xfs_dfrag.c

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/*
 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_inode_item.h"
#include "xfs_bmap.h"
#include "xfs_itable.h"
#include "xfs_dfrag.h"
#include "xfs_error.h"
#include "xfs_vnodeops.h"
#include "xfs_trace.h"


static int xfs_swap_extents(
    xfs_inode_t *ip,    /* target inode */
    xfs_inode_t *tip,   /* tmp inode */
    xfs_swapext_t   *sxp);

/*
 * ioctl interface for swapext
 */
int
xfs_swapext(
    xfs_swapext_t   *sxp)
{
    xfs_inode_t     *ip, *tip;
    struct fd   f, tmp;
    int     error = 0;

    /* Pull information for the target fd */
    f = fdget((int)sxp->sx_fdtarget);
    if (!f.file) {
        error = XFS_ERROR(EINVAL);
        goto out;
    }

    if (!(f.file->f_mode & FMODE_WRITE) ||
        !(f.file->f_mode & FMODE_READ) ||
        (f.file->f_flags & O_APPEND)) {
        error = XFS_ERROR(EBADF);
        goto out_put_file;
    }

    tmp = fdget((int)sxp->sx_fdtmp);
    if (!tmp.file) {
        error = XFS_ERROR(EINVAL);
        goto out_put_file;
    }

    if (!(tmp.file->f_mode & FMODE_WRITE) ||
        !(tmp.file->f_mode & FMODE_READ) ||
        (tmp.file->f_flags & O_APPEND)) {
        error = XFS_ERROR(EBADF);
        goto out_put_tmp_file;
    }

    if (IS_SWAPFILE(f.file->f_path.dentry->d_inode) ||
        IS_SWAPFILE(tmp.file->f_path.dentry->d_inode)) {
        error = XFS_ERROR(EINVAL);
        goto out_put_tmp_file;
    }

    ip = XFS_I(f.file->f_path.dentry->d_inode);
    tip = XFS_I(tmp.file->f_path.dentry->d_inode);

    if (ip->i_mount != tip->i_mount) {
        error = XFS_ERROR(EINVAL);
        goto out_put_tmp_file;
    }

    if (ip->i_ino == tip->i_ino) {
        error = XFS_ERROR(EINVAL);
        goto out_put_tmp_file;
    }

    if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
        error = XFS_ERROR(EIO);
        goto out_put_tmp_file;
    }

    error = xfs_swap_extents(ip, tip, sxp);

 out_put_tmp_file:
    fdput(tmp);
 out_put_file:
    fdput(f);
 out:
    return error;
}

/*
 * We need to check that the format of the data fork in the temporary inode is
 * valid for the target inode before doing the swap. This is not a problem with
 * attr1 because of the fixed fork offset, but attr2 has a dynamically sized
 * data fork depending on the space the attribute fork is taking so we can get
 * invalid formats on the target inode.
 *
 * E.g. target has space for 7 extents in extent format, temp inode only has
 * space for 6.  If we defragment down to 7 extents, then the tmp format is a
 * btree, but when swapped it needs to be in extent format. Hence we can't just
 * blindly swap data forks on attr2 filesystems.
 *
 * Note that we check the swap in both directions so that we don't end up with
 * a corrupt temporary inode, either.
 *
 * Note that fixing the way xfs_fsr sets up the attribute fork in the source
 * inode will prevent this situation from occurring, so all we do here is
 * reject and log the attempt. basically we are putting the responsibility on
 * userspace to get this right.
 */
static int
xfs_swap_extents_check_format(
    xfs_inode_t *ip,    /* target inode */
    xfs_inode_t *tip)   /* tmp inode */
{

    /* Should never get a local format */
    if (ip->i_d.di_format == XFS_DINODE_FMT_LOCAL ||
        tip->i_d.di_format == XFS_DINODE_FMT_LOCAL)
        return EINVAL;

