/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2015, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * Implementation of cl_io for VVP layer.
 *
 *   Author: Nikita Danilov <nikita.danilov@sun.com>
 *   Author: Jinshan Xiong <jinshan.xiong@whamcloud.com>
 */

#define DEBUG_SUBSYSTEM S_LLITE

#include "../include/obd.h"

#include "llite_internal.h"
#include "vvp_internal.h"

static struct vvp_io *cl2vvp_io(const struct lu_env *env,
                                const struct cl_io_slice *slice)
{
        struct vvp_io *vio;

        vio = container_of(slice, struct vvp_io, vui_cl);
        LASSERT(vio == vvp_env_io(env));

        return vio;
}

/**
 * For swapping layout. The file's layout may have changed.
 * To avoid populating pages to a wrong stripe, we have to verify the
 * correctness of layout. It works because swapping layout processes
 * have to acquire group lock.
 */
static bool can_populate_pages(const struct lu_env *env, struct cl_io *io,
                               struct inode *inode)
{
        struct ll_inode_info    *lli = ll_i2info(inode);
        struct vvp_io           *vio = vvp_env_io(env);
        bool rc = true;

        switch (io->ci_type) {
        case CIT_READ:
        case CIT_WRITE:
                /* don't need lock here to check lli_layout_gen as we have held
                 * extent lock and GROUP lock has to hold to swap layout
                 */
                if (ll_layout_version_get(lli) != vio->vui_layout_gen ||
                    OBD_FAIL_CHECK_RESET(OBD_FAIL_LLITE_LOST_LAYOUT, 0)) {
                        io->ci_need_restart = 1;
                        /* this will cause a short read/write */
                        io->ci_continue = 0;
                        rc = false;
                }
        case CIT_FAULT:
                /* fault is okay because we've already had a page. */
        default:
                break;
        }

        return rc;
}

static void vvp_object_size_lock(struct cl_object *obj)
{
        struct inode *inode = vvp_object_inode(obj);

        ll_inode_size_lock(inode);
        cl_object_attr_lock(obj);
}

static void vvp_object_size_unlock(struct cl_object *obj)
{
        struct inode *inode = vvp_object_inode(obj);

        cl_object_attr_unlock(obj);
        ll_inode_size_unlock(inode);
}

/**
 * Helper function that if necessary adjusts file size (inode->i_size), when
 * position at the offset \a pos is accessed. File size can be arbitrary stale
 * on a Lustre client, but client at least knows KMS. If accessed area is
 * inside [0, KMS], set file size to KMS, otherwise glimpse file size.
 *
 * Locking: cl_isize_lock is used to serialize changes to inode size and to
 * protect consistency between inode size and cl_object
 * attributes. cl_object_size_lock() protects consistency between cl_attr's of
 * top-object and sub-objects.
 */
static int vvp_prep_size(const struct lu_env *env, struct cl_object *obj,
                         struct cl_io *io, loff_t start, size_t count,
                         int *exceed)
{
        struct cl_attr *attr  = vvp_env_thread_attr(env);
        struct inode   *inode = vvp_object_inode(obj);
        loff_t    pos   = start + count - 1;
        loff_t kms;
        int result;

        /*
         * Consistency guarantees: following possibilities exist for the
         * relation between region being accessed and real file size at this
         * moment:
         *
         *  (A): the region is completely inside of the file;
         *
         *  (B-x): x bytes of region are inside of the file, the rest is
         *  outside;
         *
         *  (C): the region is completely outside of the file.
         *
         * This classification is stable under DLM lock already acquired by
         * the caller, because to change the class, other client has to take
         * DLM lock conflicting with our lock. Also, any updates to ->i_size
         * by other threads on this client are serialized by
         * ll_inode_size_lock(). This guarantees that short reads are handled
         * correctly in the face of concurrent writes and truncates.
         */
        vvp_object_size_lock(obj);
        result = cl_object_attr_get(env, obj, attr);
        if (result == 0) {
                kms = attr->cat_kms;
                if (pos > kms) {
                        /*
                         * A glimpse is necessary to determine whether we
                         * return a short read (B) or some zeroes at the end
                         * of the buffer (C)
                         */
                        vvp_object_size_unlock(obj);
                        result = cl_glimpse_lock(env, io, inode, obj, 0);
                        if (result == 0 && exceed) {
                                /* If objective page index exceed end-of-file
                                 * page index, return directly. Do not expect
                                 * kernel will check such case correctly.
                                 * linux-2.6.18-128.1.1 miss to do that.
                                 * --bug 17336
                                 */
                                loff_t size = i_size_read(inode);
                                loff_t cur_index = start >> PAGE_SHIFT;
                                loff_t size_index = (size - 1) >> PAGE_SHIFT;

                                if ((size == 0 && cur_index != 0) ||
                                    size_index < cur_index)
                                        *exceed = 1;
                        }
                        return result;
                }
                /*
                 * region is within kms and, hence, within real file
                 * size (A). We need to increase i_size to cover the
                 * read region so that generic_file_read() will do its
                 * job, but that doesn't mean the kms size is
                 * _correct_, it is only the _minimum_ size. If
                 * someone does a stat they will get the correct size
                 * which will always be >= the kms value here.
                 * b=11081
                 */
                if (i_size_read(inode) < kms) {
                        i_size_write(inode, kms);
                        CDEBUG(D_VFSTRACE, DFID " updating i_size %llu\n",
                               PFID(lu_object_fid(&obj->co_lu)),
                               (__u64)i_size_read(inode));
                }
        }

        vvp_object_size_unlock(obj);

        return result;
}

/*****************************************************************************
 *
 * io operations.
 *
 */

static int vvp_io_one_lock_index(const struct lu_env *env, struct cl_io *io,
                                 __u32 enqflags, enum cl_lock_mode mode,
                          pgoff_t start, pgoff_t end)
{
        struct vvp_io          *vio   = vvp_env_io(env);
        struct cl_lock_descr   *descr = &vio->vui_link.cill_descr;
        struct cl_object       *obj   = io->ci_obj;

