This commit was manufactured by cvs2svn to create branch 'vserver'.
[linux-2.6.git] / fs / ext4 / super.c
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
new file mode 100644 (file)
index 0000000..da44874
--- /dev/null
@@ -0,0 +1,2871 @@
+/*
+ *  linux/fs/ext4/super.c
+ *
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ *
+ *  from
+ *
+ *  linux/fs/minix/inode.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  Big-endian to little-endian byte-swapping/bitmaps by
+ *        David S. Miller (davem@caip.rutgers.edu), 1995
+ */
+
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/fs.h>
+#include <linux/time.h>
+#include <linux/jbd2.h>
+#include <linux/ext4_fs.h>
+#include <linux/ext4_jbd2.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <linux/parser.h>
+#include <linux/smp_lock.h>
+#include <linux/buffer_head.h>
+#include <linux/vfs.h>
+#include <linux/random.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/quotaops.h>
+#include <linux/seq_file.h>
+
+#include <asm/uaccess.h>
+
+#include "xattr.h"
+#include "acl.h"
+#include "namei.h"
+
+static int ext4_load_journal(struct super_block *, struct ext4_super_block *,
+                            unsigned long journal_devnum);
+static int ext4_create_journal(struct super_block *, struct ext4_super_block *,
+                              unsigned int);
+static void ext4_commit_super (struct super_block * sb,
+                              struct ext4_super_block * es,
+                              int sync);
+static void ext4_mark_recovery_complete(struct super_block * sb,
+                                       struct ext4_super_block * es);
+static void ext4_clear_journal_err(struct super_block * sb,
+                                  struct ext4_super_block * es);
+static int ext4_sync_fs(struct super_block *sb, int wait);
+static const char *ext4_decode_error(struct super_block * sb, int errno,
+                                    char nbuf[16]);
+static int ext4_remount (struct super_block * sb, int * flags, char * data);
+static int ext4_statfs (struct dentry * dentry, struct kstatfs * buf);
+static void ext4_unlockfs(struct super_block *sb);
+static void ext4_write_super (struct super_block * sb);
+static void ext4_write_super_lockfs(struct super_block *sb);
+
+
+ext4_fsblk_t ext4_block_bitmap(struct super_block *sb,
+                              struct ext4_group_desc *bg)
+{
+       return le32_to_cpu(bg->bg_block_bitmap) |
+               (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ?
+                (ext4_fsblk_t)le32_to_cpu(bg->bg_block_bitmap_hi) << 32 : 0);
+}
+
+ext4_fsblk_t ext4_inode_bitmap(struct super_block *sb,
+                              struct ext4_group_desc *bg)
+{
+       return le32_to_cpu(bg->bg_inode_bitmap) |
+               (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ?
+                (ext4_fsblk_t)le32_to_cpu(bg->bg_inode_bitmap_hi) << 32 : 0);
+}
+
+ext4_fsblk_t ext4_inode_table(struct super_block *sb,
+                             struct ext4_group_desc *bg)
+{
+       return le32_to_cpu(bg->bg_inode_table) |
+               (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ?
+                (ext4_fsblk_t)le32_to_cpu(bg->bg_inode_table_hi) << 32 : 0);
+}
+
+void ext4_block_bitmap_set(struct super_block *sb,
+                          struct ext4_group_desc *bg, ext4_fsblk_t blk)
+{
+       bg->bg_block_bitmap = cpu_to_le32((u32)blk);
+       if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT)
+               bg->bg_block_bitmap_hi = cpu_to_le32(blk >> 32);
+}
+
+void ext4_inode_bitmap_set(struct super_block *sb,
+                          struct ext4_group_desc *bg, ext4_fsblk_t blk)
+{
+       bg->bg_inode_bitmap  = cpu_to_le32((u32)blk);
+       if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT)
+               bg->bg_inode_bitmap_hi = cpu_to_le32(blk >> 32);
+}
+
+void ext4_inode_table_set(struct super_block *sb,
+                         struct ext4_group_desc *bg, ext4_fsblk_t blk)
+{
+       bg->bg_inode_table = cpu_to_le32((u32)blk);
+       if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT)
+               bg->bg_inode_table_hi = cpu_to_le32(blk >> 32);
+}
+
+/*
+ * Wrappers for jbd2_journal_start/end.
+ *
+ * The only special thing we need to do here is to make sure that all
+ * journal_end calls result in the superblock being marked dirty, so
+ * that sync() will call the filesystem's write_super callback if
+ * appropriate.
+ */
+handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks)
+{
+       journal_t *journal;
+
+       if (sb->s_flags & MS_RDONLY)
+               return ERR_PTR(-EROFS);
+
+       /* Special case here: if the journal has aborted behind our
+        * backs (eg. EIO in the commit thread), then we still need to
+        * take the FS itself readonly cleanly. */
+       journal = EXT4_SB(sb)->s_journal;
+       if (is_journal_aborted(journal)) {
+               ext4_abort(sb, __FUNCTION__,
+                          "Detected aborted journal");
+               return ERR_PTR(-EROFS);
+       }
+
+       return jbd2_journal_start(journal, nblocks);
+}
+
+/*
+ * The only special thing we need to do here is to make sure that all
+ * jbd2_journal_stop calls result in the superblock being marked dirty, so
+ * that sync() will call the filesystem's write_super callback if
+ * appropriate.
+ */
+int __ext4_journal_stop(const char *where, handle_t *handle)
+{
+       struct super_block *sb;
+       int err;
+       int rc;
+
+       sb = handle->h_transaction->t_journal->j_private;
+       err = handle->h_err;
+       rc = jbd2_journal_stop(handle);
+
+       if (!err)
+               err = rc;
+       if (err)
+               __ext4_std_error(sb, where, err);
+       return err;
+}
+
+void ext4_journal_abort_handle(const char *caller, const char *err_fn,
+               struct buffer_head *bh, handle_t *handle, int err)
+{
+       char nbuf[16];
+       const char *errstr = ext4_decode_error(NULL, err, nbuf);
+
+       if (bh)
+               BUFFER_TRACE(bh, "abort");
+
+       if (!handle->h_err)
+               handle->h_err = err;
+
+       if (is_handle_aborted(handle))
+               return;
+
+       printk(KERN_ERR "%s: aborting transaction: %s in %s\n",
+              caller, errstr, err_fn);
+
+       jbd2_journal_abort_handle(handle);
+}
+
+/* Deal with the reporting of failure conditions on a filesystem such as
+ * inconsistencies detected or read IO failures.
+ *
+ * On ext2, we can store the error state of the filesystem in the
+ * superblock.  That is not possible on ext4, because we may have other
+ * write ordering constraints on the superblock which prevent us from
+ * writing it out straight away; and given that the journal is about to
+ * be aborted, we can't rely on the current, or future, transactions to
+ * write out the superblock safely.
+ *
+ * We'll just use the jbd2_journal_abort() error code to record an error in
+ * the journal instead.  On recovery, the journal will compain about
+ * that error until we've noted it down and cleared it.
+ */
+
+static void ext4_handle_error(struct super_block *sb)
+{
+       struct ext4_super_block *es = EXT4_SB(sb)->s_es;
+
+       EXT4_SB(sb)->s_mount_state |= EXT4_ERROR_FS;
+       es->s_state |= cpu_to_le16(EXT4_ERROR_FS);
+
+       if (sb->s_flags & MS_RDONLY)
+               return;
+
+       if (!test_opt (sb, ERRORS_CONT)) {
+               journal_t *journal = EXT4_SB(sb)->s_journal;
+
+               EXT4_SB(sb)->s_mount_opt |= EXT4_MOUNT_ABORT;
+               if (journal)
+                       jbd2_journal_abort(journal, -EIO);
+       }
+       if (test_opt (sb, ERRORS_RO)) {
+               printk (KERN_CRIT "Remounting filesystem read-only\n");
+               sb->s_flags |= MS_RDONLY;
+       }
+       ext4_commit_super(sb, es, 1);
+       if (test_opt(sb, ERRORS_PANIC))
+               panic("EXT4-fs (device %s): panic forced after error\n",
+                       sb->s_id);
+}
+
+void ext4_error (struct super_block * sb, const char * function,
+                const char * fmt, ...)
+{
+       va_list args;
+
+       va_start(args, fmt);
+       printk(KERN_CRIT "EXT4-fs error (device %s): %s: ",sb->s_id, function);
+       vprintk(fmt, args);
+       printk("\n");
+       va_end(args);
+
+       ext4_handle_error(sb);
+}
+
+static const char *ext4_decode_error(struct super_block * sb, int errno,
+                                    char nbuf[16])
+{
+       char *errstr = NULL;
+
+       switch (errno) {
+       case -EIO:
+               errstr = "IO failure";
+               break;
+       case -ENOMEM:
+               errstr = "Out of memory";
+               break;
+       case -EROFS:
+               if (!sb || EXT4_SB(sb)->s_journal->j_flags & JBD2_ABORT)
+                       errstr = "Journal has aborted";
+               else
+                       errstr = "Readonly filesystem";
+               break;
+       default:
+               /* If the caller passed in an extra buffer for unknown
+                * errors, textualise them now.  Else we just return
+                * NULL. */
+               if (nbuf) {
+                       /* Check for truncated error codes... */
+                       if (snprintf(nbuf, 16, "error %d", -errno) >= 0)
+                               errstr = nbuf;
+               }
+               break;
+       }
+
+       return errstr;
+}
+
+/* __ext4_std_error decodes expected errors from journaling functions
+ * automatically and invokes the appropriate error response.  */
+
+void __ext4_std_error (struct super_block * sb, const char * function,
+                      int errno)
+{
+       char nbuf[16];
+       const char *errstr;
+
+       /* Special case: if the error is EROFS, and we're not already
+        * inside a transaction, then there's really no point in logging
+        * an error. */
+       if (errno == -EROFS && journal_current_handle() == NULL &&
+           (sb->s_flags & MS_RDONLY))
+               return;
+
+       errstr = ext4_decode_error(sb, errno, nbuf);
+       printk (KERN_CRIT "EXT4-fs error (device %s) in %s: %s\n",
+               sb->s_id, function, errstr);
+
+       ext4_handle_error(sb);
+}
+
+/*
+ * ext4_abort is a much stronger failure handler than ext4_error.  The
+ * abort function may be used to deal with unrecoverable failures such
+ * as journal IO errors or ENOMEM at a critical moment in log management.
+ *
+ * We unconditionally force the filesystem into an ABORT|READONLY state,
+ * unless the error response on the fs has been set to panic in which
+ * case we take the easy way out and panic immediately.
+ */
+
+void ext4_abort (struct super_block * sb, const char * function,
+                const char * fmt, ...)
+{
+       va_list args;
+
+       printk (KERN_CRIT "ext4_abort called.\n");
+
+       va_start(args, fmt);
+       printk(KERN_CRIT "EXT4-fs error (device %s): %s: ",sb->s_id, function);
+       vprintk(fmt, args);
+       printk("\n");
+       va_end(args);
+
+       if (test_opt(sb, ERRORS_PANIC))
+               panic("EXT4-fs panic from previous error\n");
+
+       if (sb->s_flags & MS_RDONLY)
+               return;
+
+       printk(KERN_CRIT "Remounting filesystem read-only\n");
+       EXT4_SB(sb)->s_mount_state |= EXT4_ERROR_FS;
+       sb->s_flags |= MS_RDONLY;
+       EXT4_SB(sb)->s_mount_opt |= EXT4_MOUNT_ABORT;
+       jbd2_journal_abort(EXT4_SB(sb)->s_journal, -EIO);
+}
+
+void ext4_warning (struct super_block * sb, const char * function,
+                  const char * fmt, ...)
+{
+       va_list args;
+
+       va_start(args, fmt);
+       printk(KERN_WARNING "EXT4-fs warning (device %s): %s: ",
+              sb->s_id, function);
+       vprintk(fmt, args);
+       printk("\n");
+       va_end(args);
+}
+
+void ext4_update_dynamic_rev(struct super_block *sb)
+{
+       struct ext4_super_block *es = EXT4_SB(sb)->s_es;
+
+       if (le32_to_cpu(es->s_rev_level) > EXT4_GOOD_OLD_REV)
+               return;
+
+       ext4_warning(sb, __FUNCTION__,
+                    "updating to rev %d because of new feature flag, "
+                    "running e2fsck is recommended",
+                    EXT4_DYNAMIC_REV);
+
+       es->s_first_ino = cpu_to_le32(EXT4_GOOD_OLD_FIRST_INO);
+       es->s_inode_size = cpu_to_le16(EXT4_GOOD_OLD_INODE_SIZE);
+       es->s_rev_level = cpu_to_le32(EXT4_DYNAMIC_REV);
+       /* leave es->s_feature_*compat flags alone */
+       /* es->s_uuid will be set by e2fsck if empty */
+
+       /*
+        * The rest of the superblock fields should be zero, and if not it
+        * means they are likely already in use, so leave them alone.  We
+        * can leave it up to e2fsck to clean up any inconsistencies there.
