staging/lustre: Properly cast ll_fid2path argument to __user in ll_dir_ioctl

[deliverable/linux.git] / drivers / staging / lustre / lustre / llite / vvp_io.c

/*
 * 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.sun.com/software/products/lustre/docs/GPLv2.pdf
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 * 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 "../include/lustre_lite.h"

#include "vvp_internal.h"

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

/**
 * True, if \a io is a normal io, False for splice_{read,write}
 */
int cl_is_normalio(const struct lu_env *env, const struct cl_io *io)
{
        struct vvp_io *vio = vvp_env_io(env);

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

        return vio->cui_io_subtype == IO_NORMAL;
}

/**
 * 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 ccc_io           *cio = ccc_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) != cio->cui_layout_gen) {
                        io->ci_need_restart = 1;
                        /* this will return application 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;
}

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

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 = ccc_object_inode(ios->cis_obj);

        LASSERT(inode ==
                file_inode(cl2ccc_io(env, ios)->cui_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 ccc_io    *cio = cl2ccc_io(env, ios);

        CLOBINVRNT(env, obj, ccc_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,
               cio->cui_layout_gen, io->ci_restore_needed);

        if (io->ci_restore_needed == 1) {
                int     rc;

                /* file was detected release, we need to restore it
                 * before finishing the io
                 */
                rc = ll_layout_restore(ccc_object_inode(obj));
                /* 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(ccc_object_inode(obj), &gen);
                io->ci_need_restart = cio->cui_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)),
                               cio->cui_layout_gen, gen);
                        /* today successful restore is the only possible
                         * case */
                        /* restore was done, clear restoring state */
                        ll_i2info(ccc_object_inode(obj))->lli_flags &=
                                ~LLIF_FILE_RESTORING;
                }
        }
}

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, ccc_object_invariant(io->ci_obj));

        if (page != NULL) {
                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 ccc_io *vio, struct cl_io *io)
{
        struct ccc_thread_info *cti = ccc_env_info(env);
        struct mm_struct       *mm = current->mm;
        struct vm_area_struct  *vma;
        struct cl_lock_descr   *descr = &cti->cti_descr;
        ldlm_policy_data_t      policy;
        unsigned long      addr;
        ssize_t          count;
        int                  result;
        struct iov_iter i;
        struct iovec iov;

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

        if (!cl_is_normalio(env, io))
                return 0;

        if (vio->cui_iter == NULL) /* nfs or loop back device write */
                return 0;

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

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

                count += addr & (~CFS_PAGE_MASK);
                addr &= CFS_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, a lockless lock will be
                                 * generated.
                                 */
                                flags = CEF_NEVER;
                        }

                        /*
                         * 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) {
                                up_read(&mm->mmap_sem);
                                return result;
                        }

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

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

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 ccc_io *cio = ccc_env_io(env);
        int result;
        int ast_flags = 0;

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

        ccc_io_update_iov(env, cio, io);

        if (io->u.ci_rw.crw_nonblock)
                ast_flags |= CEF_NONBLOCK;
        result = vvp_mmap_locks(env, cio, io);
        if (result == 0)
                result = ccc_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 ccc_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::cio_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 ccc_io *cio = ccc_env_io(env);
        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 {
                if ((io->u.ci_setattr.sa_attr.lvb_mtime >=
                     io->u.ci_setattr.sa_attr.lvb_ctime) ||
                    (io->u.ci_setattr.sa_attr.lvb_atime >=
                     io->u.ci_setattr.sa_attr.lvb_ctime))
                        return 0;
                new_size = 0;
        }
        cio->u.setattr.cui_local_lock = SETATTR_EXTENT_LOCK;
        return ccc_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_trunc(const struct lu_env *env,
                                const struct cl_io_slice *ios,
                                struct inode *inode, loff_t size)
{
        inode_dio_wait(inode);
        return 0;
}

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  = ccc_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_set(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 = ccc_object_inode(io->ci_obj);
        int result = 0;

        inode_lock(inode);
        if (cl_io_is_trunc(io))
                result = vvp_io_setattr_trunc(env, ios, inode,
                                        io->u.ci_setattr.sa_attr.lvb_size);
        if (result == 0)
                result = vvp_io_setattr_time(env, ios);
        return result;
}

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 = ccc_object_inode(io->ci_obj);

        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);
}

static void vvp_io_setattr_fini(const struct lu_env *env,
                                const struct cl_io_slice *ios)
{
        vvp_io_fini(env, ios);
}

