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    Subject[PATCH 02/38] VFS: Make lookup_hash() return a struct path
    Date
    From: Jan Blunck <jblunck@suse.de>

    This patch changes lookup_hash() into returning a struct path.

    XXX - Check for correctness, otherwise obvious

    Signed-off-by: Jan Blunck <jblunck@suse.de>
    Signed-off-by: Valerie Aurora <vaurora@redhat.com>
    Cc: Alexander Viro <viro@zeniv.linux.org.uk>
    ---
    fs/namei.c | 113 ++++++++++++++++++++++++++++++-----------------------------
    1 files changed, 57 insertions(+), 56 deletions(-)

    diff --git a/fs/namei.c b/fs/namei.c
    index ec178f1..3b43c48 100644
    --- a/fs/namei.c
    +++ b/fs/namei.c
    @@ -1155,7 +1155,7 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
    }

    static struct dentry *__lookup_hash(struct qstr *name,
    - struct dentry *base, struct nameidata *nd)
    + struct dentry *base, struct nameidata *nd)
    {
    struct dentry *dentry;
    struct inode *inode;
    @@ -1212,14 +1212,22 @@ out:
    * needs parent already locked. Doesn't follow mounts.
    * SMP-safe.
    */
    -static struct dentry *lookup_hash(struct nameidata *nd)
    +static int lookup_hash(struct nameidata *nd, struct qstr *name,
    + struct path *path)
    {
    int err;

    err = exec_permission(nd->path.dentry->d_inode);
    if (err)
    - return ERR_PTR(err);
    - return __lookup_hash(&nd->last, nd->path.dentry, nd);
    + return err;
    + path->mnt = nd->path.mnt;
    + path->dentry = __lookup_hash(name, nd->path.dentry, nd);
    + if (IS_ERR(path->dentry)) {
    + err = PTR_ERR(path->dentry);
    + path->dentry = NULL;
    + path->mnt = NULL;
    + }
    + return err;
    }

    static int __lookup_one_len(const char *name, struct qstr *this,
    @@ -1701,12 +1709,9 @@ static struct file *do_last(struct nameidata *nd, struct path *path,

    /* OK, it's O_CREAT */
    mutex_lock(&dir->d_inode->i_mutex);
    + error = lookup_hash(nd, &nd->last, path);

    - path->dentry = lookup_hash(nd);
    - path->mnt = nd->path.mnt;
    -
    - error = PTR_ERR(path->dentry);
    - if (IS_ERR(path->dentry)) {
    + if (error) {
    mutex_unlock(&dir->d_inode->i_mutex);
    goto exit;
    }
    @@ -1958,7 +1963,8 @@ EXPORT_SYMBOL(filp_open);
    */
    struct dentry *lookup_create(struct nameidata *nd, int is_dir)
    {
    - struct dentry *dentry = ERR_PTR(-EEXIST);
    + struct path path;
    + int err;

    mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
    /*
    @@ -1966,7 +1972,7 @@ struct dentry *lookup_create(struct nameidata *nd, int is_dir)
    * (foo/., foo/.., /////)
    */
    if (nd->last_type != LAST_NORM)
    - goto fail;
    + return ERR_PTR(-EEXIST);
    nd->flags &= ~LOOKUP_PARENT;
    nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL;
    nd->intent.open.flags = O_EXCL;
    @@ -1974,11 +1980,11 @@ struct dentry *lookup_create(struct nameidata *nd, int is_dir)
    /*
    * Do the final lookup.
    */
    - dentry = lookup_hash(nd);
    - if (IS_ERR(dentry))
    - goto fail;
    + err = lookup_hash(nd, &nd->last, &path);
    + if (err)
    + return ERR_PTR(err);

    - if (dentry->d_inode)
    + if (path.dentry->d_inode)
    goto eexist;
    /*
    * Special case - lookup gave negative, but... we had foo/bar/
    @@ -1987,15 +1993,14 @@ struct dentry *lookup_create(struct nameidata *nd, int is_dir)
    * been asking for (non-existent) directory. -ENOENT for you.
    */
    if (unlikely(!is_dir && nd->last.name[nd->last.len])) {
    - dput(dentry);
    - dentry = ERR_PTR(-ENOENT);
    + dput(path.dentry);
    + return ERR_PTR(-ENOENT);
    }
    - return dentry;
    +
    + return path.dentry;
    eexist:
    - dput(dentry);
    - dentry = ERR_PTR(-EEXIST);
    -fail:
    - return dentry;
    + path_put_conditional(&path, nd);
    + return ERR_PTR(-EEXIST);
    }
    EXPORT_SYMBOL_GPL(lookup_create);