+        */
+}
+
+/*
+ * Open the external journal device
+ */
+static struct block_device *ext4_blkdev_get(dev_t dev)
+{
+       struct block_device *bdev;
+       char b[BDEVNAME_SIZE];
+
+       bdev = open_by_devnum(dev, FMODE_READ|FMODE_WRITE);
+       if (IS_ERR(bdev))
+               goto fail;
+       return bdev;
+
+fail:
+       printk(KERN_ERR "EXT4: failed to open journal device %s: %ld\n",
+                       __bdevname(dev, b), PTR_ERR(bdev));
+       return NULL;
+}
+
+/*
+ * Release the journal device
+ */
+static int ext4_blkdev_put(struct block_device *bdev)
+{
+       bd_release(bdev);
+       return blkdev_put(bdev);
+}
+
+static int ext4_blkdev_remove(struct ext4_sb_info *sbi)
+{
+       struct block_device *bdev;
+       int ret = -ENODEV;
+
+       bdev = sbi->journal_bdev;
+       if (bdev) {
+               ret = ext4_blkdev_put(bdev);
+               sbi->journal_bdev = NULL;
+       }
+       return ret;
+}
+
+static inline struct inode *orphan_list_entry(struct list_head *l)
+{
+       return &list_entry(l, struct ext4_inode_info, i_orphan)->vfs_inode;
+}
+
+static void dump_orphan_list(struct super_block *sb, struct ext4_sb_info *sbi)
+{
+       struct list_head *l;
+
+       printk(KERN_ERR "sb orphan head is %d\n",
+              le32_to_cpu(sbi->s_es->s_last_orphan));
+
+       printk(KERN_ERR "sb_info orphan list:\n");
+       list_for_each(l, &sbi->s_orphan) {
+               struct inode *inode = orphan_list_entry(l);
+               printk(KERN_ERR "  "
+                      "inode %s:%lu at %p: mode %o, nlink %d, next %d\n",
+                      inode->i_sb->s_id, inode->i_ino, inode,
+                      inode->i_mode, inode->i_nlink,
+                      NEXT_ORPHAN(inode));
+       }
+}
+
+static void ext4_put_super (struct super_block * sb)
+{
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+       struct ext4_super_block *es = sbi->s_es;
+       int i;
+
+       ext4_ext_release(sb);
+       ext4_xattr_put_super(sb);
+       jbd2_journal_destroy(sbi->s_journal);
+       if (!(sb->s_flags & MS_RDONLY)) {
+               EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
+               es->s_state = cpu_to_le16(sbi->s_mount_state);
+               BUFFER_TRACE(sbi->s_sbh, "marking dirty");
+               mark_buffer_dirty(sbi->s_sbh);
+               ext4_commit_super(sb, es, 1);
+       }
+
+       for (i = 0; i < sbi->s_gdb_count; i++)
+               brelse(sbi->s_group_desc[i]);
+       kfree(sbi->s_group_desc);
+       percpu_counter_destroy(&sbi->s_freeblocks_counter);
+       percpu_counter_destroy(&sbi->s_freeinodes_counter);
+       percpu_counter_destroy(&sbi->s_dirs_counter);
+       brelse(sbi->s_sbh);
+#ifdef CONFIG_QUOTA
+       for (i = 0; i < MAXQUOTAS; i++)
+               kfree(sbi->s_qf_names[i]);
+#endif
+
+       /* Debugging code just in case the in-memory inode orphan list
+        * isn't empty.  The on-disk one can be non-empty if we've
+        * detected an error and taken the fs readonly, but the
+        * in-memory list had better be clean by this point. */
+       if (!list_empty(&sbi->s_orphan))
+               dump_orphan_list(sb, sbi);
+       J_ASSERT(list_empty(&sbi->s_orphan));
+
+       invalidate_bdev(sb->s_bdev, 0);
+       if (sbi->journal_bdev && sbi->journal_bdev != sb->s_bdev) {
+               /*
+                * Invalidate the journal device's buffers.  We don't want them
+                * floating about in memory - the physical journal device may
+                * hotswapped, and it breaks the `ro-after' testing code.
+                */
+               sync_blockdev(sbi->journal_bdev);
+               invalidate_bdev(sbi->journal_bdev, 0);
+               ext4_blkdev_remove(sbi);
+       }
+       sb->s_fs_info = NULL;
+       kfree(sbi);
+       return;
+}
+
+static struct kmem_cache *ext4_inode_cachep;
+
+/*
+ * Called inside transaction, so use GFP_NOFS
+ */
+static struct inode *ext4_alloc_inode(struct super_block *sb)
+{
+       struct ext4_inode_info *ei;
+
+       ei = kmem_cache_alloc(ext4_inode_cachep, GFP_NOFS);
+       if (!ei)
+               return NULL;
+#ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
+       ei->i_acl = EXT4_ACL_NOT_CACHED;
+       ei->i_default_acl = EXT4_ACL_NOT_CACHED;
+#endif
+       ei->i_block_alloc_info = NULL;
+       ei->vfs_inode.i_version = 1;
+       memset(&ei->i_cached_extent, 0, sizeof(struct ext4_ext_cache));
+       return &ei->vfs_inode;
+}
+
+static void ext4_destroy_inode(struct inode *inode)
+{
+       kmem_cache_free(ext4_inode_cachep, EXT4_I(inode));
+}
+
+static void init_once(void * foo, struct kmem_cache * cachep, unsigned long flags)
+{
+       struct ext4_inode_info *ei = (struct ext4_inode_info *) foo;
+
+       if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
+           SLAB_CTOR_CONSTRUCTOR) {
+               INIT_LIST_HEAD(&ei->i_orphan);
+#ifdef CONFIG_EXT4DEV_FS_XATTR
+               init_rwsem(&ei->xattr_sem);
+#endif
+               mutex_init(&ei->truncate_mutex);
+               inode_init_once(&ei->vfs_inode);
+       }
+}
+
+static int init_inodecache(void)
+{
+       ext4_inode_cachep = kmem_cache_create("ext4_inode_cache",
+                                            sizeof(struct ext4_inode_info),
+                                            0, (SLAB_RECLAIM_ACCOUNT|
+                                               SLAB_MEM_SPREAD),
+                                            init_once, NULL);
+       if (ext4_inode_cachep == NULL)
+               return -ENOMEM;
+       return 0;
+}
+
+static void destroy_inodecache(void)
+{
+       kmem_cache_destroy(ext4_inode_cachep);
+}
+
+static void ext4_clear_inode(struct inode *inode)
+{
+       struct ext4_block_alloc_info *rsv = EXT4_I(inode)->i_block_alloc_info;
+#ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
+       if (EXT4_I(inode)->i_acl &&
+                       EXT4_I(inode)->i_acl != EXT4_ACL_NOT_CACHED) {
+               posix_acl_release(EXT4_I(inode)->i_acl);
+               EXT4_I(inode)->i_acl = EXT4_ACL_NOT_CACHED;
+       }
+       if (EXT4_I(inode)->i_default_acl &&
+                       EXT4_I(inode)->i_default_acl != EXT4_ACL_NOT_CACHED) {
+               posix_acl_release(EXT4_I(inode)->i_default_acl);
+               EXT4_I(inode)->i_default_acl = EXT4_ACL_NOT_CACHED;
+       }
+#endif
+       ext4_discard_reservation(inode);
+       EXT4_I(inode)->i_block_alloc_info = NULL;
+       if (unlikely(rsv))
+               kfree(rsv);
+}
+
+static inline void ext4_show_quota_options(struct seq_file *seq, struct super_block *sb)
+{
+#if defined(CONFIG_QUOTA)
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+       if (sbi->s_jquota_fmt)
+               seq_printf(seq, ",jqfmt=%s",
+               (sbi->s_jquota_fmt == QFMT_VFS_OLD) ? "vfsold": "vfsv0");
+
+       if (sbi->s_qf_names[USRQUOTA])
+               seq_printf(seq, ",usrjquota=%s", sbi->s_qf_names[USRQUOTA]);
+
+       if (sbi->s_qf_names[GRPQUOTA])
+               seq_printf(seq, ",grpjquota=%s", sbi->s_qf_names[GRPQUOTA]);
+
+       if (sbi->s_mount_opt & EXT4_MOUNT_USRQUOTA)
+               seq_puts(seq, ",usrquota");
+
+       if (sbi->s_mount_opt & EXT4_MOUNT_GRPQUOTA)
+               seq_puts(seq, ",grpquota");
+#endif
+}
+
+static int ext4_show_options(struct seq_file *seq, struct vfsmount *vfs)
+{
+       struct super_block *sb = vfs->mnt_sb;
+
+       if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA)
+               seq_puts(seq, ",data=journal");
+       else if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_ORDERED_DATA)
+               seq_puts(seq, ",data=ordered");
+       else if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_WRITEBACK_DATA)
+               seq_puts(seq, ",data=writeback");
+
+       ext4_show_quota_options(seq, sb);
+
+       return 0;
+}
+
+
+static struct dentry *ext4_get_dentry(struct super_block *sb, void *vobjp)
+{
+       __u32 *objp = vobjp;
+       unsigned long ino = objp[0];
+       __u32 generation = objp[1];
+       struct inode *inode;
+       struct dentry *result;
+
+       if (ino < EXT4_FIRST_INO(sb) && ino != EXT4_ROOT_INO)
+               return ERR_PTR(-ESTALE);
+       if (ino > le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count))
+               return ERR_PTR(-ESTALE);
+
+       /* iget isn't really right if the inode is currently unallocated!!
+        *
+        * ext4_read_inode will return a bad_inode if the inode had been
+        * deleted, so we should be safe.
+        *
+        * Currently we don't know the generation for parent directory, so
+        * a generation of 0 means "accept any"
+        */
+       inode = iget(sb, ino);
+       if (inode == NULL)
+               return ERR_PTR(-ENOMEM);
+       if (is_bad_inode(inode) ||
+           (generation && inode->i_generation != generation)) {
+               iput(inode);
+               return ERR_PTR(-ESTALE);
+       }
+       /* now to find a dentry.
+        * If possible, get a well-connected one
+        */
+       result = d_alloc_anon(inode);
+       if (!result) {
+               iput(inode);
+               return ERR_PTR(-ENOMEM);
+       }
+       return result;
+}
+
+#ifdef CONFIG_QUOTA
+#define QTYPE2NAME(t) ((t)==USRQUOTA?"user":"group")
+#define QTYPE2MOPT(on, t) ((t)==USRQUOTA?((on)##USRJQUOTA):((on)##GRPJQUOTA))
+
+static int ext4_dquot_initialize(struct inode *inode, int type);
+static int ext4_dquot_drop(struct inode *inode);
+static int ext4_write_dquot(struct dquot *dquot);
+static int ext4_acquire_dquot(struct dquot *dquot);
+static int ext4_release_dquot(struct dquot *dquot);
+static int ext4_mark_dquot_dirty(struct dquot *dquot);
+static int ext4_write_info(struct super_block *sb, int type);
+static int ext4_quota_on(struct super_block *sb, int type, int format_id, char *path);
+static int ext4_quota_on_mount(struct super_block *sb, int type);
+static ssize_t ext4_quota_read(struct super_block *sb, int type, char *data,
+                              size_t len, loff_t off);
+static ssize_t ext4_quota_write(struct super_block *sb, int type,
+                               const char *data, size_t len, loff_t off);
+
+static struct dquot_operations ext4_quota_operations = {
+       .initialize     = ext4_dquot_initialize,
+       .drop           = ext4_dquot_drop,
+       .alloc_space    = dquot_alloc_space,
+       .alloc_inode    = dquot_alloc_inode,
+       .free_space     = dquot_free_space,
+       .free_inode     = dquot_free_inode,
+       .transfer       = dquot_transfer,
+       .write_dquot    = ext4_write_dquot,
+       .acquire_dquot  = ext4_acquire_dquot,
+       .release_dquot  = ext4_release_dquot,
+       .mark_dirty     = ext4_mark_dquot_dirty,
+       .write_info     = ext4_write_info
+};
+
+static struct quotactl_ops ext4_qctl_operations = {
+       .quota_on       = ext4_quota_on,
+       .quota_off      = vfs_quota_off,
+       .quota_sync     = vfs_quota_sync,
+       .get_info       = vfs_get_dqinfo,
+       .set_info       = vfs_set_dqinfo,
+       .get_dqblk      = vfs_get_dqblk,
+       .set_dqblk      = vfs_set_dqblk
+};
+#endif
+
+static struct super_operations ext4_sops = {
+       .alloc_inode    = ext4_alloc_inode,
+       .destroy_inode  = ext4_destroy_inode,
+       .read_inode     = ext4_read_inode,
+       .write_inode    = ext4_write_inode,
+       .dirty_inode    = ext4_dirty_inode,
+       .delete_inode   = ext4_delete_inode,
+       .put_super      = ext4_put_super,
+       .write_super    = ext4_write_super,
+       .sync_fs        = ext4_sync_fs,
+       .write_super_lockfs = ext4_write_super_lockfs,
+       .unlockfs       = ext4_unlockfs,
+       .statfs         = ext4_statfs,
+       .remount_fs     = ext4_remount,
+       .clear_inode    = ext4_clear_inode,
+       .show_options   = ext4_show_options,
+#ifdef CONFIG_QUOTA
+       .quota_read     = ext4_quota_read,
+       .quota_write    = ext4_quota_write,
+#endif
+};
+
+static struct export_operations ext4_export_ops = {
+       .get_parent = ext4_get_parent,
+       .get_dentry = ext4_get_dentry,
+};
+
+enum {
+       Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
+       Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic, Opt_err_ro,
+       Opt_nouid32, Opt_nocheck, Opt_debug, Opt_oldalloc, Opt_orlov,
+       Opt_user_xattr, Opt_nouser_xattr, Opt_acl, Opt_noacl,
+       Opt_reservation, Opt_noreservation, Opt_noload, Opt_nobh, Opt_bh,
+       Opt_commit, Opt_journal_update, Opt_journal_inum, Opt_journal_dev,
+       Opt_abort, Opt_data_journal, Opt_data_ordered, Opt_data_writeback,
+       Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
+       Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_quota, Opt_noquota,
+       Opt_ignore, Opt_barrier, Opt_err, Opt_resize, Opt_usrquota,
+       Opt_grpquota, Opt_extents, Opt_tag, Opt_notag, Opt_tagid
+};
+
+static match_table_t tokens = {
+       {Opt_bsd_df, "bsddf"},
+       {Opt_minix_df, "minixdf"},
+       {Opt_grpid, "grpid"},
+       {Opt_grpid, "bsdgroups"},
+       {Opt_nogrpid, "nogrpid"},
+       {Opt_nogrpid, "sysvgroups"},
+       {Opt_resgid, "resgid=%u"},
+       {Opt_resuid, "resuid=%u"},
+       {Opt_sb, "sb=%u"},
+       {Opt_err_cont, "errors=continue"},
+       {Opt_err_panic, "errors=panic"},
+       {Opt_err_ro, "errors=remount-ro"},
+       {Opt_nouid32, "nouid32"},
+       {Opt_nocheck, "nocheck"},
+       {Opt_nocheck, "check=none"},
+       {Opt_debug, "debug"},
+       {Opt_oldalloc, "oldalloc"},
+       {Opt_orlov, "orlov"},
+       {Opt_user_xattr, "user_xattr"},
+       {Opt_nouser_xattr, "nouser_xattr"},
+       {Opt_acl, "acl"},
+       {Opt_noacl, "noacl"},
+       {Opt_reservation, "reservation"},
+       {Opt_noreservation, "noreservation"},
+       {Opt_noload, "noload"},
+       {Opt_nobh, "nobh"},
+       {Opt_bh, "bh"},
+       {Opt_commit, "commit=%u"},
+       {Opt_journal_update, "journal=update"},
+       {Opt_journal_inum, "journal=%u"},
+       {Opt_journal_dev, "journal_dev=%u"},
+       {Opt_abort, "abort"},
+       {Opt_data_journal, "data=journal"},
