1 files changed, 243 insertions, 140 deletions

diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index d80b2aef42b6..1182b66a5491 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -34,6 +34,8 @@
 #include <linux/parser.h>
 #include <linux/seq_file.h>
 #include <linux/mount.h>
+#include <linux/math64.h>
+#include <linux/writeback.h>
 #include "ubifs.h"
 
 /*
@@ -395,6 +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;
 }
 
@@ -417,39 +420,62 @@ static int ubifs_show_options(struct seq_file *s, struct vfsmount *mnt)
         else if (c->mount_opts.chk_data_crc == 1)
                 seq_printf(s, ",no_chk_data_crc");
 
+        if (c->mount_opts.override_compr) {
+                seq_printf(s, ",compr=");
+                seq_printf(s, ubifs_compr_name(c->mount_opts.compr_type));
+        }
+
         return 0;
 }
 
 static int ubifs_sync_fs(struct super_block *sb, int wait)
 {
+        int i, err;
         struct ubifs_info *c = sb->s_fs_info;
-        int i, ret = 0, err;
-        long long bud_bytes;
+        struct writeback_control wbc = {
+                .sync_mode   = WB_SYNC_ALL,
+                .range_start = 0,
+                .range_end   = LLONG_MAX,
+                .nr_to_write = LONG_MAX,
+        };
 
-        if (c->jheads) {
-                for (i = 0; i < c->jhead_cnt; i++) {
-                        err = ubifs_wbuf_sync(&c->jheads[i].wbuf);
-                        if (err && !ret)
-                                ret = err;
-                }
+        /*
+         * Zero @wait is just an advisory thing to help the file system shove
+         * lots of data into the queues, and there will be the second
+         * '->sync_fs()' call, with non-zero @wait.
+         */
+        if (!wait)
+                return 0;
 
-                /* Commit the journal unless it has too little data */
-                spin_lock(&c->buds_lock);
-                bud_bytes = c->bud_bytes;
-                spin_unlock(&c->buds_lock);
-                if (bud_bytes > c->leb_size) {
-                        err = ubifs_run_commit(c);
-                        if (err)
-                                return err;
-                }
-        }
+        if (sb->s_flags & MS_RDONLY)
+                return 0;
+
+        /*
+         * VFS calls '->sync_fs()' before synchronizing all dirty inodes and
+         * pages, so synchronize them first, then commit the journal. Strictly
+         * speaking, it is not necessary to commit the journal here,
+         * synchronizing write-buffers would be enough. But committing makes
+         * UBIFS free space predictions much more accurate, so we want to let
+         * the user be able to get more accurate results of 'statfs()' after
+         * they synchronize the file system.
+         */
+        generic_sync_sb_inodes(sb, &wbc);
 
         /*
-         * We ought to call sync for c->ubi but it does not have one. If it had
-         * it would in turn call mtd->sync, however mtd operations are
-         * synchronous anyway, so we don't lose any sleep here.
+         * Synchronize write buffers, because 'ubifs_run_commit()' does not
+         * do this if it waits for an already running commit.
          */
-        return ret;
+        for (i = 0; i < c->jhead_cnt; i++) {
+                err = ubifs_wbuf_sync(&c->jheads[i].wbuf);
+                if (err)
+                        return err;
+        }
+
+        err = ubifs_run_commit(c);
+        if (err)
+                return err;
+
+        return ubi_sync(c->vi.ubi_num);
 }
 
 /**
@@ -548,15 +574,8 @@ static int init_constants_early(struct ubifs_info *c)
         c->ranges[UBIFS_IDX_NODE].max_len = INT_MAX;
 
