/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
 * vim:expandtab:shiftwidth=8:tabstop=8:
 *
 *  linux/mds/handler.c
 *
 *  Lustre Metadata Server (mds) request handler
 *
 *  Copyright (C) 2001, 2002 Cluster File Systems, Inc.
 *
 *  This code is issued under the GNU General Public License.
 *  See the file COPYING in this distribution
 *
 *  by Peter Braam <braam@clusterfs.com>
 *
 *  This server is single threaded at present (but can easily be multi threaded)
 *
 */

#define EXPORT_SYMTAB

#include <linux/version.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/locks.h>
#include <linux/ext2_fs.h>
#include <linux/quotaops.h>
#include <asm/unistd.h>
#include <asm/uaccess.h>

#define DEBUG_SUBSYSTEM S_MDS

#include <linux/lustre_mds.h>
#include <linux/lustre_lib.h>

int mds_sendpage(struct ptlrpc_request *req, struct file *file,
                 __u64 offset, struct niobuf *dst)
{
        int rc = 0;
        mm_segment_t oldfs = get_fs();

        if (req->rq_peer.peer_nid == 0) {
                /* dst->addr is a user address, but in a different task! */
                set_fs(KERNEL_DS);
                /* FIXME: Can't use file->f_op->read() on a directory */
                rc = generic_file_read(file, (char *)(long)dst->addr,
                                       PAGE_SIZE, &offset);
                set_fs(oldfs);

                if (rc != PAGE_SIZE) {
                        rc = -EIO;
                        GOTO(out, rc);
                }
                EXIT;
        } else {
                struct ptlrpc_bulk_desc *bulk;
                char *buf = NULL;

                bulk = ptlrpc_prep_bulk(&req->rq_peer);
                if (bulk == NULL) {
                        rc = -ENOMEM;
                        GOTO(out, rc);
                }

                bulk->b_xid = req->rq_xid;

                OBD_ALLOC(buf, PAGE_SIZE);
                if (!buf) {
                        rc = -ENOMEM;
                        GOTO(cleanup_bulk, rc);
                }

                set_fs(KERNEL_DS);
                /* FIXME: Can't use file->f_op->read() on a directory */
                //rc = file->f_op->read(file, buf, PAGE_SIZE, &offset);
                rc = generic_file_read(file, buf, PAGE_SIZE, &offset);
                set_fs(oldfs);

                if (rc != PAGE_SIZE) {
                        rc = -EIO;
                        GOTO(cleanup_buf, rc);
                }

                bulk->b_buf = buf;
                bulk->b_buflen = PAGE_SIZE;

                rc = ptlrpc_send_bulk(bulk, MDS_BULK_PORTAL);
                wait_event_interruptible(bulk->b_waitq,
                                         ptlrpc_check_bulk_sent(bulk));

                if (bulk->b_flags == PTL_RPC_INTR) {
                        rc = -EINTR;
                        GOTO(cleanup_buf, rc);
                }

                EXIT;
        cleanup_buf:
                OBD_FREE(buf, PAGE_SIZE);
        cleanup_bulk:
                OBD_FREE(bulk, sizeof(*bulk));
        }
out:
        return rc;
}

struct dentry *mds_fid2dentry(struct mds_obd *mds, struct ll_fid *fid,
                              struct vfsmount **mnt)
{
        /* stolen from NFS */
        struct super_block *sb = mds->mds_sb;
        unsigned long ino = fid->id;
        //__u32 generation = fid->generation;
        __u32 generation = 0;
        struct inode *inode;
        struct list_head *lp;
        struct dentry *result;

        if (ino == 0)
                return ERR_PTR(-ESTALE);

        inode = iget(sb, ino);
        if (inode == NULL)
                return ERR_PTR(-ENOMEM);

        CDEBUG(D_DENTRY, "--> mds_fid2dentry: sb %p\n", inode->i_sb);

        if (is_bad_inode(inode)
            || (generation && inode->i_generation != generation)
                ) {
                /* we didn't find the right inode.. */
                CERROR("bad inode %lu, link: %d ct: %d or version  %u/%u\n",
                        inode->i_ino,
                        inode->i_nlink, atomic_read(&inode->i_count),
                        inode->i_generation,
                        generation);
                BUG();
                iput(inode);
                return ERR_PTR(-ESTALE);
        }