+       {Opt_data_ordered, "data=ordered"},
+       {Opt_data_writeback, "data=writeback"},
+       {Opt_offusrjquota, "usrjquota="},
+       {Opt_usrjquota, "usrjquota=%s"},
+       {Opt_offgrpjquota, "grpjquota="},
+       {Opt_grpjquota, "grpjquota=%s"},
+       {Opt_jqfmt_vfsold, "jqfmt=vfsold"},
+       {Opt_jqfmt_vfsv0, "jqfmt=vfsv0"},
+       {Opt_grpquota, "grpquota"},
+       {Opt_noquota, "noquota"},
+       {Opt_quota, "quota"},
+       {Opt_usrquota, "usrquota"},
+       {Opt_barrier, "barrier=%u"},
+       {Opt_extents, "extents"},
+       {Opt_tag, "tag"},
+       {Opt_notag, "notag"},
+       {Opt_tagid, "tagid=%u"},
+       {Opt_tag, "tagxid"},
+       {Opt_err, NULL},
+       {Opt_resize, "resize"},
+};
+
+static ext4_fsblk_t get_sb_block(void **data)
+{
+       ext4_fsblk_t    sb_block;
+       char            *options = (char *) *data;
+
+       if (!options || strncmp(options, "sb=", 3) != 0)
+               return 1;       /* Default location */
+       options += 3;
+       /*todo: use simple_strtoll with >32bit ext4 */
+       sb_block = simple_strtoul(options, &options, 0);
+       if (*options && *options != ',') {
+               printk("EXT4-fs: Invalid sb specification: %s\n",
+                      (char *) *data);
+               return 1;
+       }
+       if (*options == ',')
+               options++;
+       *data = (void *) options;
+       return sb_block;
+}
+
+static int parse_options (char *options, struct super_block *sb,
+                         unsigned int *inum, unsigned long *journal_devnum,
+                         ext4_fsblk_t *n_blocks_count, int is_remount)
+{
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+       char * p;
+       substring_t args[MAX_OPT_ARGS];
+       int data_opt = 0;
+       int option;
+#ifdef CONFIG_QUOTA
+       int qtype;
+       char *qname;
+#endif
+
+       if (!options)
+               return 1;
+
+       while ((p = strsep (&options, ",")) != NULL) {
+               int token;
+               if (!*p)
+                       continue;
+
+               token = match_token(p, tokens, args);
+               switch (token) {
+               case Opt_bsd_df:
+                       clear_opt (sbi->s_mount_opt, MINIX_DF);
+                       break;
+               case Opt_minix_df:
+                       set_opt (sbi->s_mount_opt, MINIX_DF);
+                       break;
+               case Opt_grpid:
+                       set_opt (sbi->s_mount_opt, GRPID);
+                       break;
+               case Opt_nogrpid:
+                       clear_opt (sbi->s_mount_opt, GRPID);
+                       break;
+               case Opt_resuid:
+                       if (match_int(&args[0], &option))
+                               return 0;
+                       sbi->s_resuid = option;
+                       break;
+               case Opt_resgid:
+                       if (match_int(&args[0], &option))
+                               return 0;
+                       sbi->s_resgid = option;
+                       break;
+               case Opt_sb:
+                       /* handled by get_sb_block() instead of here */
+                       /* *sb_block = match_int(&args[0]); */
+                       break;
+               case Opt_err_panic:
+                       clear_opt (sbi->s_mount_opt, ERRORS_CONT);
+                       clear_opt (sbi->s_mount_opt, ERRORS_RO);
+                       set_opt (sbi->s_mount_opt, ERRORS_PANIC);
+                       break;
+               case Opt_err_ro:
+                       clear_opt (sbi->s_mount_opt, ERRORS_CONT);
+                       clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
+                       set_opt (sbi->s_mount_opt, ERRORS_RO);
+                       break;
+               case Opt_err_cont:
+                       clear_opt (sbi->s_mount_opt, ERRORS_RO);
+                       clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
+                       set_opt (sbi->s_mount_opt, ERRORS_CONT);
+                       break;
+               case Opt_nouid32:
+                       set_opt (sbi->s_mount_opt, NO_UID32);
+                       break;
+#ifndef CONFIG_TAGGING_NONE
+               case Opt_tag:
+                       set_opt (sbi->s_mount_opt, TAGGED);
+                       break;
+               case Opt_notag:
+                       clear_opt (sbi->s_mount_opt, TAGGED);
+                       break;
+#endif
+#ifdef CONFIG_PROPAGATE
+               case Opt_tagid:
+                       /* use args[0] */
+                       set_opt (sbi->s_mount_opt, TAGGED);
+                       break;
+#endif
+               case Opt_nocheck:
+                       clear_opt (sbi->s_mount_opt, CHECK);
+                       break;
+               case Opt_debug:
+                       set_opt (sbi->s_mount_opt, DEBUG);
+                       break;
+               case Opt_oldalloc:
+                       set_opt (sbi->s_mount_opt, OLDALLOC);
+                       break;
+               case Opt_orlov:
+                       clear_opt (sbi->s_mount_opt, OLDALLOC);
+                       break;
+#ifdef CONFIG_EXT4DEV_FS_XATTR
+               case Opt_user_xattr:
+                       set_opt (sbi->s_mount_opt, XATTR_USER);
+                       break;
+               case Opt_nouser_xattr:
+                       clear_opt (sbi->s_mount_opt, XATTR_USER);
+                       break;
+#else
+               case Opt_user_xattr:
+               case Opt_nouser_xattr:
+                       printk("EXT4 (no)user_xattr options not supported\n");
+                       break;
+#endif
+#ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
+               case Opt_acl:
+                       set_opt(sbi->s_mount_opt, POSIX_ACL);
+                       break;
+               case Opt_noacl:
+                       clear_opt(sbi->s_mount_opt, POSIX_ACL);
+                       break;
+#else
+               case Opt_acl:
+               case Opt_noacl:
+                       printk("EXT4 (no)acl options not supported\n");
+                       break;
+#endif
+               case Opt_reservation:
+                       set_opt(sbi->s_mount_opt, RESERVATION);
+                       break;
+               case Opt_noreservation:
+                       clear_opt(sbi->s_mount_opt, RESERVATION);
+                       break;
+               case Opt_journal_update:
+                       /* @@@ FIXME */
+                       /* Eventually we will want to be able to create
+                          a journal file here.  For now, only allow the
+                          user to specify an existing inode to be the
+                          journal file. */
+                       if (is_remount) {
+                               printk(KERN_ERR "EXT4-fs: cannot specify "
+                                      "journal on remount\n");
+                               return 0;
+                       }
+                       set_opt (sbi->s_mount_opt, UPDATE_JOURNAL);
+                       break;
+               case Opt_journal_inum:
+                       if (is_remount) {
+                               printk(KERN_ERR "EXT4-fs: cannot specify "
+                                      "journal on remount\n");
+                               return 0;
+                       }
+                       if (match_int(&args[0], &option))
+                               return 0;
+                       *inum = option;
+                       break;
+               case Opt_journal_dev:
+                       if (is_remount) {
+                               printk(KERN_ERR "EXT4-fs: cannot specify "
+                                      "journal on remount\n");
+                               return 0;
+                       }
+                       if (match_int(&args[0], &option))
+                               return 0;
+                       *journal_devnum = option;
+                       break;
+               case Opt_noload:
+                       set_opt (sbi->s_mount_opt, NOLOAD);
+                       break;
+               case Opt_commit:
+                       if (match_int(&args[0], &option))
+                               return 0;
+                       if (option < 0)
+                               return 0;
+                       if (option == 0)
+                               option = JBD_DEFAULT_MAX_COMMIT_AGE;
+                       sbi->s_commit_interval = HZ * option;
+                       break;
+               case Opt_data_journal:
+                       data_opt = EXT4_MOUNT_JOURNAL_DATA;
+                       goto datacheck;
+               case Opt_data_ordered:
+                       data_opt = EXT4_MOUNT_ORDERED_DATA;
+                       goto datacheck;
+               case Opt_data_writeback:
+                       data_opt = EXT4_MOUNT_WRITEBACK_DATA;
+               datacheck:
+                       if (is_remount) {
+                               if ((sbi->s_mount_opt & EXT4_MOUNT_DATA_FLAGS)
+                                               != data_opt) {
+                                       printk(KERN_ERR
+                                               "EXT4-fs: cannot change data "
+                                               "mode on remount\n");
+                                       return 0;
+                               }
+                       } else {
+                               sbi->s_mount_opt &= ~EXT4_MOUNT_DATA_FLAGS;
+                               sbi->s_mount_opt |= data_opt;
+                       }
+                       break;
+#ifdef CONFIG_QUOTA
+               case Opt_usrjquota:
+                       qtype = USRQUOTA;
+                       goto set_qf_name;
+               case Opt_grpjquota:
+                       qtype = GRPQUOTA;
+set_qf_name:
+                       if (sb_any_quota_enabled(sb)) {
+                               printk(KERN_ERR
+                                       "EXT4-fs: Cannot change journalled "
+                                       "quota options when quota turned on.\n");
+                               return 0;
+                       }
+                       qname = match_strdup(&args[0]);
+                       if (!qname) {
+                               printk(KERN_ERR
+                                       "EXT4-fs: not enough memory for "
+                                       "storing quotafile name.\n");
+                               return 0;
+                       }
+                       if (sbi->s_qf_names[qtype] &&
+                           strcmp(sbi->s_qf_names[qtype], qname)) {
+                               printk(KERN_ERR
+                                       "EXT4-fs: %s quota file already "
+                                       "specified.\n", QTYPE2NAME(qtype));
+                               kfree(qname);
+                               return 0;
+                       }
+                       sbi->s_qf_names[qtype] = qname;
+                       if (strchr(sbi->s_qf_names[qtype], '/')) {
+                               printk(KERN_ERR
+                                       "EXT4-fs: quotafile must be on "
+                                       "filesystem root.\n");
+                               kfree(sbi->s_qf_names[qtype]);
+                               sbi->s_qf_names[qtype] = NULL;
+                               return 0;
+                       }
+                       set_opt(sbi->s_mount_opt, QUOTA);
+                       break;
+               case Opt_offusrjquota:
+                       qtype = USRQUOTA;
+                       goto clear_qf_name;
+               case Opt_offgrpjquota:
+                       qtype = GRPQUOTA;
+clear_qf_name:
+                       if (sb_any_quota_enabled(sb)) {
+                               printk(KERN_ERR "EXT4-fs: Cannot change "
+                                       "journalled quota options when "
+                                       "quota turned on.\n");
+                               return 0;
+                       }
+                       /*
+                        * The space will be released later when all options
+                        * are confirmed to be correct
+                        */
+                       sbi->s_qf_names[qtype] = NULL;
+                       break;
+               case Opt_jqfmt_vfsold:
+                       sbi->s_jquota_fmt = QFMT_VFS_OLD;
+                       break;
+               case Opt_jqfmt_vfsv0:
+                       sbi->s_jquota_fmt = QFMT_VFS_V0;
+                       break;
+               case Opt_quota:
+               case Opt_usrquota:
+                       set_opt(sbi->s_mount_opt, QUOTA);
+                       set_opt(sbi->s_mount_opt, USRQUOTA);
+                       break;
+               case Opt_grpquota:
+                       set_opt(sbi->s_mount_opt, QUOTA);
+                       set_opt(sbi->s_mount_opt, GRPQUOTA);
+                       break;
+               case Opt_noquota:
+                       if (sb_any_quota_enabled(sb)) {
+                               printk(KERN_ERR "EXT4-fs: Cannot change quota "
+                                       "options when quota turned on.\n");
+                               return 0;
+                       }
+                       clear_opt(sbi->s_mount_opt, QUOTA);
+                       clear_opt(sbi->s_mount_opt, USRQUOTA);
+                       clear_opt(sbi->s_mount_opt, GRPQUOTA);
+                       break;
+#else
+               case Opt_quota:
+               case Opt_usrquota:
+               case Opt_grpquota:
+               case Opt_usrjquota:
+               case Opt_grpjquota:
+               case Opt_offusrjquota:
+               case Opt_offgrpjquota:
+               case Opt_jqfmt_vfsold:
+               case Opt_jqfmt_vfsv0:
+                       printk(KERN_ERR
+                               "EXT4-fs: journalled quota options not "
+                               "supported.\n");