    /*
     * if the target inode has less extents that then temporary inode then
     * why did userspace call us?
     */
    if (ip->i_d.di_nextents < tip->i_d.di_nextents)
        return EINVAL;

    /*
     * if the target inode is in extent form and the temp inode is in btree
     * form then we will end up with the target inode in the wrong format
     * as we already know there are less extents in the temp inode.
     */
    if (ip->i_d.di_format == XFS_DINODE_FMT_EXTENTS &&
        tip->i_d.di_format == XFS_DINODE_FMT_BTREE)
        return EINVAL;

    /* Check temp in extent form to max in target */
    if (tip->i_d.di_format == XFS_DINODE_FMT_EXTENTS &&
        XFS_IFORK_NEXTENTS(tip, XFS_DATA_FORK) >
            XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK))
        return EINVAL;

    /* Check target in extent form to max in temp */
    if (ip->i_d.di_format == XFS_DINODE_FMT_EXTENTS &&
        XFS_IFORK_NEXTENTS(ip, XFS_DATA_FORK) >
            XFS_IFORK_MAXEXT(tip, XFS_DATA_FORK))
        return EINVAL;

    /*
     * If we are in a btree format, check that the temp root block will fit
     * in the target and that it has enough extents to be in btree format
     * in the target.
     *
     * Note that we have to be careful to allow btree->extent conversions
     * (a common defrag case) which will occur when the temp inode is in
     * extent format...
     */
    if (tip->i_d.di_format == XFS_DINODE_FMT_BTREE) {
        if (XFS_IFORK_BOFF(ip) &&
            tip->i_df.if_broot_bytes > XFS_IFORK_BOFF(ip))
            return EINVAL;
        if (XFS_IFORK_NEXTENTS(tip, XFS_DATA_FORK) <=
            XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK))
            return EINVAL;
    }

    /* Reciprocal target->temp btree format checks */
    if (ip->i_d.di_format == XFS_DINODE_FMT_BTREE) {
        if (XFS_IFORK_BOFF(tip) &&
            ip->i_df.if_broot_bytes > XFS_IFORK_BOFF(tip))
            return EINVAL;

        if (XFS_IFORK_NEXTENTS(ip, XFS_DATA_FORK) <=
            XFS_IFORK_MAXEXT(tip, XFS_DATA_FORK))
            return EINVAL;
    }

    return 0;
}

static int
xfs_swap_extents(
    xfs_inode_t *ip,    /* target inode */
    xfs_inode_t *tip,   /* tmp inode */
    xfs_swapext_t   *sxp)
{
    xfs_mount_t *mp = ip->i_mount;
    xfs_trans_t *tp;
    xfs_bstat_t *sbp = &sxp->sx_stat;
    xfs_ifork_t *tempifp, *ifp, *tifp;
    int     src_log_flags, target_log_flags;
    int     error = 0;
    int     aforkblks = 0;
    int     taforkblks = 0;
    __uint64_t  tmp;

    tempifp = kmem_alloc(sizeof(xfs_ifork_t), KM_MAYFAIL);
    if (!tempifp) {
        error = XFS_ERROR(ENOMEM);
        goto out;
    }

    /*
     * we have to do two separate lock calls here to keep lockdep
     * happy. If we try to get all the locks in one call, lock will
     * report false positives when we drop the ILOCK and regain them
     * below.
     */
    xfs_lock_two_inodes(ip, tip, XFS_IOLOCK_EXCL);
    xfs_lock_two_inodes(ip, tip, XFS_ILOCK_EXCL);

    /* Verify that both files have the same format */
    if ((ip->i_d.di_mode & S_IFMT) != (tip->i_d.di_mode & S_IFMT)) {
        error = XFS_ERROR(EINVAL);
        goto out_unlock;
    }