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 ccc_io     *cio   = cl2ccc_io(env, ios);
        struct cl_io      *io    = ios->cis_io;
        struct cl_object  *obj   = io->ci_obj;
        struct inode      *inode = ccc_object_inode(obj);
        struct ll_ra_read *bead  = &vio->cui_bead;
        struct file       *file  = cio->cui_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 = cio->cui_tot_count;
        int     exceed = 0;

        CLOBINVRNT(env, obj, ccc_object_invariant(obj));

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

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

        result = ccc_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 */
        cio->cui_fd->fd_file->f_ra.ra_pages = 0;

        /* initialize read-ahead window once per syscall */
        if (!vio->cui_ra_window_set) {
                vio->cui_ra_window_set = 1;
                bead->lrr_start = cl_index(obj, pos);
                /*
                 * XXX: explicit PAGE_CACHE_SIZE
                 */
                bead->lrr_count = cl_index(obj, tot + PAGE_CACHE_SIZE - 1);
                ll_ra_read_in(file, bead);
        }

        /* BUG: 5972 */
        file_accessed(file);
        switch (vio->cui_io_subtype) {
        case IO_NORMAL:
                LASSERT(cio->cui_iocb->ki_pos == pos);
                result = generic_file_read_iter(cio->cui_iocb, cio->cui_iter);
                break;
        case IO_SPLICE:
                result = generic_file_splice_read(file, &pos,
                                vio->u.splice.cui_pipe, cnt,
                                vio->u.splice.cui_flags);
                /* LU-1109: do splice read stripe by stripe otherwise if it
                 * may make nfsd stuck if this read occupied all internal pipe
                 * buffers. */
                io->ci_continue = 0;
                break;
        default:
                CERROR("Wrong IO type %u\n", vio->cui_io_subtype);
                LBUG();
        }

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

static void vvp_io_read_fini(const struct lu_env *env, const struct cl_io_slice *ios)
{
        struct vvp_io *vio = cl2vvp_io(env, ios);
        struct ccc_io *cio = cl2ccc_io(env, ios);

        if (vio->cui_ra_window_set)
                ll_ra_read_ex(cio->cui_fd->fd_file, &vio->cui_bead);

        vvp_io_fini(env, ios);
}

static int vvp_io_write_start(const struct lu_env *env,
                              const struct cl_io_slice *ios)
{
        struct ccc_io      *cio   = cl2ccc_io(env, ios);
        struct cl_io       *io    = ios->cis_io;
        struct cl_object   *obj   = io->ci_obj;
        struct inode       *inode = ccc_object_inode(obj);
        ssize_t result = 0;
        loff_t pos = io->u.ci_wr.wr.crw_pos;
        size_t cnt = io->u.ci_wr.wr.crw_count;

        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.
                 */
                pos = io->u.ci_wr.wr.crw_pos = i_size_read(inode);
                cio->cui_iocb->ki_pos = pos;
        } else {
                LASSERT(cio->cui_iocb->ki_pos == pos);
        }

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

        if (cio->cui_iter == NULL) /* from a temp io in ll_cl_init(). */
                result = 0;
        else
                result = generic_file_write_iter(cio->cui_iocb, cio->cui_iter);

        if (result > 0) {
                if (result < cnt)
                        io->ci_continue = 0;
                io->ci_nob += result;
                ll_rw_stats_tally(ll_i2sbi(inode), current->pid,
                                  cio->cui_fd, pos, result, WRITE);
                result = 0;
        }
        return result;
}

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

        cfio->fault.ft_flags = filemap_fault(cfio->ft_vma, vmf);
        cfio->fault.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), vmf->virtual_address);
                if (unlikely(!(cfio->fault.ft_flags & VM_FAULT_LOCKED))) {
                        lock_page(vmf->page);
                        cfio->fault.ft_flags |= VM_FAULT_LOCKED;
                }

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

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

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

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

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

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   = ccc_object_inode(obj);
        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; /* last page in a file data region */

        if (fio->ft_executable &&
            inode->i_mtime.tv_sec != vio->u.fault.ft_mtime)
                CWARN("binary "DFID
                      " changed while waiting for the page fault lock\n",
                      PFID(lu_object_fid(&obj->co_lu)));

        /* 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 = ccc_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 != NULL);
                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;
        }

        if (fio->ft_mkwrite) {
                pgoff_t last_index;
                /*
                 * 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.
                 */
                last_index = cl_index(obj, size - 1);
                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 (set_page_dirty(vmpage)) {
                        struct ccc_page *cp;