        CLOBINVRNT(env, obj, vvp_object_invariant(obj));

        CDEBUG(D_VFSTRACE, "lock: %d [%lu, %lu]\n", mode, start, end);

        memset(&vio->vui_link, 0, sizeof(vio->vui_link));

        if (vio->vui_fd && (vio->vui_fd->fd_flags & LL_FILE_GROUP_LOCKED)) {
                descr->cld_mode = CLM_GROUP;
                descr->cld_gid  = vio->vui_fd->fd_grouplock.lg_gid;
                enqflags |= CEF_LOCK_MATCH;
        } else {
                descr->cld_mode  = mode;
        }
        descr->cld_obj   = obj;
        descr->cld_start = start;
        descr->cld_end   = end;
        descr->cld_enq_flags = enqflags;

        cl_io_lock_add(env, io, &vio->vui_link);
        return 0;
}

static int vvp_io_one_lock(const struct lu_env *env, struct cl_io *io,
                           __u32 enqflags, enum cl_lock_mode mode,
                           loff_t start, loff_t end)
{
        struct cl_object *obj = io->ci_obj;

        return vvp_io_one_lock_index(env, io, enqflags, mode,
                                     cl_index(obj, start), cl_index(obj, end));
}

static int vvp_io_write_iter_init(const struct lu_env *env,
                                  const struct cl_io_slice *ios)
{
        struct vvp_io *vio = cl2vvp_io(env, ios);

        cl_page_list_init(&vio->u.write.vui_queue);
        vio->u.write.vui_written = 0;
        vio->u.write.vui_from = 0;
        vio->u.write.vui_to = PAGE_SIZE;

        return 0;
}

static void vvp_io_write_iter_fini(const struct lu_env *env,
                                   const struct cl_io_slice *ios)
{
        struct vvp_io *vio = cl2vvp_io(env, ios);

        LASSERT(vio->u.write.vui_queue.pl_nr == 0);
}

static int vvp_io_fault_iter_init(const struct lu_env *env,
                                  const struct cl_io_slice *ios)
{
        struct vvp_io *vio   = cl2vvp_io(env, ios);
        struct inode  *inode = vvp_object_inode(ios->cis_obj);

        LASSERT(inode == file_inode(vio->vui_fd->fd_file));
        vio->u.fault.ft_mtime = inode->i_mtime.tv_sec;
        return 0;
}

static void vvp_io_fini(const struct lu_env *env, const struct cl_io_slice *ios)
{
        struct cl_io     *io  = ios->cis_io;
        struct cl_object *obj = io->ci_obj;
        struct vvp_io    *vio = cl2vvp_io(env, ios);
        struct inode *inode = vvp_object_inode(obj);

        CLOBINVRNT(env, obj, vvp_object_invariant(obj));

        CDEBUG(D_VFSTRACE, DFID
               " ignore/verify layout %d/%d, layout version %d restore needed %d\n",
               PFID(lu_object_fid(&obj->co_lu)),
               io->ci_ignore_layout, io->ci_verify_layout,
               vio->vui_layout_gen, io->ci_restore_needed);

        if (io->ci_restore_needed) {
                int     rc;

                /* file was detected release, we need to restore it
                 * before finishing the io
                 */
                rc = ll_layout_restore(inode, 0, OBD_OBJECT_EOF);
                /* if restore registration failed, no restart,
                 * we will return -ENODATA
                 */
                /* The layout will change after restore, so we need to
                 * block on layout lock hold by the MDT
                 * as MDT will not send new layout in lvb (see LU-3124)
                 * we have to explicitly fetch it, all this will be done
                 * by ll_layout_refresh()
                 */
                if (rc == 0) {
                        io->ci_restore_needed = 0;
                        io->ci_need_restart = 1;
                        io->ci_verify_layout = 1;
                } else {
                        io->ci_restore_needed = 1;
                        io->ci_need_restart = 0;
                        io->ci_verify_layout = 0;
                        io->ci_result = rc;
                }
        }

        if (!io->ci_ignore_layout && io->ci_verify_layout) {
                __u32 gen = 0;

                /* check layout version */
                ll_layout_refresh(inode, &gen);
                io->ci_need_restart = vio->vui_layout_gen != gen;
                if (io->ci_need_restart) {
                        CDEBUG(D_VFSTRACE,
                               DFID " layout changed from %d to %d.\n",
                               PFID(lu_object_fid(&obj->co_lu)),
                               vio->vui_layout_gen, gen);
                        /* today successful restore is the only possible case */
                        /* restore was done, clear restoring state */
                        clear_bit(LLIF_FILE_RESTORING,
                                  &ll_i2info(inode)->lli_flags);
                }
        }
}

static void vvp_io_fault_fini(const struct lu_env *env,
                              const struct cl_io_slice *ios)
{
        struct cl_io   *io   = ios->cis_io;
        struct cl_page *page = io->u.ci_fault.ft_page;

        CLOBINVRNT(env, io->ci_obj, vvp_object_invariant(io->ci_obj));

        if (page) {
                lu_ref_del(&page->cp_reference, "fault", io);
                cl_page_put(env, page);
                io->u.ci_fault.ft_page = NULL;
        }
        vvp_io_fini(env, ios);
}

static enum cl_lock_mode vvp_mode_from_vma(struct vm_area_struct *vma)
{
        /*
         * we only want to hold PW locks if the mmap() can generate
         * writes back to the file and that only happens in shared
         * writable vmas
         */
        if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE))
                return CLM_WRITE;
        return CLM_READ;
}

static int vvp_mmap_locks(const struct lu_env *env,
                          struct vvp_io *vio, struct cl_io *io)
{
        struct vvp_thread_info *cti = vvp_env_info(env);
        struct mm_struct       *mm = current->mm;
        struct vm_area_struct  *vma;
        struct cl_lock_descr   *descr = &cti->vti_descr;
        union ldlm_policy_data policy;
        unsigned long      addr;
        ssize_t          count;
        int              result = 0;
        struct iov_iter i;
        struct iovec iov;

