/*      $NetBSD: ufs_readwrite.c,v 1.130 2026/01/22 03:24:19 riastradh Exp $    */

/*-
 * 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
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(1, "$NetBSD: ufs_readwrite.c,v 1.130 2026/01/22 03:24:19 riastradh Exp $");

#include <sys/bitops.h>
#include <sys/sdt.h>

#define FS                      struct fs
#define I_FS                    i_fs
#define READ                    ffs_read
#define READ_S                  "ffs_read"
#define WRITE                   ffs_write
#define WRITE_S                 "ffs_write"
#define BUFRD                   ffs_bufrd
#define BUFWR                   ffs_bufwr
#define ufs_blkoff              ffs_blkoff
#define ufs_blksize             ffs_blksize
#define ufs_lblkno              ffs_lblkno
#define ufs_lblktosize          ffs_lblktosize
#define ufs_blkroundup          ffs_blkroundup

static int      ufs_post_read_update(struct vnode *, int, int);
static int      ufs_post_write_update(struct vnode *, struct uio *, int,
                    kauth_cred_t, off_t, int, int);

/*
 * Vnode op for reading.
 */
/* ARGSUSED */
int
READ(void *v)
{
        struct vop_read_args /* {
                struct vnode *a_vp;
                struct uio *a_uio;
                int a_ioflag;
                kauth_cred_t a_cred;
        } */ *ap = v;
        struct vnode *vp;
        struct inode *ip;
        struct uio *uio;
        struct ufsmount *ump;
        vsize_t bytelen;
        int error, ioflag, advice;

        vp = ap->a_vp;
        ip = VTOI(vp);
        ump = ip->i_ump;
        uio = ap->a_uio;
        ioflag = ap->a_ioflag;
        error = 0;

        KASSERT(uio->uio_rw == UIO_READ);
        KASSERT(vp->v_type == VREG || vp->v_type == VDIR);

        /* XXX Eliminate me by refusing directory reads from userland.  */
        if (vp->v_type == VDIR)
                return BUFRD(vp, uio, ioflag, ap->a_cred);
        if ((u_int64_t)uio->uio_offset > ump->um_maxfilesize)
                return SET_ERROR(EFBIG);
        if (uio->uio_resid == 0)
                return 0;

        if ((ip->i_flags & (SF_SNAPSHOT | SF_SNAPINVAL)) == SF_SNAPSHOT)
                return ffs_snapshot_read(vp, uio, ioflag);

        if (uio->uio_offset >= ip->i_size)
                goto out;

        KASSERT(vp->v_type == VREG);
        advice = IO_ADV_DECODE(ap->a_ioflag);
        while (uio->uio_resid > 0) {
                if (ioflag & IO_DIRECT) {
                        genfs_directio(vp, uio, ioflag);
                }
                bytelen = MIN(ip->i_size - uio->uio_offset, uio->uio_resid);
                if (bytelen == 0)
                        break;
                error = ubc_uiomove(&vp->v_uobj, uio, bytelen, advice,
                    UBC_READ | UBC_PARTIALOK | UBC_VNODE_FLAGS(vp));
                if (error)
                        break;
        }

 out:
        error = ufs_post_read_update(vp, ap->a_ioflag, error);
        return error;
}

/*
 * UFS op for reading via the buffer cache
 */
int
BUFRD(struct vnode *vp, struct uio *uio, int ioflag, kauth_cred_t cred)
{
        struct inode *ip;
        struct ufsmount *ump;
        FS *fs;
        struct buf *bp;
        daddr_t lbn, nextlbn;
        off_t bytesinfile;
        long size, xfersize, blkoffset;
        int error;

        KASSERT(VOP_ISLOCKED(vp));
        KASSERT(vp->v_type == VDIR || vp->v_type == VLNK);
        KASSERT(uio->uio_rw == UIO_READ);

        ip = VTOI(vp);
        ump = ip->i_ump;
        fs = ip->I_FS;
        error = 0;

