inode.c

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/*
 *  linux/fs/minix/inode.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Copyright (C) 1996  Gertjan van Wingerde
 *  Minix V2 fs support.
 *
 *  Modified for 680x0 by Andreas Schwab
 *  Updated to filesystem version 3 by Daniel Aragones
 */

#include <linux/module.h>
#include "minix.h"
#include <linux/buffer_head.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/highuid.h>
#include <linux/vfs.h>
#include <linux/writeback.h>

static int minix_write_inode(struct inode *inode,
        struct writeback_control *wbc);
static int minix_statfs(struct dentry *dentry, struct kstatfs *buf);
static int minix_remount (struct super_block * sb, int * flags, char * data);

static void minix_evict_inode(struct inode *inode)
{
    truncate_inode_pages(&inode->i_data, 0);
    if (!inode->i_nlink) {
        inode->i_size = 0;
        minix_truncate(inode);
    }
    invalidate_inode_buffers(inode);
    clear_inode(inode);
    if (!inode->i_nlink)
        minix_free_inode(inode);
}

static void minix_put_super(struct super_block *sb)
{
    int i;
    struct minix_sb_info *sbi = minix_sb(sb);

    if (!(sb->s_flags & MS_RDONLY)) {
        if (sbi->s_version != MINIX_V3)  /* s_state is now out from V3 sb */
            sbi->s_ms->s_state = sbi->s_mount_state;
        mark_buffer_dirty(sbi->s_sbh);
    }
    for (i = 0; i < sbi->s_imap_blocks; i++)
        brelse(sbi->s_imap[i]);
    for (i = 0; i < sbi->s_zmap_blocks; i++)
        brelse(sbi->s_zmap[i]);
    brelse (sbi->s_sbh);
    kfree(sbi->s_imap);
    sb->s_fs_info = NULL;
    kfree(sbi);
}

static struct kmem_cache * minix_inode_cachep;

static struct inode *minix_alloc_inode(struct super_block *sb)
{
    struct minix_inode_info *ei;
    ei = (struct minix_inode_info *)kmem_cache_alloc(minix_inode_cachep, GFP_KERNEL);
    if (!ei)
        return NULL;
    return &ei->vfs_inode;
}

static void minix_i_callback(struct rcu_head *head)
{
    struct inode *inode = container_of(head, struct inode, i_rcu);
    kmem_cache_free(minix_inode_cachep, minix_i(inode));
}

static void minix_destroy_inode(struct inode *inode)
{
    call_rcu(&inode->i_rcu, minix_i_callback);
}

static void init_once(void *foo)
{
    struct minix_inode_info *ei = (struct minix_inode_info *) foo;

    inode_init_once(&ei->vfs_inode);
}

static int init_inodecache(void)
{
    minix_inode_cachep = kmem_cache_create("minix_inode_cache",
                         sizeof(struct minix_inode_info),
                         0, (SLAB_RECLAIM_ACCOUNT|
                        SLAB_MEM_SPREAD),
                         init_once);
    if (minix_inode_cachep == NULL)
        return -ENOMEM;
    return 0;
}

static void destroy_inodecache(void)
{
    /*
     * Make sure all delayed rcu free inodes are flushed before we
     * destroy cache.
     */
    rcu_barrier();
    kmem_cache_destroy(minix_inode_cachep);
}

static const struct super_operations minix_sops = {
    .alloc_inode    = minix_alloc_inode,
    .destroy_inode  = minix_destroy_inode,
    .write_inode    = minix_write_inode,
    .evict_inode    = minix_evict_inode,
    .put_super  = minix_put_super,
    .statfs     = minix_statfs,
    .remount_fs = minix_remount,
};

static int minix_remount (struct super_block * sb, int * flags, char * data)
{
    struct minix_sb_info * sbi = minix_sb(sb);
    struct minix_super_block * ms;