         /*
-         * Initialize dead and dark LEB space watermarks.
-         *
-         * Dead space is the space which cannot be used. Its watermark is
-         * equivalent to min. I/O unit or minimum node size if it is greater
-         * then min. I/O unit.
-         *
-         * Dark space is the space which might be used, or might not, depending
-         * on which node should be written to the LEB. Its watermark is
-         * equivalent to maximum UBIFS node size.
+         * Initialize dead and dark LEB space watermarks. See gc.c for comments
+         * about these values.
          */
         c->dead_wm = ALIGN(MIN_WRITE_SZ, c->min_io_size);
         c->dark_wm = ALIGN(UBIFS_MAX_NODE_SZ, c->min_io_size);
@@ -596,7 +615,7 @@ static int bud_wbuf_callback(struct ubifs_info *c, int lnum, int free, int pad)
 }
 
 /*
- * init_constants_late - initialize UBIFS constants.
+ * init_constants_sb - initialize UBIFS constants.
  * @c: UBIFS file-system description object
  *
  * This is a helper function which initializes various UBIFS constants after
@@ -604,10 +623,10 @@ static int bud_wbuf_callback(struct ubifs_info *c, int lnum, int free, int pad)
  * makes sure they are all right. Returns zero in case of success and a
  * negative error code in case of failure.
  */
-static int init_constants_late(struct ubifs_info *c)
+static int init_constants_sb(struct ubifs_info *c)
 {
         int tmp, err;
-        uint64_t tmp64;
+        long long tmp64;
 
         c->main_bytes = (long long)c->main_lebs * c->leb_size;
         c->max_znode_sz = sizeof(struct ubifs_znode) +
@@ -634,9 +653,8 @@ static int init_constants_late(struct ubifs_info *c)
          * Make sure that the log is large enough to fit reference nodes for
          * all buds plus one reserved LEB.
          */
-        tmp64 = c->max_bud_bytes;
-        tmp = do_div(tmp64, c->leb_size);
-        c->max_bud_cnt = tmp64 + !!tmp;
+        tmp64 = c->max_bud_bytes + c->leb_size - 1;
+        c->max_bud_cnt = div_u64(tmp64, c->leb_size);
         tmp = (c->ref_node_alsz * c->max_bud_cnt + c->leb_size - 1);
         tmp /= c->leb_size;
         tmp += 1;
@@ -672,7 +690,7 @@ static int init_constants_late(struct ubifs_info *c)
          * Consequently, if the journal is too small, UBIFS will treat it as
          * always full.
          */
-        tmp64 = (uint64_t)(c->jhead_cnt + 1) * c->leb_size + 1;
+        tmp64 = (long long)(c->jhead_cnt + 1) * c->leb_size + 1;
         if (c->bg_bud_bytes < tmp64)
                 c->bg_bud_bytes = tmp64;
         if (c->max_bud_bytes < tmp64 + c->leb_size)
@@ -682,6 +700,21 @@ static int init_constants_late(struct ubifs_info *c)
         if (err)
                 return err;
 
+        return 0;
+}
+
+/*
+ * init_constants_master - initialize UBIFS constants.
+ * @c: UBIFS file-system description object
+ *
+ * This is a helper function which initializes various UBIFS constants after
+ * the master node has been read. It also checks various UBIFS parameters and
+ * makes sure they are all right.
+ */
+static void init_constants_master(struct ubifs_info *c)
+{
+        long long tmp64;
+
         c->min_idx_lebs = ubifs_calc_min_idx_lebs(c);
 
         /*
@@ -690,26 +723,25 @@ static int init_constants_late(struct ubifs_info *c)
          * necessary to report something for the 'statfs()' call.
          *
          * Subtract the LEB reserved for GC, the LEB which is reserved for
-         * deletions, and assume only one journal head is available.
+         * deletions, minimum LEBs for the index, and assume only one journal
+         * head is available.
          */
-        tmp64 = c->main_lebs - 2 - c->jhead_cnt + 1;
-        tmp64 *= (uint64_t)c->leb_size - c->leb_overhead;
+        tmp64 = c->main_lebs - 1 - 1 - MIN_INDEX_LEBS - c->jhead_cnt + 1;
+        tmp64 *= (long long)c->leb_size - c->leb_overhead;
         tmp64 = ubifs_reported_space(c, tmp64);
         c->block_cnt = tmp64 >> UBIFS_BLOCK_SHIFT;
-
-        return 0;
 }
 