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

                        cp = cl2ccc_page(cl_page_at(page, &vvp_device_type));
                        vvp_write_pending(cl2ccc(obj), cp);

                        /* 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_page_cache_add(env, io, page, CRT_WRITE);
                        LASSERT(cl_page_is_owned(page, io));

                        vmpage = NULL;
                        if (result < 0) {
                                cl_page_unmap(env, io, page);
                                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);
                }
        }

        last = cl_index(obj, size - 1);
        /*
         * 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);
        if (fio->ft_index == last)
                /*
                 * 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 != NULL)
                unlock_page(vmpage);
        cfio->fault.ft_flags &= ~VM_FAULT_LOCKED;
        return result;
}

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_page(const struct lu_env *env,
                            const struct cl_io_slice *ios,
                            const struct cl_page_slice *slice)
{
        struct cl_io          *io     = ios->cis_io;
        struct cl_object          *obj    = slice->cpl_obj;
        struct ccc_page    *cp     = cl2ccc_page(slice);
        struct cl_page      *page   = slice->cpl_page;
        struct inode          *inode  = ccc_object_inode(obj);
        struct ll_sb_info        *sbi    = ll_i2sbi(inode);
        struct ll_file_data       *fd     = cl2ccc_io(env, ios)->cui_fd;
        struct ll_readahead_state *ras    = &fd->fd_ras;
        struct page             *vmpage = cp->cpg_page;
        struct cl_2queue          *queue  = &io->ci_queue;
        int rc;

        CLOBINVRNT(env, obj, ccc_object_invariant(obj));
        LASSERT(slice->cpl_obj == obj);

        if (sbi->ll_ra_info.ra_max_pages_per_file &&
            sbi->ll_ra_info.ra_max_pages)
                ras_update(sbi, inode, ras, page->cp_index,
                           cp->cpg_defer_uptodate);

        /* Sanity check whether the page is protected by a lock. */
        rc = cl_page_is_under_lock(env, io, page);
        if (rc != -EBUSY) {
                CL_PAGE_HEADER(D_WARNING, env, page, "%s: %d\n",
                               rc == -ENODATA ? "without a lock" :
                               "match failed", rc);
                if (rc != -ENODATA)
                        return rc;
        }

        if (cp->cpg_defer_uptodate) {
                cp->cpg_ra_used = 1;
                cl_page_export(env, page, 1);
        }
        /*
         * Add page into the queue even when it is marked uptodate above.
         * this will unlock it automatically as part of cl_page_list_disown().
         */
        cl_page_list_add(&queue->c2_qin, page);
        if (sbi->ll_ra_info.ra_max_pages_per_file &&
            sbi->ll_ra_info.ra_max_pages)
                ll_readahead(env, io, ras,
                             vmpage->mapping, &queue->c2_qin, fd->fd_flags);

        return 0;
}

static int vvp_page_sync_io(const struct lu_env *env, struct cl_io *io,
                            struct cl_page *page, struct ccc_page *cp,
                            enum cl_req_type crt)
{
        struct cl_2queue  *queue;
        int result;

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

        queue = &io->ci_queue;
        cl_2queue_init_page(queue, page);

        result = cl_io_submit_sync(env, io, crt, queue, 0);
        LASSERT(cl_page_is_owned(page, io));

        if (crt == CRT_READ)
                /*
                 * in CRT_WRITE case page is left locked even in case of
                 * error.
                 */
                cl_page_list_disown(env, io, &queue->c2_qin);
        cl_2queue_fini(env, queue);

        return result;
}

/**
 * Prepare partially written-to page for a write.
 */
static int vvp_io_prepare_partial(const struct lu_env *env, struct cl_io *io,
                                  struct cl_object *obj, struct cl_page *pg,
                                  struct ccc_page *cp,
                                  unsigned from, unsigned to)
{
        struct cl_attr *attr   = ccc_env_thread_attr(env);
        loff_t    offset = cl_offset(obj, pg->cp_index);
        int          result;

        cl_object_attr_lock(obj);
        result = cl_object_attr_get(env, obj, attr);
        cl_object_attr_unlock(obj);
        if (result == 0) {
                /*
                 * If are writing to a new page, no need to read old data.
                 * The extent locking will have updated the KMS, and for our
                 * purposes here we can treat it like i_size.
                 */
                if (attr->cat_kms <= offset) {
                        char *kaddr = kmap_atomic(cp->cpg_page);