+                       break;
+               case Opt_noquota:
+                       break;
+#endif
+               case Opt_abort:
+                       set_opt(sbi->s_mount_opt, ABORT);
+                       break;
+               case Opt_barrier:
+                       if (match_int(&args[0], &option))
+                               return 0;
+                       if (option)
+                               set_opt(sbi->s_mount_opt, BARRIER);
+                       else
+                               clear_opt(sbi->s_mount_opt, BARRIER);
+                       break;
+               case Opt_ignore:
+                       break;
+               case Opt_resize:
+                       if (!is_remount) {
+                               printk("EXT4-fs: resize option only available "
+                                       "for remount\n");
+                               return 0;
+                       }
+                       if (match_int(&args[0], &option) != 0)
+                               return 0;
+                       *n_blocks_count = option;
+                       break;
+               case Opt_nobh:
+                       set_opt(sbi->s_mount_opt, NOBH);
+                       break;
+               case Opt_bh:
+                       clear_opt(sbi->s_mount_opt, NOBH);
+                       break;
+               case Opt_extents:
+                       set_opt (sbi->s_mount_opt, EXTENTS);
+                       break;
+               default:
+                       printk (KERN_ERR
+                               "EXT4-fs: Unrecognized mount option \"%s\" "
+                               "or missing value\n", p);
+                       return 0;
+               }
+       }
+#ifdef CONFIG_QUOTA
+       if (sbi->s_qf_names[USRQUOTA] || sbi->s_qf_names[GRPQUOTA]) {
+               if ((sbi->s_mount_opt & EXT4_MOUNT_USRQUOTA) &&
+                    sbi->s_qf_names[USRQUOTA])
+                       clear_opt(sbi->s_mount_opt, USRQUOTA);
+
+               if ((sbi->s_mount_opt & EXT4_MOUNT_GRPQUOTA) &&
+                    sbi->s_qf_names[GRPQUOTA])
+                       clear_opt(sbi->s_mount_opt, GRPQUOTA);
+
+               if ((sbi->s_qf_names[USRQUOTA] &&
+                               (sbi->s_mount_opt & EXT4_MOUNT_GRPQUOTA)) ||
+                   (sbi->s_qf_names[GRPQUOTA] &&
+                               (sbi->s_mount_opt & EXT4_MOUNT_USRQUOTA))) {
+                       printk(KERN_ERR "EXT4-fs: old and new quota "
+                                       "format mixing.\n");
+                       return 0;
+               }
+
+               if (!sbi->s_jquota_fmt) {
+                       printk(KERN_ERR "EXT4-fs: journalled quota format "
+                                       "not specified.\n");
+                       return 0;
+               }
+       } else {
+               if (sbi->s_jquota_fmt) {
+                       printk(KERN_ERR "EXT4-fs: journalled quota format "
+                                       "specified with no journalling "
+                                       "enabled.\n");
+                       return 0;
+               }
+       }
+#endif
+       return 1;
+}
+
+static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
+                           int read_only)
+{
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+       int res = 0;
+
+       if (le32_to_cpu(es->s_rev_level) > EXT4_MAX_SUPP_REV) {
+               printk (KERN_ERR "EXT4-fs warning: revision level too high, "
+                       "forcing read-only mode\n");
+               res = MS_RDONLY;
+       }
+       if (read_only)
+               return res;
+       if (!(sbi->s_mount_state & EXT4_VALID_FS))
+               printk (KERN_WARNING "EXT4-fs warning: mounting unchecked fs, "
+                       "running e2fsck is recommended\n");
+       else if ((sbi->s_mount_state & EXT4_ERROR_FS))
+               printk (KERN_WARNING
+                       "EXT4-fs warning: mounting fs with errors, "
+                       "running e2fsck is recommended\n");
+       else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
+                le16_to_cpu(es->s_mnt_count) >=
+                (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
+               printk (KERN_WARNING
+                       "EXT4-fs warning: maximal mount count reached, "
+                       "running e2fsck is recommended\n");
+       else if (le32_to_cpu(es->s_checkinterval) &&
+               (le32_to_cpu(es->s_lastcheck) +
+                       le32_to_cpu(es->s_checkinterval) <= get_seconds()))
+               printk (KERN_WARNING
+                       "EXT4-fs warning: checktime reached, "
+                       "running e2fsck is recommended\n");
+#if 0
+               /* @@@ We _will_ want to clear the valid bit if we find
+                * inconsistencies, to force a fsck at reboot.  But for
+                * a plain journaled filesystem we can keep it set as
+                * valid forever! :)
+                */
+       es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) & ~EXT4_VALID_FS);
+#endif
+       if (!(__s16) le16_to_cpu(es->s_max_mnt_count))
+               es->s_max_mnt_count = cpu_to_le16(EXT4_DFL_MAX_MNT_COUNT);
+       es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
+       es->s_mtime = cpu_to_le32(get_seconds());
+       ext4_update_dynamic_rev(sb);
+       EXT4_SET_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
+
+       ext4_commit_super(sb, es, 1);
+       if (test_opt(sb, DEBUG))
+               printk(KERN_INFO "[EXT4 FS bs=%lu, gc=%lu, "
+                               "bpg=%lu, ipg=%lu, mo=%04lx]\n",
+                       sb->s_blocksize,
+                       sbi->s_groups_count,
+                       EXT4_BLOCKS_PER_GROUP(sb),
+                       EXT4_INODES_PER_GROUP(sb),
+                       sbi->s_mount_opt);
+
+       printk(KERN_INFO "EXT4 FS on %s, ", sb->s_id);
+       if (EXT4_SB(sb)->s_journal->j_inode == NULL) {
+               char b[BDEVNAME_SIZE];
+
+               printk("external journal on %s\n",
+                       bdevname(EXT4_SB(sb)->s_journal->j_dev, b));
+       } else {
+               printk("internal journal\n");
+       }
+       return res;
+}
+
+/* Called at mount-time, super-block is locked */
+static int ext4_check_descriptors (struct super_block * sb)
+{
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+       ext4_fsblk_t first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
+       ext4_fsblk_t last_block;
+       ext4_fsblk_t block_bitmap;
+       ext4_fsblk_t inode_bitmap;
+       ext4_fsblk_t inode_table;
+       struct ext4_group_desc * gdp = NULL;
+       int desc_block = 0;
+       int i;
+
+       ext4_debug ("Checking group descriptors");
+
+       for (i = 0; i < sbi->s_groups_count; i++)
+       {
+               if (i == sbi->s_groups_count - 1)
+                       last_block = ext4_blocks_count(sbi->s_es) - 1;
+               else
+                       last_block = first_block +
+                               (EXT4_BLOCKS_PER_GROUP(sb) - 1);
+
+               if ((i % EXT4_DESC_PER_BLOCK(sb)) == 0)
+                       gdp = (struct ext4_group_desc *)
+                                       sbi->s_group_desc[desc_block++]->b_data;
+               block_bitmap = ext4_block_bitmap(sb, gdp);
+               if (block_bitmap < first_block || block_bitmap > last_block)
+               {
+                       ext4_error (sb, "ext4_check_descriptors",
+                                   "Block bitmap for group %d"
+                                   " not in group (block %llu)!",
+                                   i, block_bitmap);
+                       return 0;
+               }
+               inode_bitmap = ext4_inode_bitmap(sb, gdp);
+               if (inode_bitmap < first_block || inode_bitmap > last_block)
+               {
+                       ext4_error (sb, "ext4_check_descriptors",
+                                   "Inode bitmap for group %d"
+                                   " not in group (block %llu)!",
+                                   i, inode_bitmap);
+                       return 0;
+               }
+               inode_table = ext4_inode_table(sb, gdp);
+               if (inode_table < first_block ||
+                   inode_table + sbi->s_itb_per_group > last_block)
+               {
+                       ext4_error (sb, "ext4_check_descriptors",
+                                   "Inode table for group %d"
+                                   " not in group (block %llu)!",
+                                   i, inode_table);
+                       return 0;
+               }
+               first_block += EXT4_BLOCKS_PER_GROUP(sb);
+               gdp = (struct ext4_group_desc *)
+                       ((__u8 *)gdp + EXT4_DESC_SIZE(sb));
+       }
+
+       ext4_free_blocks_count_set(sbi->s_es, ext4_count_free_blocks(sb));
+       sbi->s_es->s_free_inodes_count=cpu_to_le32(ext4_count_free_inodes(sb));
+       return 1;
+}
+
+
+/* ext4_orphan_cleanup() walks a singly-linked list of inodes (starting at
+ * the superblock) which were deleted from all directories, but held open by
+ * a process at the time of a crash.  We walk the list and try to delete these
+ * inodes at recovery time (only with a read-write filesystem).
+ *
+ * In order to keep the orphan inode chain consistent during traversal (in
+ * case of crash during recovery), we link each inode into the superblock
+ * orphan list_head and handle it the same way as an inode deletion during
+ * normal operation (which journals the operations for us).
+ *
+ * We only do an iget() and an iput() on each inode, which is very safe if we
+ * accidentally point at an in-use or already deleted inode.  The worst that
+ * can happen in this case is that we get a "bit already cleared" message from
+ * ext4_free_inode().  The only reason we would point at a wrong inode is if
+ * e2fsck was run on this filesystem, and it must have already done the orphan
+ * inode cleanup for us, so we can safely abort without any further action.
+ */
+static void ext4_orphan_cleanup (struct super_block * sb,
+                                struct ext4_super_block * es)
+{
+       unsigned int s_flags = sb->s_flags;
+       int nr_orphans = 0, nr_truncates = 0;
+#ifdef CONFIG_QUOTA
+       int i;
+#endif
+       if (!es->s_last_orphan) {
+               jbd_debug(4, "no orphan inodes to clean up\n");
+               return;
+       }
+
+       if (bdev_read_only(sb->s_bdev)) {
+               printk(KERN_ERR "EXT4-fs: write access "
+                       "unavailable, skipping orphan cleanup.\n");
+               return;
+       }
+
+       if (EXT4_SB(sb)->s_mount_state & EXT4_ERROR_FS) {
+               if (es->s_last_orphan)
+                       jbd_debug(1, "Errors on filesystem, "
+                                 "clearing orphan list.\n");
+               es->s_last_orphan = 0;
+               jbd_debug(1, "Skipping orphan recovery on fs with errors.\n");
+               return;
+       }
+
+       if (s_flags & MS_RDONLY) {
+               printk(KERN_INFO "EXT4-fs: %s: orphan cleanup on readonly fs\n",
+                      sb->s_id);
+               sb->s_flags &= ~MS_RDONLY;
+       }
+#ifdef CONFIG_QUOTA
+       /* Needed for iput() to work correctly and not trash data */
+       sb->s_flags |= MS_ACTIVE;
+       /* Turn on quotas so that they are updated correctly */
+       for (i = 0; i < MAXQUOTAS; i++) {
+               if (EXT4_SB(sb)->s_qf_names[i]) {
+                       int ret = ext4_quota_on_mount(sb, i);
+                       if (ret < 0)
+                               printk(KERN_ERR
+                                       "EXT4-fs: Cannot turn on journalled "
+                                       "quota: error %d\n", ret);
+               }
+       }
+#endif
+
+       while (es->s_last_orphan) {
+               struct inode *inode;
+
+               if (!(inode =
+                     ext4_orphan_get(sb, le32_to_cpu(es->s_last_orphan)))) {
+                       es->s_last_orphan = 0;
+                       break;
+               }
+
+               list_add(&EXT4_I(inode)->i_orphan, &EXT4_SB(sb)->s_orphan);
+               DQUOT_INIT(inode);
+               if (inode->i_nlink) {
+                       printk(KERN_DEBUG
+                               "%s: truncating inode %lu to %Ld bytes\n",
+                               __FUNCTION__, inode->i_ino, inode->i_size);
+                       jbd_debug(2, "truncating inode %lu to %Ld bytes\n",
+                                 inode->i_ino, inode->i_size);
+                       ext4_truncate(inode);
+                       nr_truncates++;
+               } else {
+                       printk(KERN_DEBUG
+                               "%s: deleting unreferenced inode %lu\n",
+                               __FUNCTION__, inode->i_ino);
+                       jbd_debug(2, "deleting unreferenced inode %lu\n",
+                                 inode->i_ino);
+                       nr_orphans++;
+               }
+               iput(inode);  /* The delete magic happens here! */
+       }
+
+#define PLURAL(x) (x), ((x)==1) ? "" : "s"
+
+       if (nr_orphans)
+               printk(KERN_INFO "EXT4-fs: %s: %d orphan inode%s deleted\n",
+                      sb->s_id, PLURAL(nr_orphans));
+       if (nr_truncates)
+               printk(KERN_INFO "EXT4-fs: %s: %d truncate%s cleaned up\n",
+                      sb->s_id, PLURAL(nr_truncates));
+#ifdef CONFIG_QUOTA
+       /* Turn quotas off */
+       for (i = 0; i < MAXQUOTAS; i++) {
+               if (sb_dqopt(sb)->files[i])
+                       vfs_quota_off(sb, i);
+       }
+#endif
+       sb->s_flags = s_flags; /* Restore MS_RDONLY status */
+}
+
+#define log2(n) ffz(~(n))
+
+/*
+ * Maximal file size.  There is a direct, and {,double-,triple-}indirect
+ * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
+ * We need to be 1 filesystem block less than the 2^32 sector limit.
