dir.c

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/*
 * Directory operations for Coda filesystem
 * Original version: (C) 1996 P. Braam and M. Callahan
 * Rewritten for Linux 2.1. (C) 1997 Carnegie Mellon University
 * 
 * Carnegie Mellon encourages users to contribute improvements to
 * the Coda project. Contact Peter Braam ([email protected]).
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/namei.h>

#include <asm/uaccess.h>

#include <linux/coda.h>
#include <linux/coda_psdev.h>
#include "coda_linux.h"
#include "coda_cache.h"

#include "coda_int.h"

/* dir inode-ops */
static int coda_create(struct inode *dir, struct dentry *new, umode_t mode, bool excl);
static struct dentry *coda_lookup(struct inode *dir, struct dentry *target, unsigned int flags);
static int coda_link(struct dentry *old_dentry, struct inode *dir_inode, 
             struct dentry *entry);
static int coda_unlink(struct inode *dir_inode, struct dentry *entry);
static int coda_symlink(struct inode *dir_inode, struct dentry *entry,
            const char *symname);
static int coda_mkdir(struct inode *dir_inode, struct dentry *entry, umode_t mode);
static int coda_rmdir(struct inode *dir_inode, struct dentry *entry);
static int coda_rename(struct inode *old_inode, struct dentry *old_dentry, 
                       struct inode *new_inode, struct dentry *new_dentry);

/* dir file-ops */
static int coda_readdir(struct file *file, void *buf, filldir_t filldir);

/* dentry ops */
static int coda_dentry_revalidate(struct dentry *de, unsigned int flags);
static int coda_dentry_delete(const struct dentry *);

/* support routines */
static int coda_venus_readdir(struct file *coda_file, void *buf,
                  filldir_t filldir);

/* same as fs/bad_inode.c */
static int coda_return_EIO(void)
{
    return -EIO;
}
#define CODA_EIO_ERROR ((void *) (coda_return_EIO))

const struct dentry_operations coda_dentry_operations =
{
    .d_revalidate   = coda_dentry_revalidate,
    .d_delete   = coda_dentry_delete,
};

const struct inode_operations coda_dir_inode_operations =
{
    .create     = coda_create,
    .lookup     = coda_lookup,
    .link       = coda_link,
    .unlink     = coda_unlink,
    .symlink    = coda_symlink,
    .mkdir      = coda_mkdir,
    .rmdir      = coda_rmdir,
    .mknod      = CODA_EIO_ERROR,
    .rename     = coda_rename,
    .permission = coda_permission,
    .getattr    = coda_getattr,
    .setattr    = coda_setattr,
};

const struct file_operations coda_dir_operations = {
    .llseek     = generic_file_llseek,
    .read       = generic_read_dir,
    .readdir    = coda_readdir,
    .open       = coda_open,
    .release    = coda_release,
    .fsync      = coda_fsync,
};


/* inode operations for directories */
/* access routines: lookup, readlink, permission */
static struct dentry *coda_lookup(struct inode *dir, struct dentry *entry, unsigned int flags)
{
    struct super_block *sb = dir->i_sb;
    const char *name = entry->d_name.name;
    size_t length = entry->d_name.len;
    struct inode *inode;
    int type = 0;

    if (length > CODA_MAXNAMLEN) {
        printk(KERN_ERR "name too long: lookup, %s (%*s)\n",
               coda_i2s(dir), (int)length, name);
        return ERR_PTR(-ENAMETOOLONG);
    }

