dmu_diff.c

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/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include <sys/dmu.h>
#include <sys/dmu_impl.h>
#include <sys/dmu_tx.h>
#include <sys/dbuf.h>
#include <sys/dnode.h>
#include <sys/zfs_context.h>
#include <sys/dmu_objset.h>
#include <sys/dmu_traverse.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_pool.h>
#include <sys/dsl_synctask.h>
#include <sys/zfs_ioctl.h>
#include <sys/zap.h>
#include <sys/zio_checksum.h>
#include <sys/zfs_znode.h>

struct diffarg {
        struct file *da_fp;             /* file to which we are reporting */
        offset_t *da_offp;
        int da_err;                     /* error that stopped diff search */
        dmu_diff_record_t da_ddr;
        kthread_t *da_td;
};

static int
write_bytes(struct diffarg *da)
{
        struct uio auio;
        struct iovec aiov;

        aiov.iov_base = (caddr_t)&da->da_ddr;
        aiov.iov_len = sizeof (da->da_ddr);
        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        auio.uio_resid = aiov.iov_len;
        auio.uio_segflg = UIO_SYSSPACE;
        auio.uio_rw = UIO_WRITE;
        auio.uio_offset = (off_t)-1;
        auio.uio_td = da->da_td;
#ifdef _KERNEL
        if (da->da_fp->f_type == DTYPE_VNODE)
                bwillwrite();
        return (fo_write(da->da_fp, &auio, da->da_td->td_ucred, 0, da->da_td));
#else
        fprintf(stderr, "%s: returning EOPNOTSUPP\n", __func__);
        return (EOPNOTSUPP);
#endif
}

static int
write_record(struct diffarg *da)
{

        if (da->da_ddr.ddr_type == DDR_NONE) {
                da->da_err = 0;
                return (0);
        }

        da->da_err = write_bytes(da);
        *da->da_offp += sizeof (da->da_ddr);
        return (da->da_err);
}

static int
report_free_dnode_range(struct diffarg *da, uint64_t first, uint64_t last)
{
        ASSERT(first <= last);
        if (da->da_ddr.ddr_type != DDR_FREE ||
            first != da->da_ddr.ddr_last + 1) {
                if (write_record(da) != 0)
                        return (da->da_err);
                da->da_ddr.ddr_type = DDR_FREE;
                da->da_ddr.ddr_first = first;
                da->da_ddr.ddr_last = last;
                return (0);
        }
        da->da_ddr.ddr_last = last;
        return (0);
}

static int
report_dnode(struct diffarg *da, uint64_t object, dnode_phys_t *dnp)
{
        ASSERT(dnp != NULL);
        if (dnp->dn_type == DMU_OT_NONE)
                return (report_free_dnode_range(da, object, object));

        if (da->da_ddr.ddr_type != DDR_INUSE ||
            object != da->da_ddr.ddr_last + 1) {
                if (write_record(da) != 0)
                        return (da->da_err);
                da->da_ddr.ddr_type = DDR_INUSE;
                da->da_ddr.ddr_first = da->da_ddr.ddr_last = object;
                return (0);
        }
        da->da_ddr.ddr_last = object;
        return (0);
}

#define DBP_SPAN(dnp, level)                              \
        (((uint64_t)dnp->dn_datablkszsec) << (SPA_MINBLOCKSHIFT + \
        (level) * (dnp->dn_indblkshift - SPA_BLKPTRSHIFT)))

/* ARGSUSED */
static int
diff_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp, arc_buf_t *pbuf,
    const zbookmark_t *zb, const dnode_phys_t *dnp, void *arg)
{
        struct diffarg *da = arg;
        int err = 0;

        if (issig(JUSTLOOKING) && issig(FORREAL))
                return (EINTR);

        if (zb->zb_object != DMU_META_DNODE_OBJECT)
                return (0);

        if (bp == NULL) {
                uint64_t span = DBP_SPAN(dnp, zb->zb_level);
                uint64_t dnobj = (zb->zb_blkid * span) >> DNODE_SHIFT;

                err = report_free_dnode_range(da, dnobj,
                    dnobj + (span >> DNODE_SHIFT) - 1);
                if (err)
                        return (err);
        } else if (zb->zb_level == 0) {
                dnode_phys_t *blk;
                arc_buf_t *abuf;
                uint32_t aflags = ARC_WAIT;
                int blksz = BP_GET_LSIZE(bp);
                int i;

                if (dsl_read(NULL, spa, bp, pbuf,
                    arc_getbuf_func, &abuf, ZIO_PRIORITY_ASYNC_READ,
                    ZIO_FLAG_CANFAIL, &aflags, zb) != 0)
                        return (EIO);

                blk = abuf->b_data;
                for (i = 0; i < blksz >> DNODE_SHIFT; i++) {
                        uint64_t dnobj = (zb->zb_blkid <<
                            (DNODE_BLOCK_SHIFT - DNODE_SHIFT)) + i;
                        err = report_dnode(da, dnobj, blk+i);
                        if (err)
                                break;
                }
                (void) arc_buf_remove_ref(abuf, &abuf);
                if (err)
                        return (err);
                /* Don't care about the data blocks */
                return (TRAVERSE_VISIT_NO_CHILDREN);
        }
        return (0);
}

int
dmu_diff(objset_t *tosnap, objset_t *fromsnap, struct file *fp, offset_t *offp)
{
        struct diffarg da;
        dsl_dataset_t *ds = tosnap->os_dsl_dataset;
        dsl_dataset_t *fromds = fromsnap->os_dsl_dataset;
        dsl_dataset_t *findds;
        dsl_dataset_t *relds;
        int err = 0;

        /* make certain we are looking at snapshots */
        if (!dsl_dataset_is_snapshot(ds) || !dsl_dataset_is_snapshot(fromds))
                return (EINVAL);

        /* fromsnap must be earlier and from the same lineage as tosnap */
        if (fromds->ds_phys->ds_creation_txg >= ds->ds_phys->ds_creation_txg)
                return (EXDEV);

        relds = NULL;
        findds = ds;

        while (fromds->ds_dir != findds->ds_dir) {
                dsl_pool_t *dp = ds->ds_dir->dd_pool;

                if (!dsl_dir_is_clone(findds->ds_dir)) {
                        if (relds)
                                dsl_dataset_rele(relds, FTAG);
                        return (EXDEV);
                }

                rw_enter(&dp->dp_config_rwlock, RW_READER);
                err = dsl_dataset_hold_obj(dp,
                    findds->ds_dir->dd_phys->dd_origin_obj, FTAG, &findds);
                rw_exit(&dp->dp_config_rwlock);

                if (relds)
                        dsl_dataset_rele(relds, FTAG);

                if (err)
                        return (EXDEV);

                relds = findds;
        }

        if (relds)
                dsl_dataset_rele(relds, FTAG);

        da.da_fp = fp;
        da.da_offp = offp;
        da.da_ddr.ddr_type = DDR_NONE;
        da.da_ddr.ddr_first = da.da_ddr.ddr_last = 0;
        da.da_err = 0;
        da.da_td = curthread;

        err = traverse_dataset(ds, fromds->ds_phys->ds_creation_txg,
            TRAVERSE_PRE | TRAVERSE_PREFETCH_METADATA, diff_cb, &da);

        if (err) {
                da.da_err = err;
        } else {
                /* we set the da.da_err we return as side-effect */
                (void) write_record(&da);
        }

        return (da.da_err);
}