        LASSERT(io->ci_type == CIT_READ || io->ci_type == CIT_WRITE);

        if (!vio->vui_iter) /* nfs or loop back device write */
                return 0;

        /* No MM (e.g. NFS)? No vmas too. */
        if (!mm)
                return 0;

        iov_for_each(iov, i, *vio->vui_iter) {
                addr = (unsigned long)iov.iov_base;
                count = iov.iov_len;
                if (count == 0)
                        continue;

                count += addr & (~PAGE_MASK);
                addr &= PAGE_MASK;

                down_read(&mm->mmap_sem);
                while ((vma = our_vma(mm, addr, count)) != NULL) {
                        struct inode *inode = file_inode(vma->vm_file);
                        int flags = CEF_MUST;

                        if (ll_file_nolock(vma->vm_file)) {
                                /*
                                 * For no lock case is not allowed for mmap
                                 */
                                result = -EINVAL;
                                break;
                        }

                        /*
                         * XXX: Required lock mode can be weakened: CIT_WRITE
                         * io only ever reads user level buffer, and CIT_READ
                         * only writes on it.
                         */
                        policy_from_vma(&policy, vma, addr, count);
                        descr->cld_mode = vvp_mode_from_vma(vma);
                        descr->cld_obj = ll_i2info(inode)->lli_clob;
                        descr->cld_start = cl_index(descr->cld_obj,
                                                    policy.l_extent.start);
                        descr->cld_end = cl_index(descr->cld_obj,
                                                  policy.l_extent.end);
                        descr->cld_enq_flags = flags;
                        result = cl_io_lock_alloc_add(env, io, descr);

                        CDEBUG(D_VFSTRACE, "lock: %d: [%lu, %lu]\n",
                               descr->cld_mode, descr->cld_start,
                               descr->cld_end);

                        if (result < 0)
                                break;

                        if (vma->vm_end - addr >= count)
                                break;

                        count -= vma->vm_end - addr;
                        addr = vma->vm_end;
                }
                up_read(&mm->mmap_sem);
                if (result < 0)
                        break;
        }
        return result;
}

static void vvp_io_advance(const struct lu_env *env,
                           const struct cl_io_slice *ios,
                           size_t nob)
{
        struct cl_object *obj = ios->cis_io->ci_obj;
        struct vvp_io    *vio = cl2vvp_io(env, ios);

        CLOBINVRNT(env, obj, vvp_object_invariant(obj));

        vio->vui_tot_count -= nob;
        iov_iter_reexpand(vio->vui_iter, vio->vui_tot_count);
}

static void vvp_io_update_iov(const struct lu_env *env,
                              struct vvp_io *vio, struct cl_io *io)
{
        size_t size = io->u.ci_rw.crw_count;

        if (!vio->vui_iter)
                return;

        iov_iter_truncate(vio->vui_iter, size);
}

static int vvp_io_rw_lock(const struct lu_env *env, struct cl_io *io,
                          enum cl_lock_mode mode, loff_t start, loff_t end)
{
        struct vvp_io *vio = vvp_env_io(env);
        int result;
        int ast_flags = 0;

        LASSERT(io->ci_type == CIT_READ || io->ci_type == CIT_WRITE);

        vvp_io_update_iov(env, vio, io);

        if (io->u.ci_rw.crw_nonblock)
                ast_flags |= CEF_NONBLOCK;
        result = vvp_mmap_locks(env, vio, io);
        if (result == 0)
                result = vvp_io_one_lock(env, io, ast_flags, mode, start, end);
        return result;
}

static int vvp_io_read_lock(const struct lu_env *env,
                            const struct cl_io_slice *ios)
{
        struct cl_io     *io = ios->cis_io;
        struct cl_io_rw_common *rd = &io->u.ci_rd.rd;
        int result;

        result = vvp_io_rw_lock(env, io, CLM_READ, rd->crw_pos,
                                rd->crw_pos + rd->crw_count - 1);

        return result;
}

static int vvp_io_fault_lock(const struct lu_env *env,
                             const struct cl_io_slice *ios)
{
        struct cl_io *io   = ios->cis_io;
        struct vvp_io *vio = cl2vvp_io(env, ios);
        /*
         * XXX LDLM_FL_CBPENDING
         */
        return vvp_io_one_lock_index(env,
                                     io, 0,
                                     vvp_mode_from_vma(vio->u.fault.ft_vma),
                                     io->u.ci_fault.ft_index,
                                     io->u.ci_fault.ft_index);
}

static int vvp_io_write_lock(const struct lu_env *env,
                             const struct cl_io_slice *ios)
{
        struct cl_io *io = ios->cis_io;
        loff_t start;
        loff_t end;

        if (io->u.ci_wr.wr_append) {
                start = 0;
                end   = OBD_OBJECT_EOF;
        } else {
                start = io->u.ci_wr.wr.crw_pos;
                end   = start + io->u.ci_wr.wr.crw_count - 1;
        }
        return vvp_io_rw_lock(env, io, CLM_WRITE, start, end);
}

static int vvp_io_setattr_iter_init(const struct lu_env *env,
                                    const struct cl_io_slice *ios)
{
        return 0;
}