    /* Verify both files are either real-time or non-realtime */
    if (XFS_IS_REALTIME_INODE(ip) != XFS_IS_REALTIME_INODE(tip)) {
        error = XFS_ERROR(EINVAL);
        goto out_unlock;
    }

    if (VN_CACHED(VFS_I(tip)) != 0) {
        error = xfs_flushinval_pages(tip, 0, -1,
                FI_REMAPF_LOCKED);
        if (error)
            goto out_unlock;
    }

    /* Verify O_DIRECT for ftmp */
    if (VN_CACHED(VFS_I(tip)) != 0) {
        error = XFS_ERROR(EINVAL);
        goto out_unlock;
    }

    /* Verify all data are being swapped */
    if (sxp->sx_offset != 0 ||
        sxp->sx_length != ip->i_d.di_size ||
        sxp->sx_length != tip->i_d.di_size) {
        error = XFS_ERROR(EFAULT);
        goto out_unlock;
    }

    trace_xfs_swap_extent_before(ip, 0);
    trace_xfs_swap_extent_before(tip, 1);

    /* check inode formats now that data is flushed */
    error = xfs_swap_extents_check_format(ip, tip);
    if (error) {
        xfs_notice(mp,
            "%s: inode 0x%llx format is incompatible for exchanging.",
                __func__, ip->i_ino);
        goto out_unlock;
    }

    /*
     * Compare the current change & modify times with that
     * passed in.  If they differ, we abort this swap.
     * This is the mechanism used to ensure the calling
     * process that the file was not changed out from
     * under it.
     */
    if ((sbp->bs_ctime.tv_sec != VFS_I(ip)->i_ctime.tv_sec) ||
        (sbp->bs_ctime.tv_nsec != VFS_I(ip)->i_ctime.tv_nsec) ||
        (sbp->bs_mtime.tv_sec != VFS_I(ip)->i_mtime.tv_sec) ||
        (sbp->bs_mtime.tv_nsec != VFS_I(ip)->i_mtime.tv_nsec)) {
        error = XFS_ERROR(EBUSY);
        goto out_unlock;
    }

    /* We need to fail if the file is memory mapped.  Once we have tossed
     * all existing pages, the page fault will have no option
     * but to go to the filesystem for pages. By making the page fault call
     * vop_read (or write in the case of autogrow) they block on the iolock
     * until we have switched the extents.
     */
    if (VN_MAPPED(VFS_I(ip))) {
        error = XFS_ERROR(EBUSY);
        goto out_unlock;
    }

    xfs_iunlock(ip, XFS_ILOCK_EXCL);
    xfs_iunlock(tip, XFS_ILOCK_EXCL);

    /*
     * There is a race condition here since we gave up the
     * ilock.  However, the data fork will not change since
     * we have the iolock (locked for truncation too) so we
     * are safe.  We don't really care if non-io related
     * fields change.
     */

    xfs_tosspages(ip, 0, -1, FI_REMAPF);

    tp = xfs_trans_alloc(mp, XFS_TRANS_SWAPEXT);
    if ((error = xfs_trans_reserve(tp, 0,
                     XFS_ICHANGE_LOG_RES(mp), 0,
                     0, 0))) {
        xfs_iunlock(ip,  XFS_IOLOCK_EXCL);
        xfs_iunlock(tip, XFS_IOLOCK_EXCL);
        xfs_trans_cancel(tp, 0);
        goto out;
    }
    xfs_lock_two_inodes(ip, tip, XFS_ILOCK_EXCL);

    /*
     * Count the number of extended attribute blocks
     */
    if ( ((XFS_IFORK_Q(ip) != 0) && (ip->i_d.di_anextents > 0)) &&
         (ip->i_d.di_aformat != XFS_DINODE_FMT_LOCAL)) {
        error = xfs_bmap_count_blocks(tp, ip, XFS_ATTR_FORK, &aforkblks);
        if (error)
            goto out_trans_cancel;
    }
    if ( ((XFS_IFORK_Q(tip) != 0) && (tip->i_d.di_anextents > 0)) &&
         (tip->i_d.di_aformat != XFS_DINODE_FMT_LOCAL)) {
        error = xfs_bmap_count_blocks(tp, tip, XFS_ATTR_FORK,
            &taforkblks);
        if (error)
            goto out_trans_cancel;
    }

