Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2: (45 commits)
  nilfs2: reject filesystem with unsupported block size
  nilfs2: avoid rec_len overflow with 64KB block size
  nilfs2: simplify nilfs_get_page function
  nilfs2: reject incompatible filesystem
  nilfs2: add feature set fields to super block
  nilfs2: clarify byte offset in super block format
  nilfs2: apply read-ahead for nilfs_btree_lookup_contig
  nilfs2: introduce check flag to btree node buffer
  nilfs2: add btree get block function with readahead option
  nilfs2: add read ahead mode to nilfs_btnode_submit_block
  nilfs2: fix buffer head leak in nilfs_btnode_submit_block
  nilfs2: eliminate inline keywords in btree implementation
  nilfs2: get maximum number of child nodes from bmap object
  nilfs2: reduce repetitive calculation of max number of child nodes
  nilfs2: optimize calculation of min/max number of btree node children
  nilfs2: remove redundant pointer checks in bmap lookup functions
  nilfs2: get rid of nilfs_bmap_union
  nilfs2: unify bmap set_target_v operations
  nilfs2: get rid of nilfs_btree uses
  nilfs2: get rid of nilfs_direct uses
  ...

1 files changed, 234 insertions, 99 deletions

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 414ef68931cf..26078b3407c9 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -55,6 +55,8 @@
 #include "nilfs.h"
 #include "mdt.h"
 #include "alloc.h"
+#include "btree.h"
+#include "btnode.h"
 #include "page.h"
 #include "cpfile.h"
 #include "ifile.h"
@@ -74,6 +76,25 @@ struct kmem_cache *nilfs_btree_path_cache;
 
 static int nilfs_remount(struct super_block *sb, int *flags, char *data);
 
+static void nilfs_set_error(struct nilfs_sb_info *sbi)
+{
+        struct the_nilfs *nilfs = sbi->s_nilfs;
+        struct nilfs_super_block **sbp;
+
+        down_write(&nilfs->ns_sem);
+        if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
+                nilfs->ns_mount_state |= NILFS_ERROR_FS;
+                sbp = nilfs_prepare_super(sbi, 0);
+                if (likely(sbp)) {
+                        sbp[0]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
+                        if (sbp[1])
+                                sbp[1]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
+                        nilfs_commit_super(sbi, NILFS_SB_COMMIT_ALL);
+                }
+        }
+        up_write(&nilfs->ns_sem);
+}
+
 /**
  * nilfs_error() - report failure condition on a filesystem
  *
@@ -99,16 +120,7 @@ void nilfs_error(struct super_block *sb, const char *function,
         va_end(args);
 
         if (!(sb->s_flags & MS_RDONLY)) {
-                struct the_nilfs *nilfs = sbi->s_nilfs;
-
-                down_write(&nilfs->ns_sem);
-                if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
-                        nilfs->ns_mount_state |= NILFS_ERROR_FS;
-                        nilfs->ns_sbp[0]->s_state |=
-                                cpu_to_le16(NILFS_ERROR_FS);
-                        nilfs_commit_super(sbi, 1);
-                }
-                up_write(&nilfs->ns_sem);
+                nilfs_set_error(sbi);
 
                 if (nilfs_test_opt(sbi, ERRORS_RO)) {
                         printk(KERN_CRIT "Remounting filesystem read-only\n");
@@ -176,7 +188,7 @@ static void nilfs_clear_inode(struct inode *inode)
         nilfs_btnode_cache_clear(&ii->i_btnode_cache);
 }
 
-static int nilfs_sync_super(struct nilfs_sb_info *sbi, int dupsb)
+static int nilfs_sync_super(struct nilfs_sb_info *sbi, int flag)
 {
         struct the_nilfs *nilfs = sbi->s_nilfs;
         int err;
@@ -202,12 +214,20 @@ static int nilfs_sync_super(struct nilfs_sb_info *sbi, int dupsb)
                 printk(KERN_ERR
                        "NILFS: unable to write superblock (err=%d)\n", err);
                 if (err == -EIO && nilfs->ns_sbh[1]) {
+                        /*
+                         * sbp[0] points to newer log than sbp[1],
+                         * so copy sbp[0] to sbp[1] to take over sbp[0].
+                         */
+                        memcpy(nilfs->ns_sbp[1], nilfs->ns_sbp[0],
+                               nilfs->ns_sbsize);
                         nilfs_fall_back_super_block(nilfs);
                         goto retry;
                 }
         } else {
                 struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
 