        KASSERT(vp->v_type != VLNK || ip->i_size >= ump->um_maxsymlinklen);
        KASSERT(vp->v_type != VLNK || ump->um_maxsymlinklen != 0 ||
            DIP(ip, blocks) != 0);

        if (uio->uio_offset > ump->um_maxfilesize)
                return SET_ERROR(EFBIG);
        if (uio->uio_resid == 0)
                return 0;

        KASSERT(!ISSET(ip->i_flags, (SF_SNAPSHOT | SF_SNAPINVAL)));

        if (uio->uio_offset >= ip->i_size)
                goto out;

        for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {
                bytesinfile = ip->i_size - uio->uio_offset;
                if (bytesinfile <= 0)
                        break;
                lbn = ufs_lblkno(fs, uio->uio_offset);
                nextlbn = lbn + 1;
                size = ufs_blksize(fs, ip, lbn);
                blkoffset = ufs_blkoff(fs, uio->uio_offset);
                xfersize = MIN(MIN(fs->fs_bsize - blkoffset, uio->uio_resid),
                    bytesinfile);

                if (ufs_lblktosize(fs, nextlbn) >= ip->i_size)
                        error = bread(vp, lbn, size, 0, &bp);
                else {
                        int nextsize = ufs_blksize(fs, ip, nextlbn);
                        error = breadn(vp, lbn,
                            size, &nextlbn, &nextsize, 1, 0, &bp);
                }
                if (error)
                        break;

                /*
                 * 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.
                 */
                size -= bp->b_resid;
                if (size < xfersize) {
                        if (size == 0)
                                break;
                        xfersize = size;
                }
                error = uiomove((char *)bp->b_data + blkoffset, xfersize, uio);
                if (error)
                        break;
                brelse(bp, 0);
        }
        if (bp != NULL)
                brelse(bp, 0);

 out:
        error = ufs_post_read_update(vp, ioflag, error);
        return error;
}

static int
ufs_post_read_update(struct vnode *vp, int ioflag, int oerror)
{
        struct inode *ip = VTOI(vp);
        int error = oerror;

        if (!(vp->v_mount->mnt_flag & MNT_NOATIME)) {
                ip->i_flag |= IN_ACCESS;
                if ((ioflag & IO_SYNC) == IO_SYNC) {
                        error = UFS_WAPBL_BEGIN(vp->v_mount);
                        if (error)
                                goto out;
                        error = UFS_UPDATE(vp, NULL, NULL, UPDATE_WAIT);
                        UFS_WAPBL_END(vp->v_mount);
                }
        }

out:
        /* Read error overrides any inode update error.  */
        if (oerror)
                error = oerror;
        return error;
}

/*
 * Vnode op for writing.
 */
int
WRITE(void *v)
{
        struct vop_write_args /* {
                struct vnode *a_vp;
                struct uio *a_uio;
                int a_ioflag;
                kauth_cred_t a_cred;
        } */ *ap = v;
        struct vnode *vp;
        struct uio *uio;
        struct inode *ip;
        FS *fs;
        kauth_cred_t cred;
        off_t osize, origoff, oldoff, preallocoff, endallocoff, nsize;
        int blkoffset, error, flags, ioflag, resid;
        int aflag;
        vsize_t bytelen;
        bool async;
        struct ufsmount *ump;
        const unsigned int fshift = ilog2(MAXPHYS);

        cred = ap->a_cred;
        ioflag = ap->a_ioflag;
        uio = ap->a_uio;
        vp = ap->a_vp;
        ip = VTOI(vp);
        ump = ip->i_ump;

        KASSERT(vp->v_size == ip->i_size);
        KASSERT(uio->uio_rw == UIO_WRITE);
        KASSERT(vp->v_type == VREG);
        KASSERT(!ISSET(ioflag, IO_JOURNALLOCKED));
        UFS_WAPBL_JUNLOCK_ASSERT(vp->v_mount);

        if (ioflag & IO_APPEND)
                uio->uio_offset = ip->i_size;
        if ((ip->i_flags & APPEND) && uio->uio_offset != ip->i_size)
                return SET_ERROR(EPERM);

        fs = ip->I_FS;
        if (uio->uio_offset < 0 ||
            (u_int64_t)uio->uio_offset + uio->uio_resid > ump->um_maxfilesize)
                return SET_ERROR(EFBIG);
        if (uio->uio_resid == 0)
                return 0;

        flags = ioflag & IO_SYNC ? B_SYNC : 0;
        async = vp->v_mount->mnt_flag & MNT_ASYNC;
        origoff = uio->uio_offset;
        resid = uio->uio_resid;
        osize = ip->i_size;
        error = 0;