 /**
  * 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)
 {
@@ -720,10 +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);
@@ -878,6 +906,7 @@ static int check_volume_empty(struct ubifs_info *c)
  * Opt_no_bulk_read: disable bulk-reads
  * Opt_chk_data_crc: check CRCs when reading data nodes
  * Opt_no_chk_data_crc: do not check CRCs when reading data nodes
+ * Opt_override_compr: override default compressor
  * Opt_err: just end of array marker
  */
 enum {
@@ -887,6 +916,7 @@ enum {
         Opt_no_bulk_read,
         Opt_chk_data_crc,
         Opt_no_chk_data_crc,
+        Opt_override_compr,
         Opt_err,
 };
 
@@ -897,6 +927,7 @@ static const match_table_t tokens = {
         {Opt_no_bulk_read, "no_bulk_read"},
         {Opt_chk_data_crc, "chk_data_crc"},
         {Opt_no_chk_data_crc, "no_chk_data_crc"},
+        {Opt_override_compr, "compr=%s"},
         {Opt_err, NULL},
 };
 
@@ -926,13 +957,16 @@ static int ubifs_parse_options(struct ubifs_info *c, char *options,
 
                 token = match_token(p, tokens, args);
                 switch (token) {
+                /*
+                 * %Opt_fast_unmount and %Opt_norm_unmount options are ignored.
+                 * We accepte them in order to be backware-compatible. But this
+                 * should be removed at some point.
+                 */
                 case Opt_fast_unmount:
                         c->mount_opts.unmount_mode = 2;
-                        c->fast_unmount = 1;
                         break;
                 case Opt_norm_unmount:
                         c->mount_opts.unmount_mode = 1;
-                        c->fast_unmount = 0;
                         break;
                 case Opt_bulk_read:
                         c->mount_opts.bulk_read = 2;
@@ -950,6 +984,28 @@ static int ubifs_parse_options(struct ubifs_info *c, char *options,
                         c->mount_opts.chk_data_crc = 1;
                         c->no_chk_data_crc = 1;
                         break;
+                case Opt_override_compr:
+                {
+                        char *name = match_strdup(&args[0]);
+
+                        if (!name)
+                                return -ENOMEM;
+                        if (!strcmp(name, "none"))
+                                c->mount_opts.compr_type = UBIFS_COMPR_NONE;
+                        else if (!strcmp(name, "lzo"))
+                                c->mount_opts.compr_type = UBIFS_COMPR_LZO;
+                        else if (!strcmp(name, "zlib"))
+                                c->mount_opts.compr_type = UBIFS_COMPR_ZLIB;
+                        else {
+                                ubifs_err("unknown compressor \"%s\"", name);
+                                kfree(name);
+                                return -EINVAL;
+                        }
+                        kfree(name);
+                        c->mount_opts.override_compr = 1;
+                        c->default_compr = c->mount_opts.compr_type;
+                        break;
+                }
                 default:
                         ubifs_err("unrecognized mount option \"%s\" "
                                   "or missing value", p);
@@ -1019,6 +1075,25 @@ again:
 }
 
 /**
+ * check_free_space - check if there is enough free space to mount.
+ * @c: UBIFS file-system description object
+ *
+ * This function makes sure UBIFS has enough free space to be mounted in
+ * read/write mode. UBIFS must always have some free space to allow deletions.
+ */
+static int check_free_space(struct ubifs_info *c)
+{
+        ubifs_assert(c->dark_wm > 0);
+        if (c->lst.total_free + c->lst.total_dirty < c->dark_wm) {
+                ubifs_err("insufficient free space to mount in read/write mode");
+                dbg_dump_budg(c);
+                dbg_dump_lprops(c);
+                return -ENOSPC;
+        }
+        return 0;
+}
+
+/**
  * mount_ubifs - mount UBIFS file-system.
  * @c: UBIFS file-system description object
  *
@@ -1039,11 +1114,9 @@ static int mount_ubifs(struct ubifs_info *c)
         if (err)
                 return err;
 
