[safe/jmp/linux-2.6] / fs / xfs / linux-2.6 / xfs_sync.c

/*
 * Copyright (c) 2000-2005 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_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_inode.h"
#include "xfs_dinode.h"
#include "xfs_error.h"
#include "xfs_mru_cache.h"
#include "xfs_filestream.h"
#include "xfs_vnodeops.h"
#include "xfs_utils.h"
#include "xfs_buf_item.h"
#include "xfs_inode_item.h"
#include "xfs_rw.h"

#include <linux/kthread.h>
#include <linux/freezer.h>

/*
 * Sync all the inodes in the given AG according to the
 * direction given by the flags.
 */
STATIC int
xfs_sync_inodes_ag(
        xfs_mount_t     *mp,
        int             ag,
        int             flags)
{
        xfs_perag_t     *pag = &mp->m_perag[ag];
        int             nr_found;
        int             first_index = 0;
        int             error = 0;
        int             last_error = 0;
        int             fflag = XFS_B_ASYNC;
        int             lock_flags = XFS_ILOCK_SHARED;

        if (flags & SYNC_DELWRI)
                fflag = XFS_B_DELWRI;
        if (flags & SYNC_WAIT)
                fflag = 0;              /* synchronous overrides all */

        if (flags & SYNC_DELWRI) {
                /*
                 * We need the I/O lock if we're going to call any of
                 * the flush/inval routines.
                 */
                lock_flags |= XFS_IOLOCK_SHARED;
        }

        do {
                struct inode    *inode;
                boolean_t       inode_refed;
                xfs_inode_t     *ip = NULL;

                /*
                 * use a gang lookup to find the next inode in the tree
                 * as the tree is sparse and a gang lookup walks to find
                 * the number of objects requested.
                 */
                read_lock(&pag->pag_ici_lock);
                nr_found = radix_tree_gang_lookup(&pag->pag_ici_root,
                                (void**)&ip, first_index, 1);

                if (!nr_found) {
                        read_unlock(&pag->pag_ici_lock);
                        break;
                }

                /* update the index for the next lookup */
                first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);

                /*
                 * skip inodes in reclaim. Let xfs_syncsub do that for
                 * us so we don't need to worry.
                 */
                if (xfs_iflags_test(ip, (XFS_IRECLAIM|XFS_IRECLAIMABLE))) {
                        read_unlock(&pag->pag_ici_lock);
                        continue;
                }

                /* bad inodes are dealt with elsewhere */
                inode = VFS_I(ip);
                if (is_bad_inode(inode)) {
                        read_unlock(&pag->pag_ici_lock);
                        continue;
                }

                /* nothing to sync during shutdown */
                if (XFS_FORCED_SHUTDOWN(mp)) {
                        read_unlock(&pag->pag_ici_lock);
                        return 0;
                }

                /*
                 * If we can't get a reference on the VFS_I, the inode must be
                 * in reclaim. If we can get the inode lock without blocking,
                 * it is safe to flush the inode because we hold the tree lock
                 * and xfs_iextract will block right now. Hence if we lock the
                 * inode while holding the tree lock, xfs_ireclaim() is
                 * guaranteed to block on the inode lock we now hold and hence
                 * it is safe to reference the inode until we drop the inode
                 * locks completely.
                 */
                inode_refed = B_FALSE;
                if (igrab(inode)) {
                        read_unlock(&pag->pag_ici_lock);
                        xfs_ilock(ip, lock_flags);
                        inode_refed = B_TRUE;
                } else {
                        if (!xfs_ilock_nowait(ip, lock_flags)) {
                                /* leave it to reclaim */
                                read_unlock(&pag->pag_ici_lock);
                                continue;
                        }
                        read_unlock(&pag->pag_ici_lock);
                }

                /*
                 * If we have to flush data or wait for I/O completion
                 * we need to drop the ilock that we currently hold.
                 * If we need to drop the lock, insert a marker if we
                 * have not already done so.
                 */
                if ((flags & SYNC_DELWRI) && VN_DIRTY(inode)) {
                        xfs_iunlock(ip, XFS_ILOCK_SHARED);
                        error = xfs_flush_pages(ip, 0, -1, fflag, FI_NONE);
                        if (flags & SYNC_IOWAIT)
                                vn_iowait(ip);
                        xfs_ilock(ip, XFS_ILOCK_SHARED);
                }