        /* now to find a dentry.
         * If possible, get a well-connected one
         */
        if (mnt)
                *mnt = mds->mds_vfsmnt;
        spin_lock(&dcache_lock);
        for (lp = inode->i_dentry.next; lp != &inode->i_dentry ; lp=lp->next) {
                result = list_entry(lp,struct dentry, d_alias);
                if (! (result->d_flags & DCACHE_NFSD_DISCONNECTED)) {
                        dget_locked(result);
                        result->d_vfs_flags |= DCACHE_REFERENCED;
                        spin_unlock(&dcache_lock);
                        iput(inode);
                        if (mnt)
                                mntget(*mnt);
                        return result;
                }
        }
        spin_unlock(&dcache_lock);
        result = d_alloc_root(inode);
        if (result == NULL) {
                iput(inode);
                return ERR_PTR(-ENOMEM);
        }
        if (mnt)
                mntget(*mnt);
        result->d_flags |= DCACHE_NFSD_DISCONNECTED;
        return result;
}

static inline void mds_get_objid(struct inode *inode, __u64 *id)
{
        /* FIXME: it is only by luck that this works on ext3 */
        memcpy(id, &inode->u.ext2_i.i_data, sizeof(*id));
}

int mds_getattr(struct ptlrpc_request *req)
{
        struct dentry *de;
        struct inode *inode;
        struct mds_rep *rep;
        int rc;

        rc = mds_pack_rep(NULL, 0, NULL, 0, &req->rq_rephdr, &req->rq_rep,
                          &req->rq_replen, &req->rq_repbuf);
        if (rc) {
                CERROR("mds: out of memory\n");
                req->rq_status = -ENOMEM;
                RETURN(0);
        }

        req->rq_rephdr->xid = req->rq_reqhdr->xid;
        rep = req->rq_rep.mds;

        de = mds_fid2dentry(&req->rq_obd->u.mds, &req->rq_req.mds->fid1, NULL);
        if (IS_ERR(de)) {
                req->rq_rephdr->status = -ENOENT;
                RETURN(0);
        }

        inode = de->d_inode;
        rep->ino = inode->i_ino;
        rep->atime = inode->i_atime;
        rep->ctime = inode->i_ctime;
        rep->mtime = inode->i_mtime;
        rep->uid = inode->i_uid;
        rep->gid = inode->i_gid;
        rep->size = inode->i_size;
        rep->mode = inode->i_mode;
        rep->nlink = inode->i_nlink;
        rep->valid = ~0;
        mds_get_objid(inode, &rep->objid);
        dput(de);
        return 0;
}

int mds_open(struct ptlrpc_request *req)
{
        struct dentry *de;
        struct mds_rep *rep;
        struct file *file;
        struct vfsmount *mnt;
        __u32 flags;
        int rc;

        rc = mds_pack_rep(NULL, 0, NULL, 0, &req->rq_rephdr, &req->rq_rep,
                          &req->rq_replen, &req->rq_repbuf);
        if (rc) {
                CERROR("mds: out of memory\n");
                req->rq_status = -ENOMEM;
                RETURN(0);
        }

        req->rq_rephdr->xid = req->rq_reqhdr->xid;
        rep = req->rq_rep.mds;

        de = mds_fid2dentry(&req->rq_obd->u.mds, &req->rq_req.mds->fid1, &mnt);
        if (IS_ERR(de)) {
                req->rq_rephdr->status = -ENOENT;
                RETURN(0);
        }
        flags = req->rq_req.mds->flags;
        file = dentry_open(de, mnt, flags);
        if (!file || IS_ERR(file)) {
                req->rq_rephdr->status = -EINVAL;
                RETURN(0);
        }

        rep->objid = (__u64) (unsigned long)file;
        return 0;
}

int mds_close(struct ptlrpc_request *req)
{
        struct dentry *de;
        struct mds_rep *rep;
        struct file *file;
        struct vfsmount *mnt;
        int rc;

        rc = mds_pack_rep(NULL, 0, NULL, 0, &req->rq_rephdr, &req->rq_rep,
                          &req->rq_replen, &req->rq_repbuf);
        if (rc) {
                CERROR("mds: out of memory\n");
                req->rq_status = -ENOMEM;
                RETURN(0);
        }