/**
 * Implementation of cl_io_operations::vio_lock() method for CIT_SETATTR io.
 *
 * Handles "lockless io" mode when extent locking is done by server.
 */
static int vvp_io_setattr_lock(const struct lu_env *env,
                               const struct cl_io_slice *ios)
{
        struct cl_io  *io  = ios->cis_io;
        __u64 new_size;
        __u32 enqflags = 0;

        if (cl_io_is_trunc(io)) {
                new_size = io->u.ci_setattr.sa_attr.lvb_size;
                if (new_size == 0)
                        enqflags = CEF_DISCARD_DATA;
        } else {
                unsigned int valid = io->u.ci_setattr.sa_valid;

                if (!(valid & TIMES_SET_FLAGS))
                        return 0;

                if ((!(valid & ATTR_MTIME) ||
                     io->u.ci_setattr.sa_attr.lvb_mtime >=
                     io->u.ci_setattr.sa_attr.lvb_ctime) &&
                    (!(valid & ATTR_ATIME) ||
                     io->u.ci_setattr.sa_attr.lvb_atime >=
                     io->u.ci_setattr.sa_attr.lvb_ctime))
                        return 0;
                new_size = 0;
        }

        return vvp_io_one_lock(env, io, enqflags, CLM_WRITE,
                               new_size, OBD_OBJECT_EOF);
}

static int vvp_do_vmtruncate(struct inode *inode, size_t size)
{
        int     result;
        /*
         * Only ll_inode_size_lock is taken at this level.
         */
        ll_inode_size_lock(inode);
        result = inode_newsize_ok(inode, size);
        if (result < 0) {
                ll_inode_size_unlock(inode);
                return result;
        }
        truncate_setsize(inode, size);
        ll_inode_size_unlock(inode);
        return result;
}

static int vvp_io_setattr_time(const struct lu_env *env,
                               const struct cl_io_slice *ios)
{
        struct cl_io       *io    = ios->cis_io;
        struct cl_object   *obj   = io->ci_obj;
        struct cl_attr     *attr  = vvp_env_thread_attr(env);
        int result;
        unsigned valid = CAT_CTIME;

        cl_object_attr_lock(obj);
        attr->cat_ctime = io->u.ci_setattr.sa_attr.lvb_ctime;
        if (io->u.ci_setattr.sa_valid & ATTR_ATIME_SET) {
                attr->cat_atime = io->u.ci_setattr.sa_attr.lvb_atime;
                valid |= CAT_ATIME;
        }
        if (io->u.ci_setattr.sa_valid & ATTR_MTIME_SET) {
                attr->cat_mtime = io->u.ci_setattr.sa_attr.lvb_mtime;
                valid |= CAT_MTIME;
        }
        result = cl_object_attr_update(env, obj, attr, valid);
        cl_object_attr_unlock(obj);

        return result;
}

static int vvp_io_setattr_start(const struct lu_env *env,
                                const struct cl_io_slice *ios)
{
        struct cl_io    *io    = ios->cis_io;
        struct inode    *inode = vvp_object_inode(io->ci_obj);
        struct ll_inode_info *lli = ll_i2info(inode);

        if (cl_io_is_trunc(io)) {
                down_write(&lli->lli_trunc_sem);
                inode_lock(inode);
                inode_dio_wait(inode);
        } else {
                inode_lock(inode);
        }

        if (io->u.ci_setattr.sa_valid & TIMES_SET_FLAGS)
                return vvp_io_setattr_time(env, ios);

        return 0;
}

static void vvp_io_setattr_end(const struct lu_env *env,
                               const struct cl_io_slice *ios)
{
        struct cl_io *io    = ios->cis_io;
        struct inode *inode = vvp_object_inode(io->ci_obj);
        struct ll_inode_info *lli = ll_i2info(inode);

        if (cl_io_is_trunc(io)) {
                /* Truncate in memory pages - they must be clean pages
                 * because osc has already notified to destroy osc_extents.
                 */
                vvp_do_vmtruncate(inode, io->u.ci_setattr.sa_attr.lvb_size);
                inode_unlock(inode);
                up_write(&lli->lli_trunc_sem);
        } else {
                inode_unlock(inode);
        }
}

static void vvp_io_setattr_fini(const struct lu_env *env,
                                const struct cl_io_slice *ios)
{
        bool restore_needed = ios->cis_io->ci_restore_needed;
        struct inode *inode = vvp_object_inode(ios->cis_obj);

        vvp_io_fini(env, ios);

        if (restore_needed && !ios->cis_io->ci_restore_needed) {
                /* restore finished, set data modified flag for HSM */
                set_bit(LLIF_DATA_MODIFIED, &(ll_i2info(inode))->lli_flags);
        }
}

static int vvp_io_read_start(const struct lu_env *env,
                             const struct cl_io_slice *ios)
{
        struct vvp_io     *vio   = cl2vvp_io(env, ios);
        struct cl_io      *io    = ios->cis_io;
        struct cl_object  *obj   = io->ci_obj;
        struct inode      *inode = vvp_object_inode(obj);
        struct ll_inode_info *lli = ll_i2info(inode);
        struct file       *file  = vio->vui_fd->fd_file;

        int     result;
        loff_t  pos = io->u.ci_rd.rd.crw_pos;
        long    cnt = io->u.ci_rd.rd.crw_count;
        long    tot = vio->vui_tot_count;
        int     exceed = 0;

        CLOBINVRNT(env, obj, vvp_object_invariant(obj));

        CDEBUG(D_VFSTRACE, "read: -> [%lli, %lli)\n", pos, pos + cnt);

        down_read(&lli->lli_trunc_sem);

        if (!can_populate_pages(env, io, inode))
                return 0;

        result = vvp_prep_size(env, obj, io, pos, tot, &exceed);
        if (result != 0)
                return result;
        else if (exceed != 0)
                goto out;

        LU_OBJECT_HEADER(D_INODE, env, &obj->co_lu,
                         "Read ino %lu, %lu bytes, offset %lld, size %llu\n",
                         inode->i_ino, cnt, pos, i_size_read(inode));