+                nilfs->ns_sbwcount++;
+
                 /*
                  * The latest segment becomes trailable from the position
                  * written in superblock.
@@ -216,66 +236,122 @@ static int nilfs_sync_super(struct nilfs_sb_info *sbi, int dupsb)
 
                 /* update GC protection for recent segments */
                 if (nilfs->ns_sbh[1]) {
-                        sbp = NULL;
-                        if (dupsb) {
+                        if (flag == NILFS_SB_COMMIT_ALL) {
                                 set_buffer_dirty(nilfs->ns_sbh[1]);
-                                if (!sync_dirty_buffer(nilfs->ns_sbh[1]))
-                                        sbp = nilfs->ns_sbp[1];
+                                if (sync_dirty_buffer(nilfs->ns_sbh[1]) < 0)
+                                        goto out;
                         }
+                        if (le64_to_cpu(nilfs->ns_sbp[1]->s_last_cno) <
+                            le64_to_cpu(nilfs->ns_sbp[0]->s_last_cno))
+                                sbp = nilfs->ns_sbp[1];
                 }
-                if (sbp) {
-                        spin_lock(&nilfs->ns_last_segment_lock);
-                        nilfs->ns_prot_seq = le64_to_cpu(sbp->s_last_seq);
-                        spin_unlock(&nilfs->ns_last_segment_lock);
-                }
-        }
 
+                spin_lock(&nilfs->ns_last_segment_lock);
+                nilfs->ns_prot_seq = le64_to_cpu(sbp->s_last_seq);
+                spin_unlock(&nilfs->ns_last_segment_lock);
+        }
+ out:
         return err;
 }
 
-int nilfs_commit_super(struct nilfs_sb_info *sbi, int dupsb)
+void nilfs_set_log_cursor(struct nilfs_super_block *sbp,
+                          struct the_nilfs *nilfs)
+{
+        sector_t nfreeblocks;
+
+        /* nilfs->ns_sem must be locked by the caller. */
+        nilfs_count_free_blocks(nilfs, &nfreeblocks);
+        sbp->s_free_blocks_count = cpu_to_le64(nfreeblocks);
+
+        spin_lock(&nilfs->ns_last_segment_lock);
+        sbp->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
+        sbp->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
+        sbp->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
+        spin_unlock(&nilfs->ns_last_segment_lock);
+}
+
+struct nilfs_super_block **nilfs_prepare_super(struct nilfs_sb_info *sbi,
+                                               int flip)
 {
         struct the_nilfs *nilfs = sbi->s_nilfs;
         struct nilfs_super_block **sbp = nilfs->ns_sbp;
-        sector_t nfreeblocks;
-        time_t t;
-        int err;
 
-        /* nilfs->sem must be locked by the caller. */
+        /* nilfs->ns_sem must be locked by the caller. */
         if (sbp[0]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
-                if (sbp[1] && sbp[1]->s_magic == cpu_to_le16(NILFS_SUPER_MAGIC))
-                        nilfs_swap_super_block(nilfs);
-                else {
+                if (sbp[1] &&
+                    sbp[1]->s_magic == cpu_to_le16(NILFS_SUPER_MAGIC)) {
+                        memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
+                } else {
                         printk(KERN_CRIT "NILFS: superblock broke on dev %s\n",
                                sbi->s_super->s_id);
-                        return -EIO;
+                        return NULL;
                 }
+        } else if (sbp[1] &&
+                   sbp[1]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
+                        memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
         }
-        err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
-        if (unlikely(err)) {
-                printk(KERN_ERR "NILFS: failed to count free blocks\n");
-                return err;
-        }
-        spin_lock(&nilfs->ns_last_segment_lock);
-        sbp[0]->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
-        sbp[0]->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
-        sbp[0]->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
-        spin_unlock(&nilfs->ns_last_segment_lock);
 