        req->rq_rephdr->xid = req->rq_reqhdr->xid;
        rep = req->rq_rep.mds;

        de = mds_fid2dentry(&req->rq_obd->u.mds, &req->rq_req.mds->fid1, &mnt);
        if (IS_ERR(de)) {
                req->rq_rephdr->status = -ENOENT;
                RETURN(0);
        }

        file = (struct file *)(unsigned long) req->rq_req.mds->objid;

        req->rq_rephdr->status = filp_close(file, 0);
        dput(de);
        return 0;
}


int mds_readpage(struct ptlrpc_request *req)
{
        struct vfsmount *mnt;
        struct dentry *de;
        struct file *file;
        struct niobuf *niobuf;
        struct mds_rep *rep;
        int rc;

        ENTRY;

        rc = mds_pack_rep(NULL, 0, NULL, 0, &req->rq_rephdr, &req->rq_rep,
                          &req->rq_replen, &req->rq_repbuf);
        if (rc) {
                CERROR("mds: out of memory\n");
                req->rq_status = -ENOMEM;
                RETURN(0);
        }

        req->rq_rephdr->xid = req->rq_reqhdr->xid;
        rep = req->rq_rep.mds;

        de = mds_fid2dentry(&req->rq_obd->u.mds, &req->rq_req.mds->fid1, &mnt);
        if (IS_ERR(de)) {
                req->rq_rephdr->status = PTR_ERR(de);
                RETURN(0);
        }

        CDEBUG(D_INODE, "ino %ld\n", de->d_inode->i_ino);

        file = dentry_open(de, mnt, O_RDONLY | O_LARGEFILE);
        /* note: in case of an error, dentry_open puts dentry */
        if (IS_ERR(file)) {
                req->rq_rephdr->status = PTR_ERR(file);
                RETURN(0);
        }

        niobuf = mds_req_tgt(req->rq_req.mds);

        /* to make this asynchronous make sure that the handling function
           doesn't send a reply when this function completes. Instead a
           callback function would send the reply */
        rc = mds_sendpage(req, file, req->rq_req.mds->size, niobuf);

        filp_close(file, 0);
        req->rq_rephdr->status = rc;
        RETURN(0);
}

int mds_reint(struct ptlrpc_request *req)
{
        char *buf;
        int rc, len;
        struct mds_update_record rec;

        buf = mds_req_tgt(req->rq_req.mds);
        len = req->rq_req.mds->tgtlen;

        rc = mds_update_unpack(buf, len, &rec);
        if (rc) {
                CERROR("invalid record\n");
                req->rq_status = -EINVAL;
                return 0;
        }
        /* rc will be used to interrupt a for loop over multiple records */
        rc = mds_reint_rec(&rec, req);
        return 0;
}

int mds_handle(struct obd_device *dev, struct ptlrpc_service *svc,
               struct ptlrpc_request *req)
{
        int rc;
        struct ptlreq_hdr *hdr;

        ENTRY;

        hdr = (struct ptlreq_hdr *)req->rq_reqbuf;

        if (NTOH__u32(hdr->type) != MDS_TYPE_REQ) {
                CERROR("lustre_mds: wrong packet type sent %d\n",
                       NTOH__u32(hdr->type));
                rc = -EINVAL;
                GOTO(out, rc);
        }

        rc = mds_unpack_req(req->rq_reqbuf, req->rq_reqlen,
                            &req->rq_reqhdr, &req->rq_req);
        if (rc) {
                CERROR("lustre_mds: Invalid request\n");
                GOTO(out, rc);
        }

        switch (req->rq_reqhdr->opc) {

        case MDS_GETATTR:
                CDEBUG(D_INODE, "getattr\n");
                OBD_CHECK_DROP_PACKET(req, OBD_INST_MDS_GETATTR);
                rc = mds_getattr(req);
                break;

        case MDS_READPAGE:
                CDEBUG(D_INODE, "readpage\n");
                OBD_CHECK_DROP_PACKET(req, OBD_INST_MDS_READPAGE);
                rc = mds_readpage(req);
                break;

        case MDS_REINT:
                CDEBUG(D_INODE, "reint\n");
                OBD_CHECK_DROP_PACKET(req, OBD_INST_MDS_REINT);
                rc = mds_reint(req);
                break;

        case MDS_OPEN:
                CDEBUG(D_INODE, "open\n");
                OBD_CHECK_DROP_PACKET(req, OBD_INST_MDS_OPEN);
                rc = mds_open(req);
                break;

        case MDS_CLOSE:
                CDEBUG(D_INODE, "close\n");
                OBD_CHECK_DROP_PACKET(req, OBD_INST_MDS_CLOSE);
                rc = mds_close(req);
                break;

        default:
                rc = ptlrpc_error(dev, svc, req);
                RETURN(rc);
        }