        /* turn off the kernel's read-ahead */
        vio->vui_fd->fd_file->f_ra.ra_pages = 0;

        /* initialize read-ahead window once per syscall */
        if (!vio->vui_ra_valid) {
                vio->vui_ra_valid = true;
                vio->vui_ra_start = cl_index(obj, pos);
                vio->vui_ra_count = cl_index(obj, tot + PAGE_SIZE - 1);
                ll_ras_enter(file);
        }

        /* BUG: 5972 */
        file_accessed(file);
        LASSERT(vio->vui_iocb->ki_pos == pos);
        result = generic_file_read_iter(vio->vui_iocb, vio->vui_iter);

out:
        if (result >= 0) {
                if (result < cnt)
                        io->ci_continue = 0;
                io->ci_nob += result;
                ll_rw_stats_tally(ll_i2sbi(inode), current->pid,
                                  vio->vui_fd, pos, result, READ);
                result = 0;
        }
        return result;
}

static int vvp_io_commit_sync(const struct lu_env *env, struct cl_io *io,
                              struct cl_page_list *plist, int from, int to)
{
        struct cl_2queue *queue = &io->ci_queue;
        struct cl_page *page;
        unsigned int bytes = 0;
        int rc = 0;

        if (plist->pl_nr == 0)
                return 0;

        if (from > 0 || to != PAGE_SIZE) {
                page = cl_page_list_first(plist);
                if (plist->pl_nr == 1) {
                        cl_page_clip(env, page, from, to);
                } else {
                        if (from > 0)
                                cl_page_clip(env, page, from, PAGE_SIZE);
                        if (to != PAGE_SIZE) {
                                page = cl_page_list_last(plist);
                                cl_page_clip(env, page, 0, to);
                        }
                }
        }

        cl_2queue_init(queue);
        cl_page_list_splice(plist, &queue->c2_qin);
        rc = cl_io_submit_sync(env, io, CRT_WRITE, queue, 0);

        /* plist is not sorted any more */
        cl_page_list_splice(&queue->c2_qin, plist);
        cl_page_list_splice(&queue->c2_qout, plist);
        cl_2queue_fini(env, queue);

        if (rc == 0) {
                /* calculate bytes */
                bytes = plist->pl_nr << PAGE_SHIFT;
                bytes -= from + PAGE_SIZE - to;

                while (plist->pl_nr > 0) {
                        page = cl_page_list_first(plist);
                        cl_page_list_del(env, plist, page);

                        cl_page_clip(env, page, 0, PAGE_SIZE);

                        SetPageUptodate(cl_page_vmpage(page));
                        cl_page_disown(env, io, page);

                        /* held in ll_cl_init() */
                        lu_ref_del(&page->cp_reference, "cl_io", io);
                        cl_page_put(env, page);
                }
        }

        return bytes > 0 ? bytes : rc;
}

static void write_commit_callback(const struct lu_env *env, struct cl_io *io,
                                  struct cl_page *page)
{
        struct page *vmpage = page->cp_vmpage;

        SetPageUptodate(vmpage);
        set_page_dirty(vmpage);

        cl_page_disown(env, io, page);

        /* held in ll_cl_init() */
        lu_ref_del(&page->cp_reference, "cl_io", cl_io_top(io));
        cl_page_put(env, page);
}

/* make sure the page list is contiguous */
static bool page_list_sanity_check(struct cl_object *obj,
                                   struct cl_page_list *plist)
{
        struct cl_page *page;
        pgoff_t index = CL_PAGE_EOF;

        cl_page_list_for_each(page, plist) {
                struct vvp_page *vpg = cl_object_page_slice(obj, page);

                if (index == CL_PAGE_EOF) {
                        index = vvp_index(vpg);
                        continue;
                }

                ++index;
                if (index == vvp_index(vpg))
                        continue;

                return false;
        }
        return true;
}

/* Return how many bytes have queued or written */
int vvp_io_write_commit(const struct lu_env *env, struct cl_io *io)
{
        struct cl_object *obj = io->ci_obj;
        struct inode *inode = vvp_object_inode(obj);
        struct vvp_io *vio = vvp_env_io(env);
        struct cl_page_list *queue = &vio->u.write.vui_queue;
        struct cl_page *page;
        int rc = 0;
        int bytes = 0;
        unsigned int npages = vio->u.write.vui_queue.pl_nr;

        if (npages == 0)
                return 0;

        CDEBUG(D_VFSTRACE, "commit async pages: %d, from %d, to %d\n",
               npages, vio->u.write.vui_from, vio->u.write.vui_to);

        LASSERT(page_list_sanity_check(obj, queue));

        /* submit IO with async write */
        rc = cl_io_commit_async(env, io, queue,
                                vio->u.write.vui_from, vio->u.write.vui_to,
                                write_commit_callback);
        npages -= queue->pl_nr; /* already committed pages */
        if (npages > 0) {
                /* calculate how many bytes were written */
                bytes = npages << PAGE_SHIFT;

                /* first page */
                bytes -= vio->u.write.vui_from;
                if (queue->pl_nr == 0) /* last page */
                        bytes -= PAGE_SIZE - vio->u.write.vui_to;
                LASSERTF(bytes > 0, "bytes = %d, pages = %d\n", bytes, npages);

                vio->u.write.vui_written += bytes;

                CDEBUG(D_VFSTRACE, "Committed %d pages %d bytes, tot: %ld\n",
                       npages, bytes, vio->u.write.vui_written);

                /* the first page must have been written. */
                vio->u.write.vui_from = 0;
        }
        LASSERT(page_list_sanity_check(obj, queue));
        LASSERT(ergo(rc == 0, queue->pl_nr == 0));

