super.c

ARM 嵌入式 系统 设计与实例开发 实验教材 二源码

/*
 * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
 *
 * Trivial changes by Alan Cox to add the LFS fixes
 *
 * Trivial Changes:
 * Rights granted to Hans Reiser to redistribute under other terms providing
 * he accepts all liability including but not limited to patent, fitness
 * for purpose, and direct or indirect claims arising from failure to perform.
 *
 * NO WARRANTY
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <asm/uaccess.h>
#include <linux/reiserfs_fs.h>
#include <linux/smp_lock.h>
#include <linux/locks.h>
#include <linux/init.h>

#define REISERFS_OLD_BLOCKSIZE 4096
#define REISERFS_SUPER_MAGIC_STRING_OFFSET_NJ 20

char reiserfs_super_magic_string[] = REISERFS_SUPER_MAGIC_STRING;
char reiser2fs_super_magic_string[] = REISER2FS_SUPER_MAGIC_STRING;

static int reiserfs_remount (struct super_block * s, int * flags, char * data);
static int reiserfs_statfs (struct super_block * s, struct statfs * buf);

//
// a portion of this function, particularly the VFS interface portion,
// was derived from minix or ext2's analog and evolved as the
// prototype did. You should be able to tell which portion by looking
// at the ext2 code and comparing. It's subfunctions contain no code
// used as a template unless they are so labeled.
//
static void reiserfs_write_super (struct super_block * s)
{

  int dirty = 0 ;
  lock_kernel() ;
  if (!(s->s_flags & MS_RDONLY)) {
    dirty = flush_old_commits(s, 1) ;
  }
  s->s_dirt = dirty;
  unlock_kernel() ;
}

//
// a portion of this function, particularly the VFS interface portion,
// was derived from minix or ext2's analog and evolved as the
// prototype did. You should be able to tell which portion by looking
// at the ext2 code and comparing. It's subfunctions contain no code
// used as a template unless they are so labeled.
//
static void reiserfs_write_super_lockfs (struct super_block * s)
{

  int dirty = 0 ;
  struct reiserfs_transaction_handle th ;
  lock_kernel() ;
  if (!(s->s_flags & MS_RDONLY)) {
    journal_begin(&th, s, 1) ;
    reiserfs_prepare_for_journal(s, SB_BUFFER_WITH_SB(s), 1);
    journal_mark_dirty(&th, s, SB_BUFFER_WITH_SB (s));
    reiserfs_block_writes(&th) ;
    journal_end(&th, s, 1) ;
  }
  s->s_dirt = dirty;
  unlock_kernel() ;
}

void reiserfs_unlockfs(struct super_block *s) {
  reiserfs_allow_writes(s) ;
}

extern const struct key  MAX_KEY;


/* this is used to delete "save link" when there are no items of a
   file it points to. It can either happen if unlink is completed but
   "save unlink" removal, or if file has both unlink and truncate
   pending and as unlink completes first (because key of "save link"
   protecting unlink is bigger that a key lf "save link" which
   protects truncate), so there left no items to make truncate
   completion on */
static void remove_save_link_only (struct super_block * s, struct key * key, int oid_free)
{
    struct reiserfs_transaction_handle th;

     /* we are going to do one balancing */
     journal_begin (&th, s, JOURNAL_PER_BALANCE_CNT);
 
     reiserfs_delete_solid_item (&th, key);
     if (oid_free)
        /* removals are protected by direct items */
        reiserfs_release_objectid (&th, le32_to_cpu (key->k_objectid));

     journal_end (&th, s, JOURNAL_PER_BALANCE_CNT);
}
 
 
/* look for uncompleted unlinks and truncates and complete them */
static void finish_unfinished (struct super_block * s)
{
    INITIALIZE_PATH (path);
    struct cpu_key max_cpu_key, obj_key;
    struct key save_link_key;
    int retval;
    struct item_head * ih;
    struct buffer_head * bh;
    int item_pos;
    char * item;
    int done;
    struct inode * inode;
    int truncate;
 
 
    /* compose key to look for "save" links */
    max_cpu_key.version = KEY_FORMAT_3_5;
    max_cpu_key.on_disk_key = MAX_KEY;
    max_cpu_key.key_length = 3;
 
    done = 0;
    s -> u.reiserfs_sb.s_is_unlinked_ok = 1;
    while (1) {
        retval = search_item (s, &max_cpu_key, &path);
        if (retval != ITEM_NOT_FOUND) {
            reiserfs_warning ("vs-2140: finish_unfinished: search_by_key returned %d\n",
                              retval);
            break;
        }
        
        bh = get_last_bh (&path);
        item_pos = get_item_pos (&path);
        if (item_pos != B_NR_ITEMS (bh)) {
            reiserfs_warning ("vs-2060: finish_unfinished: wrong position found\n");
            break;
        }
        item_pos --;
        ih = B_N_PITEM_HEAD (bh, item_pos);
 
        if (le32_to_cpu (ih->ih_key.k_dir_id) != MAX_KEY_OBJECTID)
            /* there are no "save" links anymore */
            break;
 
        save_link_key = ih->ih_key;
        if (is_indirect_le_ih (ih))
            truncate = 1;
        else
            truncate = 0;
 