        KASSERT(vp->v_type == VREG);

        /*
         * XXX The entire write operation must occur in a single WAPBL
         * transaction because it may allocate disk blocks, if
         * appending or filling holes, which is allowed to happen only
         * if the write fully succeeds.
         *
         * If ubc_uiomove fails in the middle with EFAULT, we can clean
         * up at the end with UFS_TRUNCATE.  But if the power fails in
         * the middle, there would be nobody to deallocate the blocks,
         * without an fsck to globally analyze the file system.
         *
         * If the increasingly inaccurately named WAPBL were augmented
         * with rollback records for block allocations, then we could
         * split this into multiple transactions and commit the
         * allocations in the last one.
         *
         * But WAPBL doesn't have that notion now, so we'll have to
         * live with gigantic transactions and WAPBL tentacles in
         * genfs_getpages/putpages to cope with the possibility that
         * the transaction may or may not be locked on entry to the
         * page cache.
         *
         * And even if we added that notion to WAPBL, it wouldn't help
         * us get rid of the tentacles in genfs_getpages/putpages
         * because we'd have to interoperate with old implementations
         * that assume they can replay the log without fsck.
         */
        error = UFS_WAPBL_BEGIN(vp->v_mount);
        if (error) {
                return error;
        }


        preallocoff = round_page(ufs_blkroundup(fs, MAX(osize, uio->uio_offset)));
        aflag = ioflag & IO_SYNC ? B_SYNC : 0;
        nsize = MAX(osize, uio->uio_offset + uio->uio_resid);
        endallocoff = nsize - ufs_blkoff(fs, nsize);

        /*
         * if we're increasing the file size, deal with expanding
         * the fragment if there is one.
         */

        if (nsize > osize && ufs_lblkno(fs, osize) < UFS_NDADDR &&
            ufs_lblkno(fs, osize) != ufs_lblkno(fs, nsize) &&
            ufs_blkroundup(fs, osize) != osize) {
                off_t eob;

                eob = ufs_blkroundup(fs, osize);
                uvm_vnp_setwritesize(vp, eob);
                error = ufs_balloc_range(vp, osize, eob - osize, cred, aflag);
                if (error)
                        goto out;
                if (flags & B_SYNC) {
                        rw_enter(vp->v_uobj.vmobjlock, RW_WRITER);
                        VOP_PUTPAGES(vp, trunc_page(osize & fs->fs_bmask),
                            round_page(eob),
                            PGO_CLEANIT | PGO_SYNCIO | PGO_JOURNALLOCKED);
                }
        }

        while (uio->uio_resid > 0) {
                int ubc_flags = UBC_WRITE;
                bool overwrite; /* if we're overwrite a whole block */
                off_t newoff;

                if (ioflag & IO_DIRECT) {
                        genfs_directio(vp, uio, ioflag | IO_JOURNALLOCKED);
                }

                oldoff = uio->uio_offset;
                blkoffset = ufs_blkoff(fs, uio->uio_offset);
                bytelen = MIN(fs->fs_bsize - blkoffset, uio->uio_resid);
                if (bytelen == 0) {
                        break;
                }

                /*
                 * if we're filling in a hole, allocate the blocks now and
                 * initialize the pages first.  if we're extending the file,
                 * we can safely allocate blocks without initializing pages
                 * since the new blocks will be inaccessible until the write
                 * is complete.
                 */
                overwrite = uio->uio_offset >= preallocoff &&
                    uio->uio_offset < endallocoff;
                if (!overwrite && (vp->v_vflag & VV_MAPPED) == 0 &&
                    ufs_blkoff(fs, uio->uio_offset) == 0 &&
                    (uio->uio_offset & PAGE_MASK) == 0) {
                        vsize_t len;