+        if (flip && sbp[1])
+                nilfs_swap_super_block(nilfs);
+
+        return sbp;
+}
+
+int nilfs_commit_super(struct nilfs_sb_info *sbi, int flag)
+{
+        struct the_nilfs *nilfs = sbi->s_nilfs;
+        struct nilfs_super_block **sbp = nilfs->ns_sbp;
+        time_t t;
+
+        /* nilfs->ns_sem must be locked by the caller. */
         t = get_seconds();
-        nilfs->ns_sbwtime[0] = t;
-        sbp[0]->s_free_blocks_count = cpu_to_le64(nfreeblocks);
+        nilfs->ns_sbwtime = t;
         sbp[0]->s_wtime = cpu_to_le64(t);
         sbp[0]->s_sum = 0;
         sbp[0]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
                                              (unsigned char *)sbp[0],
                                              nilfs->ns_sbsize));
-        if (dupsb && sbp[1]) {
-                memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
-                nilfs->ns_sbwtime[1] = t;
+        if (flag == NILFS_SB_COMMIT_ALL && sbp[1]) {
+                sbp[1]->s_wtime = sbp[0]->s_wtime;
+                sbp[1]->s_sum = 0;
+                sbp[1]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
+                                            (unsigned char *)sbp[1],
+                                            nilfs->ns_sbsize));
         }
         clear_nilfs_sb_dirty(nilfs);
-        return nilfs_sync_super(sbi, dupsb);
+        return nilfs_sync_super(sbi, flag);
+}
+
+/**
+ * nilfs_cleanup_super() - write filesystem state for cleanup
+ * @sbi: nilfs_sb_info to be unmounted or degraded to read-only
+ *
+ * This function restores state flags in the on-disk super block.
+ * This will set "clean" flag (i.e. NILFS_VALID_FS) unless the
+ * filesystem was not clean previously.
+ */
+int nilfs_cleanup_super(struct nilfs_sb_info *sbi)
+{
+        struct nilfs_super_block **sbp;
+        int flag = NILFS_SB_COMMIT;
+        int ret = -EIO;
+
+        sbp = nilfs_prepare_super(sbi, 0);
+        if (sbp) {
+                sbp[0]->s_state = cpu_to_le16(sbi->s_nilfs->ns_mount_state);
+                nilfs_set_log_cursor(sbp[0], sbi->s_nilfs);
+                if (sbp[1] && sbp[0]->s_last_cno == sbp[1]->s_last_cno) {
+                        /*
+                         * make the "clean" flag also to the opposite
+                         * super block if both super blocks point to
+                         * the same checkpoint.
+                         */
+                        sbp[1]->s_state = sbp[0]->s_state;
+                        flag = NILFS_SB_COMMIT_ALL;
+                }
+                ret = nilfs_commit_super(sbi, flag);
+        }
+        return ret;
 }
 
 static void nilfs_put_super(struct super_block *sb)
@@ -289,8 +365,7 @@ static void nilfs_put_super(struct super_block *sb)
 
         if (!(sb->s_flags & MS_RDONLY)) {
                 down_write(&nilfs->ns_sem);
-                nilfs->ns_sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
-                nilfs_commit_super(sbi, 1);
+                nilfs_cleanup_super(sbi);
                 up_write(&nilfs->ns_sem);
         }
         down_write(&nilfs->ns_super_sem);
@@ -311,6 +386,7 @@ static int nilfs_sync_fs(struct super_block *sb, int wait)
 {
         struct nilfs_sb_info *sbi = NILFS_SB(sb);
         struct the_nilfs *nilfs = sbi->s_nilfs;
+        struct nilfs_super_block **sbp;
         int err = 0;
 