    @@ -2230,7 +2235,7 @@ static long do_rmdir(int dfd, const char __user *pathname)
    {
    int error = 0;
    char * name;
    - struct dentry *dentry;
    + struct path path;
    struct nameidata nd;

    error = user_path_parent(dfd, pathname, &nd, &name);
    @@ -2252,21 +2257,20 @@ static long do_rmdir(int dfd, const char __user *pathname)
    nd.flags &= ~LOOKUP_PARENT;

    mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
    - dentry = lookup_hash(&nd);
    - error = PTR_ERR(dentry);
    - if (IS_ERR(dentry))
    + error = lookup_hash(&nd, &nd.last, &path);
    + if (error)
    goto exit2;
    error = mnt_want_write(nd.path.mnt);
    if (error)
    goto exit3;
    - error = security_path_rmdir(&nd.path, dentry);
    + error = security_path_rmdir(&nd.path, path.dentry);
    if (error)
    goto exit4;
    - error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
    + error = vfs_rmdir(nd.path.dentry->d_inode, path.dentry);
    exit4:
    mnt_drop_write(nd.path.mnt);
    exit3:
    - dput(dentry);
    + path_put_conditional(&path, &nd);
    exit2:
    mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
    exit1:
    @@ -2322,7 +2326,7 @@ static long do_unlinkat(int dfd, const char __user *pathname)
    {
    int error;
    char *name;
    - struct dentry *dentry;
    + struct path path;
    struct nameidata nd;
    struct inode *inode = NULL;

    @@ -2337,26 +2341,25 @@ static long do_unlinkat(int dfd, const char __user *pathname)
    nd.flags &= ~LOOKUP_PARENT;

    mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
    - dentry = lookup_hash(&nd);
    - error = PTR_ERR(dentry);
    - if (!IS_ERR(dentry)) {
    + error = lookup_hash(&nd, &nd.last, &path);
    + if (!error) {
    /* Why not before? Because we want correct error value */
    if (nd.last.name[nd.last.len])
    goto slashes;
    - inode = dentry->d_inode;
    + inode = path.dentry->d_inode;
    if (inode)
    atomic_inc(&inode->i_count);
    error = mnt_want_write(nd.path.mnt);
    if (error)
    goto exit2;
    - error = security_path_unlink(&nd.path, dentry);
    + error = security_path_unlink(&nd.path, path.dentry);
    if (error)
    goto exit3;
    - error = vfs_unlink(nd.path.dentry->d_inode, dentry);
    + error = vfs_unlink(nd.path.dentry->d_inode, path.dentry);
    exit3:
    mnt_drop_write(nd.path.mnt);
    exit2:
    - dput(dentry);
    + path_put_conditional(&path, &nd);
    }
    mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
    if (inode)
    @@ -2367,8 +2370,8 @@ exit1:
    return error;

    slashes:
    - error = !dentry->d_inode ? -ENOENT :
    - S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
    + error = !path.dentry->d_inode ? -ENOENT :
    + S_ISDIR(path.dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
    goto exit2;
    }

    @@ -2706,7 +2709,7 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
    int, newdfd, const char __user *, newname)
    {
    struct dentry *old_dir, *new_dir;
    - struct dentry *old_dentry, *new_dentry;
    + struct path old, new;
    struct dentry *trap;
    struct nameidata oldnd, newnd;
    char *from;
    @@ -2740,16 +2743,15 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,

    trap = lock_rename(new_dir, old_dir);

    - old_dentry = lookup_hash(&oldnd);
    - error = PTR_ERR(old_dentry);
    - if (IS_ERR(old_dentry))
    + error = lookup_hash(&oldnd, &oldnd.last, &old);
    + if (error)
    goto exit3;
    /* source must exist */
    error = -ENOENT;
    - if (!old_dentry->d_inode)
    + if (!old.dentry->d_inode)
    goto exit4;
    /* unless the source is a directory trailing slashes give -ENOTDIR */
    - if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
    + if (!S_ISDIR(old.dentry->d_inode->i_mode)) {
    error = -ENOTDIR;
    if (oldnd.last.name[oldnd.last.len])
    goto exit4;
    @@ -2758,32 +2760,31 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
    }
    /* source should not be ancestor of target */
    error = -EINVAL;
    - if (old_dentry == trap)
    + if (old.dentry == trap)
    goto exit4;
    - new_dentry = lookup_hash(&newnd);
    - error = PTR_ERR(new_dentry);
    - if (IS_ERR(new_dentry))
    + error = lookup_hash(&newnd, &newnd.last, &new);
    + if (error)
    goto exit4;
    /* target should not be an ancestor of source */
    error = -ENOTEMPTY;
    - if (new_dentry == trap)
    + if (new.dentry == trap)
    goto exit5;

    error = mnt_want_write(oldnd.path.mnt);
    if (error)
    goto exit5;
    - error = security_path_rename(&oldnd.path, old_dentry,
    - &newnd.path, new_dentry);
    + error = security_path_rename(&oldnd.path, old.dentry,
    + &newnd.path, new.dentry);
    if (error)
    goto exit6;
    - error = vfs_rename(old_dir->d_inode, old_dentry,
    - new_dir->d_inode, new_dentry);
    + error = vfs_rename(old_dir->d_inode, old.dentry,
    + new_dir->d_inode, new.dentry);
    exit6:
    mnt_drop_write(oldnd.path.mnt);
    exit5:
    - dput(new_dentry);
    + path_put_conditional(&new, &newnd);
    exit4:
    - dput(old_dentry);
    + path_put_conditional(&old, &oldnd);
    exit3:
    unlock_rename(new_dir, old_dir);
    exit2:
    --
    1.6.3.3


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