/*-
 * Copyright (c) 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)ufs_readwrite.c     8.11 (Berkeley) 5/8/95
 * $FreeBSD: src/sys/ufs/ufs/ufs_readwrite.c,v 1.65.2.14 2003/04/04 22:21:29 tegge Exp $
 */

#define BLKSIZE(a, b, c)        blksize(a, b, c)
#define FS                      struct fs
#define I_FS                    i_fs

#include <vm/vm.h>
#include <vm/vm_object.h>
#include <vm/vm_pager.h>
#include <vm/vm_map.h>
#include <vm/vnode_pager.h>
#include <sys/event.h>
#include <sys/vmmeter.h>
#include <sys/sysctl.h>
#include <vm/vm_page2.h>

#define VN_KNOTE(vp, b) KNOTE(&vp->v_pollinfo.vpi_kqinfo.ki_note, (b))

SYSCTL_DECL(_vfs_ffs);

/*
 * Vnode op for reading.
 *
 * ffs_read(struct vnode *a_vp, struct uio *a_uio, int a_ioflag,
 *          struct ucred *a_cred)
 */
/* ARGSUSED */
int
ffs_read(struct vop_read_args *ap)
{
        struct vnode *vp;
        struct inode *ip;
        struct uio *uio;
        FS *fs;
        struct buf *bp;
        off_t bytesinfile;
        int xfersize, blkoffset;
        int error, orig_resid;
        int seqcount;
        int ioflag;

        vp = ap->a_vp;
        seqcount = ap->a_ioflag >> IO_SEQSHIFT;
        ip = VTOI(vp);
        uio = ap->a_uio;
        ioflag = ap->a_ioflag;
#ifdef DIAGNOSTIC
        if (uio->uio_rw != UIO_READ)
                panic("ffs_read: mode");

        if (vp->v_type == VLNK) {
                if ((int)ip->i_size < vp->v_mount->mnt_maxsymlinklen)
                        panic("ffs_read: short symlink");
        } else if (vp->v_type != VREG && vp->v_type != VDIR)
                panic("ffs_read: type %d", vp->v_type);
#endif
        fs = ip->I_FS;
        if ((uint64_t)uio->uio_offset > fs->fs_maxfilesize)
                return (EFBIG);

        orig_resid = uio->uio_resid;
        if (orig_resid <= 0)
                return (0);

        bytesinfile = ip->i_size - uio->uio_offset;
        if (bytesinfile <= 0) {
                if ((vp->v_mount->mnt_flag & MNT_NOATIME) == 0)
                        ip->i_flag |= IN_ACCESS;
                return 0;
        }

        /*
         * Ok so we couldn't do it all in one vm trick...
         * so cycle around trying smaller bites..
         */
        for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {
                if ((bytesinfile = ip->i_size - uio->uio_offset) <= 0)
                        break;

                error = ffs_blkatoff_ra(vp, uio->uio_offset, NULL,
                                        &bp, seqcount);
                if (error)
                        break;

                /*
                 * If IO_DIRECT then set B_DIRECT for the buffer.  This
                 * will cause us to attempt to release the buffer later on
                 * and will cause the buffer cache to attempt to free the
                 * underlying pages.
                 */
                if (ioflag & IO_DIRECT)
                        bp->b_flags |= B_DIRECT;

                /*
                 * We should only get non-zero b_resid when an I/O error
                 * has occurred, which should cause us to break above.
                 * However, if the short read did not cause an error,
                 * then we want to ensure that we do not uiomove bad
                 * or uninitialized data.
                 *
                 * XXX b_resid is only valid when an actual I/O has occured
                 * and may be incorrect if the buffer is B_CACHE or if the
                 * last op on the buffer was a failed write.  This KASSERT
                 * is a precursor to removing it from the UFS code.
                 */
                KASSERT(bp->b_resid == 0, ("bp->b_resid != 0"));

                /*
                 * Calculate how much data we can copy
                 */
                blkoffset = blkoff(fs, uio->uio_offset);
                xfersize = bp->b_bufsize - blkoffset;
                if (xfersize > uio->uio_resid)
                        xfersize = uio->uio_resid;
                if (xfersize > bytesinfile)
                        xfersize = bytesinfile;
                if (xfersize <= 0) {
                        panic("ufs_readwrite: impossible xfersize: %d",
                              xfersize);
                }