    ms = sbi->s_ms;
    if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
        return 0;
    if (*flags & MS_RDONLY) {
        if (ms->s_state & MINIX_VALID_FS ||
            !(sbi->s_mount_state & MINIX_VALID_FS))
            return 0;
        /* Mounting a rw partition read-only. */
        if (sbi->s_version != MINIX_V3)
            ms->s_state = sbi->s_mount_state;
        mark_buffer_dirty(sbi->s_sbh);
    } else {
        /* Mount a partition which is read-only, read-write. */
        if (sbi->s_version != MINIX_V3) {
            sbi->s_mount_state = ms->s_state;
            ms->s_state &= ~MINIX_VALID_FS;
        } else {
            sbi->s_mount_state = MINIX_VALID_FS;
        }
        mark_buffer_dirty(sbi->s_sbh);

        if (!(sbi->s_mount_state & MINIX_VALID_FS))
            printk("MINIX-fs warning: remounting unchecked fs, "
                "running fsck is recommended\n");
        else if ((sbi->s_mount_state & MINIX_ERROR_FS))
            printk("MINIX-fs warning: remounting fs with errors, "
                "running fsck is recommended\n");
    }
    return 0;
}

static int minix_fill_super(struct super_block *s, void *data, int silent)
{
    struct buffer_head *bh;
    struct buffer_head **map;
    struct minix_super_block *ms;
    struct minix3_super_block *m3s = NULL;
    unsigned long i, block;
    struct inode *root_inode;
    struct minix_sb_info *sbi;
    int ret = -EINVAL;

    sbi = kzalloc(sizeof(struct minix_sb_info), GFP_KERNEL);
    if (!sbi)
        return -ENOMEM;
    s->s_fs_info = sbi;

    BUILD_BUG_ON(32 != sizeof (struct minix_inode));
    BUILD_BUG_ON(64 != sizeof(struct minix2_inode));

    if (!sb_set_blocksize(s, BLOCK_SIZE))
        goto out_bad_hblock;

    if (!(bh = sb_bread(s, 1)))
        goto out_bad_sb;

    ms = (struct minix_super_block *) bh->b_data;
    sbi->s_ms = ms;
    sbi->s_sbh = bh;
    sbi->s_mount_state = ms->s_state;
    sbi->s_ninodes = ms->s_ninodes;
    sbi->s_nzones = ms->s_nzones;
    sbi->s_imap_blocks = ms->s_imap_blocks;
    sbi->s_zmap_blocks = ms->s_zmap_blocks;
    sbi->s_firstdatazone = ms->s_firstdatazone;
    sbi->s_log_zone_size = ms->s_log_zone_size;
    sbi->s_max_size = ms->s_max_size;
    s->s_magic = ms->s_magic;
    if (s->s_magic == MINIX_SUPER_MAGIC) {
        sbi->s_version = MINIX_V1;
        sbi->s_dirsize = 16;
        sbi->s_namelen = 14;
        s->s_max_links = MINIX_LINK_MAX;
    } else if (s->s_magic == MINIX_SUPER_MAGIC2) {
        sbi->s_version = MINIX_V1;
        sbi->s_dirsize = 32;
        sbi->s_namelen = 30;
        s->s_max_links = MINIX_LINK_MAX;
    } else if (s->s_magic == MINIX2_SUPER_MAGIC) {
        sbi->s_version = MINIX_V2;
        sbi->s_nzones = ms->s_zones;
        sbi->s_dirsize = 16;
        sbi->s_namelen = 14;
        s->s_max_links = MINIX2_LINK_MAX;
    } else if (s->s_magic == MINIX2_SUPER_MAGIC2) {
        sbi->s_version = MINIX_V2;
        sbi->s_nzones = ms->s_zones;
        sbi->s_dirsize = 32;
        sbi->s_namelen = 30;
        s->s_max_links = MINIX2_LINK_MAX;
    } else if ( *(__u16 *)(bh->b_data + 24) == MINIX3_SUPER_MAGIC) {
        m3s = (struct minix3_super_block *) bh->b_data;
        s->s_magic = m3s->s_magic;
        sbi->s_imap_blocks = m3s->s_imap_blocks;
        sbi->s_zmap_blocks = m3s->s_zmap_blocks;
        sbi->s_firstdatazone = m3s->s_firstdatazone;
        sbi->s_log_zone_size = m3s->s_log_zone_size;
        sbi->s_max_size = m3s->s_max_size;
        sbi->s_ninodes = m3s->s_ninodes;
        sbi->s_nzones = m3s->s_zones;
        sbi->s_dirsize = 64;
        sbi->s_namelen = 60;
        sbi->s_version = MINIX_V3;
        sbi->s_mount_state = MINIX_VALID_FS;
        sb_set_blocksize(s, m3s->s_blocksize);
        s->s_max_links = MINIX2_LINK_MAX;
    } else
        goto out_no_fs;