                        memset(kaddr, 0, cl_page_size(obj));
                        kunmap_atomic(kaddr);
                } else if (cp->cpg_defer_uptodate)
                        cp->cpg_ra_used = 1;
                else
                        result = vvp_page_sync_io(env, io, pg, cp, CRT_READ);
                /*
                 * In older implementations, obdo_refresh_inode is called here
                 * to update the inode because the write might modify the
                 * object info at OST. However, this has been proven useless,
                 * since LVB functions will be called when user space program
                 * tries to retrieve inode attribute.  Also, see bug 15909 for
                 * details. -jay
                 */
                if (result == 0)
                        cl_page_export(env, pg, 1);
        }
        return result;
}

static int vvp_io_prepare_write(const struct lu_env *env,
                                const struct cl_io_slice *ios,
                                const struct cl_page_slice *slice,
                                unsigned from, unsigned to)
{
        struct cl_object *obj    = slice->cpl_obj;
        struct ccc_page  *cp     = cl2ccc_page(slice);
        struct cl_page   *pg     = slice->cpl_page;
        struct page       *vmpage = cp->cpg_page;

        int result;

        LINVRNT(cl_page_is_vmlocked(env, pg));
        LASSERT(vmpage->mapping->host == ccc_object_inode(obj));

        result = 0;

        CL_PAGE_HEADER(D_PAGE, env, pg, "preparing: [%d, %d]\n", from, to);
        if (!PageUptodate(vmpage)) {
                /*
                 * We're completely overwriting an existing page, so _don't_
                 * set it up to date until commit_write
                 */
                if (from == 0 && to == PAGE_CACHE_SIZE) {
                        CL_PAGE_HEADER(D_PAGE, env, pg, "full page write\n");
                        POISON_PAGE(page, 0x11);
                } else
                        result = vvp_io_prepare_partial(env, ios->cis_io, obj,
                                                        pg, cp, from, to);
        } else
                CL_PAGE_HEADER(D_PAGE, env, pg, "uptodate\n");
        return result;
}

static int vvp_io_commit_write(const struct lu_env *env,
                               const struct cl_io_slice *ios,
                               const struct cl_page_slice *slice,
                               unsigned from, unsigned to)
{
        struct cl_object  *obj    = slice->cpl_obj;
        struct cl_io      *io     = ios->cis_io;
        struct ccc_page   *cp     = cl2ccc_page(slice);
        struct cl_page    *pg     = slice->cpl_page;
        struct inode      *inode  = ccc_object_inode(obj);
        struct ll_sb_info *sbi    = ll_i2sbi(inode);
        struct ll_inode_info *lli = ll_i2info(inode);
        struct page     *vmpage = cp->cpg_page;

        int    result;
        int    tallyop;
        loff_t size;

        LINVRNT(cl_page_is_vmlocked(env, pg));
        LASSERT(vmpage->mapping->host == inode);

        LU_OBJECT_HEADER(D_INODE, env, &obj->co_lu, "committing page write\n");
        CL_PAGE_HEADER(D_PAGE, env, pg, "committing: [%d, %d]\n", from, to);

        /*
         * queue a write for some time in the future the first time we
         * dirty the page.
         *
         * This is different from what other file systems do: they usually
         * just mark page (and some of its buffers) dirty and rely on
         * balance_dirty_pages() to start a write-back. Lustre wants write-back
         * to be started earlier for the following reasons:
         *
         *     (1) with a large number of clients we need to limit the amount
         *     of cached data on the clients a lot;
         *
         *     (2) large compute jobs generally want compute-only then io-only
         *     and the IO should complete as quickly as possible;
         *
         *     (3) IO is batched up to the RPC size and is async until the
         *     client max cache is hit
         *     (/proc/fs/lustre/osc/OSC.../max_dirty_mb)
         *
         */
        if (!PageDirty(vmpage)) {
                tallyop = LPROC_LL_DIRTY_MISSES;
                result = cl_page_cache_add(env, io, pg, CRT_WRITE);
                if (result == 0) {
                        /* page was added into cache successfully. */
                        set_page_dirty(vmpage);
                        vvp_write_pending(cl2ccc(obj), cp);
                } else if (result == -EDQUOT) {
                        pgoff_t last_index = i_size_read(inode) >> PAGE_CACHE_SHIFT;
                        bool need_clip = true;