                /*
                 * otherwise use the general form
                 */
                error = uiomovebp(bp, bp->b_data + blkoffset, xfersize, uio);

                if (error)
                        break;

                if ((ioflag & (IO_VMIO|IO_DIRECT)) && 
                    (LIST_FIRST(&bp->b_dep) == NULL)) {
                        /*
                         * If there are no dependencies, and it's VMIO,
                         * then we don't need the buf, mark it available
                         * for freeing. The VM has the data.
                         */
                        bp->b_flags |= B_RELBUF;
                        brelse(bp);
                } else {
                        /*
                         * Otherwise let whoever
                         * made the request take care of
                         * freeing it. We just queue
                         * it onto another list.
                         */
                        bqrelse(bp);
                }
        }

        /* 
         * This can only happen in the case of an error
         * because the loop above resets bp to NULL on each iteration
         * and on normal completion has not set a new value into it.
         * so it must have come from a 'break' statement
         */
        if (bp != NULL) {
                if ((ioflag & (IO_VMIO|IO_DIRECT)) && 
                    (LIST_FIRST(&bp->b_dep) == NULL)) {
                        bp->b_flags |= B_RELBUF;
                        brelse(bp);
                } else {
                        bqrelse(bp);
                }
        }

        if ((error == 0 || uio->uio_resid != orig_resid) &&
            (vp->v_mount->mnt_flag & MNT_NOATIME) == 0)
                ip->i_flag |= IN_ACCESS;
        return (error);
}

/*
 * Vnode op for writing.
 *
 * ffs_write(struct vnode *a_vp, struct uio *a_uio, int a_ioflag,
 *           struct ucred *a_cred)
 */
int
ffs_write(struct vop_write_args *ap)
{
        struct vnode *vp;
        struct uio *uio;
        struct inode *ip;
        FS *fs;
        struct buf *bp;
        ufs_daddr_t lbn;
        off_t osize;
        off_t nsize;
        int seqcount;
        int blkoffset, error, extended, flags, ioflag, resid, size, xfersize;
        struct thread *td;

        extended = 0;
        seqcount = ap->a_ioflag >> IO_SEQSHIFT;
        ioflag = ap->a_ioflag;
        uio = ap->a_uio;
        vp = ap->a_vp;
        ip = VTOI(vp);

#ifdef DIAGNOSTIC
        if (uio->uio_rw != UIO_WRITE)
                panic("ffs_write: mode");
#endif

        switch (vp->v_type) {
        case VREG:
                if (ioflag & IO_APPEND)
                        uio->uio_offset = ip->i_size;
                if ((ip->i_flags & APPEND) && uio->uio_offset != ip->i_size)
                        return (EPERM);
                /* FALLTHROUGH */
        case VLNK:
                break;
        case VDIR:
                panic("ffs_write: dir write");
                break;
        default:
                panic("ffs_write: type %p %d (%d,%d)", vp, (int)vp->v_type,
                        (int)uio->uio_offset,
                        (int)uio->uio_resid
                );
        }

        fs = ip->I_FS;
        if (uio->uio_offset < 0 ||
            (uint64_t)uio->uio_offset + uio->uio_resid > fs->fs_maxfilesize) {
                return (EFBIG);
        }
        /*
         * Maybe this should be above the vnode op call, but so long as
         * file servers have no limits, I don't think it matters.
         */
        td = uio->uio_td;
        if (vp->v_type == VREG && td && td->td_proc &&
            uio->uio_offset + uio->uio_resid >
            td->td_proc->p_rlimit[RLIMIT_FSIZE].rlim_cur) {
                lwpsignal(td->td_proc, td->td_lwp, SIGXFSZ);
                return (EFBIG);
        }

        resid = uio->uio_resid;
        osize = ip->i_size;

        /*
         * NOTE! These B_ flags are actually balloc-only flags, not buffer
         * flags.  They are similar to the BA_ flags in fbsd.
         */
        if (seqcount > B_SEQMAX)
                flags = B_SEQMAX << B_SEQSHIFT;
        else
                flags = seqcount << B_SEQSHIFT;
        if ((ioflag & IO_SYNC) && !DOINGASYNC(vp))
                flags |= B_SYNC;

        if (uio->uio_segflg == UIO_NOCOPY)
                ip->i_flag |= IN_NOCOPYWRITE;
        else
                vclrflags(vp, VLASTWRITETS);

        for (error = 0; uio->uio_resid > 0;) {
                lbn = lblkno(fs, uio->uio_offset);
                blkoffset = blkoff(fs, uio->uio_offset);
                xfersize = fs->fs_bsize - blkoffset;
                if (uio->uio_resid < xfersize)
                        xfersize = uio->uio_resid;

                if (uio->uio_offset + xfersize > ip->i_size) {
                        nsize = uio->uio_offset + xfersize;
                        nvnode_pager_setsize(vp, nsize,
                                blkoffresize(fs, nsize), blkoff(fs, nsize));
                }