         /* This function is called when super block should be written back */
@@ -318,8 +394,13 @@ static int nilfs_sync_fs(struct super_block *sb, int wait)
                 err = nilfs_construct_segment(sb);
 
         down_write(&nilfs->ns_sem);
-        if (nilfs_sb_dirty(nilfs))
-                nilfs_commit_super(sbi, 1);
+        if (nilfs_sb_dirty(nilfs)) {
+                sbp = nilfs_prepare_super(sbi, nilfs_sb_will_flip(nilfs));
+                if (likely(sbp)) {
+                        nilfs_set_log_cursor(sbp[0], nilfs);
+                        nilfs_commit_super(sbi, NILFS_SB_COMMIT);
+                }
+        }
         up_write(&nilfs->ns_sem);
 
         return err;
@@ -442,20 +523,20 @@ static int nilfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
         struct nilfs_sb_info *sbi = NILFS_SB(sb);
 
         if (!nilfs_test_opt(sbi, BARRIER))
-                seq_printf(seq, ",nobarrier");
+                seq_puts(seq, ",nobarrier");
         if (nilfs_test_opt(sbi, SNAPSHOT))
                 seq_printf(seq, ",cp=%llu",
                            (unsigned long long int)sbi->s_snapshot_cno);
         if (nilfs_test_opt(sbi, ERRORS_PANIC))
-                seq_printf(seq, ",errors=panic");
+                seq_puts(seq, ",errors=panic");
         if (nilfs_test_opt(sbi, ERRORS_CONT))
-                seq_printf(seq, ",errors=continue");
+                seq_puts(seq, ",errors=continue");
         if (nilfs_test_opt(sbi, STRICT_ORDER))
-                seq_printf(seq, ",order=strict");
+                seq_puts(seq, ",order=strict");
         if (nilfs_test_opt(sbi, NORECOVERY))
-                seq_printf(seq, ",norecovery");
+                seq_puts(seq, ",norecovery");
         if (nilfs_test_opt(sbi, DISCARD))
-                seq_printf(seq, ",discard");
+                seq_puts(seq, ",discard");
 
         return 0;
 }
@@ -524,23 +605,25 @@ static const struct export_operations nilfs_export_ops = {
 
 enum {
         Opt_err_cont, Opt_err_panic, Opt_err_ro,
-        Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
-        Opt_discard, Opt_err,
+        Opt_barrier, Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
+        Opt_discard, Opt_nodiscard, Opt_err,
 };
 
 static match_table_t tokens = {
         {Opt_err_cont, "errors=continue"},
         {Opt_err_panic, "errors=panic"},
         {Opt_err_ro, "errors=remount-ro"},
+        {Opt_barrier, "barrier"},
         {Opt_nobarrier, "nobarrier"},
         {Opt_snapshot, "cp=%u"},
         {Opt_order, "order=%s"},
         {Opt_norecovery, "norecovery"},
         {Opt_discard, "discard"},
+        {Opt_nodiscard, "nodiscard"},
         {Opt_err, NULL}
 };
 
-static int parse_options(char *options, struct super_block *sb)
+static int parse_options(char *options, struct super_block *sb, int is_remount)
 {
         struct nilfs_sb_info *sbi = NILFS_SB(sb);
         char *p;
@@ -557,6 +640,9 @@ static int parse_options(char *options, struct super_block *sb)
 