                        len = trunc_page(bytelen);
                        len -= ufs_blkoff(fs, len);
                        if (len > 0) {
                                overwrite = true;
                                bytelen = len;
                        }
                }

                newoff = oldoff + bytelen;
                if (vp->v_size < newoff) {
                        uvm_vnp_setwritesize(vp, newoff);
                }

                if (!overwrite) {
                        error = ufs_balloc_range(vp, uio->uio_offset, bytelen,
                            cred, aflag);
                        if (error)
                                break;
                } else {
                        genfs_node_wrlock(vp);
                        error = GOP_ALLOC(vp, uio->uio_offset, bytelen,
                            aflag, cred);
                        genfs_node_unlock(vp);
                        if (error)
                                break;
                        ubc_flags |= UBC_FAULTBUSY;
                }

                /*
                 * copy the data.
                 */

                error = ubc_uiomove(&vp->v_uobj, uio, bytelen,
                    IO_ADV_DECODE(ioflag), ubc_flags | UBC_VNODE_FLAGS(vp));

                /*
                 * update UVM's notion of the size now that we've
                 * copied the data into the vnode's pages.
                 *
                 * we should update the size even when uiomove failed.
                 */

                if (vp->v_size < newoff) {
                        uvm_vnp_setsize(vp, newoff);
                }

                if (error)
                        break;

                /*
                 * flush what we just wrote if necessary.
                 * XXXUBC simplistic async flushing.
                 */

                if (!async && oldoff >> fshift != uio->uio_offset >> fshift) {
                        rw_enter(vp->v_uobj.vmobjlock, RW_WRITER);
                        error = VOP_PUTPAGES(vp, (oldoff >> fshift) << fshift,
                            (uio->uio_offset >> fshift) << fshift,
                            PGO_CLEANIT | PGO_JOURNALLOCKED | PGO_LAZY);
                        if (error)
                                break;
                }
        }
        if (error == 0 && ioflag & IO_SYNC) {
                rw_enter(vp->v_uobj.vmobjlock, RW_WRITER);
                error = VOP_PUTPAGES(vp, trunc_page(origoff & fs->fs_bmask),
                    round_page(ufs_blkroundup(fs, uio->uio_offset)),
                    PGO_CLEANIT | PGO_SYNCIO | PGO_JOURNALLOCKED);
        }

out:
        error = ufs_post_write_update(vp, uio, ioflag, cred, osize, resid,
            error);
        UFS_WAPBL_END(vp->v_mount);

        return error;
}

/*
 * UFS op for writing via the buffer cache
 */
int
BUFWR(struct vnode *vp, struct uio *uio, int ioflag, kauth_cred_t cred)
{
        struct inode *ip;
        struct ufsmount *ump;
        FS *fs;
        int flags;
        struct buf *bp;
        off_t osize;
        int resid, xfersize, size, blkoffset;
        daddr_t lbn;
        int error;

        KASSERT(ISSET(ioflag, IO_NODELOCKED));
        KASSERT(VOP_ISLOCKED(vp) == LK_EXCLUSIVE);
        KASSERT(vp->v_type == VDIR || vp->v_type == VLNK);
        KASSERT(vp->v_type != VDIR || ISSET(ioflag, IO_SYNC));
        KASSERT(uio->uio_rw == UIO_WRITE);
        KASSERT(ISSET(ioflag, IO_JOURNALLOCKED));
        UFS_WAPBL_JLOCK_ASSERT(vp->v_mount);

        ip = VTOI(vp);
        ump = ip->i_ump;
        fs = ip->I_FS;

        KASSERT(vp->v_size == ip->i_size);

        if (uio->uio_offset < 0 ||
            uio->uio_resid > ump->um_maxfilesize ||
            uio->uio_offset > (ump->um_maxfilesize - uio->uio_resid))
                return SET_ERROR(EFBIG);
        if (uio->uio_resid == 0)
                return 0;

        flags = ioflag & IO_SYNC ? B_SYNC : 0;
        resid = uio->uio_resid;
        osize = ip->i_size;
        error = 0;