-#ifdef CONFIG_UBIFS_FS_DEBUG
-        c->dbg_buf = vmalloc(c->leb_size);
-        if (!c->dbg_buf)
-                return -ENOMEM;
-#endif
+        err = ubifs_debugging_init(c);
+        if (err)
+                return err;
 
         err = check_volume_empty(c);
         if (err)
@@ -1100,27 +1173,25 @@ static int mount_ubifs(struct ubifs_info *c)
                 goto out_free;
 
         /*
-         * Make sure the compressor which is set as the default on in the
-         * superblock was actually compiled in.
+         * Make sure the compressor which is set as default in the superblock
+         * or overridden by mount options is actually compiled in.
          */
         if (!ubifs_compr_present(c->default_compr)) {
-                ubifs_warn("'%s' compressor is set by superblock, but not "
-                           "compiled in", ubifs_compr_name(c->default_compr));
-                c->default_compr = UBIFS_COMPR_NONE;
+                ubifs_err("'compressor \"%s\" is not compiled in",
+                          ubifs_compr_name(c->default_compr));
+                goto out_free;
         }
 
-        dbg_failure_mode_registration(c);
-
-        err = init_constants_late(c);
+        err = init_constants_sb(c);
         if (err)
-                goto out_dereg;
+                goto out_free;
 
         sz = ALIGN(c->max_idx_node_sz, c->min_io_size);
         sz = ALIGN(sz + c->max_idx_node_sz, c->min_io_size);
         c->cbuf = kmalloc(sz, GFP_NOFS);
         if (!c->cbuf) {
                 err = -ENOMEM;
-                goto out_dereg;
+                goto out_free;
         }
 
         sprintf(c->bgt_name, BGT_NAME_PATTERN, c->vi.ubi_num, c->vi.vol_id);
@@ -1145,6 +1216,8 @@ static int mount_ubifs(struct ubifs_info *c)
         if (err)
                 goto out_master;
 
+        init_constants_master(c);
+
         if ((c->mst_node->flags & cpu_to_le32(UBIFS_MST_DIRTY)) != 0) {
                 ubifs_msg("recovery needed");
                 c->need_recovery = 1;
@@ -1183,12 +1256,9 @@ static int mount_ubifs(struct ubifs_info *c)
         if (!mounted_read_only) {
                 int lnum;
 
-                /* Check for enough free space */
-                if (ubifs_calc_available(c, c->min_idx_lebs) <= 0) {
-                        ubifs_err("insufficient available space");
-                        err = -EINVAL;
+                err = check_free_space(c);
+                if (err)
                         goto out_orphans;
-                }
 
                 /* Check for enough log space */
                 lnum = c->lhead_lnum + 1;
@@ -1205,10 +1275,19 @@ 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)
@@ -1217,6 +1296,16 @@ 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);
@@ -1229,13 +1318,20 @@ static int mount_ubifs(struct ubifs_info *c)
                 else {
                         c->need_recovery = 0;
                         ubifs_msg("recovery completed");
+                        /* GC LEB has to be empty and taken at this point */
+                        ubifs_assert(c->lst.taken_empty_lebs == 1);
                 }
-        }
+        } else
+                ubifs_assert(c->lst.taken_empty_lebs == 1);
 
         err = dbg_check_filesystem(c);
         if (err)
                 goto out_infos;
 