                 token = match_token(p, tokens, args);
                 switch (token) {
+                case Opt_barrier:
+                        nilfs_set_opt(sbi, BARRIER);
+                        break;
                 case Opt_nobarrier:
                         nilfs_clear_opt(sbi, BARRIER);
                         break;
@@ -582,8 +668,26 @@ static int parse_options(char *options, struct super_block *sb)
                 case Opt_snapshot:
                         if (match_int(&args[0], &option) || option <= 0)
                                 return 0;
-                        if (!(sb->s_flags & MS_RDONLY))
+                        if (is_remount) {
+                                if (!nilfs_test_opt(sbi, SNAPSHOT)) {
+                                        printk(KERN_ERR
+                                               "NILFS: cannot change regular "
+                                               "mount to snapshot.\n");
+                                        return 0;
+                                } else if (option != sbi->s_snapshot_cno) {
+                                        printk(KERN_ERR
+                                               "NILFS: cannot remount to a "
+                                               "different snapshot.\n");
+                                        return 0;
+                                }
+                                break;
+                        }
+                        if (!(sb->s_flags & MS_RDONLY)) {
+                                printk(KERN_ERR "NILFS: cannot mount snapshot "
+                                       "read/write.  A read-only option is "
+                                       "required.\n");
                                 return 0;
+                        }
                         sbi->s_snapshot_cno = option;
                         nilfs_set_opt(sbi, SNAPSHOT);
                         break;
@@ -593,6 +697,9 @@ static int parse_options(char *options, struct super_block *sb)
                 case Opt_discard:
                         nilfs_set_opt(sbi, DISCARD);
                         break;
+                case Opt_nodiscard:
+                        nilfs_clear_opt(sbi, DISCARD);
+                        break;
                 default:
                         printk(KERN_ERR
                                "NILFS: Unrecognized mount option \"%s\"\n", p);
@@ -613,11 +720,18 @@ nilfs_set_default_options(struct nilfs_sb_info *sbi,
 static int nilfs_setup_super(struct nilfs_sb_info *sbi)
 {
         struct the_nilfs *nilfs = sbi->s_nilfs;
-        struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
-        int max_mnt_count = le16_to_cpu(sbp->s_max_mnt_count);
-        int mnt_count = le16_to_cpu(sbp->s_mnt_count);
+        struct nilfs_super_block **sbp;
+        int max_mnt_count;
+        int mnt_count;
+
+        /* nilfs->ns_sem must be locked by the caller. */
+        sbp = nilfs_prepare_super(sbi, 0);
+        if (!sbp)
+                return -EIO;
+
+        max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
+        mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
 
-        /* nilfs->sem must be locked by the caller. */
         if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
                 printk(KERN_WARNING
                        "NILFS warning: mounting fs with errors\n");
@@ -628,12 +742,15 @@ static int nilfs_setup_super(struct nilfs_sb_info *sbi)
 #endif
         }
         if (!max_mnt_count)
-                sbp->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
-
-        sbp->s_mnt_count = cpu_to_le16(mnt_count + 1);
-        sbp->s_state = cpu_to_le16(le16_to_cpu(sbp->s_state) & ~NILFS_VALID_FS);
-        sbp->s_mtime = cpu_to_le64(get_seconds());
-        return nilfs_commit_super(sbi, 1);
+                sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
+
+        sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
+        sbp[0]->s_state =
+                cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
+        sbp[0]->s_mtime = cpu_to_le64(get_seconds());
+        /* synchronize sbp[1] with sbp[0] */
+        memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
+        return nilfs_commit_super(sbi, NILFS_SB_COMMIT_ALL);
 }
 
 struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
@@ -670,7 +787,31 @@ int nilfs_store_magic_and_option(struct super_block *sb,
         sbi->s_interval = le32_to_cpu(sbp->s_c_interval);
         sbi->s_watermark = le32_to_cpu(sbp->s_c_block_max);
 
-        return !parse_options(data, sb) ? -EINVAL : 0 ;
+        return !parse_options(data, sb, 0) ? -EINVAL : 0 ;
+}
+
+int nilfs_check_feature_compatibility(struct super_block *sb,
+                                      struct nilfs_super_block *sbp)
+{
+        __u64 features;
+
+        features = le64_to_cpu(sbp->s_feature_incompat) &
+                ~NILFS_FEATURE_INCOMPAT_SUPP;
+        if (features) {
+                printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
+                       "optional features (%llx)\n",
+                       (unsigned long long)features);
+                return -EINVAL;
+        }
+        features = le64_to_cpu(sbp->s_feature_compat_ro) &
+                ~NILFS_FEATURE_COMPAT_RO_SUPP;
+        if (!(sb->s_flags & MS_RDONLY) && features) {
+                printk(KERN_ERR "NILFS: couldn't mount RDWR because of "
+                       "unsupported optional features (%llx)\n",
+                       (unsigned long long)features);
+                return -EINVAL;
+        }
+        return 0;
 }
 