    /*
     * Allocate the buffer map to keep the superblock small.
     */
    if (sbi->s_imap_blocks == 0 || sbi->s_zmap_blocks == 0)
        goto out_illegal_sb;
    i = (sbi->s_imap_blocks + sbi->s_zmap_blocks) * sizeof(bh);
    map = kzalloc(i, GFP_KERNEL);
    if (!map)
        goto out_no_map;
    sbi->s_imap = &map[0];
    sbi->s_zmap = &map[sbi->s_imap_blocks];

    block=2;
    for (i=0 ; i < sbi->s_imap_blocks ; i++) {
        if (!(sbi->s_imap[i]=sb_bread(s, block)))
            goto out_no_bitmap;
        block++;
    }
    for (i=0 ; i < sbi->s_zmap_blocks ; i++) {
        if (!(sbi->s_zmap[i]=sb_bread(s, block)))
            goto out_no_bitmap;
        block++;
    }

    minix_set_bit(0,sbi->s_imap[0]->b_data);
    minix_set_bit(0,sbi->s_zmap[0]->b_data);

    /* Apparently minix can create filesystems that allocate more blocks for
     * the bitmaps than needed.  We simply ignore that, but verify it didn't
     * create one with not enough blocks and bail out if so.
     */
    block = minix_blocks_needed(sbi->s_ninodes, s->s_blocksize);
    if (sbi->s_imap_blocks < block) {
        printk("MINIX-fs: file system does not have enough "
                "imap blocks allocated.  Refusing to mount\n");
        goto out_no_bitmap;
    }

    block = minix_blocks_needed(
            (sbi->s_nzones - (sbi->s_firstdatazone + 1)),
            s->s_blocksize);
    if (sbi->s_zmap_blocks < block) {
        printk("MINIX-fs: file system does not have enough "
                "zmap blocks allocated.  Refusing to mount.\n");
        goto out_no_bitmap;
    }

    /* set up enough so that it can read an inode */
    s->s_op = &minix_sops;
    root_inode = minix_iget(s, MINIX_ROOT_INO);
    if (IS_ERR(root_inode)) {
        ret = PTR_ERR(root_inode);
        goto out_no_root;
    }

    ret = -ENOMEM;
    s->s_root = d_make_root(root_inode);
    if (!s->s_root)
        goto out_no_root;

    if (!(s->s_flags & MS_RDONLY)) {
        if (sbi->s_version != MINIX_V3) /* s_state is now out from V3 sb */
            ms->s_state &= ~MINIX_VALID_FS;
        mark_buffer_dirty(bh);
    }
    if (!(sbi->s_mount_state & MINIX_VALID_FS))
        printk("MINIX-fs: mounting unchecked file system, "
            "running fsck is recommended\n");
    else if (sbi->s_mount_state & MINIX_ERROR_FS)
        printk("MINIX-fs: mounting file system with errors, "
            "running fsck is recommended\n");

    return 0;

out_no_root:
    if (!silent)
        printk("MINIX-fs: get root inode failed\n");
    goto out_freemap;

out_no_bitmap:
    printk("MINIX-fs: bad superblock or unable to read bitmaps\n");
out_freemap:
    for (i = 0; i < sbi->s_imap_blocks; i++)
        brelse(sbi->s_imap[i]);
    for (i = 0; i < sbi->s_zmap_blocks; i++)
        brelse(sbi->s_zmap[i]);
    kfree(sbi->s_imap);
    goto out_release;

