uml: speed up page table walking

[pv_ops_mirror.git] / fs / xfs / xfs_rw.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_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_inode_item.h"
#include "xfs_itable.h"
#include "xfs_btree.h"
#include "xfs_alloc.h"
#include "xfs_ialloc.h"
#include "xfs_attr.h"
#include "xfs_bmap.h"
#include "xfs_acl.h"
#include "xfs_error.h"
#include "xfs_buf_item.h"
#include "xfs_rw.h"

/*
 * This is a subroutine for xfs_write() and other writers (xfs_ioctl)
 * which clears the setuid and setgid bits when a file is written.
 */
int
xfs_write_clear_setuid(
        xfs_inode_t     *ip)
{
        xfs_mount_t     *mp;
        xfs_trans_t     *tp;
        int             error;

        mp = ip->i_mount;
        tp = xfs_trans_alloc(mp, XFS_TRANS_WRITEID);
        if ((error = xfs_trans_reserve(tp, 0,
                                      XFS_WRITEID_LOG_RES(mp),
                                      0, 0, 0))) {
                xfs_trans_cancel(tp, 0);
                return error;
        }
        xfs_ilock(ip, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
        xfs_trans_ihold(tp, ip);
        ip->i_d.di_mode &= ~S_ISUID;

        /*
         * Note that we don't have to worry about mandatory
         * file locking being disabled here because we only
         * clear the S_ISGID bit if the Group execute bit is
         * on, but if it was on then mandatory locking wouldn't
         * have been enabled.
         */
        if (ip->i_d.di_mode & S_IXGRP) {
                ip->i_d.di_mode &= ~S_ISGID;
        }
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        xfs_trans_set_sync(tp);
        error = xfs_trans_commit(tp, 0, NULL);
        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        return 0;
}

/*
 * Handle logging requirements of various synchronous types of write.
 */
int
xfs_write_sync_logforce(
        xfs_mount_t     *mp,
        xfs_inode_t     *ip)
{
        int             error = 0;

        /*
         * If we're treating this as O_DSYNC and we have not updated the
         * size, force the log.
         */
        if (!(mp->m_flags & XFS_MOUNT_OSYNCISOSYNC) &&
            !(ip->i_update_size)) {
                xfs_inode_log_item_t    *iip = ip->i_itemp;

                /*
                 * If an allocation transaction occurred
                 * without extending the size, then we have to force
                 * the log up the proper point to ensure that the
                 * allocation is permanent.  We can't count on
                 * the fact that buffered writes lock out direct I/O
                 * writes - the direct I/O write could have extended
                 * the size nontransactionally, then finished before
                 * we started.  xfs_write_file will think that the file
                 * didn't grow but the update isn't safe unless the
                 * size change is logged.
                 *
                 * Force the log if we've committed a transaction
                 * against the inode or if someone else has and
                 * the commit record hasn't gone to disk (e.g.
                 * the inode is pinned).  This guarantees that
                 * all changes affecting the inode are permanent
                 * when we return.
                 */
                if (iip && iip->ili_last_lsn) {
                        xfs_log_force(mp, iip->ili_last_lsn,
                                        XFS_LOG_FORCE | XFS_LOG_SYNC);
                } else if (xfs_ipincount(ip) > 0) {
                        xfs_log_force(mp, (xfs_lsn_t)0,
                                        XFS_LOG_FORCE | XFS_LOG_SYNC);
                }

        } else {
                xfs_trans_t     *tp;

                /*
                 * O_SYNC or O_DSYNC _with_ a size update are handled
                 * the same way.
                 *
                 * If the write was synchronous then we need to make
                 * sure that the inode modification time is permanent.
                 * We'll have updated the timestamp above, so here
                 * we use a synchronous transaction to log the inode.
                 * It's not fast, but it's necessary.
                 *
                 * If this a dsync write and the size got changed
                 * non-transactionally, then we need to ensure that
                 * the size change gets logged in a synchronous
                 * transaction.
                 */
                tp = xfs_trans_alloc(mp, XFS_TRANS_WRITE_SYNC);
                if ((error = xfs_trans_reserve(tp, 0,
                                                XFS_SWRITE_LOG_RES(mp),
                                                0, 0, 0))) {
                        /* Transaction reserve failed */
                        xfs_trans_cancel(tp, 0);
                } else {
                        /* Transaction reserve successful */
                        xfs_ilock(ip, XFS_ILOCK_EXCL);
                        xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
                        xfs_trans_ihold(tp, ip);
                        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
                        xfs_trans_set_sync(tp);
                        error = xfs_trans_commit(tp, 0, NULL);
                        xfs_iunlock(ip, XFS_ILOCK_EXCL);
                }
        }