                if ((flags & SYNC_ATTR) && !xfs_inode_clean(ip)) {
                        if (flags & SYNC_WAIT) {
                                xfs_iflock(ip);
                                if (!xfs_inode_clean(ip))
                                        error = xfs_iflush(ip, XFS_IFLUSH_SYNC);
                                else
                                        xfs_ifunlock(ip);
                        } else if (xfs_iflock_nowait(ip)) {
                                if (!xfs_inode_clean(ip))
                                        error = xfs_iflush(ip, XFS_IFLUSH_DELWRI);
                                else
                                        xfs_ifunlock(ip);
                        }
                }

                if (lock_flags)
                        xfs_iunlock(ip, lock_flags);

                if (inode_refed) {
                        IRELE(ip);
                }

                if (error)
                        last_error = error;
                /*
                 * bail out if the filesystem is corrupted.
                 */
                if (error == EFSCORRUPTED)
                        return XFS_ERROR(error);

        } while (nr_found);

        return last_error;
}

int
xfs_sync_inodes(
        xfs_mount_t     *mp,
        int             flags)
{
        int             error;
        int             last_error;
        int             i;
        int             lflags = XFS_LOG_FORCE;

        if (mp->m_flags & XFS_MOUNT_RDONLY)
                return 0;
        error = 0;
        last_error = 0;

        if (flags & SYNC_WAIT)
                lflags |= XFS_LOG_SYNC;

        for (i = 0; i < mp->m_sb.sb_agcount; i++) {
                if (!mp->m_perag[i].pag_ici_init)
                        continue;
                error = xfs_sync_inodes_ag(mp, i, flags);
                if (error)
                        last_error = error;
                if (error == EFSCORRUPTED)
                        break;
        }
        if (flags & SYNC_DELWRI)
                xfs_log_force(mp, 0, lflags);

        return XFS_ERROR(last_error);
}

STATIC int
xfs_commit_dummy_trans(
        struct xfs_mount        *mp,
        uint                    log_flags)
{
        struct xfs_inode        *ip = mp->m_rootip;
        struct xfs_trans        *tp;
        int                     error;

        /*
         * Put a dummy transaction in the log to tell recovery
         * that all others are OK.
         */
        tp = xfs_trans_alloc(mp, XFS_TRANS_DUMMY1);
        error = xfs_trans_reserve(tp, 0, XFS_ICHANGE_LOG_RES(mp), 0, 0, 0);
        if (error) {
                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);
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        /* XXX(hch): ignoring the error here.. */
        error = xfs_trans_commit(tp, 0);

        xfs_iunlock(ip, XFS_ILOCK_EXCL);

        xfs_log_force(mp, 0, log_flags);
        return 0;
}

int
xfs_sync_fsdata(
        struct xfs_mount        *mp,
        int                     flags)
{
        struct xfs_buf          *bp;
        struct xfs_buf_log_item *bip;
        int                     error = 0;

        /*
         * If this is xfssyncd() then only sync the superblock if we can
         * lock it without sleeping and it is not pinned.
         */
        if (flags & SYNC_BDFLUSH) {
                ASSERT(!(flags & SYNC_WAIT));

                bp = xfs_getsb(mp, XFS_BUF_TRYLOCK);
                if (!bp)
                        goto out;

                bip = XFS_BUF_FSPRIVATE(bp, struct xfs_buf_log_item *);
                if (!bip || !xfs_buf_item_dirty(bip) || XFS_BUF_ISPINNED(bp))
                        goto out_brelse;
        } else {
                bp = xfs_getsb(mp, 0);

                /*
                 * If the buffer is pinned then push on the log so we won't
                 * get stuck waiting in the write for someone, maybe
                 * ourselves, to flush the log.
                 *
                 * Even though we just pushed the log above, we did not have
                 * the superblock buffer locked at that point so it can
                 * become pinned in between there and here.
                 */
                if (XFS_BUF_ISPINNED(bp))
                        xfs_log_force(mp, 0, XFS_LOG_FORCE);
        }


        if (flags & SYNC_WAIT)
                XFS_BUF_UNASYNC(bp);
        else
                XFS_BUF_ASYNC(bp);

        return xfs_bwrite(mp, bp);