    /* control object, create inode on the fly */
    if (coda_isroot(dir) && coda_iscontrol(name, length)) {
        inode = coda_cnode_makectl(sb);
        type = CODA_NOCACHE;
    } else {
        struct CodaFid fid = { { 0, } };
        int error = venus_lookup(sb, coda_i2f(dir), name, length,
                     &type, &fid);
        inode = !error ? coda_cnode_make(&fid, sb) : ERR_PTR(error);
    }

    if (!IS_ERR(inode) && (type & CODA_NOCACHE))
        coda_flag_inode(inode, C_VATTR | C_PURGE);

    if (inode == ERR_PTR(-ENOENT))
        inode = NULL;

    return d_splice_alias(inode, entry);
}


int coda_permission(struct inode *inode, int mask)
{
    int error;

    if (mask & MAY_NOT_BLOCK)
        return -ECHILD;

    mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
 
    if (!mask)
        return 0;

    if ((mask & MAY_EXEC) && !execute_ok(inode))
        return -EACCES;

    if (coda_cache_check(inode, mask))
        return 0;

    error = venus_access(inode->i_sb, coda_i2f(inode), mask);
    
    if (!error)
        coda_cache_enter(inode, mask);

    return error;
}


static inline void coda_dir_update_mtime(struct inode *dir)
{
#ifdef REQUERY_VENUS_FOR_MTIME
    /* invalidate the directory cnode's attributes so we refetch the
     * attributes from venus next time the inode is referenced */
    coda_flag_inode(dir, C_VATTR);
#else
    /* optimistically we can also act as if our nose bleeds. The
     * granularity of the mtime is coarse anyways so we might actually be
     * right most of the time. Note: we only do this for directories. */
    dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
#endif
}

/* we have to wrap inc_nlink/drop_nlink because sometimes userspace uses a
 * trick to fool GNU find's optimizations. If we can't be sure of the link
 * (because of volume mount points) we set i_nlink to 1 which forces find
 * to consider every child as a possible directory. We should also never
 * see an increment or decrement for deleted directories where i_nlink == 0 */
static inline void coda_dir_inc_nlink(struct inode *dir)
{
    if (dir->i_nlink >= 2)
        inc_nlink(dir);
}

static inline void coda_dir_drop_nlink(struct inode *dir)
{
    if (dir->i_nlink > 2)
        drop_nlink(dir);
}

/* creation routines: create, mknod, mkdir, link, symlink */
static int coda_create(struct inode *dir, struct dentry *de, umode_t mode, bool excl)
{
    int error;
    const char *name=de->d_name.name;
    int length=de->d_name.len;
    struct inode *inode;
    struct CodaFid newfid;
    struct coda_vattr attrs;

    if (coda_isroot(dir) && coda_iscontrol(name, length))
        return -EPERM;

    error = venus_create(dir->i_sb, coda_i2f(dir), name, length, 
                0, mode, &newfid, &attrs);
    if (error)
        goto err_out;

    inode = coda_iget(dir->i_sb, &newfid, &attrs);
    if (IS_ERR(inode)) {
        error = PTR_ERR(inode);
        goto err_out;
    }

    /* invalidate the directory cnode's attributes */
    coda_dir_update_mtime(dir);
    d_instantiate(de, inode);
    return 0;
err_out:
    d_drop(de);
    return error;
}

static int coda_mkdir(struct inode *dir, struct dentry *de, umode_t mode)
{
    struct inode *inode;
    struct coda_vattr attrs;
    const char *name = de->d_name.name;
    int len = de->d_name.len;
    int error;
    struct CodaFid newfid;

    if (coda_isroot(dir) && coda_iscontrol(name, len))
        return -EPERM;

    attrs.va_mode = mode;
    error = venus_mkdir(dir->i_sb, coda_i2f(dir), 
                   name, len, &newfid, &attrs);
    if (error)
        goto err_out;
         
    inode = coda_iget(dir->i_sb, &newfid, &attrs);
    if (IS_ERR(inode)) {
        error = PTR_ERR(inode);
        goto err_out;
    }

    /* invalidate the directory cnode's attributes */
    coda_dir_inc_nlink(dir);
    coda_dir_update_mtime(dir);
    d_instantiate(de, inode);
    return 0;
err_out:
    d_drop(de);
    return error;
}