out_no_map:
    ret = -ENOMEM;
    if (!silent)
        printk("MINIX-fs: can't allocate map\n");
    goto out_release;

out_illegal_sb:
    if (!silent)
        printk("MINIX-fs: bad superblock\n");
    goto out_release;

out_no_fs:
    if (!silent)
        printk("VFS: Can't find a Minix filesystem V1 | V2 | V3 "
               "on device %s.\n", s->s_id);
out_release:
    brelse(bh);
    goto out;

out_bad_hblock:
    printk("MINIX-fs: blocksize too small for device\n");
    goto out;

out_bad_sb:
    printk("MINIX-fs: unable to read superblock\n");
out:
    s->s_fs_info = NULL;
    kfree(sbi);
    return ret;
}

static int minix_statfs(struct dentry *dentry, struct kstatfs *buf)
{
    struct super_block *sb = dentry->d_sb;
    struct minix_sb_info *sbi = minix_sb(sb);
    u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
    buf->f_type = sb->s_magic;
    buf->f_bsize = sb->s_blocksize;
    buf->f_blocks = (sbi->s_nzones - sbi->s_firstdatazone) << sbi->s_log_zone_size;
    buf->f_bfree = minix_count_free_blocks(sb);
    buf->f_bavail = buf->f_bfree;
    buf->f_files = sbi->s_ninodes;
    buf->f_ffree = minix_count_free_inodes(sb);
    buf->f_namelen = sbi->s_namelen;
    buf->f_fsid.val[0] = (u32)id;
    buf->f_fsid.val[1] = (u32)(id >> 32);

    return 0;
}

static int minix_get_block(struct inode *inode, sector_t block,
            struct buffer_head *bh_result, int create)
{
    if (INODE_VERSION(inode) == MINIX_V1)
        return V1_minix_get_block(inode, block, bh_result, create);
    else
        return V2_minix_get_block(inode, block, bh_result, create);
}

static int minix_writepage(struct page *page, struct writeback_control *wbc)
{
    return block_write_full_page(page, minix_get_block, wbc);
}

static int minix_readpage(struct file *file, struct page *page)
{
    return block_read_full_page(page,minix_get_block);
}

int minix_prepare_chunk(struct page *page, loff_t pos, unsigned len)
{
    return __block_write_begin(page, pos, len, minix_get_block);
}

static int minix_write_begin(struct file *file, struct address_space *mapping,
            loff_t pos, unsigned len, unsigned flags,
            struct page **pagep, void **fsdata)
{
    int ret;

    ret = block_write_begin(mapping, pos, len, flags, pagep,
                minix_get_block);
    if (unlikely(ret)) {
        loff_t isize = mapping->host->i_size;
        if (pos + len > isize)
            vmtruncate(mapping->host, isize);
    }

    return ret;
}

static sector_t minix_bmap(struct address_space *mapping, sector_t block)
{
    return generic_block_bmap(mapping,block,minix_get_block);
}

static const struct address_space_operations minix_aops = {
    .readpage = minix_readpage,
    .writepage = minix_writepage,
    .write_begin = minix_write_begin,
    .write_end = generic_write_end,
    .bmap = minix_bmap
};

static const struct inode_operations minix_symlink_inode_operations = {
    .readlink   = generic_readlink,
    .follow_link    = page_follow_link_light,
    .put_link   = page_put_link,
    .getattr    = minix_getattr,
};

void minix_set_inode(struct inode *inode, dev_t rdev)
{
    if (S_ISREG(inode->i_mode)) {
        inode->i_op = &minix_file_inode_operations;
        inode->i_fop = &minix_file_operations;
        inode->i_mapping->a_ops = &minix_aops;
    } else if (S_ISDIR(inode->i_mode)) {
        inode->i_op = &minix_dir_inode_operations;
        inode->i_fop = &minix_dir_operations;
        inode->i_mapping->a_ops = &minix_aops;
    } else if (S_ISLNK(inode->i_mode)) {
        inode->i_op = &minix_symlink_inode_operations;
        inode->i_mapping->a_ops = &minix_aops;
    } else
        init_special_inode(inode, inode->i_mode, rdev);
}

