit(c);
-                } else
+                } else {
                         err = take_gc_lnum(c);
-                if (err)
-                        goto out_orphans;
+                        if (err)
+                                goto out_orphans;
+
+                        /*
+                         * GC LEB may contain garbage if there was an unclean
+                         * reboot, and it should be un-mapped.
+                         */
+                        err = ubifs_leb_unmap(c, c->gc_lnum);
+                        if (err)
+                                return err;
+                }
 
                 err = dbg_check_lprops(c);
                 if (err)
@@ -1292,6 +1298,16 @@ static int mount_ubifs(struct ubifs_info *c)
                 err = ubifs_recover_size(c);
                 if (err)
                         goto out_orphans;
+        } else {
+                /*
+                 * Even if we mount read-only, we have to set space in GC LEB
+                 * to proper value because this affects UBIFS free space
+                 * reporting. We do not want to have a situation when
+                 * re-mounting from R/O to R/W changes amount of free space.
+                 */
+                err = take_gc_lnum(c);
+                if (err)
+                        goto out_orphans;
         }
 
         spin_lock(&ubifs_infos_lock);
@@ -1316,6 +1332,8 @@ static int mount_ubifs(struct ubifs_info *c)
                 goto out_infos;
 
         c->always_chk_crc = 0;
+        /* GC LEB has to be empty and taken at this point */
+        ubifs_assert(c->lst.taken_empty_lebs == 1);
 
         ubifs_msg("mounted UBI device %d, volume %d, name \"%s\"",
                   c->vi.ubi_num, c->vi.vol_id, c->vi.name);
@@ -1561,7 +1579,7 @@ static int ubifs_remount_rw(struct ubifs_info *c)
         if (c->need_recovery)
                 err = ubifs_rcvry_gc_commit(c);
         else
-                err = take_gc_lnum(c);
+                err = ubifs_leb_unmap(c, c->gc_lnum);
         if (err)
                 goto out;
 
@@ -1786,6 +1804,7 @@ static int ubifs_remount_fs(struct super_block *sb, int *flags, char *data)
                 c->bu.buf = NULL;
         }
 
+        ubifs_assert(c->lst.taken_empty_lebs == 1);
         return 0;
 }