 out_brelse:
        xfs_buf_relse(bp);
 out:
        return error;
}

/*
 * When remounting a filesystem read-only or freezing the filesystem, we have
 * two phases to execute. This first phase is syncing the data before we
 * quiesce the filesystem, and the second is flushing all the inodes out after
 * we've waited for all the transactions created by the first phase to
 * complete. The second phase ensures that the inodes are written to their
 * location on disk rather than just existing in transactions in the log. This
 * means after a quiesce there is no log replay required to write the inodes to
 * disk (this is the main difference between a sync and a quiesce).
 */
/*
 * First stage of freeze - no writers will make progress now we are here,
 * so we flush delwri and delalloc buffers here, then wait for all I/O to
 * complete.  Data is frozen at that point. Metadata is not frozen,
 * transactions can still occur here so don't bother flushing the buftarg
 * because it'll just get dirty again.
 */
int
xfs_quiesce_data(
        struct xfs_mount        *mp)
{
        int error;

        /* push non-blocking */
        xfs_sync_inodes(mp, SYNC_DELWRI|SYNC_BDFLUSH);
        XFS_QM_DQSYNC(mp, SYNC_BDFLUSH);
        xfs_filestream_flush(mp);

        /* push and block */
        xfs_sync_inodes(mp, SYNC_DELWRI|SYNC_WAIT|SYNC_IOWAIT);
        XFS_QM_DQSYNC(mp, SYNC_WAIT);

        /* write superblock and hoover up shutdown errors */
        error = xfs_sync_fsdata(mp, 0);

        /* flush data-only devices */
        if (mp->m_rtdev_targp)
                XFS_bflush(mp->m_rtdev_targp);

        return error;
}

STATIC void
xfs_quiesce_fs(
        struct xfs_mount        *mp)
{
        int     count = 0, pincount;

        xfs_flush_buftarg(mp->m_ddev_targp, 0);
        xfs_reclaim_inodes(mp, 0, XFS_IFLUSH_DELWRI_ELSE_ASYNC);

        /*
         * This loop must run at least twice.  The first instance of the loop
         * will flush most meta data but that will generate more meta data
         * (typically directory updates).  Which then must be flushed and
         * logged before we can write the unmount record.
         */
        do {
                xfs_sync_inodes(mp, SYNC_ATTR|SYNC_WAIT);
                pincount = xfs_flush_buftarg(mp->m_ddev_targp, 1);
                if (!pincount) {
                        delay(50);
                        count++;
                }
        } while (count < 2);
}

/*
 * Second stage of a quiesce. The data is already synced, now we have to take
 * care of the metadata. New transactions are already blocked, so we need to
 * wait for any remaining transactions to drain out before proceding.
 */
void
xfs_quiesce_attr(
        struct xfs_mount        *mp)
{
        int     error = 0;

        /* wait for all modifications to complete */
        while (atomic_read(&mp->m_active_trans) > 0)
                delay(100);

        /* flush inodes and push all remaining buffers out to disk */
        xfs_quiesce_fs(mp);

        ASSERT_ALWAYS(atomic_read(&mp->m_active_trans) == 0);

        /* Push the superblock and write an unmount record */
        error = xfs_log_sbcount(mp, 1);
        if (error)
                xfs_fs_cmn_err(CE_WARN, mp,
                                "xfs_attr_quiesce: failed to log sb changes. "
                                "Frozen image may not be consistent.");
        xfs_log_unmount_write(mp);
        xfs_unmountfs_writesb(mp);
}

/*
 * Enqueue a work item to be picked up by the vfs xfssyncd thread.
 * Doing this has two advantages:
 * - It saves on stack space, which is tight in certain situations
 * - It can be used (with care) as a mechanism to avoid deadlocks.
 * Flushing while allocating in a full filesystem requires both.
 */
STATIC void
xfs_syncd_queue_work(
        struct xfs_mount *mp,
        void            *data,
        void            (*syncer)(struct xfs_mount *, void *))
{
        struct bhv_vfs_sync_work *work;

        work = kmem_alloc(sizeof(struct bhv_vfs_sync_work), KM_SLEEP);
        INIT_LIST_HEAD(&work->w_list);
        work->w_syncer = syncer;
        work->w_data = data;
        work->w_mount = mp;
        spin_lock(&mp->m_sync_lock);
        list_add_tail(&work->w_list, &mp->m_sync_list);
        spin_unlock(&mp->m_sync_lock);
        wake_up_process(mp->m_sync_task);
}