+ */
+static loff_t ext4_max_size(int bits)
+{
+       loff_t res = EXT4_NDIR_BLOCKS;
+       /* This constant is calculated to be the largest file size for a
+        * dense, 4k-blocksize file such that the total number of
+        * sectors in the file, including data and all indirect blocks,
+        * does not exceed 2^32. */
+       const loff_t upper_limit = 0x1ff7fffd000LL;
+
+       res += 1LL << (bits-2);
+       res += 1LL << (2*(bits-2));
+       res += 1LL << (3*(bits-2));
+       res <<= bits;
+       if (res > upper_limit)
+               res = upper_limit;
+       return res;
+}
+
+static ext4_fsblk_t descriptor_loc(struct super_block *sb,
+                               ext4_fsblk_t logical_sb_block, int nr)
+{
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+       unsigned long bg, first_meta_bg;
+       int has_super = 0;
+
+       first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
+
+       if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
+           nr < first_meta_bg)
+               return logical_sb_block + nr + 1;
+       bg = sbi->s_desc_per_block * nr;
+       if (ext4_bg_has_super(sb, bg))
+               has_super = 1;
+       return (has_super + ext4_group_first_block_no(sb, bg));
+}
+
+
+static int ext4_fill_super (struct super_block *sb, void *data, int silent)
+{
+       struct buffer_head * bh;
+       struct ext4_super_block *es = NULL;
+       struct ext4_sb_info *sbi;
+       ext4_fsblk_t block;
+       ext4_fsblk_t sb_block = get_sb_block(&data);
+       ext4_fsblk_t logical_sb_block;
+       unsigned long offset = 0;
+       unsigned int journal_inum = 0;
+       unsigned long journal_devnum = 0;
+       unsigned long def_mount_opts;
+       struct inode *root;
+       int blocksize;
+       int hblock;
+       int db_count;
+       int i;
+       int needs_recovery;
+       __le32 features;
+       __u64 blocks_count;
+
+       sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
+       if (!sbi)
+               return -ENOMEM;
+       sb->s_fs_info = sbi;
+       sbi->s_mount_opt = 0;
+       sbi->s_resuid = EXT4_DEF_RESUID;
+       sbi->s_resgid = EXT4_DEF_RESGID;
+
+       unlock_kernel();
+
+       blocksize = sb_min_blocksize(sb, EXT4_MIN_BLOCK_SIZE);
+       if (!blocksize) {
+               printk(KERN_ERR "EXT4-fs: unable to set blocksize\n");
+               goto out_fail;
+       }
+
+       /*
+        * The ext4 superblock will not be buffer aligned for other than 1kB
+        * block sizes.  We need to calculate the offset from buffer start.
+        */
+       if (blocksize != EXT4_MIN_BLOCK_SIZE) {
+               logical_sb_block = sb_block * EXT4_MIN_BLOCK_SIZE;
+               offset = do_div(logical_sb_block, blocksize);
+       } else {
+               logical_sb_block = sb_block;
+       }
+
+       if (!(bh = sb_bread(sb, logical_sb_block))) {
+               printk (KERN_ERR "EXT4-fs: unable to read superblock\n");
+               goto out_fail;
+       }
+       /*
+        * Note: s_es must be initialized as soon as possible because
+        *       some ext4 macro-instructions depend on its value
+        */
+       es = (struct ext4_super_block *) (((char *)bh->b_data) + offset);
+       sbi->s_es = es;
+       sb->s_magic = le16_to_cpu(es->s_magic);
+       if (sb->s_magic != EXT4_SUPER_MAGIC)
+               goto cantfind_ext4;
+
+       /* Set defaults before we parse the mount options */
+       def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
+       if (def_mount_opts & EXT4_DEFM_DEBUG)
+               set_opt(sbi->s_mount_opt, DEBUG);
+       if (def_mount_opts & EXT4_DEFM_BSDGROUPS)
+               set_opt(sbi->s_mount_opt, GRPID);
+       if (def_mount_opts & EXT4_DEFM_UID16)
+               set_opt(sbi->s_mount_opt, NO_UID32);
+#ifdef CONFIG_EXT4DEV_FS_XATTR
+       if (def_mount_opts & EXT4_DEFM_XATTR_USER)
+               set_opt(sbi->s_mount_opt, XATTR_USER);
+#endif
+#ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
+       if (def_mount_opts & EXT4_DEFM_ACL)
+               set_opt(sbi->s_mount_opt, POSIX_ACL);
+#endif
+       if ((def_mount_opts & EXT4_DEFM_JMODE) == EXT4_DEFM_JMODE_DATA)
+               sbi->s_mount_opt |= EXT4_MOUNT_JOURNAL_DATA;
+       else if ((def_mount_opts & EXT4_DEFM_JMODE) == EXT4_DEFM_JMODE_ORDERED)
+               sbi->s_mount_opt |= EXT4_MOUNT_ORDERED_DATA;
+       else if ((def_mount_opts & EXT4_DEFM_JMODE) == EXT4_DEFM_JMODE_WBACK)
+               sbi->s_mount_opt |= EXT4_MOUNT_WRITEBACK_DATA;
+
+       if (le16_to_cpu(sbi->s_es->s_errors) == EXT4_ERRORS_PANIC)
+               set_opt(sbi->s_mount_opt, ERRORS_PANIC);
+       else if (le16_to_cpu(sbi->s_es->s_errors) == EXT4_ERRORS_RO)
+               set_opt(sbi->s_mount_opt, ERRORS_RO);
+       else
+               set_opt(sbi->s_mount_opt, ERRORS_CONT);
+
+       sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
+       sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
+
+       set_opt(sbi->s_mount_opt, RESERVATION);
+
+       if (!parse_options ((char *) data, sb, &journal_inum, &journal_devnum,
+                           NULL, 0))
+               goto failed_mount;
+
+       if (EXT4_SB(sb)->s_mount_opt & EXT4_MOUNT_TAGGED)
+               sb->s_flags |= MS_TAGGED;
+
+       sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
+               ((sbi->s_mount_opt & EXT4_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
+
+       if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV &&
+           (EXT4_HAS_COMPAT_FEATURE(sb, ~0U) ||
+            EXT4_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
+            EXT4_HAS_INCOMPAT_FEATURE(sb, ~0U)))
+               printk(KERN_WARNING
+                      "EXT4-fs warning: feature flags set on rev 0 fs, "
+                      "running e2fsck is recommended\n");
+       /*
+        * Check feature flags regardless of the revision level, since we
+        * previously didn't change the revision level when setting the flags,
+        * so there is a chance incompat flags are set on a rev 0 filesystem.
+        */
+       features = EXT4_HAS_INCOMPAT_FEATURE(sb, ~EXT4_FEATURE_INCOMPAT_SUPP);
+       if (features) {
+               printk(KERN_ERR "EXT4-fs: %s: couldn't mount because of "
+                      "unsupported optional features (%x).\n",
+                      sb->s_id, le32_to_cpu(features));
+               goto failed_mount;
+       }
+       features = EXT4_HAS_RO_COMPAT_FEATURE(sb, ~EXT4_FEATURE_RO_COMPAT_SUPP);
+       if (!(sb->s_flags & MS_RDONLY) && features) {
+               printk(KERN_ERR "EXT4-fs: %s: couldn't mount RDWR because of "
+                      "unsupported optional features (%x).\n",
+                      sb->s_id, le32_to_cpu(features));
+               goto failed_mount;
+       }
+       blocksize = BLOCK_SIZE << le32_to_cpu(es->s_log_block_size);
+
+       if (blocksize < EXT4_MIN_BLOCK_SIZE ||
+           blocksize > EXT4_MAX_BLOCK_SIZE) {
+               printk(KERN_ERR
+                      "EXT4-fs: Unsupported filesystem blocksize %d on %s.\n",
+                      blocksize, sb->s_id);
+               goto failed_mount;
+       }
+
+       hblock = bdev_hardsect_size(sb->s_bdev);
+       if (sb->s_blocksize != blocksize) {
+               /*
+                * Make sure the blocksize for the filesystem is larger
+                * than the hardware sectorsize for the machine.
+                */
+               if (blocksize < hblock) {
+                       printk(KERN_ERR "EXT4-fs: blocksize %d too small for "
+                              "device blocksize %d.\n", blocksize, hblock);
+                       goto failed_mount;
+               }
+
+               brelse (bh);
+               sb_set_blocksize(sb, blocksize);
+               logical_sb_block = sb_block * EXT4_MIN_BLOCK_SIZE;
+               offset = do_div(logical_sb_block, blocksize);
+               bh = sb_bread(sb, logical_sb_block);
+               if (!bh) {
+                       printk(KERN_ERR
+                              "EXT4-fs: Can't read superblock on 2nd try.\n");
+                       goto failed_mount;
+               }
+               es = (struct ext4_super_block *)(((char *)bh->b_data) + offset);
+               sbi->s_es = es;
+               if (es->s_magic != cpu_to_le16(EXT4_SUPER_MAGIC)) {
+                       printk (KERN_ERR
+                               "EXT4-fs: Magic mismatch, very weird !\n");
+                       goto failed_mount;
+               }
+       }
+
+       sb->s_maxbytes = ext4_max_size(sb->s_blocksize_bits);
+
+       if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV) {
+               sbi->s_inode_size = EXT4_GOOD_OLD_INODE_SIZE;
+               sbi->s_first_ino = EXT4_GOOD_OLD_FIRST_INO;
+       } else {
+               sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
+               sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
+               if ((sbi->s_inode_size < EXT4_GOOD_OLD_INODE_SIZE) ||
+                   (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
+                   (sbi->s_inode_size > blocksize)) {
+                       printk (KERN_ERR
+                               "EXT4-fs: unsupported inode size: %d\n",
+                               sbi->s_inode_size);
+                       goto failed_mount;
+               }
+       }
+       sbi->s_frag_size = EXT4_MIN_FRAG_SIZE <<
+                                  le32_to_cpu(es->s_log_frag_size);
+       if (blocksize != sbi->s_frag_size) {
+               printk(KERN_ERR
+                      "EXT4-fs: fragsize %lu != blocksize %u (unsupported)\n",
+                      sbi->s_frag_size, blocksize);
+               goto failed_mount;
+       }
+       sbi->s_desc_size = le16_to_cpu(es->s_desc_size);
+       if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_64BIT)) {
+               if (sbi->s_desc_size < EXT4_MIN_DESC_SIZE_64BIT ||
+                   sbi->s_desc_size > EXT4_MAX_DESC_SIZE ||
+                   sbi->s_desc_size & (sbi->s_desc_size - 1)) {
+                       printk(KERN_ERR
+                              "EXT4-fs: unsupported descriptor size %lu\n",
+                              sbi->s_desc_size);
+                       goto failed_mount;
+               }
+       } else
+               sbi->s_desc_size = EXT4_MIN_DESC_SIZE;
+       sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
+       sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
+       sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
+       if (EXT4_INODE_SIZE(sb) == 0)
+               goto cantfind_ext4;
+       sbi->s_inodes_per_block = blocksize / EXT4_INODE_SIZE(sb);
+       if (sbi->s_inodes_per_block == 0)
+               goto cantfind_ext4;
+       sbi->s_itb_per_group = sbi->s_inodes_per_group /
+                                       sbi->s_inodes_per_block;
+       sbi->s_desc_per_block = blocksize / EXT4_DESC_SIZE(sb);
+       sbi->s_sbh = bh;
+       sbi->s_mount_state = le16_to_cpu(es->s_state);
+       sbi->s_addr_per_block_bits = log2(EXT4_ADDR_PER_BLOCK(sb));
+       sbi->s_desc_per_block_bits = log2(EXT4_DESC_PER_BLOCK(sb));
+       for (i=0; i < 4; i++)
+               sbi->s_hash_seed[i] = le32_to_cpu(es->s_hash_seed[i]);
+       sbi->s_def_hash_version = es->s_def_hash_version;
+
+       if (sbi->s_blocks_per_group > blocksize * 8) {
+               printk (KERN_ERR
+                       "EXT4-fs: #blocks per group too big: %lu\n",
+                       sbi->s_blocks_per_group);
+               goto failed_mount;
+       }
+       if (sbi->s_frags_per_group > blocksize * 8) {
+               printk (KERN_ERR
+                       "EXT4-fs: #fragments per group too big: %lu\n",
+                       sbi->s_frags_per_group);
+               goto failed_mount;
+       }
+       if (sbi->s_inodes_per_group > blocksize * 8) {
+               printk (KERN_ERR
+                       "EXT4-fs: #inodes per group too big: %lu\n",
+                       sbi->s_inodes_per_group);
+               goto failed_mount;
+       }
+
+       if (ext4_blocks_count(es) >
+                   (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
+               printk(KERN_ERR "EXT4-fs: filesystem on %s:"
+                       " too large to mount safely\n", sb->s_id);
+               if (sizeof(sector_t) < 8)
+                       printk(KERN_WARNING "EXT4-fs: CONFIG_LBD not "
+                                       "enabled\n");
+               goto failed_mount;
+       }
+
+       if (EXT4_BLOCKS_PER_GROUP(sb) == 0)
+               goto cantfind_ext4;
+       blocks_count = (ext4_blocks_count(es) -
+                       le32_to_cpu(es->s_first_data_block) +
+                       EXT4_BLOCKS_PER_GROUP(sb) - 1);
+       do_div(blocks_count, EXT4_BLOCKS_PER_GROUP(sb));
+       sbi->s_groups_count = blocks_count;
+       db_count = (sbi->s_groups_count + EXT4_DESC_PER_BLOCK(sb) - 1) /
+                  EXT4_DESC_PER_BLOCK(sb);
+       sbi->s_group_desc = kmalloc(db_count * sizeof (struct buffer_head *),
+                                   GFP_KERNEL);
+       if (sbi->s_group_desc == NULL) {
+               printk (KERN_ERR "EXT4-fs: not enough memory\n");
+               goto failed_mount;
+       }
+
+       bgl_lock_init(&sbi->s_blockgroup_lock);
+
+       for (i = 0; i < db_count; i++) {
+               block = descriptor_loc(sb, logical_sb_block, i);
+               sbi->s_group_desc[i] = sb_bread(sb, block);
+               if (!sbi->s_group_desc[i]) {
+                       printk (KERN_ERR "EXT4-fs: "
+                               "can't read group descriptor %d\n", i);
+                       db_count = i;
+                       goto failed_mount2;
+               }
+       }
+       if (!ext4_check_descriptors (sb)) {
+               printk(KERN_ERR "EXT4-fs: group descriptors corrupted!\n");
+               goto failed_mount2;
+       }
+       sbi->s_gdb_count = db_count;
+       get_random_bytes(&sbi->s_next_generation, sizeof(u32));
+       spin_lock_init(&sbi->s_next_gen_lock);
+
+       percpu_counter_init(&sbi->s_freeblocks_counter,
+               ext4_count_free_blocks(sb));
+       percpu_counter_init(&sbi->s_freeinodes_counter,
+               ext4_count_free_inodes(sb));
+       percpu_counter_init(&sbi->s_dirs_counter,
+               ext4_count_dirs(sb));
+
+       /* per fileystem reservation list head & lock */
+       spin_lock_init(&sbi->s_rsv_window_lock);
+       sbi->s_rsv_window_root = RB_ROOT;
+       /* Add a single, static dummy reservation to the start of the
+        * reservation window list --- it gives us a placeholder for
+        * append-at-start-of-list which makes the allocation logic
+        * _much_ simpler. */
+       sbi->s_rsv_window_head.rsv_start = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
+       sbi->s_rsv_window_head.rsv_end = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
+       sbi->s_rsv_window_head.rsv_alloc_hit = 0;
+       sbi->s_rsv_window_head.rsv_goal_size = 0;
+       ext4_rsv_window_add(sb, &sbi->s_rsv_window_head);
+
+       /*
+        * set up enough so that it can read an inode
+        */
+       sb->s_op = &ext4_sops;
+       sb->s_export_op = &ext4_export_ops;
+       sb->s_xattr = ext4_xattr_handlers;
+#ifdef CONFIG_QUOTA
+       sb->s_qcop = &ext4_qctl_operations;
+       sb->dq_op = &ext4_quota_operations;
+#endif
+       INIT_LIST_HEAD(&sbi->s_orphan); /* unlinked but open files */
+
+       sb->s_root = NULL;
+
+       needs_recovery = (es->s_last_orphan != 0 ||
+                         EXT4_HAS_INCOMPAT_FEATURE(sb,
+                                   EXT4_FEATURE_INCOMPAT_RECOVER));
+
+       /*
+        * The first inode we look at is the journal inode.  Don't try
+        * root first: it may be modified in the journal!