+        err = dbg_debugfs_init_fs(c);
+        if (err)
+                goto out_infos;
+
         c->always_chk_crc = 0;
 
         ubifs_msg("mounted UBI device %d, volume %d, name \"%s\"",
@@ -1266,7 +1362,6 @@ static int mount_ubifs(struct ubifs_info *c)
                c->uuid[4], c->uuid[5], c->uuid[6], c->uuid[7],
                c->uuid[8], c->uuid[9], c->uuid[10], c->uuid[11],
                c->uuid[12], c->uuid[13], c->uuid[14], c->uuid[15]);
-        dbg_msg("fast unmount:        %d", c->fast_unmount);
         dbg_msg("big_lpt              %d", c->big_lpt);
         dbg_msg("log LEBs:            %d (%d - %d)",
                 c->log_lebs, UBIFS_LOG_LNUM, c->log_last);
@@ -1283,8 +1378,20 @@ static int mount_ubifs(struct ubifs_info *c)
         dbg_msg("tree fanout:         %d", c->fanout);
         dbg_msg("reserved GC LEB:     %d", c->gc_lnum);
         dbg_msg("first main LEB:      %d", c->main_first);
+        dbg_msg("max. znode size      %d", c->max_znode_sz);
+        dbg_msg("max. index node size %d", c->max_idx_node_sz);
+        dbg_msg("node sizes:          data %zu, inode %zu, dentry %zu",
+                UBIFS_DATA_NODE_SZ, UBIFS_INO_NODE_SZ, UBIFS_DENT_NODE_SZ);
+        dbg_msg("node sizes:          trun %zu, sb %zu, master %zu",
+                UBIFS_TRUN_NODE_SZ, UBIFS_SB_NODE_SZ, UBIFS_MST_NODE_SZ);
+        dbg_msg("node sizes:          ref %zu, cmt. start %zu, orph %zu",
+                UBIFS_REF_NODE_SZ, UBIFS_CS_NODE_SZ, UBIFS_ORPH_NODE_SZ);
+        dbg_msg("max. node sizes:     data %zu, inode %zu dentry %zu",
+                UBIFS_MAX_DATA_NODE_SZ, UBIFS_MAX_INO_NODE_SZ,
+                UBIFS_MAX_DENT_NODE_SZ);
         dbg_msg("dead watermark:      %d", c->dead_wm);
         dbg_msg("dark watermark:      %d", c->dark_wm);
+        dbg_msg("LEB overhead:        %d", c->leb_overhead);
         x = (long long)c->main_lebs * c->dark_wm;
         dbg_msg("max. dark space:     %lld (%lld KiB, %lld MiB)",
                 x, x >> 10, x >> 20);
@@ -1320,14 +1427,12 @@ out_wbufs:
         free_wbufs(c);
 out_cbuf:
         kfree(c->cbuf);
-out_dereg:
-        dbg_failure_mode_deregistration(c);
 out_free:
         kfree(c->bu.buf);
         vfree(c->ileb_buf);
         vfree(c->sbuf);
         kfree(c->bottom_up_buf);
-        UBIFS_DBG(vfree(c->dbg_buf));
+        ubifs_debugging_exit(c);
         return err;
 }
 
@@ -1345,6 +1450,7 @@ static void ubifs_umount(struct ubifs_info *c)
         dbg_gen("un-mounting UBI device %d, volume %d", c->vi.ubi_num,
                 c->vi.vol_id);
 
+        dbg_debugfs_exit_fs(c);
         spin_lock(&ubifs_infos_lock);
         list_del(&c->infos_list);
         spin_unlock(&ubifs_infos_lock);
@@ -1364,8 +1470,7 @@ static void ubifs_umount(struct ubifs_info *c)
         vfree(c->ileb_buf);
         vfree(c->sbuf);
         kfree(c->bottom_up_buf);
-        UBIFS_DBG(vfree(c->dbg_buf));
-        dbg_failure_mode_deregistration(c);
+        ubifs_debugging_exit(c);
 }
 
 /**
@@ -1380,19 +1485,14 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 {
         int err, lnum;
 
-        if (c->ro_media)
-                return -EINVAL;
-
         mutex_lock(&c->umount_mutex);
+        dbg_save_space_info(c);
         c->remounting_rw = 1;
         c->always_chk_crc = 1;
 