        /* out of quota, try sync write */
        if (rc == -EDQUOT && !cl_io_is_mkwrite(io)) {
                rc = vvp_io_commit_sync(env, io, queue,
                                        vio->u.write.vui_from,
                                        vio->u.write.vui_to);
                if (rc > 0) {
                        vio->u.write.vui_written += rc;
                        rc = 0;
                }
        }

        /* update inode size */
        ll_merge_attr(env, inode);

        /* Now the pages in queue were failed to commit, discard them
         * unless they were dirtied before.
         */
        while (queue->pl_nr > 0) {
                page = cl_page_list_first(queue);
                cl_page_list_del(env, queue, page);

                if (!PageDirty(cl_page_vmpage(page)))
                        cl_page_discard(env, io, page);

                cl_page_disown(env, io, page);

                /* held in ll_cl_init() */
                lu_ref_del(&page->cp_reference, "cl_io", io);
                cl_page_put(env, page);
        }
        cl_page_list_fini(env, queue);

        return rc;
}

static int vvp_io_write_start(const struct lu_env *env,
                              const struct cl_io_slice *ios)
{
        struct vvp_io      *vio   = cl2vvp_io(env, ios);
        struct cl_io       *io    = ios->cis_io;
        struct cl_object   *obj   = io->ci_obj;
        struct inode       *inode = vvp_object_inode(obj);
        struct ll_inode_info *lli = ll_i2info(inode);
        ssize_t result = 0;
        loff_t pos = io->u.ci_wr.wr.crw_pos;
        size_t cnt = io->u.ci_wr.wr.crw_count;

        down_read(&lli->lli_trunc_sem);

        if (!can_populate_pages(env, io, inode))
                return 0;

        if (cl_io_is_append(io)) {
                /*
                 * PARALLEL IO This has to be changed for parallel IO doing
                 * out-of-order writes.
                 */
                ll_merge_attr(env, inode);
                pos = i_size_read(inode);
                io->u.ci_wr.wr.crw_pos = pos;
                vio->vui_iocb->ki_pos = pos;
        } else {
                LASSERT(vio->vui_iocb->ki_pos == pos);
        }

        CDEBUG(D_VFSTRACE, "write: [%lli, %lli)\n", pos, pos + (long long)cnt);

        /*
         * The maximum Lustre file size is variable, based on the OST maximum
         * object size and number of stripes.  This needs another check in
         * addition to the VFS checks earlier.
         */
        if (pos + cnt > ll_file_maxbytes(inode)) {
                CDEBUG(D_INODE,
                       "%s: file " DFID " offset %llu > maxbytes %llu\n",
                       ll_get_fsname(inode->i_sb, NULL, 0),
                       PFID(ll_inode2fid(inode)), pos + cnt,
                       ll_file_maxbytes(inode));
                return -EFBIG;
        }

        if (!vio->vui_iter) {
                /* from a temp io in ll_cl_init(). */
                result = 0;
        } else {
                /*
                 * When using the locked AIO function (generic_file_aio_write())
                 * testing has shown the inode mutex to be a limiting factor
                 * with multi-threaded single shared file performance. To get
                 * around this, we now use the lockless version. To maintain
                 * consistency, proper locking to protect against writes,
                 * trucates, etc. is handled in the higher layers of lustre.
                 */
                bool lock_node = !IS_NOSEC(inode);

                if (lock_node)
                        inode_lock(inode);
                result = __generic_file_write_iter(vio->vui_iocb,
                                                   vio->vui_iter);
                if (lock_node)
                        inode_unlock(inode);

                if (result > 0 || result == -EIOCBQUEUED)
                        result = generic_write_sync(vio->vui_iocb, result);
        }

        if (result > 0) {
                result = vvp_io_write_commit(env, io);
                if (vio->u.write.vui_written > 0) {
                        result = vio->u.write.vui_written;
                        io->ci_nob += result;

                        CDEBUG(D_VFSTRACE, "write: nob %zd, result: %zd\n",
                               io->ci_nob, result);
                }
        }
        if (result > 0) {
                set_bit(LLIF_DATA_MODIFIED, &(ll_i2info(inode))->lli_flags);

                if (result < cnt)
                        io->ci_continue = 0;
                ll_rw_stats_tally(ll_i2sbi(inode), current->pid,
                                  vio->vui_fd, pos, result, WRITE);

                result = 0;
        }
        return result;
}

static void vvp_io_rw_end(const struct lu_env *env,
                          const struct cl_io_slice *ios)
{
        struct inode *inode = vvp_object_inode(ios->cis_obj);
        struct ll_inode_info *lli = ll_i2info(inode);

        up_read(&lli->lli_trunc_sem);
}

static int vvp_io_kernel_fault(struct vvp_fault_io *cfio)
{
        struct vm_fault *vmf = cfio->ft_vmf;

        cfio->ft_flags = filemap_fault(vmf);
        cfio->ft_flags_valid = 1;

        if (vmf->page) {
                CDEBUG(D_PAGE,
                       "page %p map %p index %lu flags %lx count %u priv %0lx: got addr %p type NOPAGE\n",
                       vmf->page, vmf->page->mapping, vmf->page->index,
                       (long)vmf->page->flags, page_count(vmf->page),
                       page_private(vmf->page), (void *)vmf->address);
                if (unlikely(!(cfio->ft_flags & VM_FAULT_LOCKED))) {
                        lock_page(vmf->page);
                        cfio->ft_flags |= VM_FAULT_LOCKED;
                }

                cfio->ft_vmpage = vmf->page;
                return 0;
        }

        if (cfio->ft_flags & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV)) {
                CDEBUG(D_PAGE, "got addr %p - SIGBUS\n", (void *)vmf->address);
                return -EFAULT;
        }

        if (cfio->ft_flags & VM_FAULT_OOM) {
                CDEBUG(D_PAGE, "got addr %p - OOM\n", (void *)vmf->address);
                return -ENOMEM;
        }

        if (cfio->ft_flags & VM_FAULT_RETRY)
                return -EAGAIN;