+        */
+       if (!test_opt(sb, NOLOAD) &&
+           EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL)) {
+               if (ext4_load_journal(sb, es, journal_devnum))
+                       goto failed_mount3;
+       } else if (journal_inum) {
+               if (ext4_create_journal(sb, es, journal_inum))
+                       goto failed_mount3;
+       } else {
+               if (!silent)
+                       printk (KERN_ERR
+                               "ext4: No journal on filesystem on %s\n",
+                               sb->s_id);
+               goto failed_mount3;
+       }
+
+       /* We have now updated the journal if required, so we can
+        * validate the data journaling mode. */
+       switch (test_opt(sb, DATA_FLAGS)) {
+       case 0:
+               /* No mode set, assume a default based on the journal
+                * capabilities: ORDERED_DATA if the journal can
+                * cope, else JOURNAL_DATA
+                */
+               if (jbd2_journal_check_available_features
+                   (sbi->s_journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE))
+                       set_opt(sbi->s_mount_opt, ORDERED_DATA);
+               else
+                       set_opt(sbi->s_mount_opt, JOURNAL_DATA);
+               break;
+
+       case EXT4_MOUNT_ORDERED_DATA:
+       case EXT4_MOUNT_WRITEBACK_DATA:
+               if (!jbd2_journal_check_available_features
+                   (sbi->s_journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE)) {
+                       printk(KERN_ERR "EXT4-fs: Journal does not support "
+                              "requested data journaling mode\n");
+                       goto failed_mount4;
+               }
+       default:
+               break;
+       }
+
+       if (test_opt(sb, NOBH)) {
+               if (!(test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_WRITEBACK_DATA)) {
+                       printk(KERN_WARNING "EXT4-fs: Ignoring nobh option - "
+                               "its supported only with writeback mode\n");
+                       clear_opt(sbi->s_mount_opt, NOBH);
+               }
+       }
+       /*
+        * The jbd2_journal_load will have done any necessary log recovery,
+        * so we can safely mount the rest of the filesystem now.
+        */
+
+       root = iget(sb, EXT4_ROOT_INO);
+       sb->s_root = d_alloc_root(root);
+       if (!sb->s_root) {
+               printk(KERN_ERR "EXT4-fs: get root inode failed\n");
+               iput(root);
+               goto failed_mount4;
+       }
+       if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
+               dput(sb->s_root);
+               sb->s_root = NULL;
+               printk(KERN_ERR "EXT4-fs: corrupt root inode, run e2fsck\n");
+               goto failed_mount4;
+       }
+
+       ext4_setup_super (sb, es, sb->s_flags & MS_RDONLY);
+       /*
+        * akpm: core read_super() calls in here with the superblock locked.
+        * That deadlocks, because orphan cleanup needs to lock the superblock
+        * in numerous places.  Here we just pop the lock - it's relatively
+        * harmless, because we are now ready to accept write_super() requests,
+        * and aviro says that's the only reason for hanging onto the
+        * superblock lock.
+        */
+       EXT4_SB(sb)->s_mount_state |= EXT4_ORPHAN_FS;
+       ext4_orphan_cleanup(sb, es);
+       EXT4_SB(sb)->s_mount_state &= ~EXT4_ORPHAN_FS;
+       if (needs_recovery)
+               printk (KERN_INFO "EXT4-fs: recovery complete.\n");
+       ext4_mark_recovery_complete(sb, es);
+       printk (KERN_INFO "EXT4-fs: mounted filesystem with %s data mode.\n",
+               test_opt(sb,DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA ? "journal":
+               test_opt(sb,DATA_FLAGS) == EXT4_MOUNT_ORDERED_DATA ? "ordered":
+               "writeback");
+
+       ext4_ext_init(sb);
+
+       lock_kernel();
+       return 0;
+
+cantfind_ext4:
+       if (!silent)
+               printk(KERN_ERR "VFS: Can't find ext4 filesystem on dev %s.\n",
+                      sb->s_id);
+       goto failed_mount;
+
+failed_mount4:
+       jbd2_journal_destroy(sbi->s_journal);
+failed_mount3:
+       percpu_counter_destroy(&sbi->s_freeblocks_counter);
+       percpu_counter_destroy(&sbi->s_freeinodes_counter);
+       percpu_counter_destroy(&sbi->s_dirs_counter);
+failed_mount2:
+       for (i = 0; i < db_count; i++)
+               brelse(sbi->s_group_desc[i]);
+       kfree(sbi->s_group_desc);
+failed_mount:
+#ifdef CONFIG_QUOTA
+       for (i = 0; i < MAXQUOTAS; i++)
+               kfree(sbi->s_qf_names[i]);
+#endif
+       ext4_blkdev_remove(sbi);
+       brelse(bh);
+out_fail:
+       sb->s_fs_info = NULL;
+       kfree(sbi);
+       lock_kernel();
+       return -EINVAL;
+}
+
+/*
+ * Setup any per-fs journal parameters now.  We'll do this both on
+ * initial mount, once the journal has been initialised but before we've
+ * done any recovery; and again on any subsequent remount.
+ */
+static void ext4_init_journal_params(struct super_block *sb, journal_t *journal)
+{
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+       if (sbi->s_commit_interval)
+               journal->j_commit_interval = sbi->s_commit_interval;
+       /* We could also set up an ext4-specific default for the commit
+        * interval here, but for now we'll just fall back to the jbd
+        * default. */
+
+       spin_lock(&journal->j_state_lock);
+       if (test_opt(sb, BARRIER))
+               journal->j_flags |= JBD2_BARRIER;
+       else
+               journal->j_flags &= ~JBD2_BARRIER;
+       spin_unlock(&journal->j_state_lock);
+}
+
+static journal_t *ext4_get_journal(struct super_block *sb,
+                                  unsigned int journal_inum)
+{
+       struct inode *journal_inode;
+       journal_t *journal;
+
+       /* First, test for the existence of a valid inode on disk.  Bad
+        * things happen if we iget() an unused inode, as the subsequent
+        * iput() will try to delete it. */
+
+       journal_inode = iget(sb, journal_inum);
+       if (!journal_inode) {
+               printk(KERN_ERR "EXT4-fs: no journal found.\n");
+               return NULL;
+       }
+       if (!journal_inode->i_nlink) {
+               make_bad_inode(journal_inode);
+               iput(journal_inode);
+               printk(KERN_ERR "EXT4-fs: journal inode is deleted.\n");
+               return NULL;
+       }
+
+       jbd_debug(2, "Journal inode found at %p: %Ld bytes\n",
+                 journal_inode, journal_inode->i_size);
+       if (is_bad_inode(journal_inode) || !S_ISREG(journal_inode->i_mode)) {
+               printk(KERN_ERR "EXT4-fs: invalid journal inode.\n");
+               iput(journal_inode);
+               return NULL;
+       }
+
+       journal = jbd2_journal_init_inode(journal_inode);
+       if (!journal) {
+               printk(KERN_ERR "EXT4-fs: Could not load journal inode\n");
+               iput(journal_inode);
+               return NULL;
+       }
+       journal->j_private = sb;
+       ext4_init_journal_params(sb, journal);
+       return journal;
+}
+
+static journal_t *ext4_get_dev_journal(struct super_block *sb,
+                                      dev_t j_dev)
+{
+       struct buffer_head * bh;
+       journal_t *journal;
+       ext4_fsblk_t start;
+       ext4_fsblk_t len;
+       int hblock, blocksize;
+       ext4_fsblk_t sb_block;
+       unsigned long offset;
+       struct ext4_super_block * es;
+       struct block_device *bdev;
+
+       bdev = ext4_blkdev_get(j_dev);
+       if (bdev == NULL)
+               return NULL;
+
+       if (bd_claim(bdev, sb)) {
+               printk(KERN_ERR
+                       "EXT4: failed to claim external journal device.\n");
+               blkdev_put(bdev);
+               return NULL;
+       }
+
+       blocksize = sb->s_blocksize;
+       hblock = bdev_hardsect_size(bdev);
+       if (blocksize < hblock) {
+               printk(KERN_ERR
+                       "EXT4-fs: blocksize too small for journal device.\n");
+               goto out_bdev;
+       }
+
+       sb_block = EXT4_MIN_BLOCK_SIZE / blocksize;
+       offset = EXT4_MIN_BLOCK_SIZE % blocksize;
+       set_blocksize(bdev, blocksize);
+       if (!(bh = __bread(bdev, sb_block, blocksize))) {
+               printk(KERN_ERR "EXT4-fs: couldn't read superblock of "
+                      "external journal\n");
+               goto out_bdev;
+       }
+
+       es = (struct ext4_super_block *) (((char *)bh->b_data) + offset);
+       if ((le16_to_cpu(es->s_magic) != EXT4_SUPER_MAGIC) ||
+           !(le32_to_cpu(es->s_feature_incompat) &
+             EXT4_FEATURE_INCOMPAT_JOURNAL_DEV)) {
+               printk(KERN_ERR "EXT4-fs: external journal has "
+                                       "bad superblock\n");
+               brelse(bh);
+               goto out_bdev;
+       }
+
+       if (memcmp(EXT4_SB(sb)->s_es->s_journal_uuid, es->s_uuid, 16)) {
+               printk(KERN_ERR "EXT4-fs: journal UUID does not match\n");
+               brelse(bh);
+               goto out_bdev;
+       }
+
+       len = ext4_blocks_count(es);
+       start = sb_block + 1;
+       brelse(bh);     /* we're done with the superblock */
+
+       journal = jbd2_journal_init_dev(bdev, sb->s_bdev,
+                                       start, len, blocksize);
+       if (!journal) {
+               printk(KERN_ERR "EXT4-fs: failed to create device journal\n");
+               goto out_bdev;
+       }
+       journal->j_private = sb;
+       ll_rw_block(READ, 1, &journal->j_sb_buffer);
+       wait_on_buffer(journal->j_sb_buffer);
+       if (!buffer_uptodate(journal->j_sb_buffer)) {
+               printk(KERN_ERR "EXT4-fs: I/O error on journal device\n");
+               goto out_journal;
+       }
+       if (be32_to_cpu(journal->j_superblock->s_nr_users) != 1) {
+               printk(KERN_ERR "EXT4-fs: External journal has more than one "
+                                       "user (unsupported) - %d\n",
+                       be32_to_cpu(journal->j_superblock->s_nr_users));
+               goto out_journal;
+       }
+       EXT4_SB(sb)->journal_bdev = bdev;
+       ext4_init_journal_params(sb, journal);
+       return journal;
+out_journal:
+       jbd2_journal_destroy(journal);
+out_bdev:
+       ext4_blkdev_put(bdev);
+       return NULL;
+}
+
+static int ext4_load_journal(struct super_block *sb,
+                            struct ext4_super_block *es,
+                            unsigned long journal_devnum)
+{
+       journal_t *journal;
+       unsigned int journal_inum = le32_to_cpu(es->s_journal_inum);
+       dev_t journal_dev;
+       int err = 0;
+       int really_read_only;
+
+       if (journal_devnum &&
+           journal_devnum != le32_to_cpu(es->s_journal_dev)) {
+               printk(KERN_INFO "EXT4-fs: external journal device major/minor "
+                       "numbers have changed\n");
+               journal_dev = new_decode_dev(journal_devnum);
+       } else
+               journal_dev = new_decode_dev(le32_to_cpu(es->s_journal_dev));
+
+       really_read_only = bdev_read_only(sb->s_bdev);
+
+       /*
+        * Are we loading a blank journal or performing recovery after a
+        * crash?  For recovery, we need to check in advance whether we
+        * can get read-write access to the device.