-        /* Check for enough free space */
-        if (ubifs_calc_available(c, c->min_idx_lebs) <= 0) {
-                ubifs_err("insufficient available space");
-                err = -EINVAL;
+        err = check_free_space(c);
+        if (err)
                 goto out;
-        }
 
         if (c->old_leb_cnt != c->leb_cnt) {
                 struct ubifs_sb_node *sup;
@@ -1422,6 +1522,12 @@ static int ubifs_remount_rw(struct ubifs_info *c)
                 err = ubifs_recover_inl_heads(c, c->sbuf);
                 if (err)
                         goto out;
+        } else {
+                /* A readonly mount is not allowed to have orphans */
+                ubifs_assert(c->tot_orphans == 0);
+                err = ubifs_clear_orphans(c);
+                if (err)
+                        goto out;
         }
 
         if (!(c->mst_node->flags & cpu_to_le32(UBIFS_MST_DIRTY))) {
@@ -1477,7 +1583,7 @@ 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;
 
@@ -1490,8 +1596,9 @@ static int ubifs_remount_rw(struct ubifs_info *c)
         c->vfs_sb->s_flags &= ~MS_RDONLY;
         c->remounting_rw = 0;
         c->always_chk_crc = 0;
+        err = dbg_check_space_info(c);
         mutex_unlock(&c->umount_mutex);
-        return 0;
+        return err;
 
 out:
         vfree(c->orph_buf);
@@ -1511,39 +1618,18 @@ out:
 }
 
 /**
- * commit_on_unmount - commit the journal when un-mounting.
- * @c: UBIFS file-system description object
- *
- * This function is called during un-mounting and re-mounting, and it commits
- * the journal unless the "fast unmount" mode is enabled. It also avoids
- * committing the journal if it contains too few data.
- */
-static void commit_on_unmount(struct ubifs_info *c)
-{
-        if (!c->fast_unmount) {
-                long long bud_bytes;
-
-                spin_lock(&c->buds_lock);
-                bud_bytes = c->bud_bytes;
-                spin_unlock(&c->buds_lock);
-                if (bud_bytes > c->leb_size)
-                        ubifs_run_commit(c);
-        }
-}
-
-/**
  * ubifs_remount_ro - re-mount in read-only mode.
  * @c: UBIFS file-system description object
  *
- * We rely on VFS to have stopped writing. Possibly the background thread could
- * be running a commit, however kthread_stop will wait in that case.
+ * We assume VFS has stopped writing. Possibly the background thread could be
+ * running a commit, however kthread_stop will wait in that case.
  */
 static void ubifs_remount_ro(struct ubifs_info *c)
 {
         int i, err;
 
         ubifs_assert(!c->need_recovery);
-        commit_on_unmount(c);
+        ubifs_assert(!(c->vfs_sb->s_flags & MS_RDONLY));
 
         mutex_lock(&c->umount_mutex);
         if (c->bgt) {
@@ -1551,27 +1637,29 @@ static void ubifs_remount_ro(struct ubifs_info *c)
                 c->bgt = NULL;
         }
 
+        dbg_save_space_info(c);
+
         for (i = 0; i < c->jhead_cnt; i++) {
                 ubifs_wbuf_sync(&c->jheads[i].wbuf);
                 del_timer_sync(&c->jheads[i].wbuf.timer);
         }
 
-        if (!c->ro_media) {
-                c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_DIRTY);
-                c->mst_node->flags |= cpu_to_le32(UBIFS_MST_NO_ORPHS);
-                c->mst_node->gc_lnum = cpu_to_le32(c->gc_lnum);
-                err = ubifs_write_master(c);
-                if (err)
-                        ubifs_ro_mode(c, err);
-        }
+        c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_DIRTY);
+        c->mst_node->flags |= cpu_to_le32(UBIFS_MST_NO_ORPHS);
+        c->mst_node->gc_lnum = cpu_to_le32(c->gc_lnum);
+        err = ubifs_write_master(c);
+        if (err)
+                ubifs_ro_mode(c, err);
 