    /*
     * Swap the data forks of the inodes
     */
    ifp = &ip->i_df;
    tifp = &tip->i_df;
    *tempifp = *ifp;    /* struct copy */
    *ifp = *tifp;       /* struct copy */
    *tifp = *tempifp;   /* struct copy */

    /*
     * Fix the on-disk inode values
     */
    tmp = (__uint64_t)ip->i_d.di_nblocks;
    ip->i_d.di_nblocks = tip->i_d.di_nblocks - taforkblks + aforkblks;
    tip->i_d.di_nblocks = tmp + taforkblks - aforkblks;

    tmp = (__uint64_t) ip->i_d.di_nextents;
    ip->i_d.di_nextents = tip->i_d.di_nextents;
    tip->i_d.di_nextents = tmp;

    tmp = (__uint64_t) ip->i_d.di_format;
    ip->i_d.di_format = tip->i_d.di_format;
    tip->i_d.di_format = tmp;

    /*
     * The extents in the source inode could still contain speculative
     * preallocation beyond EOF (e.g. the file is open but not modified
     * while defrag is in progress). In that case, we need to copy over the
     * number of delalloc blocks the data fork in the source inode is
     * tracking beyond EOF so that when the fork is truncated away when the
     * temporary inode is unlinked we don't underrun the i_delayed_blks
     * counter on that inode.
     */
    ASSERT(tip->i_delayed_blks == 0);
    tip->i_delayed_blks = ip->i_delayed_blks;
    ip->i_delayed_blks = 0;

    src_log_flags = XFS_ILOG_CORE;
    switch (ip->i_d.di_format) {
    case XFS_DINODE_FMT_EXTENTS:
        /* If the extents fit in the inode, fix the
         * pointer.  Otherwise it's already NULL or
         * pointing to the extent.
         */
        if (ip->i_d.di_nextents <= XFS_INLINE_EXTS) {
            ifp->if_u1.if_extents =
                ifp->if_u2.if_inline_ext;
        }
        src_log_flags |= XFS_ILOG_DEXT;
        break;
    case XFS_DINODE_FMT_BTREE:
        src_log_flags |= XFS_ILOG_DBROOT;
        break;
    }

    target_log_flags = XFS_ILOG_CORE;
    switch (tip->i_d.di_format) {
    case XFS_DINODE_FMT_EXTENTS:
        /* If the extents fit in the inode, fix the
         * pointer.  Otherwise it's already NULL or
         * pointing to the extent.
         */
        if (tip->i_d.di_nextents <= XFS_INLINE_EXTS) {
            tifp->if_u1.if_extents =
                tifp->if_u2.if_inline_ext;
        }
        target_log_flags |= XFS_ILOG_DEXT;
        break;
    case XFS_DINODE_FMT_BTREE:
        target_log_flags |= XFS_ILOG_DBROOT;
        break;
    }


    xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
    xfs_trans_ijoin(tp, tip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);

    xfs_trans_log_inode(tp, ip,  src_log_flags);
    xfs_trans_log_inode(tp, tip, target_log_flags);

    /*
     * If this is a synchronous mount, make sure that the
     * transaction goes to disk before returning to the user.
     */
    if (mp->m_flags & XFS_MOUNT_WSYNC)
        xfs_trans_set_sync(tp);

    error = xfs_trans_commit(tp, 0);

    trace_xfs_swap_extent_after(ip, 0);
    trace_xfs_swap_extent_after(tip, 1);
out:
    kmem_free(tempifp);
    return error;

out_unlock:
    xfs_iunlock(ip,  XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
    xfs_iunlock(tip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
    goto out;

out_trans_cancel:
    xfs_trans_cancel(tp, 0);
    goto out_unlock;
}