+        */
+
+       if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER)) {
+               if (sb->s_flags & MS_RDONLY) {
+                       printk(KERN_INFO "EXT4-fs: INFO: recovery "
+                                       "required on readonly filesystem.\n");
+                       if (really_read_only) {
+                               printk(KERN_ERR "EXT4-fs: write access "
+                                       "unavailable, cannot proceed.\n");
+                               return -EROFS;
+                       }
+                       printk (KERN_INFO "EXT4-fs: write access will "
+                                       "be enabled during recovery.\n");
+               }
+       }
+
+       if (journal_inum && journal_dev) {
+               printk(KERN_ERR "EXT4-fs: filesystem has both journal "
+                      "and inode journals!\n");
+               return -EINVAL;
+       }
+
+       if (journal_inum) {
+               if (!(journal = ext4_get_journal(sb, journal_inum)))
+                       return -EINVAL;
+       } else {
+               if (!(journal = ext4_get_dev_journal(sb, journal_dev)))
+                       return -EINVAL;
+       }
+
+       if (!really_read_only && test_opt(sb, UPDATE_JOURNAL)) {
+               err = jbd2_journal_update_format(journal);
+               if (err)  {
+                       printk(KERN_ERR "EXT4-fs: error updating journal.\n");
+                       jbd2_journal_destroy(journal);
+                       return err;
+               }
+       }
+
+       if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER))
+               err = jbd2_journal_wipe(journal, !really_read_only);
+       if (!err)
+               err = jbd2_journal_load(journal);
+
+       if (err) {
+               printk(KERN_ERR "EXT4-fs: error loading journal.\n");
+               jbd2_journal_destroy(journal);
+               return err;
+       }
+
+       EXT4_SB(sb)->s_journal = journal;
+       ext4_clear_journal_err(sb, es);
+
+       if (journal_devnum &&
+           journal_devnum != le32_to_cpu(es->s_journal_dev)) {
+               es->s_journal_dev = cpu_to_le32(journal_devnum);
+               sb->s_dirt = 1;
+
+               /* Make sure we flush the recovery flag to disk. */
+               ext4_commit_super(sb, es, 1);
+       }
+
+       return 0;
+}
+
+static int ext4_create_journal(struct super_block * sb,
+                              struct ext4_super_block * es,
+                              unsigned int journal_inum)
+{
+       journal_t *journal;
+
+       if (sb->s_flags & MS_RDONLY) {
+               printk(KERN_ERR "EXT4-fs: readonly filesystem when trying to "
+                               "create journal.\n");
+               return -EROFS;
+       }
+
+       if (!(journal = ext4_get_journal(sb, journal_inum)))
+               return -EINVAL;
+
+       printk(KERN_INFO "EXT4-fs: creating new journal on inode %u\n",
+              journal_inum);
+
+       if (jbd2_journal_create(journal)) {
+               printk(KERN_ERR "EXT4-fs: error creating journal.\n");
+               jbd2_journal_destroy(journal);
+               return -EIO;
+       }
+
+       EXT4_SB(sb)->s_journal = journal;
+
+       ext4_update_dynamic_rev(sb);
+       EXT4_SET_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
+       EXT4_SET_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL);
+
+       es->s_journal_inum = cpu_to_le32(journal_inum);
+       sb->s_dirt = 1;
+
+       /* Make sure we flush the recovery flag to disk. */
+       ext4_commit_super(sb, es, 1);
+
+       return 0;
+}
+
+static void ext4_commit_super (struct super_block * sb,
+                              struct ext4_super_block * es,
+                              int sync)
+{
+       struct buffer_head *sbh = EXT4_SB(sb)->s_sbh;
+
+       if (!sbh)
+               return;
+       es->s_wtime = cpu_to_le32(get_seconds());
+       ext4_free_blocks_count_set(es, ext4_count_free_blocks(sb));
+       es->s_free_inodes_count = cpu_to_le32(ext4_count_free_inodes(sb));
+       BUFFER_TRACE(sbh, "marking dirty");
+       mark_buffer_dirty(sbh);
+       if (sync)
+               sync_dirty_buffer(sbh);
+}
+
+
+/*
+ * Have we just finished recovery?  If so, and if we are mounting (or
+ * remounting) the filesystem readonly, then we will end up with a
+ * consistent fs on disk.  Record that fact.
+ */
+static void ext4_mark_recovery_complete(struct super_block * sb,
+                                       struct ext4_super_block * es)
+{
+       journal_t *journal = EXT4_SB(sb)->s_journal;
+
+       jbd2_journal_lock_updates(journal);
+       jbd2_journal_flush(journal);
+       if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER) &&
+           sb->s_flags & MS_RDONLY) {
+               EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
+               sb->s_dirt = 0;
+               ext4_commit_super(sb, es, 1);
+       }
+       jbd2_journal_unlock_updates(journal);
+}
+
+/*
+ * If we are mounting (or read-write remounting) a filesystem whose journal
+ * has recorded an error from a previous lifetime, move that error to the
+ * main filesystem now.
+ */
+static void ext4_clear_journal_err(struct super_block * sb,
+                                  struct ext4_super_block * es)
+{
+       journal_t *journal;
+       int j_errno;
+       const char *errstr;
+
+       journal = EXT4_SB(sb)->s_journal;
+
+       /*
+        * Now check for any error status which may have been recorded in the
+        * journal by a prior ext4_error() or ext4_abort()
+        */
+
+       j_errno = jbd2_journal_errno(journal);
+       if (j_errno) {
+               char nbuf[16];
+
+               errstr = ext4_decode_error(sb, j_errno, nbuf);
+               ext4_warning(sb, __FUNCTION__, "Filesystem error recorded "
+                            "from previous mount: %s", errstr);
+               ext4_warning(sb, __FUNCTION__, "Marking fs in need of "
+                            "filesystem check.");
+
+               EXT4_SB(sb)->s_mount_state |= EXT4_ERROR_FS;
+               es->s_state |= cpu_to_le16(EXT4_ERROR_FS);
+               ext4_commit_super (sb, es, 1);
+
+               jbd2_journal_clear_err(journal);
+       }
+}
+
+/*
+ * Force the running and committing transactions to commit,
+ * and wait on the commit.
+ */
+int ext4_force_commit(struct super_block *sb)
+{
+       journal_t *journal;
+       int ret;
+
+       if (sb->s_flags & MS_RDONLY)
+               return 0;
+
+       journal = EXT4_SB(sb)->s_journal;
+       sb->s_dirt = 0;
+       ret = ext4_journal_force_commit(journal);
+       return ret;
+}
+
+/*
+ * Ext4 always journals updates to the superblock itself, so we don't
+ * have to propagate any other updates to the superblock on disk at this
+ * point.  Just start an async writeback to get the buffers on their way
+ * to the disk.
+ *
+ * This implicitly triggers the writebehind on sync().
+ */
+
+static void ext4_write_super (struct super_block * sb)
+{
+       if (mutex_trylock(&sb->s_lock) != 0)
+               BUG();
+       sb->s_dirt = 0;
+}
+
+static int ext4_sync_fs(struct super_block *sb, int wait)
+{
+       tid_t target;
+
+       sb->s_dirt = 0;
+       if (jbd2_journal_start_commit(EXT4_SB(sb)->s_journal, &target)) {
+               if (wait)
+                       jbd2_log_wait_commit(EXT4_SB(sb)->s_journal, target);
+       }
+       return 0;
+}
+
+/*
+ * LVM calls this function before a (read-only) snapshot is created.  This
+ * gives us a chance to flush the journal completely and mark the fs clean.
+ */
+static void ext4_write_super_lockfs(struct super_block *sb)
+{
+       sb->s_dirt = 0;
+
+       if (!(sb->s_flags & MS_RDONLY)) {
+               journal_t *journal = EXT4_SB(sb)->s_journal;
+
+               /* Now we set up the journal barrier. */
+               jbd2_journal_lock_updates(journal);
+               jbd2_journal_flush(journal);
+
+               /* Journal blocked and flushed, clear needs_recovery flag. */
+               EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
+               ext4_commit_super(sb, EXT4_SB(sb)->s_es, 1);
+       }
+}
+
+/*
+ * Called by LVM after the snapshot is done.  We need to reset the RECOVER
+ * flag here, even though the filesystem is not technically dirty yet.
+ */
+static void ext4_unlockfs(struct super_block *sb)
+{
+       if (!(sb->s_flags & MS_RDONLY)) {
+               lock_super(sb);
+               /* Reser the needs_recovery flag before the fs is unlocked. */
+               EXT4_SET_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
+               ext4_commit_super(sb, EXT4_SB(sb)->s_es, 1);
+               unlock_super(sb);
+               jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
+       }
+}
+
+static int ext4_remount (struct super_block * sb, int * flags, char * data)
+{
+       struct ext4_super_block * es;
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+       ext4_fsblk_t n_blocks_count = 0;
+       unsigned long old_sb_flags;
+       struct ext4_mount_options old_opts;
+       int err;
+#ifdef CONFIG_QUOTA
+       int i;
+#endif
+
+       /* Store the original options */
+       old_sb_flags = sb->s_flags;
+       old_opts.s_mount_opt = sbi->s_mount_opt;
+       old_opts.s_resuid = sbi->s_resuid;
+       old_opts.s_resgid = sbi->s_resgid;
+       old_opts.s_commit_interval = sbi->s_commit_interval;
+#ifdef CONFIG_QUOTA
+       old_opts.s_jquota_fmt = sbi->s_jquota_fmt;
+       for (i = 0; i < MAXQUOTAS; i++)
+               old_opts.s_qf_names[i] = sbi->s_qf_names[i];
+#endif
+
+       /*
+        * Allow the "check" option to be passed as a remount option.
+        */
+       if (!parse_options(data, sb, NULL, NULL, &n_blocks_count, 1)) {
+               err = -EINVAL;
+               goto restore_opts;
+       }
+
+       if (sbi->s_mount_opt & EXT4_MOUNT_ABORT)
+               ext4_abort(sb, __FUNCTION__, "Abort forced by user");
+       if ((sbi->s_mount_opt & EXT4_MOUNT_TAGGED) &&
+               !(sb->s_flags & MS_TAGGED)) {
+               printk("EXT4-fs: %s: tagging not permitted on remount.\n",
+                       sb->s_id);
+               return -EINVAL;
+       }
+
+       sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
+               ((sbi->s_mount_opt & EXT4_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
+
+       es = sbi->s_es;
+
+       ext4_init_journal_params(sb, sbi->s_journal);
+
+       if ((*flags & MS_RDONLY) != (sb->s_flags & MS_RDONLY) ||
+               n_blocks_count > ext4_blocks_count(es)) {
+               if (sbi->s_mount_opt & EXT4_MOUNT_ABORT) {
+                       err = -EROFS;
+                       goto restore_opts;
+               }
+
+               if (*flags & MS_RDONLY) {
+                       /*
+                        * First of all, the unconditional stuff we have to do
+                        * to disable replay of the journal when we next remount
+                        */
+                       sb->s_flags |= MS_RDONLY;
+
+                       /*
+                        * OK, test if we are remounting a valid rw partition
+                        * readonly, and if so set the rdonly flag and then
+                        * mark the partition as valid again.
+                        */
+                       if (!(es->s_state & cpu_to_le16(EXT4_VALID_FS)) &&
+                           (sbi->s_mount_state & EXT4_VALID_FS))
+                               es->s_state = cpu_to_le16(sbi->s_mount_state);
+
+                       ext4_mark_recovery_complete(sb, es);
+               } else {
+                       __le32 ret;
+                       if ((ret = EXT4_HAS_RO_COMPAT_FEATURE(sb,
+                                       ~EXT4_FEATURE_RO_COMPAT_SUPP))) {
+                               printk(KERN_WARNING "EXT4-fs: %s: couldn't "
+                                      "remount RDWR because of unsupported "
+                                      "optional features (%x).\n",
+                                      sb->s_id, le32_to_cpu(ret));
+                               err = -EROFS;
+                               goto restore_opts;
+                       }
+                       /*
+                        * Mounting a RDONLY partition read-write, so reread
+                        * and store the current valid flag.  (It may have
+                        * been changed by e2fsck since we originally mounted
+                        * the partition.)