-        ubifs_destroy_idx_gc(c);
         free_wbufs(c);
         vfree(c->orph_buf);
         c->orph_buf = NULL;
         vfree(c->ileb_buf);
         c->ileb_buf = NULL;
         ubifs_lpt_free(c, 1);
+        err = dbg_check_space_info(c);
+        if (err)
+                ubifs_ro_mode(c, err);
         mutex_unlock(&c->umount_mutex);
 }
 
@@ -1664,11 +1752,20 @@ static int ubifs_remount_fs(struct super_block *sb, int *flags, char *data)
         }
 
         if ((sb->s_flags & MS_RDONLY) && !(*flags & MS_RDONLY)) {
+                if (c->ro_media) {
+                        ubifs_msg("cannot re-mount due to prior errors");
+                        return -EROFS;
+                }
                 err = ubifs_remount_rw(c);
                 if (err)
                         return err;
-        } else if (!(sb->s_flags & MS_RDONLY) && (*flags & MS_RDONLY))
+        } else if (!(sb->s_flags & MS_RDONLY) && (*flags & MS_RDONLY)) {
+                if (c->ro_media) {
+                        ubifs_msg("cannot re-mount due to prior errors");
+                        return -EROFS;
+                }
                 ubifs_remount_ro(c);
+        }
 
         if (c->bulk_read == 1)
                 bu_init(c);
@@ -1678,10 +1775,11 @@ 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;
 }
 
-struct super_operations ubifs_super_operations = {
+const struct super_operations ubifs_super_operations = {
         .alloc_inode   = ubifs_alloc_inode,
         .destroy_inode = ubifs_destroy_inode,
         .put_super     = ubifs_put_super,
@@ -1849,7 +1947,6 @@ static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
                 goto out_iput;
 
         mutex_unlock(&c->umount_mutex);
-
         return 0;
 
 out_iput:
@@ -1949,15 +2046,6 @@ out_close:
 
 static void ubifs_kill_sb(struct super_block *sb)
 {
-        struct ubifs_info *c = sb->s_fs_info;
-
-        /*
-         * We do 'commit_on_unmount()' here instead of 'ubifs_put_super()'
-         * in order to be outside BKL.
-         */
-        if (sb->s_root && !(sb->s_flags & MS_RDONLY))
-                commit_on_unmount(c);
-        /* The un-mount routine is actually done in put_super() */
         generic_shutdown_super(sb);
 }
 
@@ -2021,6 +2109,14 @@ static int __init ubifs_init(void)
         BUILD_BUG_ON(UBIFS_REF_NODE_SZ != 64);
 
         /*
+         * We use 2 bit wide bit-fields to store compression type, which should
+         * be amended if more compressors are added. The bit-fields are:
+         * @compr_type in 'struct ubifs_inode', @default_compr in
+         * 'struct ubifs_info' and @compr_type in 'struct ubifs_mount_opts'.
+         */
+        BUILD_BUG_ON(UBIFS_COMPR_TYPES_CNT > 4);
+
+        /*
          * We require that PAGE_CACHE_SIZE is greater-than-or-equal-to
          * UBIFS_BLOCK_SIZE. It is assumed that both are powers of 2.
          */
@@ -2049,11 +2145,17 @@ static int __init ubifs_init(void)
 
         err = ubifs_compressors_init();
         if (err)
+                goto out_shrinker;
+
+        err = dbg_debugfs_init();
+        if (err)
                 goto out_compr;
 
         return 0;
 
 out_compr:
+        ubifs_compressors_exit();
+out_shrinker:
         unregister_shrinker(&ubifs_shrinker_info);
         kmem_cache_destroy(ubifs_inode_slab);
 out_reg:
@@ -2068,6 +2170,7 @@ static void __exit ubifs_exit(void)
         ubifs_assert(list_empty(&ubifs_infos));
         ubifs_assert(atomic_long_read(&ubifs_clean_zn_cnt) == 0);
 
+        dbg_debugfs_exit();
         ubifs_compressors_exit();
         unregister_shrinker(&ubifs_shrinker_info);
         kmem_cache_destroy(ubifs_inode_slab);