        /* reiserfs_iget needs k_dirid and k_objectid only */
        item = B_I_PITEM (bh, ih);
        obj_key.on_disk_key.k_dir_id = le32_to_cpu (*(__u32 *)item);
        obj_key.on_disk_key.k_objectid = le32_to_cpu (ih->ih_key.k_objectid);
	obj_key.on_disk_key.u.k_offset_v1.k_offset = 0;
	obj_key.on_disk_key.u.k_offset_v1.k_uniqueness = 0;
	
        pathrelse (&path);
 
        inode = reiserfs_iget (s, &obj_key);
        if (!inode) {
            /* the unlink almost completed, it just did not manage to remove
	       "save" link and release objectid */
            reiserfs_warning ("vs-2180: finish_unfinished: iget failed for %K\n",
                              &obj_key);
            remove_save_link_only (s, &save_link_key, 1);
            continue;
        }

	if (!truncate && inode->i_nlink) {
	    /* file is not unlinked */
            reiserfs_warning ("vs-2185: finish_unfinished: file %K is not unlinked\n",
                              &obj_key);
            remove_save_link_only (s, &save_link_key, 0);
            continue;
	}

	if (truncate && S_ISDIR (inode->i_mode) ) {
	    /* We got a truncate request for a dir which is impossible.
	       The only imaginable way is to execute unfinished truncate request
	       then boot into old kernel, remove the file and create dir with
	       the same key. */
	    reiserfs_warning("green-2101: impossible truncate on a directory %k. Please report\n", INODE_PKEY (inode));
	    remove_save_link_only (s, &save_link_key, 0);
	    truncate = 0;
	    iput (inode); 
	    continue;
	}
 
        if (truncate) {
            inode -> u.reiserfs_i.i_flags |= i_link_saved_truncate_mask;
            /* not completed truncate found. New size was committed together
	       with "save" link */
            reiserfs_warning ("Truncating %k to %Ld ..",
                              INODE_PKEY (inode), inode->i_size);
            reiserfs_truncate_file (inode, 0/*don't update modification time*/);
            remove_save_link (inode, truncate);
        } else {
            inode -> u.reiserfs_i.i_flags |= i_link_saved_unlink_mask;
            /* not completed unlink (rmdir) found */
            reiserfs_warning ("Removing %k..", INODE_PKEY (inode));
            /* removal gets completed in iput */
        }
 
        iput (inode);
        reiserfs_warning ("done\n");
        done ++;
    }
    s -> u.reiserfs_sb.s_is_unlinked_ok = 0;
     
    pathrelse (&path);
    if (done)
        reiserfs_warning ("There were %d uncompleted unlinks/truncates. "
                          "Completed\n", done);
}
 
/* to protect file being unlinked from getting lost we "safe" link files
   being unlinked. This link will be deleted in the same transaction with last
   item of file. mounting the filesytem we scan all these links and remove
   files which almost got lost */
void add_save_link (struct reiserfs_transaction_handle * th,
		    struct inode * inode, int truncate)
{
    INITIALIZE_PATH (path);
    int retval;
    struct cpu_key key;
    struct item_head ih;
    __u32 link;

    /* file can only get one "save link" of each kind */
    RFALSE( truncate && 
	    ( inode -> u.reiserfs_i.i_flags & i_link_saved_truncate_mask ),
	    "saved link already exists for truncated inode %lx",
	    ( long ) inode -> i_ino );
    RFALSE( !truncate && 
	    ( inode -> u.reiserfs_i.i_flags & i_link_saved_unlink_mask ),
	    "saved link already exists for unlinked inode %lx",
	    ( long ) inode -> i_ino );

    /* setup key of "save" link */
    key.version = KEY_FORMAT_3_5;
    key.on_disk_key.k_dir_id = MAX_KEY_OBJECTID;
    key.on_disk_key.k_objectid = inode->i_ino;
    if (!truncate) {
	/* unlink, rmdir, rename */
	set_cpu_key_k_offset (&key, 1 + inode->i_sb->s_blocksize);
	set_cpu_key_k_type (&key, TYPE_DIRECT);

	/* item head of "safe" link */
	make_le_item_head (&ih, &key, key.version, 1 + inode->i_sb->s_blocksize, TYPE_DIRECT,
			   4/*length*/, 0xffff/*free space*/);
    } else {
	/* truncate */
	if (S_ISDIR (inode->i_mode))
	    reiserfs_warning("green-2102: Adding a truncate savelink for a directory %k! Please report\n", INODE_PKEY(inode));
	set_cpu_key_k_offset (&key, 1);
	set_cpu_key_k_type (&key, TYPE_INDIRECT);