        KASSERT(vp->v_type != VREG);


        /* XXX Should never have pages cached here.  */
        KASSERT(vp->v_uobj.uo_npages == 0);
        while (uio->uio_resid > 0) {
                lbn = ufs_lblkno(fs, uio->uio_offset);
                blkoffset = ufs_blkoff(fs, uio->uio_offset);
                xfersize = MIN(fs->fs_bsize - blkoffset, uio->uio_resid);
                if (fs->fs_bsize > xfersize)
                        flags |= B_CLRBUF;
                else
                        flags &= ~B_CLRBUF;

                error = UFS_BALLOC(vp, uio->uio_offset, xfersize, cred, flags,
                    &bp);

                if (error)
                        break;
                if (uio->uio_offset + xfersize > ip->i_size) {
                        ip->i_size = uio->uio_offset + xfersize;
                        DIP_ASSIGN(ip, size, ip->i_size);
                        uvm_vnp_setsize(vp, ip->i_size);
                }
                size = ufs_blksize(fs, ip, lbn) - bp->b_resid;
                if (xfersize > size)
                        xfersize = size;

                error = uiomove((char *)bp->b_data + blkoffset, xfersize, uio);

                /*
                 * if we didn't clear the block and the uiomove failed,
                 * the buf will now contain part of some other file,
                 * so we need to invalidate it.
                 */
                if (error && (flags & B_CLRBUF) == 0) {
                        brelse(bp, BC_INVAL);
                        break;
                }
                if (ioflag & IO_SYNC)
                        (void)bwrite(bp);
                else if (xfersize + blkoffset == fs->fs_bsize)
                        bawrite(bp);
                else
                        bdwrite(bp);
                if (error || xfersize == 0)
                        break;
        }

        error = ufs_post_write_update(vp, uio, ioflag, cred, osize, resid,
            error);

        return error;
}

static int
ufs_post_write_update(struct vnode *vp, struct uio *uio, int ioflag,
    kauth_cred_t cred, off_t osize, int resid, int oerror)
{
        struct inode *ip = VTOI(vp);
        int error = oerror;

        /* Trigger ctime and mtime updates, and atime if MNT_RELATIME.  */
        ip->i_flag |= IN_CHANGE | IN_UPDATE;
        if (vp->v_mount->mnt_flag & MNT_RELATIME)
                ip->i_flag |= IN_ACCESS;

        /*
         * 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 && cred) {
                if (ip->i_mode & ISUID) {
                        if (kauth_authorize_vnode(cred,
                            KAUTH_VNODE_RETAIN_SUID, vp, NULL, EPERM) != 0) {
                                ip->i_mode &= ~ISUID;
                                DIP_ASSIGN(ip, mode, ip->i_mode);
                        }
                }

                if (ip->i_mode & ISGID) {
                        if (kauth_authorize_vnode(cred,
                            KAUTH_VNODE_RETAIN_SGID, vp, NULL, EPERM) != 0) {
                                ip->i_mode &= ~ISGID;
                                DIP_ASSIGN(ip, mode, ip->i_mode);
                        }
                }
        }

        /*
         * Update the size on disk: truncate back to original size on
         * error, or reflect the new size on success.
         */
        if (error) {
                (void) UFS_TRUNCATE(vp, osize, ioflag & IO_SYNC, cred);
                uio->uio_offset -= resid - uio->uio_resid;
                uio->uio_resid = resid;
        } else if (resid > uio->uio_resid && (ioflag & IO_SYNC) == IO_SYNC)
                error = UFS_UPDATE(vp, NULL, NULL, UPDATE_WAIT);
        else
                UFS_WAPBL_UPDATE(vp, NULL, NULL, 0);

        /* Make sure the vnode uvm size matches the inode file size.  */
        KASSERT(vp->v_size == ip->i_size);

        /* Write error overrides any inode update error.  */
        if (oerror)
                error = oerror;
        return error;
}