/* try to make de an entry in dir_inodde linked to source_de */ 
static int coda_link(struct dentry *source_de, struct inode *dir_inode, 
      struct dentry *de)
{
    struct inode *inode = source_de->d_inode;
        const char * name = de->d_name.name;
    int len = de->d_name.len;
    int error;

    if (coda_isroot(dir_inode) && coda_iscontrol(name, len))
        return -EPERM;

    error = venus_link(dir_inode->i_sb, coda_i2f(inode),
               coda_i2f(dir_inode), (const char *)name, len);
    if (error) {
        d_drop(de);
        return error;
    }

    coda_dir_update_mtime(dir_inode);
    ihold(inode);
    d_instantiate(de, inode);
    inc_nlink(inode);
    return 0;
}


static int coda_symlink(struct inode *dir_inode, struct dentry *de,
            const char *symname)
{
    const char *name = de->d_name.name;
    int len = de->d_name.len;
    int symlen;
    int error;

    if (coda_isroot(dir_inode) && coda_iscontrol(name, len))
        return -EPERM;

    symlen = strlen(symname);
    if (symlen > CODA_MAXPATHLEN)
        return -ENAMETOOLONG;

    /*
     * This entry is now negative. Since we do not create
     * an inode for the entry we have to drop it.
     */
    d_drop(de);
    error = venus_symlink(dir_inode->i_sb, coda_i2f(dir_inode), name, len,
                  symname, symlen);

    /* mtime is no good anymore */
    if (!error)
        coda_dir_update_mtime(dir_inode);

    return error;
}

/* destruction routines: unlink, rmdir */
static int coda_unlink(struct inode *dir, struct dentry *de)
{
        int error;
    const char *name = de->d_name.name;
    int len = de->d_name.len;

    error = venus_remove(dir->i_sb, coda_i2f(dir), name, len);
    if (error)
        return error;

    coda_dir_update_mtime(dir);
    drop_nlink(de->d_inode);
    return 0;
}

static int coda_rmdir(struct inode *dir, struct dentry *de)
{
    const char *name = de->d_name.name;
    int len = de->d_name.len;
    int error;

    error = venus_rmdir(dir->i_sb, coda_i2f(dir), name, len);
    if (!error) {
        /* VFS may delete the child */
        if (de->d_inode)
            clear_nlink(de->d_inode);

        /* fix the link count of the parent */
        coda_dir_drop_nlink(dir);
        coda_dir_update_mtime(dir);
    }
    return error;
}

/* rename */
static int coda_rename(struct inode *old_dir, struct dentry *old_dentry,
               struct inode *new_dir, struct dentry *new_dentry)
{
    const char *old_name = old_dentry->d_name.name;
    const char *new_name = new_dentry->d_name.name;
    int old_length = old_dentry->d_name.len;
    int new_length = new_dentry->d_name.len;
    int error;

    error = venus_rename(old_dir->i_sb, coda_i2f(old_dir),
                 coda_i2f(new_dir), old_length, new_length,
                 (const char *) old_name, (const char *)new_name);
    if (!error) {
        if (new_dentry->d_inode) {
            if (S_ISDIR(new_dentry->d_inode->i_mode)) {
                coda_dir_drop_nlink(old_dir);
                coda_dir_inc_nlink(new_dir);
            }
            coda_dir_update_mtime(old_dir);
            coda_dir_update_mtime(new_dir);
            coda_flag_inode(new_dentry->d_inode, C_VATTR);
        } else {
            coda_flag_inode(old_dir, C_VATTR);
            coda_flag_inode(new_dir, C_VATTR);
        }
    }
    return error;
}