+                        */
+                       ext4_clear_journal_err(sb, es);
+                       sbi->s_mount_state = le16_to_cpu(es->s_state);
+                       if ((err = ext4_group_extend(sb, es, n_blocks_count)))
+                               goto restore_opts;
+                       if (!ext4_setup_super (sb, es, 0))
+                               sb->s_flags &= ~MS_RDONLY;
+               }
+       }
+#ifdef CONFIG_QUOTA
+       /* Release old quota file names */
+       for (i = 0; i < MAXQUOTAS; i++)
+               if (old_opts.s_qf_names[i] &&
+                   old_opts.s_qf_names[i] != sbi->s_qf_names[i])
+                       kfree(old_opts.s_qf_names[i]);
+#endif
+       return 0;
+restore_opts:
+       sb->s_flags = old_sb_flags;
+       sbi->s_mount_opt = old_opts.s_mount_opt;
+       sbi->s_resuid = old_opts.s_resuid;
+       sbi->s_resgid = old_opts.s_resgid;
+       sbi->s_commit_interval = old_opts.s_commit_interval;
+#ifdef CONFIG_QUOTA
+       sbi->s_jquota_fmt = old_opts.s_jquota_fmt;
+       for (i = 0; i < MAXQUOTAS; i++) {
+               if (sbi->s_qf_names[i] &&
+                   old_opts.s_qf_names[i] != sbi->s_qf_names[i])
+                       kfree(sbi->s_qf_names[i]);
+               sbi->s_qf_names[i] = old_opts.s_qf_names[i];
+       }
+#endif
+       return err;
+}
+
+static int ext4_statfs (struct dentry * dentry, struct kstatfs * buf)
+{
+       struct super_block *sb = dentry->d_sb;
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+       struct ext4_super_block *es = sbi->s_es;
+       ext4_fsblk_t overhead;
+       int i;
+       u64 fsid;
+
+       if (test_opt (sb, MINIX_DF))
+               overhead = 0;
+       else {
+               unsigned long ngroups;
+               ngroups = EXT4_SB(sb)->s_groups_count;
+               smp_rmb();
+
+               /*
+                * Compute the overhead (FS structures)
+                */
+
+               /*
+                * All of the blocks before first_data_block are
+                * overhead
+                */
+               overhead = le32_to_cpu(es->s_first_data_block);
+
+               /*
+                * Add the overhead attributed to the superblock and
+                * block group descriptors.  If the sparse superblocks
+                * feature is turned on, then not all groups have this.
+                */
+               for (i = 0; i < ngroups; i++) {
+                       overhead += ext4_bg_has_super(sb, i) +
+                               ext4_bg_num_gdb(sb, i);
+                       cond_resched();
+               }
+
+               /*
+                * Every block group has an inode bitmap, a block
+                * bitmap, and an inode table.
+                */
+               overhead += (ngroups * (2 + EXT4_SB(sb)->s_itb_per_group));
+       }
+
+       buf->f_type = EXT4_SUPER_MAGIC;
+       buf->f_bsize = sb->s_blocksize;
+       buf->f_blocks = ext4_blocks_count(es) - overhead;
+       buf->f_bfree = percpu_counter_sum(&sbi->s_freeblocks_counter);
+       buf->f_bavail = buf->f_bfree - ext4_r_blocks_count(es);
+       if (buf->f_bfree < ext4_r_blocks_count(es))
+               buf->f_bavail = 0;
+       buf->f_files = le32_to_cpu(es->s_inodes_count);
+       buf->f_ffree = percpu_counter_sum(&sbi->s_freeinodes_counter);
+       buf->f_namelen = EXT4_NAME_LEN;
+       fsid = le64_to_cpup((void *)es->s_uuid) ^
+              le64_to_cpup((void *)es->s_uuid + sizeof(u64));
+       buf->f_fsid.val[0] = fsid & 0xFFFFFFFFUL;
+       buf->f_fsid.val[1] = (fsid >> 32) & 0xFFFFFFFFUL;
+       return 0;
+}
+
+/* Helper function for writing quotas on sync - we need to start transaction before quota file
+ * is locked for write. Otherwise the are possible deadlocks:
+ * Process 1                         Process 2
+ * ext4_create()                     quota_sync()
+ *   jbd2_journal_start()                   write_dquot()
+ *   DQUOT_INIT()                        down(dqio_mutex)
+ *     down(dqio_mutex)                    jbd2_journal_start()
+ *
+ */
+
+#ifdef CONFIG_QUOTA
+
+static inline struct inode *dquot_to_inode(struct dquot *dquot)
+{
+       return sb_dqopt(dquot->dq_sb)->files[dquot->dq_type];
+}
+
+static int ext4_dquot_initialize(struct inode *inode, int type)
+{
+       handle_t *handle;
+       int ret, err;
+
+       /* We may create quota structure so we need to reserve enough blocks */
+       handle = ext4_journal_start(inode, 2*EXT4_QUOTA_INIT_BLOCKS(inode->i_sb));
+       if (IS_ERR(handle))
+               return PTR_ERR(handle);
+       ret = dquot_initialize(inode, type);
+       err = ext4_journal_stop(handle);
+       if (!ret)
+               ret = err;
+       return ret;
+}
+
+static int ext4_dquot_drop(struct inode *inode)
+{
+       handle_t *handle;
+       int ret, err;
+
+       /* We may delete quota structure so we need to reserve enough blocks */
+       handle = ext4_journal_start(inode, 2*EXT4_QUOTA_DEL_BLOCKS(inode->i_sb));
+       if (IS_ERR(handle))
+               return PTR_ERR(handle);
+       ret = dquot_drop(inode);
+       err = ext4_journal_stop(handle);
+       if (!ret)
+               ret = err;
+       return ret;
+}
+
+static int ext4_write_dquot(struct dquot *dquot)
+{
+       int ret, err;
+       handle_t *handle;
+       struct inode *inode;
+
+       inode = dquot_to_inode(dquot);
+       handle = ext4_journal_start(inode,
+                                       EXT4_QUOTA_TRANS_BLOCKS(dquot->dq_sb));
+       if (IS_ERR(handle))
+               return PTR_ERR(handle);
+       ret = dquot_commit(dquot);
+       err = ext4_journal_stop(handle);
+       if (!ret)
+               ret = err;
+       return ret;
+}
+
+static int ext4_acquire_dquot(struct dquot *dquot)
+{
+       int ret, err;
+       handle_t *handle;
+
+       handle = ext4_journal_start(dquot_to_inode(dquot),
+                                       EXT4_QUOTA_INIT_BLOCKS(dquot->dq_sb));
+       if (IS_ERR(handle))
+               return PTR_ERR(handle);
+       ret = dquot_acquire(dquot);
+       err = ext4_journal_stop(handle);
+       if (!ret)
+               ret = err;
+       return ret;
+}
+
+static int ext4_release_dquot(struct dquot *dquot)
+{
+       int ret, err;
+       handle_t *handle;
+
+       handle = ext4_journal_start(dquot_to_inode(dquot),
+                                       EXT4_QUOTA_DEL_BLOCKS(dquot->dq_sb));
+       if (IS_ERR(handle))
+               return PTR_ERR(handle);
+       ret = dquot_release(dquot);
+       err = ext4_journal_stop(handle);
+       if (!ret)
+               ret = err;
+       return ret;
+}
+
+static int ext4_mark_dquot_dirty(struct dquot *dquot)
+{
+       /* Are we journalling quotas? */
+       if (EXT4_SB(dquot->dq_sb)->s_qf_names[USRQUOTA] ||
+           EXT4_SB(dquot->dq_sb)->s_qf_names[GRPQUOTA]) {
+               dquot_mark_dquot_dirty(dquot);
+               return ext4_write_dquot(dquot);
+       } else {
+               return dquot_mark_dquot_dirty(dquot);
+       }
+}
+
+static int ext4_write_info(struct super_block *sb, int type)
+{
+       int ret, err;
+       handle_t *handle;
+
+       /* Data block + inode block */
+       handle = ext4_journal_start(sb->s_root->d_inode, 2);
+       if (IS_ERR(handle))
+               return PTR_ERR(handle);
+       ret = dquot_commit_info(sb, type);
+       err = ext4_journal_stop(handle);
+       if (!ret)
+               ret = err;
+       return ret;
+}
+
+/*
+ * Turn on quotas during mount time - we need to find
+ * the quota file and such...
+ */
+static int ext4_quota_on_mount(struct super_block *sb, int type)
+{
+       return vfs_quota_on_mount(sb, EXT4_SB(sb)->s_qf_names[type],
+                       EXT4_SB(sb)->s_jquota_fmt, type);
+}
+
+/*
+ * Standard function to be called on quota_on
+ */
+static int ext4_quota_on(struct super_block *sb, int type, int format_id,
+                        char *path)
+{
+       int err;
+       struct nameidata nd;
+
+       if (!test_opt(sb, QUOTA))
+               return -EINVAL;
+       /* Not journalling quota? */
+       if (!EXT4_SB(sb)->s_qf_names[USRQUOTA] &&
+           !EXT4_SB(sb)->s_qf_names[GRPQUOTA])
+               return vfs_quota_on(sb, type, format_id, path);
+       err = path_lookup(path, LOOKUP_FOLLOW, &nd);
+       if (err)
+               return err;
+       /* Quotafile not on the same filesystem? */
+       if (nd.mnt->mnt_sb != sb) {
+               path_release(&nd);
+               return -EXDEV;
+       }
+       /* Quotafile not of fs root? */
+       if (nd.dentry->d_parent->d_inode != sb->s_root->d_inode)
+               printk(KERN_WARNING
+                       "EXT4-fs: Quota file not on filesystem root. "
+                       "Journalled quota will not work.\n");
+       path_release(&nd);
+       return vfs_quota_on(sb, type, format_id, path);
+}
+
+/* Read data from quotafile - avoid pagecache and such because we cannot afford
+ * acquiring the locks... As quota files are never truncated and quota code
+ * itself serializes the operations (and noone else should touch the files)
+ * we don't have to be afraid of races */
+static ssize_t ext4_quota_read(struct super_block *sb, int type, char *data,
+                              size_t len, loff_t off)
+{
+       struct inode *inode = sb_dqopt(sb)->files[type];
+       sector_t blk = off >> EXT4_BLOCK_SIZE_BITS(sb);
+       int err = 0;
+       int offset = off & (sb->s_blocksize - 1);
+       int tocopy;
+       size_t toread;
+       struct buffer_head *bh;
+       loff_t i_size = i_size_read(inode);
+
+       if (off > i_size)
+               return 0;
+       if (off+len > i_size)
+               len = i_size-off;
+       toread = len;
+       while (toread > 0) {
+               tocopy = sb->s_blocksize - offset < toread ?
+                               sb->s_blocksize - offset : toread;
+               bh = ext4_bread(NULL, inode, blk, 0, &err);
+               if (err)
+                       return err;
+               if (!bh)        /* A hole? */
+                       memset(data, 0, tocopy);
+               else
+                       memcpy(data, bh->b_data+offset, tocopy);
+               brelse(bh);
+               offset = 0;
+               toread -= tocopy;
+               data += tocopy;
+               blk++;
+       }
+       return len;
+}
+
+/* Write to quotafile (we know the transaction is already started and has
+ * enough credits) */
+static ssize_t ext4_quota_write(struct super_block *sb, int type,
+                               const char *data, size_t len, loff_t off)
+{
+       struct inode *inode = sb_dqopt(sb)->files[type];
+       sector_t blk = off >> EXT4_BLOCK_SIZE_BITS(sb);
+       int err = 0;
+       int offset = off & (sb->s_blocksize - 1);
+       int tocopy;
+       int journal_quota = EXT4_SB(sb)->s_qf_names[type] != NULL;
+       size_t towrite = len;
+       struct buffer_head *bh;
+       handle_t *handle = journal_current_handle();
+
+       mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
+       while (towrite > 0) {
+               tocopy = sb->s_blocksize - offset < towrite ?
+                               sb->s_blocksize - offset : towrite;
+               bh = ext4_bread(handle, inode, blk, 1, &err);
+               if (!bh)
+                       goto out;
+               if (journal_quota) {
+                       err = ext4_journal_get_write_access(handle, bh);
+                       if (err) {
+                               brelse(bh);
+                               goto out;
+                       }
+               }
+               lock_buffer(bh);
+               memcpy(bh->b_data+offset, data, tocopy);
+               flush_dcache_page(bh->b_page);
+               unlock_buffer(bh);
+               if (journal_quota)
+                       err = ext4_journal_dirty_metadata(handle, bh);
+               else {
+                       /* Always do at least ordered writes for quotas */
+                       err = ext4_journal_dirty_data(handle, bh);
+                       mark_buffer_dirty(bh);
+               }
+               brelse(bh);
+               if (err)
+                       goto out;
+               offset = 0;
+               towrite -= tocopy;
+               data += tocopy;
+               blk++;
+       }
+out:
+       if (len == towrite)
+               return err;
+       if (inode->i_size < off+len-towrite) {
+               i_size_write(inode, off+len-towrite);
+               EXT4_I(inode)->i_disksize = inode->i_size;
+       }
+       inode->i_version++;
+       inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+       ext4_mark_inode_dirty(handle, inode);
+       mutex_unlock(&inode->i_mutex);
+       return len - towrite;
+}
+
+#endif
+
+static int ext4_get_sb(struct file_system_type *fs_type,
+       int flags, const char *dev_name, void *data, struct vfsmount *mnt)
+{
+       return get_sb_bdev(fs_type, flags, dev_name, data, ext4_fill_super, mnt);
+}
+
+static struct file_system_type ext4dev_fs_type = {
+       .owner          = THIS_MODULE,
+       .name           = "ext4dev",
+       .get_sb         = ext4_get_sb,
+       .kill_sb        = kill_block_super,
+       .fs_flags       = FS_REQUIRES_DEV,
+};
+
+static int __init init_ext4_fs(void)
+{
+       int err = init_ext4_xattr();
+       if (err)
+               return err;
+       err = init_inodecache();
+       if (err)
+               goto out1;
+       err = register_filesystem(&ext4dev_fs_type);
+       if (err)
+               goto out;
+       return 0;
+out:
+       destroy_inodecache();
+out1:
+       exit_ext4_xattr();
+       return err;
+}
+
+static void __exit exit_ext4_fs(void)
+{
+       unregister_filesystem(&ext4dev_fs_type);
+       destroy_inodecache();
+       exit_ext4_xattr();
+}
+
+MODULE_AUTHOR("Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others");
+MODULE_DESCRIPTION("Fourth Extended Filesystem with extents");
+MODULE_LICENSE("GPL");
+module_init(init_ext4_fs)
+module_exit(exit_ext4_fs)