        return error;
}

/*
 * Force a shutdown of the filesystem instantly while keeping
 * the filesystem consistent. We don't do an unmount here; just shutdown
 * the shop, make sure that absolutely nothing persistent happens to
 * this filesystem after this point.
 */

void
xfs_do_force_shutdown(
        bhv_desc_t      *bdp,
        int             flags,
        char            *fname,
        int             lnnum)
{
        int             logerror;
        xfs_mount_t     *mp;

        mp = XFS_BHVTOM(bdp);
        logerror = flags & SHUTDOWN_LOG_IO_ERROR;

        if (!(flags & SHUTDOWN_FORCE_UMOUNT)) {
                cmn_err(CE_NOTE, "xfs_force_shutdown(%s,0x%x) called from "
                                 "line %d of file %s.  Return address = 0x%p",
                        mp->m_fsname, flags, lnnum, fname, __return_address);
        }
        /*
         * No need to duplicate efforts.
         */
        if (XFS_FORCED_SHUTDOWN(mp) && !logerror)
                return;

        /*
         * This flags XFS_MOUNT_FS_SHUTDOWN, makes sure that we don't
         * queue up anybody new on the log reservations, and wakes up
         * everybody who's sleeping on log reservations to tell them
         * the bad news.
         */
        if (xfs_log_force_umount(mp, logerror))
                return;

        if (flags & SHUTDOWN_CORRUPT_INCORE) {
                xfs_cmn_err(XFS_PTAG_SHUTDOWN_CORRUPT, CE_ALERT, mp,
    "Corruption of in-memory data detected.  Shutting down filesystem: %s",
                        mp->m_fsname);
                if (XFS_ERRLEVEL_HIGH <= xfs_error_level) {
                        xfs_stack_trace();
                }
        } else if (!(flags & SHUTDOWN_FORCE_UMOUNT)) {
                if (logerror) {
                        xfs_cmn_err(XFS_PTAG_SHUTDOWN_LOGERROR, CE_ALERT, mp,
                "Log I/O Error Detected.  Shutting down filesystem: %s",
                                mp->m_fsname);
                } else if (flags & SHUTDOWN_DEVICE_REQ) {
                        xfs_cmn_err(XFS_PTAG_SHUTDOWN_IOERROR, CE_ALERT, mp,
                "All device paths lost.  Shutting down filesystem: %s",
                                mp->m_fsname);
                } else if (!(flags & SHUTDOWN_REMOTE_REQ)) {
                        xfs_cmn_err(XFS_PTAG_SHUTDOWN_IOERROR, CE_ALERT, mp,
                "I/O Error Detected.  Shutting down filesystem: %s",
                                mp->m_fsname);
                }
        }
        if (!(flags & SHUTDOWN_FORCE_UMOUNT)) {
                cmn_err(CE_ALERT, "Please umount the filesystem, "
                                  "and rectify the problem(s)");
        }
}


/*
 * Called when we want to stop a buffer from getting written or read.
 * We attach the EIO error, muck with its flags, and call biodone
 * so that the proper iodone callbacks get called.
 */
int
xfs_bioerror(
        xfs_buf_t *bp)
{

#ifdef XFSERRORDEBUG
        ASSERT(XFS_BUF_ISREAD(bp) || bp->b_iodone);
#endif

        /*
         * No need to wait until the buffer is unpinned.
         * We aren't flushing it.
         */
        xfs_buftrace("XFS IOERROR", bp);
        XFS_BUF_ERROR(bp, EIO);
        /*
         * We're calling biodone, so delete B_DONE flag. Either way
         * we have to call the iodone callback, and calling biodone
         * probably is the best way since it takes care of
         * GRIO as well.
         */
        XFS_BUF_UNREAD(bp);
        XFS_BUF_UNDELAYWRITE(bp);
        XFS_BUF_UNDONE(bp);
        XFS_BUF_STALE(bp);

        XFS_BUF_CLR_BDSTRAT_FUNC(bp);
        xfs_biodone(bp);

        return (EIO);
}

/*
 * Same as xfs_bioerror, except that we are releasing the buffer
 * here ourselves, and avoiding the biodone call.
 * This is meant for userdata errors; metadata bufs come with
 * iodone functions attached, so that we can track down errors.
 */
int
xfs_bioerror_relse(
        xfs_buf_t *bp)
{
        int64_t fl;