        EXIT;
out:
        if (rc) {
                CERROR("no header\n");
                return 0;
        }

        if( req->rq_status) {
                ptlrpc_error(dev, svc, req);
        } else {
                CDEBUG(D_NET, "sending reply\n");
                ptlrpc_reply(dev, svc, req);
        }

        return 0;
}


/* mount the file system (secretly) */
static int mds_setup(struct obd_device *obddev, obd_count len, void *buf)
{
        struct obd_ioctl_data* data = buf;
        struct mds_obd *mds = &obddev->u.mds;
        struct vfsmount *mnt;
        int err;
        ENTRY;

        mnt = do_kern_mount(data->ioc_inlbuf2, 0, data->ioc_inlbuf1, NULL);
        err = PTR_ERR(mnt);
        if (IS_ERR(mnt)) {
                CERROR("do_kern_mount failed: %d\n", err);
                RETURN(err);
        }

        mds->mds_sb = mnt->mnt_root->d_inode->i_sb;
        if (!mds->mds_sb)
                RETURN(-ENODEV);

        mds->mds_vfsmnt = mnt;
        mds->mds_fstype = strdup(data->ioc_inlbuf2);

        mds->mds_ctxt.pwdmnt = mnt;
        mds->mds_ctxt.pwd = mnt->mnt_root;
        mds->mds_ctxt.fs = KERNEL_DS;

        mds->mds_service = ptlrpc_init_svc(64 * 1024,
                                           MDS_REQUEST_PORTAL,
                                           MDC_REPLY_PORTAL,
                                           "self",
                                           mds_unpack_req,
                                           mds_pack_rep,
                                           mds_handle);

        rpc_register_service(mds->mds_service, "self");

        err = ptlrpc_start_thread(obddev, mds->mds_service, "lustre_mds");
        if (err)
                CERROR("cannot start thread\n");

        MOD_INC_USE_COUNT;
        RETURN(0);
}

static int mds_cleanup(struct obd_device * obddev)
{
        struct super_block *sb;
        struct mds_obd *mds = &obddev->u.mds;

        ENTRY;

        if (!(obddev->obd_flags & OBD_SET_UP))
                RETURN(0);

        if ( !list_empty(&obddev->obd_gen_clients) ) {
                CERROR("still has clients!\n");
                RETURN(-EBUSY);
        }

        ptlrpc_stop_thread(mds->mds_service);
        rpc_unregister_service(mds->mds_service);

        if (!list_empty(&mds->mds_service->srv_reqs)) {
                // XXX reply with errors and clean up
                CERROR("Request list not empty!\n");
        }

        rpc_unregister_service(mds->mds_service);
        OBD_FREE(mds->mds_service, sizeof(*mds->mds_service));

        sb = mds->mds_sb;
        if (!mds->mds_sb)
                RETURN(0);

        unlock_kernel();
        mntput(mds->mds_vfsmnt);
        mds->mds_sb = 0;
        kfree(mds->mds_fstype);
        lock_kernel();

        MOD_DEC_USE_COUNT;
        RETURN(0);
}

/* use obd ops to offer management infrastructure */
static struct obd_ops mds_obd_ops = {
        o_setup:       mds_setup,
        o_cleanup:     mds_cleanup,
};

static int __init mds_init(void)
{
        obd_register_type(&mds_obd_ops, LUSTRE_MDS_NAME);
        return 0;
}

static void __exit mds_exit(void)
{
        obd_unregister_type(LUSTRE_MDS_NAME);
}

MODULE_AUTHOR("Peter J. Braam <braam@clusterfs.com>");
MODULE_DESCRIPTION("Lustre Metadata Server (MDS) v0.01");
MODULE_LICENSE("GPL");

module_init(mds_init);
module_exit(mds_exit);