/*
 * The minix V1 function to read an inode.
 */
static struct inode *V1_minix_iget(struct inode *inode)
{
    struct buffer_head * bh;
    struct minix_inode * raw_inode;
    struct minix_inode_info *minix_inode = minix_i(inode);
    int i;

    raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
    if (!raw_inode) {
        iget_failed(inode);
        return ERR_PTR(-EIO);
    }
    inode->i_mode = raw_inode->i_mode;
    i_uid_write(inode, raw_inode->i_uid);
    i_gid_write(inode, raw_inode->i_gid);
    set_nlink(inode, raw_inode->i_nlinks);
    inode->i_size = raw_inode->i_size;
    inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = raw_inode->i_time;
    inode->i_mtime.tv_nsec = 0;
    inode->i_atime.tv_nsec = 0;
    inode->i_ctime.tv_nsec = 0;
    inode->i_blocks = 0;
    for (i = 0; i < 9; i++)
        minix_inode->u.i1_data[i] = raw_inode->i_zone[i];
    minix_set_inode(inode, old_decode_dev(raw_inode->i_zone[0]));
    brelse(bh);
    unlock_new_inode(inode);
    return inode;
}

/*
 * The minix V2 function to read an inode.
 */
static struct inode *V2_minix_iget(struct inode *inode)
{
    struct buffer_head * bh;
    struct minix2_inode * raw_inode;
    struct minix_inode_info *minix_inode = minix_i(inode);
    int i;

    raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
    if (!raw_inode) {
        iget_failed(inode);
        return ERR_PTR(-EIO);
    }
    inode->i_mode = raw_inode->i_mode;
    i_uid_write(inode, raw_inode->i_uid);
    i_gid_write(inode, raw_inode->i_gid);
    set_nlink(inode, raw_inode->i_nlinks);
    inode->i_size = raw_inode->i_size;
    inode->i_mtime.tv_sec = raw_inode->i_mtime;
    inode->i_atime.tv_sec = raw_inode->i_atime;
    inode->i_ctime.tv_sec = raw_inode->i_ctime;
    inode->i_mtime.tv_nsec = 0;
    inode->i_atime.tv_nsec = 0;
    inode->i_ctime.tv_nsec = 0;
    inode->i_blocks = 0;
    for (i = 0; i < 10; i++)
        minix_inode->u.i2_data[i] = raw_inode->i_zone[i];
    minix_set_inode(inode, old_decode_dev(raw_inode->i_zone[0]));
    brelse(bh);
    unlock_new_inode(inode);
    return inode;
}

/*
 * The global function to read an inode.
 */
struct inode *minix_iget(struct super_block *sb, unsigned long ino)
{
    struct inode *inode;

    inode = iget_locked(sb, ino);
    if (!inode)
        return ERR_PTR(-ENOMEM);
    if (!(inode->i_state & I_NEW))
        return inode;

    if (INODE_VERSION(inode) == MINIX_V1)
        return V1_minix_iget(inode);
    else
        return V2_minix_iget(inode);
}

/*
 * The minix V1 function to synchronize an inode.
 */
static struct buffer_head * V1_minix_update_inode(struct inode * inode)
{
    struct buffer_head * bh;
    struct minix_inode * raw_inode;
    struct minix_inode_info *minix_inode = minix_i(inode);
    int i;

    raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
    if (!raw_inode)
        return NULL;
    raw_inode->i_mode = inode->i_mode;
    raw_inode->i_uid = fs_high2lowuid(i_uid_read(inode));
    raw_inode->i_gid = fs_high2lowgid(i_gid_read(inode));
    raw_inode->i_nlinks = inode->i_nlink;
    raw_inode->i_size = inode->i_size;
    raw_inode->i_time = inode->i_mtime.tv_sec;
    if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
        raw_inode->i_zone[0] = old_encode_dev(inode->i_rdev);
    else for (i = 0; i < 9; i++)
        raw_inode->i_zone[i] = minix_inode->u.i1_data[i];
    mark_buffer_dirty(bh);
    return bh;
}