                        /*
                         * Client ran out of disk space grant. Possible
                         * strategies are:
                         *
                         *     (a) do a sync write, renewing grant;
                         *
                         *     (b) stop writing on this stripe, switch to the
                         *     next one.
                         *
                         * (b) is a part of "parallel io" design that is the
                         * ultimate goal. (a) is what "old" client did, and
                         * what the new code continues to do for the time
                         * being.
                         */
                        if (last_index > pg->cp_index) {
                                to = PAGE_CACHE_SIZE;
                                need_clip = false;
                        } else if (last_index == pg->cp_index) {
                                int size_to = i_size_read(inode) & ~CFS_PAGE_MASK;

                                if (to < size_to)
                                        to = size_to;
                        }
                        if (need_clip)
                                cl_page_clip(env, pg, 0, to);
                        result = vvp_page_sync_io(env, io, pg, cp, CRT_WRITE);
                        if (result)
                                CERROR("Write page %lu of inode %p failed %d\n",
                                       pg->cp_index, inode, result);
                }
        } else {
                tallyop = LPROC_LL_DIRTY_HITS;
                result = 0;
        }
        ll_stats_ops_tally(sbi, tallyop, 1);

        /* Inode should be marked DIRTY even if no new page was marked DIRTY
         * because page could have been not flushed between 2 modifications.
         * It is important the file is marked DIRTY as soon as the I/O is done
         * Indeed, when cache is flushed, file could be already closed and it
         * is too late to warn the MDT.
         * It is acceptable that file is marked DIRTY even if I/O is dropped
         * for some reasons before being flushed to OST.
         */
        if (result == 0) {
                spin_lock(&lli->lli_lock);
                lli->lli_flags |= LLIF_DATA_MODIFIED;
                spin_unlock(&lli->lli_lock);
        }

        size = cl_offset(obj, pg->cp_index) + to;

        ll_inode_size_lock(inode);
        if (result == 0) {
                if (size > i_size_read(inode)) {
                        cl_isize_write_nolock(inode, size);
                        CDEBUG(D_VFSTRACE, DFID" updating i_size %lu\n",
                               PFID(lu_object_fid(&obj->co_lu)),
                               (unsigned long)size);
                }
                cl_page_export(env, pg, 1);
        } else {
                if (size > i_size_read(inode))
                        cl_page_discard(env, io, pg);
        }
        ll_inode_size_unlock(inode);
        return result;
}

static const struct cl_io_operations vvp_io_ops = {
        .op = {
                [CIT_READ] = {
                        .cio_fini      = vvp_io_read_fini,
                        .cio_lock      = vvp_io_read_lock,
                        .cio_start     = vvp_io_read_start,
                        .cio_advance   = ccc_io_advance
                },
                [CIT_WRITE] = {
                        .cio_fini      = vvp_io_fini,
                        .cio_lock      = vvp_io_write_lock,
                        .cio_start     = vvp_io_write_start,
                        .cio_advance   = ccc_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       = ccc_io_end
                },
                [CIT_FSYNC] = {
                        .cio_start  = vvp_io_fsync_start,
                        .cio_fini   = vvp_io_fini
                },
                [CIT_MISC] = {
                        .cio_fini   = vvp_io_fini
                }
        },
        .cio_read_page     = vvp_io_read_page,
        .cio_prepare_write = vvp_io_prepare_write,
        .cio_commit_write  = vvp_io_commit_write
};

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 ccc_io      *cio   = ccc_env_io(env);
        struct inode       *inode = ccc_object_inode(obj);
        int              result;

        CLOBINVRNT(env, obj, ccc_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,
               cio->cui_layout_gen, io->ci_restore_needed);

        CL_IO_SLICE_CLEAN(cio, cui_cl);
        cl_io_slice_add(io, &cio->cui_cl, obj, &vvp_io_ops);
        vio->cui_ra_window_set = 0;
        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
                        cio->cui_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;
        }

        /* ignore layout change for generic CIT_MISC but not for glimpse.
         * io context for glimpse must set ci_verify_layout to true,
         * see cl_glimpse_size0() for details. */
        if (io->ci_type == CIT_MISC && !io->ci_verify_layout)
                io->ci_ignore_layout = 1;

        /* 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, &cio->cui_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;
}

static struct vvp_io *cl2vvp_io(const struct lu_env *env,
                                const struct cl_io_slice *slice)
{
        /* Calling just for assertion */
        cl2ccc_io(env, slice);
        return vvp_env_io(env);
}