/* file operations for directories */
static int coda_readdir(struct file *coda_file, void *buf, filldir_t filldir)
{
    struct coda_file_info *cfi;
    struct file *host_file;
    int ret;

    cfi = CODA_FTOC(coda_file);
    BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
    host_file = cfi->cfi_container;

    if (!host_file->f_op)
        return -ENOTDIR;

    if (host_file->f_op->readdir)
    {
        /* potemkin case: we were handed a directory inode.
         * We can't use vfs_readdir because we have to keep the file
         * position in sync between the coda_file and the host_file.
         * and as such we need grab the inode mutex. */
        struct inode *host_inode = host_file->f_path.dentry->d_inode;

        mutex_lock(&host_inode->i_mutex);
        host_file->f_pos = coda_file->f_pos;

        ret = -ENOENT;
        if (!IS_DEADDIR(host_inode)) {
            ret = host_file->f_op->readdir(host_file, buf, filldir);
            file_accessed(host_file);
        }

        coda_file->f_pos = host_file->f_pos;
        mutex_unlock(&host_inode->i_mutex);
    }
    else /* Venus: we must read Venus dirents from a file */
        ret = coda_venus_readdir(coda_file, buf, filldir);

    return ret;
}

static inline unsigned int CDT2DT(unsigned char cdt)
{
    unsigned int dt;

    switch(cdt) {
    case CDT_UNKNOWN: dt = DT_UNKNOWN; break;
    case CDT_FIFO:    dt = DT_FIFO;    break;
    case CDT_CHR:     dt = DT_CHR;     break;
    case CDT_DIR:     dt = DT_DIR;     break;
    case CDT_BLK:     dt = DT_BLK;     break;
    case CDT_REG:     dt = DT_REG;     break;
    case CDT_LNK:     dt = DT_LNK;     break;
    case CDT_SOCK:    dt = DT_SOCK;    break;
    case CDT_WHT:     dt = DT_WHT;     break;
    default:      dt = DT_UNKNOWN; break;
    }
    return dt;
}

/* support routines */
static int coda_venus_readdir(struct file *coda_file, void *buf,
                  filldir_t filldir)
{
    int result = 0; /* # of entries returned */
    struct coda_file_info *cfi;
    struct coda_inode_info *cii;
    struct file *host_file;
    struct dentry *de;
    struct venus_dirent *vdir;
    unsigned long vdir_size = offsetof(struct venus_dirent, d_name);
    unsigned int type;
    struct qstr name;
    ino_t ino;
    int ret;

    cfi = CODA_FTOC(coda_file);
    BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
    host_file = cfi->cfi_container;

    de = coda_file->f_path.dentry;
    cii = ITOC(de->d_inode);

    vdir = kmalloc(sizeof(*vdir), GFP_KERNEL);
    if (!vdir) return -ENOMEM;

    if (coda_file->f_pos == 0) {
        ret = filldir(buf, ".", 1, 0, de->d_inode->i_ino, DT_DIR);
        if (ret < 0)
            goto out;
        result++;
        coda_file->f_pos++;
    }
    if (coda_file->f_pos == 1) {
        ret = filldir(buf, "..", 2, 1, parent_ino(de), DT_DIR);
        if (ret < 0)
            goto out;
        result++;
        coda_file->f_pos++;
    }
    while (1) {
        /* read entries from the directory file */
        ret = kernel_read(host_file, coda_file->f_pos - 2, (char *)vdir,
                  sizeof(*vdir));
        if (ret < 0) {
            printk(KERN_ERR "coda readdir: read dir %s failed %d\n",
                   coda_f2s(&cii->c_fid), ret);
            break;
        }
        if (ret == 0) break; /* end of directory file reached */

        /* catch truncated reads */
        if (ret < vdir_size || ret < vdir_size + vdir->d_namlen) {
            printk(KERN_ERR "coda readdir: short read on %s\n",
                   coda_f2s(&cii->c_fid));
            ret = -EBADF;
            break;
        }
        /* validate whether the directory file actually makes sense */
        if (vdir->d_reclen < vdir_size + vdir->d_namlen) {
            printk(KERN_ERR "coda readdir: invalid dir %s\n",
                   coda_f2s(&cii->c_fid));
            ret = -EBADF;
            break;
        }

        name.len = vdir->d_namlen;
        name.name = vdir->d_name;