        CERROR("Unknown error in page fault %d!\n", cfio->ft_flags);
        return -EINVAL;
}

static void mkwrite_commit_callback(const struct lu_env *env, struct cl_io *io,
                                    struct cl_page *page)
{
        set_page_dirty(page->cp_vmpage);
}

static int vvp_io_fault_start(const struct lu_env *env,
                              const struct cl_io_slice *ios)
{
        struct vvp_io       *vio     = cl2vvp_io(env, ios);
        struct cl_io    *io      = ios->cis_io;
        struct cl_object    *obj     = io->ci_obj;
        struct inode        *inode   = vvp_object_inode(obj);
        struct ll_inode_info *lli = ll_i2info(inode);
        struct cl_fault_io  *fio     = &io->u.ci_fault;
        struct vvp_fault_io *cfio    = &vio->u.fault;
        loff_t         offset;
        int               result  = 0;
        struct page       *vmpage  = NULL;
        struct cl_page      *page;
        loff_t         size;
        pgoff_t              last_index;

        down_read(&lli->lli_trunc_sem);

        /* offset of the last byte on the page */
        offset = cl_offset(obj, fio->ft_index + 1) - 1;
        LASSERT(cl_index(obj, offset) == fio->ft_index);
        result = vvp_prep_size(env, obj, io, 0, offset + 1, NULL);
        if (result != 0)
                return result;

        /* must return locked page */
        if (fio->ft_mkwrite) {
                LASSERT(cfio->ft_vmpage);
                lock_page(cfio->ft_vmpage);
        } else {
                result = vvp_io_kernel_fault(cfio);
                if (result != 0)
                        return result;
        }

        vmpage = cfio->ft_vmpage;
        LASSERT(PageLocked(vmpage));

        if (OBD_FAIL_CHECK(OBD_FAIL_LLITE_FAULT_TRUNC_RACE))
                ll_invalidate_page(vmpage);

        size = i_size_read(inode);
        /* Though we have already held a cl_lock upon this page, but
         * it still can be truncated locally.
         */
        if (unlikely((vmpage->mapping != inode->i_mapping) ||
                     (page_offset(vmpage) > size))) {
                CDEBUG(D_PAGE, "llite: fault and truncate race happened!\n");

                /* return +1 to stop cl_io_loop() and ll_fault() will catch
                 * and retry.
                 */
                result = 1;
                goto out;
        }

        last_index = cl_index(obj, size - 1);

        if (fio->ft_mkwrite) {
                /*
                 * Capture the size while holding the lli_trunc_sem from above
                 * we want to make sure that we complete the mkwrite action
                 * while holding this lock. We need to make sure that we are
                 * not past the end of the file.
                 */
                if (last_index < fio->ft_index) {
                        CDEBUG(D_PAGE,
                               "llite: mkwrite and truncate race happened: %p: 0x%lx 0x%lx\n",
                               vmpage->mapping, fio->ft_index, last_index);
                        /*
                         * We need to return if we are
                         * passed the end of the file. This will propagate
                         * up the call stack to ll_page_mkwrite where
                         * we will return VM_FAULT_NOPAGE. Any non-negative
                         * value returned here will be silently
                         * converted to 0. If the vmpage->mapping is null
                         * the error code would be converted back to ENODATA
                         * in ll_page_mkwrite0. Thus we return -ENODATA
                         * to handle both cases
                         */
                        result = -ENODATA;
                        goto out;
                }
        }

        page = cl_page_find(env, obj, fio->ft_index, vmpage, CPT_CACHEABLE);
        if (IS_ERR(page)) {
                result = PTR_ERR(page);
                goto out;
        }

        /* if page is going to be written, we should add this page into cache
         * earlier.
         */
        if (fio->ft_mkwrite) {
                wait_on_page_writeback(vmpage);
                if (!PageDirty(vmpage)) {
                        struct cl_page_list *plist = &io->ci_queue.c2_qin;
                        struct vvp_page *vpg = cl_object_page_slice(obj, page);
                        int to = PAGE_SIZE;

                        /* vvp_page_assume() calls wait_on_page_writeback(). */
                        cl_page_assume(env, io, page);

                        cl_page_list_init(plist);
                        cl_page_list_add(plist, page);

                        /* size fixup */
                        if (last_index == vvp_index(vpg))
                                to = size & ~PAGE_MASK;

                        /* Do not set Dirty bit here so that in case IO is
                         * started before the page is really made dirty, we
                         * still have chance to detect it.
                         */
                        result = cl_io_commit_async(env, io, plist, 0, to,
                                                    mkwrite_commit_callback);
                        LASSERT(cl_page_is_owned(page, io));
                        cl_page_list_fini(env, plist);

                        vmpage = NULL;
                        if (result < 0) {
                                cl_page_discard(env, io, page);
                                cl_page_disown(env, io, page);

                                cl_page_put(env, page);

                                /* we're in big trouble, what can we do now? */
                                if (result == -EDQUOT)
                                        result = -ENOSPC;
                                goto out;
                        } else {
                                cl_page_disown(env, io, page);
                        }
                }
        }

        /*
         * The ft_index is only used in the case of
         * a mkwrite action. We need to check
         * our assertions are correct, since
         * we should have caught this above
         */
        LASSERT(!fio->ft_mkwrite || fio->ft_index <= last_index);
        if (fio->ft_index == last_index)
                /*
                 * Last page is mapped partially.
                 */
                fio->ft_nob = size - cl_offset(obj, fio->ft_index);
        else
                fio->ft_nob = cl_page_size(obj);

        lu_ref_add(&page->cp_reference, "fault", io);
        fio->ft_page = page;

out:
        /* return unlocked vmpage to avoid deadlocking */
        if (vmpage)
                unlock_page(vmpage);

        cfio->ft_flags &= ~VM_FAULT_LOCKED;

        return result;
}

static void vvp_io_fault_end(const struct lu_env *env,
                             const struct cl_io_slice *ios)
{
        struct inode *inode = vvp_object_inode(ios->cis_obj);
        struct ll_inode_info *lli = ll_i2info(inode);