/*
 * The minix V2 function to synchronize an inode.
 */
static struct buffer_head * V2_minix_update_inode(struct inode * inode)
{
    struct buffer_head * bh;
    struct minix2_inode * raw_inode;
    struct minix_inode_info *minix_inode = minix_i(inode);
    int i;

    raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
    if (!raw_inode)
        return NULL;
    raw_inode->i_mode = inode->i_mode;
    raw_inode->i_uid = fs_high2lowuid(i_uid_read(inode));
    raw_inode->i_gid = fs_high2lowgid(i_gid_read(inode));
    raw_inode->i_nlinks = inode->i_nlink;
    raw_inode->i_size = inode->i_size;
    raw_inode->i_mtime = inode->i_mtime.tv_sec;
    raw_inode->i_atime = inode->i_atime.tv_sec;
    raw_inode->i_ctime = inode->i_ctime.tv_sec;
    if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
        raw_inode->i_zone[0] = old_encode_dev(inode->i_rdev);
    else for (i = 0; i < 10; i++)
        raw_inode->i_zone[i] = minix_inode->u.i2_data[i];
    mark_buffer_dirty(bh);
    return bh;
}

static int minix_write_inode(struct inode *inode, struct writeback_control *wbc)
{
    int err = 0;
    struct buffer_head *bh;

    if (INODE_VERSION(inode) == MINIX_V1)
        bh = V1_minix_update_inode(inode);
    else
        bh = V2_minix_update_inode(inode);
    if (!bh)
        return -EIO;
    if (wbc->sync_mode == WB_SYNC_ALL && buffer_dirty(bh)) {
        sync_dirty_buffer(bh);
        if (buffer_req(bh) && !buffer_uptodate(bh)) {
            printk("IO error syncing minix inode [%s:%08lx]\n",
                inode->i_sb->s_id, inode->i_ino);
            err = -EIO;
        }
    }
    brelse (bh);
    return err;
}

int minix_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
    struct super_block *sb = dentry->d_sb;
    generic_fillattr(dentry->d_inode, stat);
    if (INODE_VERSION(dentry->d_inode) == MINIX_V1)
        stat->blocks = (BLOCK_SIZE / 512) * V1_minix_blocks(stat->size, sb);
    else
        stat->blocks = (sb->s_blocksize / 512) * V2_minix_blocks(stat->size, sb);
    stat->blksize = sb->s_blocksize;
    return 0;
}

/*
 * The function that is called for file truncation.
 */
void minix_truncate(struct inode * inode)
{
    if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)))
        return;
    if (INODE_VERSION(inode) == MINIX_V1)
        V1_minix_truncate(inode);
    else
        V2_minix_truncate(inode);
}

static struct dentry *minix_mount(struct file_system_type *fs_type,
    int flags, const char *dev_name, void *data)
{
    return mount_bdev(fs_type, flags, dev_name, data, minix_fill_super);
}

static struct file_system_type minix_fs_type = {
    .owner      = THIS_MODULE,
    .name       = "minix",
    .mount      = minix_mount,
    .kill_sb    = kill_block_super,
    .fs_flags   = FS_REQUIRES_DEV,
};

static int __init init_minix_fs(void)
{
    int err = init_inodecache();
    if (err)
        goto out1;
    err = register_filesystem(&minix_fs_type);
    if (err)
        goto out;
    return 0;
out:
    destroy_inodecache();
out1:
    return err;
}

static void __exit exit_minix_fs(void)
{
        unregister_filesystem(&minix_fs_type);
    destroy_inodecache();
}

module_init(init_minix_fs)
module_exit(exit_minix_fs)
MODULE_LICENSE("GPL");