NFC: Fix next target_idx type and rename for clarity

[linux-2.6.git] / fs / xfs / xfs_dfrag.c

/*
 * 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_bit.h"
#include "xfs_log.h"
#include "xfs_inum.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 file     *file, *tmp_file;
        int             error = 0;

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

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

        tmp_file = fget((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(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(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:
        fput(tmp_file);
 out_put_file:
        fput(file);
 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;
}