        CLOBINVRNT(env, ios->cis_io->ci_obj,
                   vvp_object_invariant(ios->cis_io->ci_obj));
        up_read(&lli->lli_trunc_sem);
}

static int vvp_io_fsync_start(const struct lu_env *env,
                              const struct cl_io_slice *ios)
{
        /* we should mark TOWRITE bit to each dirty page in radix tree to
         * verify pages have been written, but this is difficult because of
         * race.
         */
        return 0;
}

static int vvp_io_read_ahead(const struct lu_env *env,
                             const struct cl_io_slice *ios,
                             pgoff_t start, struct cl_read_ahead *ra)
{
        int result = 0;

        if (ios->cis_io->ci_type == CIT_READ ||
            ios->cis_io->ci_type == CIT_FAULT) {
                struct vvp_io *vio = cl2vvp_io(env, ios);

                if (unlikely(vio->vui_fd->fd_flags & LL_FILE_GROUP_LOCKED)) {
                        ra->cra_end = CL_PAGE_EOF;
                        result = 1; /* no need to call down */
                }
        }

        return result;
}

static const struct cl_io_operations vvp_io_ops = {
        .op = {
                [CIT_READ] = {
                        .cio_fini       = vvp_io_fini,
                        .cio_lock      = vvp_io_read_lock,
                        .cio_start     = vvp_io_read_start,
                        .cio_end        = vvp_io_rw_end,
                        .cio_advance    = vvp_io_advance,
                },
                [CIT_WRITE] = {
                        .cio_fini      = vvp_io_fini,
                        .cio_iter_init = vvp_io_write_iter_init,
                        .cio_iter_fini = vvp_io_write_iter_fini,
                        .cio_lock      = vvp_io_write_lock,
                        .cio_start     = vvp_io_write_start,
                        .cio_end        = vvp_io_rw_end,
                        .cio_advance   = vvp_io_advance,
                },
                [CIT_SETATTR] = {
                        .cio_fini       = vvp_io_setattr_fini,
                        .cio_iter_init  = vvp_io_setattr_iter_init,
                        .cio_lock       = vvp_io_setattr_lock,
                        .cio_start      = vvp_io_setattr_start,
                        .cio_end        = vvp_io_setattr_end
                },
                [CIT_FAULT] = {
                        .cio_fini      = vvp_io_fault_fini,
                        .cio_iter_init = vvp_io_fault_iter_init,
                        .cio_lock      = vvp_io_fault_lock,
                        .cio_start     = vvp_io_fault_start,
                        .cio_end       = vvp_io_fault_end,
                },
                [CIT_FSYNC] = {
                        .cio_start  = vvp_io_fsync_start,
                        .cio_fini   = vvp_io_fini
                },
                [CIT_MISC] = {
                        .cio_fini   = vvp_io_fini
                }
        },
        .cio_read_ahead = vvp_io_read_ahead,
};

int vvp_io_init(const struct lu_env *env, struct cl_object *obj,
                struct cl_io *io)
{
        struct vvp_io      *vio   = vvp_env_io(env);
        struct inode       *inode = vvp_object_inode(obj);
        int              result;

        CLOBINVRNT(env, obj, vvp_object_invariant(obj));

        CDEBUG(D_VFSTRACE, DFID
               " ignore/verify layout %d/%d, layout version %d restore needed %d\n",
               PFID(lu_object_fid(&obj->co_lu)),
               io->ci_ignore_layout, io->ci_verify_layout,
               vio->vui_layout_gen, io->ci_restore_needed);

        CL_IO_SLICE_CLEAN(vio, vui_cl);
        cl_io_slice_add(io, &vio->vui_cl, obj, &vvp_io_ops);
        vio->vui_ra_valid = false;
        result = 0;
        if (io->ci_type == CIT_READ || io->ci_type == CIT_WRITE) {
                size_t count;
                struct ll_inode_info *lli = ll_i2info(inode);

                count = io->u.ci_rw.crw_count;
                /* "If nbyte is 0, read() will return 0 and have no other
                 *  results."  -- Single Unix Spec
                 */
                if (count == 0)
                        result = 1;
                else
                        vio->vui_tot_count = count;

                /* for read/write, we store the jobid in the inode, and
                 * it'll be fetched by osc when building RPC.
                 *
                 * it's not accurate if the file is shared by different
                 * jobs.
                 */
                lustre_get_jobid(lli->lli_jobid);
        } else if (io->ci_type == CIT_SETATTR) {
                if (!cl_io_is_trunc(io))
                        io->ci_lockreq = CILR_MANDATORY;
        }

        /* Enqueue layout lock and get layout version. We need to do this
         * even for operations requiring to open file, such as read and write,
         * because it might not grant layout lock in IT_OPEN.
         */
        if (result == 0 && !io->ci_ignore_layout) {
                result = ll_layout_refresh(inode, &vio->vui_layout_gen);
                if (result == -ENOENT)
                        /* If the inode on MDS has been removed, but the objects
                         * on OSTs haven't been destroyed (async unlink), layout
                         * fetch will return -ENOENT, we'd ignore this error
                         * and continue with dirty flush. LU-3230.
                         */
                        result = 0;
                if (result < 0)
                        CERROR("%s: refresh file layout " DFID " error %d.\n",
                               ll_get_fsname(inode->i_sb, NULL, 0),
                               PFID(lu_object_fid(&obj->co_lu)), result);
        }

        return result;
}