        /* Make sure we skip '.' and '..', we already got those */
        if (name.name[0] == '.' && (name.len == 1 ||
            (vdir->d_name[1] == '.' && name.len == 2)))
            vdir->d_fileno = name.len = 0;

        /* skip null entries */
        if (vdir->d_fileno && name.len) {
            /* try to look up this entry in the dcache, that way
             * userspace doesn't have to worry about breaking
             * getcwd by having mismatched inode numbers for
             * internal volume mountpoints. */
            ino = find_inode_number(de, &name);
            if (!ino) ino = vdir->d_fileno;

            type = CDT2DT(vdir->d_type);
            ret = filldir(buf, name.name, name.len,
                      coda_file->f_pos, ino, type);
            /* failure means no space for filling in this round */
            if (ret < 0) break;
            result++;
        }
        /* we'll always have progress because d_reclen is unsigned and
         * we've already established it is non-zero. */
        coda_file->f_pos += vdir->d_reclen;
    }
out:
    kfree(vdir);
    return result ? result : ret;
}

/* called when a cache lookup succeeds */
static int coda_dentry_revalidate(struct dentry *de, unsigned int flags)
{
    struct inode *inode;
    struct coda_inode_info *cii;

    if (flags & LOOKUP_RCU)
        return -ECHILD;

    inode = de->d_inode;
    if (!inode || coda_isroot(inode))
        goto out;
    if (is_bad_inode(inode))
        goto bad;

    cii = ITOC(de->d_inode);
    if (!(cii->c_flags & (C_PURGE | C_FLUSH)))
        goto out;

    shrink_dcache_parent(de);

    /* propagate for a flush */
    if (cii->c_flags & C_FLUSH) 
        coda_flag_inode_children(inode, C_FLUSH);

    if (de->d_count > 1)
        /* pretend it's valid, but don't change the flags */
        goto out;

    /* clear the flags. */
    spin_lock(&cii->c_lock);
    cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
    spin_unlock(&cii->c_lock);
bad:
    return 0;
out:
    return 1;
}

/*
 * This is the callback from dput() when d_count is going to 0.
 * We use this to unhash dentries with bad inodes.
 */
static int coda_dentry_delete(const struct dentry * dentry)
{
    int flags;

    if (!dentry->d_inode) 
        return 0;

    flags = (ITOC(dentry->d_inode)->c_flags) & C_PURGE;
    if (is_bad_inode(dentry->d_inode) || flags) {
        return 1;
    }
    return 0;
}



/*
 * This is called when we want to check if the inode has
 * changed on the server.  Coda makes this easy since the
 * cache manager Venus issues a downcall to the kernel when this 
 * happens 
 */
int coda_revalidate_inode(struct dentry *dentry)
{
    struct coda_vattr attr;
    int error;
    int old_mode;
    ino_t old_ino;
    struct inode *inode = dentry->d_inode;
    struct coda_inode_info *cii = ITOC(inode);

    if (!cii->c_flags)
        return 0;

    if (cii->c_flags & (C_VATTR | C_PURGE | C_FLUSH)) {
        error = venus_getattr(inode->i_sb, &(cii->c_fid), &attr);
        if (error)
            return -EIO;

        /* this inode may be lost if:
           - it's ino changed 
           - type changes must be permitted for repair and
           missing mount points.
        */
        old_mode = inode->i_mode;
        old_ino = inode->i_ino;
        coda_vattr_to_iattr(inode, &attr);

        if ((old_mode & S_IFMT) != (inode->i_mode & S_IFMT)) {
            printk("Coda: inode %ld, fid %s changed type!\n",
                   inode->i_ino, coda_f2s(&(cii->c_fid)));
        }

        /* the following can happen when a local fid is replaced 
           with a global one, here we lose and declare the inode bad */
        if (inode->i_ino != old_ino)
            return -EIO;
        
        coda_flag_inode_children(inode, C_FLUSH);

        spin_lock(&cii->c_lock);
        cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
        spin_unlock(&cii->c_lock);
    }
    return 0;
}