 /**
@@ -819,7 +960,6 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
 static int nilfs_remount(struct super_block *sb, int *flags, char *data)
 {
         struct nilfs_sb_info *sbi = NILFS_SB(sb);
-        struct nilfs_super_block *sbp;
         struct the_nilfs *nilfs = sbi->s_nilfs;
         unsigned long old_sb_flags;
         struct nilfs_mount_options old_opts;
@@ -833,32 +973,17 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
         old_opts.snapshot_cno = sbi->s_snapshot_cno;
         was_snapshot = nilfs_test_opt(sbi, SNAPSHOT);
 
-        if (!parse_options(data, sb)) {
+        if (!parse_options(data, sb, 1)) {
                 err = -EINVAL;
                 goto restore_opts;
         }
         sb->s_flags = (sb->s_flags & ~MS_POSIXACL);
 
         err = -EINVAL;
-        if (was_snapshot) {
-                if (!(*flags & MS_RDONLY)) {
-                        printk(KERN_ERR "NILFS (device %s): cannot remount "
-                               "snapshot read/write.\n",
-                               sb->s_id);
-                        goto restore_opts;
-                } else if (sbi->s_snapshot_cno != old_opts.snapshot_cno) {
-                        printk(KERN_ERR "NILFS (device %s): cannot "
-                               "remount to a different snapshot.\n",
-                               sb->s_id);
-                        goto restore_opts;
-                }
-        } else {
-                if (nilfs_test_opt(sbi, SNAPSHOT)) {
-                        printk(KERN_ERR "NILFS (device %s): cannot change "
-                               "a regular mount to a snapshot.\n",
-                               sb->s_id);
-                        goto restore_opts;
-                }
+        if (was_snapshot && !(*flags & MS_RDONLY)) {
+                printk(KERN_ERR "NILFS (device %s): cannot remount snapshot "
+                       "read/write.\n", sb->s_id);
+                goto restore_opts;
         }
 
         if (!nilfs_valid_fs(nilfs)) {
@@ -880,19 +1005,29 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
                  * the RDONLY flag and then mark the partition as valid again.
                  */
                 down_write(&nilfs->ns_sem);
-                sbp = nilfs->ns_sbp[0];
-                if (!(sbp->s_state & le16_to_cpu(NILFS_VALID_FS)) &&
-                    (nilfs->ns_mount_state & NILFS_VALID_FS))
-                        sbp->s_state = cpu_to_le16(nilfs->ns_mount_state);
-                sbp->s_mtime = cpu_to_le64(get_seconds());
-                nilfs_commit_super(sbi, 1);
+                nilfs_cleanup_super(sbi);
                 up_write(&nilfs->ns_sem);
         } else {
+                __u64 features;
+
                 /*
                  * Mounting a RDONLY partition read-write, so reread and
                  * store the current valid flag.  (It may have been changed
                  * by fsck since we originally mounted the partition.)
                  */
+                down_read(&nilfs->ns_sem);
+                features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
+                        ~NILFS_FEATURE_COMPAT_RO_SUPP;
+                up_read(&nilfs->ns_sem);
+                if (features) {
+                        printk(KERN_WARNING "NILFS (device %s): couldn't "
+                               "remount RDWR because of unsupported optional "
+                               "features (%llx)\n",
+                               sb->s_id, (unsigned long long)features);
+                        err = -EROFS;
+                        goto restore_opts;
+                }
+
                 sb->s_flags &= ~MS_RDONLY;
 
                 err = nilfs_attach_segment_constructor(sbi);
@@ -1119,7 +1254,7 @@ static void nilfs_inode_init_once(void *obj)
         init_rwsem(&ii->xattr_sem);
 #endif
         nilfs_btnode_cache_init_once(&ii->i_btnode_cache);
-        ii->i_bmap = (struct nilfs_bmap *)&ii->i_bmap_union;
+        ii->i_bmap = &ii->i_bmap_data;
         inode_init_once(&ii->vfs_inode);
 }