#if 0
                /*      
                 * If doing a dummy write to flush the buffer for a
                 * putpages we must perform a read-before-write to
                 * fill in any missing spots and clear any invalid
                 * areas.  Otherwise a multi-page buffer may not properly
                 * flush.
                 *
                 * We must clear any invalid areas
                 */
                if (uio->uio_segflg == UIO_NOCOPY) {
                        error = ffs_blkatoff(vp, uio->uio_offset, NULL, &bp);
                        if (error)
                                break;
                        bqrelse(bp);
                }
#endif

                /*
                 * We must clear invalid areas.
                 */
                if (xfersize < fs->fs_bsize || uio->uio_segflg == UIO_NOCOPY)
                        flags |= B_CLRBUF;
                else
                        flags &= ~B_CLRBUF;
/* XXX is uio->uio_offset the right thing here? */
                error = VOP_BALLOC(vp, uio->uio_offset, xfersize,
                                   ap->a_cred, flags, &bp);
                if (error != 0)
                        break;
                /*
                 * If the buffer is not valid and we did not clear garbage
                 * out above, we have to do so here even though the write
                 * covers the entire buffer in order to avoid a mmap()/write
                 * race where another process may see the garbage prior to
                 * the uiomove() for a write replacing it.
                 */
                if ((bp->b_flags & B_CACHE) == 0 && (flags & B_CLRBUF) == 0)
                        vfs_bio_clrbuf(bp);
                if (ioflag & IO_DIRECT)
                        bp->b_flags |= B_DIRECT;
                if ((ioflag & (IO_SYNC|IO_INVAL)) == (IO_SYNC|IO_INVAL))
                        bp->b_flags |= B_NOCACHE;

                if (uio->uio_offset + xfersize > ip->i_size) {
                        ip->i_size = uio->uio_offset + xfersize;
                        extended = 1;
                }

                size = BLKSIZE(fs, ip, lbn) - bp->b_resid;
                if (size < xfersize)
                        xfersize = size;

                error = uiomovebp(bp, bp->b_data + blkoffset, xfersize, uio);
                if ((ioflag & (IO_VMIO|IO_DIRECT)) && 
                    (LIST_FIRST(&bp->b_dep) == NULL)) {
                        bp->b_flags |= B_RELBUF;
                }

                /*
                 * If IO_SYNC each buffer is written synchronously.  Otherwise
                 * if we have a severe page deficiency write the buffer 
                 * asynchronously.  Otherwise try to cluster, and if that
                 * doesn't do it then either do an async write (if O_DIRECT),
                 * or a delayed write (if not).
                 */

                if (ioflag & IO_SYNC) {
                        (void)bwrite(bp);
                } else if (vm_paging_severe() ||
                            buf_dirty_count_severe() ||
                            (ioflag & IO_ASYNC)) {
                        bp->b_flags |= B_CLUSTEROK;
                        bawrite(bp);
                } else if (xfersize + blkoffset == fs->fs_bsize) {
                        if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERW) == 0) {
                                bp->b_flags |= B_CLUSTEROK;
                                cluster_write(bp, (off_t)ip->i_size, fs->fs_bsize, seqcount);
                        } else {
                                bawrite(bp);
                        }
                } else if (ioflag & IO_DIRECT) {
                        bp->b_flags |= B_CLUSTEROK;
                        bawrite(bp);
                } else {
                        bp->b_flags |= B_CLUSTEROK;
                        bdwrite(bp);
                }
                if (error || xfersize == 0)
                        break;
                ip->i_flag |= IN_CHANGE | IN_UPDATE;
        }
        /*
         * If we successfully wrote any data, and we are not the superuser
         * we clear the setuid and setgid bits as a precaution against
         * tampering.
         */
        if (resid > uio->uio_resid && ap->a_cred && ap->a_cred->cr_uid != 0)
                ip->i_mode &= ~(ISUID | ISGID);
        if (resid > uio->uio_resid)
                VN_KNOTE(vp, NOTE_WRITE | (extended ? NOTE_EXTEND : 0));
        if (error) {
                if (ioflag & IO_UNIT) {
                        (void)ffs_truncate(vp, osize, ioflag & IO_SYNC,
                                           ap->a_cred);
                        uio->uio_offset -= resid - uio->uio_resid;
                        uio->uio_resid = resid;
                }
        } else if (resid > uio->uio_resid && (ioflag & IO_SYNC)) {
                error = ffs_update(vp, 1);
        } else {
                ufs_itimes(vp);
        }
        if (uio->uio_segflg == UIO_NOCOPY)
                ip->i_flag &= ~IN_NOCOPYWRITE;

        return (error);
}