        ASSERT(XFS_BUF_IODONE_FUNC(bp) != xfs_buf_iodone_callbacks);
        ASSERT(XFS_BUF_IODONE_FUNC(bp) != xlog_iodone);

        xfs_buftrace("XFS IOERRELSE", bp);
        fl = XFS_BUF_BFLAGS(bp);
        /*
         * No need to wait until the buffer is unpinned.
         * We aren't flushing it.
         *
         * chunkhold expects B_DONE to be set, whether
         * we actually finish the I/O or not. We don't want to
         * change that interface.
         */
        XFS_BUF_UNREAD(bp);
        XFS_BUF_UNDELAYWRITE(bp);
        XFS_BUF_DONE(bp);
        XFS_BUF_STALE(bp);
        XFS_BUF_CLR_IODONE_FUNC(bp);
        XFS_BUF_CLR_BDSTRAT_FUNC(bp);
        if (!(fl & XFS_B_ASYNC)) {
                /*
                 * Mark b_error and B_ERROR _both_.
                 * Lot's of chunkcache code assumes that.
                 * There's no reason to mark error for
                 * ASYNC buffers.
                 */
                XFS_BUF_ERROR(bp, EIO);
                XFS_BUF_V_IODONESEMA(bp);
        } else {
                xfs_buf_relse(bp);
        }
        return (EIO);
}

/*
 * Prints out an ALERT message about I/O error.
 */
void
xfs_ioerror_alert(
        char                    *func,
        struct xfs_mount        *mp,
        xfs_buf_t               *bp,
        xfs_daddr_t             blkno)
{
        cmn_err(CE_ALERT,
 "I/O error in filesystem (\"%s\") meta-data dev %s block 0x%llx"
 "       (\"%s\") error %d buf count %zd",
                (!mp || !mp->m_fsname) ? "(fs name not set)" : mp->m_fsname,
                XFS_BUFTARG_NAME(XFS_BUF_TARGET(bp)),
                (__uint64_t)blkno, func,
                XFS_BUF_GETERROR(bp), XFS_BUF_COUNT(bp));
}

/*
 * This isn't an absolute requirement, but it is
 * just a good idea to call xfs_read_buf instead of
 * directly doing a read_buf call. For one, we shouldn't
 * be doing this disk read if we are in SHUTDOWN state anyway,
 * so this stops that from happening. Secondly, this does all
 * the error checking stuff and the brelse if appropriate for
 * the caller, so the code can be a little leaner.
 */

int
xfs_read_buf(
        struct xfs_mount *mp,
        xfs_buftarg_t    *target,
        xfs_daddr_t      blkno,
        int              len,
        uint             flags,
        xfs_buf_t        **bpp)
{
        xfs_buf_t        *bp;
        int              error;

        if (flags)
                bp = xfs_buf_read_flags(target, blkno, len, flags);
        else
                bp = xfs_buf_read(target, blkno, len, flags);
        if (!bp)
                return XFS_ERROR(EIO);
        error = XFS_BUF_GETERROR(bp);
        if (bp && !error && !XFS_FORCED_SHUTDOWN(mp)) {
                *bpp = bp;
        } else {
                *bpp = NULL;
                if (error) {
                        xfs_ioerror_alert("xfs_read_buf", mp, bp, XFS_BUF_ADDR(bp));
                } else {
                        error = XFS_ERROR(EIO);
                }
                if (bp) {
                        XFS_BUF_UNDONE(bp);
                        XFS_BUF_UNDELAYWRITE(bp);
                        XFS_BUF_STALE(bp);
                        /*
                         * brelse clears B_ERROR and b_error
                         */
                        xfs_buf_relse(bp);
                }
        }
        return (error);
}

/*
 * Wrapper around bwrite() so that we can trap
 * write errors, and act accordingly.
 */
int
xfs_bwrite(
        struct xfs_mount *mp,
        struct xfs_buf   *bp)
{
        int     error;

        /*
         * XXXsup how does this work for quotas.
         */
        XFS_BUF_SET_BDSTRAT_FUNC(bp, xfs_bdstrat_cb);
        XFS_BUF_SET_FSPRIVATE3(bp, mp);
        XFS_BUF_WRITE(bp);

        if ((error = XFS_bwrite(bp))) {
                ASSERT(mp);
                /*
                 * Cannot put a buftrace here since if the buffer is not
                 * B_HOLD then we will brelse() the buffer before returning
                 * from bwrite and we could be tracing a buffer that has
                 * been reused.
                 */
                xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
        }
        return (error);
}