	/* item head of "safe" link */
	make_le_item_head (&ih, &key, key.version, 1, TYPE_INDIRECT,
			   4/*length*/, 0/*free space*/);
    }
    key.key_length = 3;

    /* look for its place in the tree */
    retval = search_item (inode->i_sb, &key, &path);
    if (retval != ITEM_NOT_FOUND) {
	reiserfs_warning ("vs-2100: add_save_link:"
			  "search_by_key (%K) returned %d\n", &key, retval);
	pathrelse (&path);
	return;
    }

    /* body of "save" link */
    link = cpu_to_le32 (INODE_PKEY (inode)->k_dir_id);

    /* put "save" link inot tree */
    retval = reiserfs_insert_item (th, &path, &key, &ih, (char *)&link);
    if (retval)
	reiserfs_warning ("vs-2120: add_save_link: insert_item returned %d\n",
			  retval);
    else {
	if( truncate )
	    inode -> u.reiserfs_i.i_flags |= i_link_saved_truncate_mask;
	else
	    inode -> u.reiserfs_i.i_flags |= i_link_saved_unlink_mask;
    }
}


/* this opens transaction unlike add_save_link */
void remove_save_link (struct inode * inode, int truncate)
{
    struct reiserfs_transaction_handle th;
    struct key key;
 
 
    /* we are going to do one balancing only */
    journal_begin (&th, inode->i_sb, JOURNAL_PER_BALANCE_CNT);
 
    /* setup key of "save" link */
    key.k_dir_id = cpu_to_le32 (MAX_KEY_OBJECTID);
    key.k_objectid = INODE_PKEY (inode)->k_objectid;
    if (!truncate) {
        /* unlink, rmdir, rename */
        set_le_key_k_offset (KEY_FORMAT_3_5, &key,
			     1 + inode->i_sb->s_blocksize);
        set_le_key_k_type (KEY_FORMAT_3_5, &key, TYPE_DIRECT);
    } else {
        /* truncate */
        set_le_key_k_offset (KEY_FORMAT_3_5, &key, 1);
        set_le_key_k_type (KEY_FORMAT_3_5, &key, TYPE_INDIRECT);
    }
 
    if( ( truncate && 
          ( inode -> u.reiserfs_i.i_flags & i_link_saved_truncate_mask ) ) ||
        ( !truncate && 
          ( inode -> u.reiserfs_i.i_flags & i_link_saved_unlink_mask ) ) )
	reiserfs_delete_solid_item (&th, &key);
    if (!truncate) {
	reiserfs_release_objectid (&th, inode->i_ino);
	inode -> u.reiserfs_i.i_flags &= ~i_link_saved_unlink_mask;
    } else
	inode -> u.reiserfs_i.i_flags &= ~i_link_saved_truncate_mask;
 
    journal_end (&th, inode->i_sb, JOURNAL_PER_BALANCE_CNT);
}


//
// a portion of this function, particularly the VFS interface portion,
// was derived from minix or ext2's analog and evolved as the
// prototype did. You should be able to tell which portion by looking
// at the ext2 code and comparing. It's subfunctions contain no code
// used as a template unless they are so labeled.
//
static void reiserfs_put_super (struct super_block * s)
{
  int i;
  struct reiserfs_transaction_handle th ;
  
  /* change file system state to current state if it was mounted with read-write permissions */
  if (!(s->s_flags & MS_RDONLY)) {
    journal_begin(&th, s, 10) ;
    reiserfs_prepare_for_journal(s, SB_BUFFER_WITH_SB(s), 1) ;
    set_sb_state( SB_DISK_SUPER_BLOCK(s), s->u.reiserfs_sb.s_mount_state );
    journal_mark_dirty(&th, s, SB_BUFFER_WITH_SB (s));
  }

  /* note, journal_release checks for readonly mount, and can decide not
  ** to do a journal_end
  */
  journal_release(&th, s) ;

  for (i = 0; i < SB_BMAP_NR (s); i ++)
    brelse (SB_AP_BITMAP (s)[i]);

  reiserfs_kfree (SB_AP_BITMAP (s), sizeof (struct buffer_head *) * SB_BMAP_NR (s), s);

  brelse (SB_BUFFER_WITH_SB (s));

  print_statistics (s);

  if (s->u.reiserfs_sb.s_kmallocs != 0) {
    reiserfs_warning ("vs-2004: reiserfs_put_super: allocated memory left %d\n",
		      s->u.reiserfs_sb.s_kmallocs);
  }

  reiserfs_proc_unregister( s, "journal" );
  reiserfs_proc_unregister( s, "oidmap" );
  reiserfs_proc_unregister( s, "on-disk-super" );
  reiserfs_proc_unregister( s, "bitmap" );