/*
 * Flush delayed allocate data, attempting to free up reserved space
 * from existing allocations.  At this point a new allocation attempt
 * has failed with ENOSPC and we are in the process of scratching our
 * heads, looking about for more room...
 */
STATIC void
xfs_flush_inode_work(
        struct xfs_mount *mp,
        void            *arg)
{
        struct inode    *inode = arg;
        filemap_flush(inode->i_mapping);
        iput(inode);
}

void
xfs_flush_inode(
        xfs_inode_t     *ip)
{
        struct inode    *inode = VFS_I(ip);

        igrab(inode);
        xfs_syncd_queue_work(ip->i_mount, inode, xfs_flush_inode_work);
        delay(msecs_to_jiffies(500));
}

/*
 * This is the "bigger hammer" version of xfs_flush_inode_work...
 * (IOW, "If at first you don't succeed, use a Bigger Hammer").
 */
STATIC void
xfs_flush_device_work(
        struct xfs_mount *mp,
        void            *arg)
{
        struct inode    *inode = arg;
        sync_blockdev(mp->m_super->s_bdev);
        iput(inode);
}

void
xfs_flush_device(
        xfs_inode_t     *ip)
{
        struct inode    *inode = VFS_I(ip);

        igrab(inode);
        xfs_syncd_queue_work(ip->i_mount, inode, xfs_flush_device_work);
        delay(msecs_to_jiffies(500));
        xfs_log_force(ip->i_mount, (xfs_lsn_t)0, XFS_LOG_FORCE|XFS_LOG_SYNC);
}

/*
 * Every sync period we need to unpin all items, reclaim inodes, sync
 * quota and write out the superblock. We might need to cover the log
 * to indicate it is idle.
 */
STATIC void
xfs_sync_worker(
        struct xfs_mount *mp,
        void            *unused)
{
        int             error;

        if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
                xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
                xfs_reclaim_inodes(mp, 0, XFS_IFLUSH_DELWRI_ELSE_ASYNC);
                /* dgc: errors ignored here */
                error = XFS_QM_DQSYNC(mp, SYNC_BDFLUSH);
                error = xfs_sync_fsdata(mp, SYNC_BDFLUSH);
                if (xfs_log_need_covered(mp))
                        error = xfs_commit_dummy_trans(mp, XFS_LOG_FORCE);
        }
        mp->m_sync_seq++;
        wake_up(&mp->m_wait_single_sync_task);
}

STATIC int
xfssyncd(
        void                    *arg)
{
        struct xfs_mount        *mp = arg;
        long                    timeleft;
        bhv_vfs_sync_work_t     *work, *n;
        LIST_HEAD               (tmp);

        set_freezable();
        timeleft = xfs_syncd_centisecs * msecs_to_jiffies(10);
        for (;;) {
                timeleft = schedule_timeout_interruptible(timeleft);
                /* swsusp */
                try_to_freeze();
                if (kthread_should_stop() && list_empty(&mp->m_sync_list))
                        break;

                spin_lock(&mp->m_sync_lock);
                /*
                 * We can get woken by laptop mode, to do a sync -
                 * that's the (only!) case where the list would be
                 * empty with time remaining.
                 */
                if (!timeleft || list_empty(&mp->m_sync_list)) {
                        if (!timeleft)
                                timeleft = xfs_syncd_centisecs *
                                                        msecs_to_jiffies(10);
                        INIT_LIST_HEAD(&mp->m_sync_work.w_list);
                        list_add_tail(&mp->m_sync_work.w_list,
                                        &mp->m_sync_list);
                }
                list_for_each_entry_safe(work, n, &mp->m_sync_list, w_list)
                        list_move(&work->w_list, &tmp);
                spin_unlock(&mp->m_sync_lock);

                list_for_each_entry_safe(work, n, &tmp, w_list) {
                        (*work->w_syncer)(mp, work->w_data);
                        list_del(&work->w_list);
                        if (work == &mp->m_sync_work)
                                continue;
                        kmem_free(work);
                }
        }

        return 0;
}

int
xfs_syncd_init(
        struct xfs_mount        *mp)
{
        mp->m_sync_work.w_syncer = xfs_sync_worker;
        mp->m_sync_work.w_mount = mp;
        mp->m_sync_task = kthread_run(xfssyncd, mp, "xfssyncd");
        if (IS_ERR(mp->m_sync_task))
                return -PTR_ERR(mp->m_sync_task);
        return 0;
}

void
xfs_syncd_stop(
        struct xfs_mount        *mp)
{
        kthread_stop(mp->m_sync_task);
}

int
xfs_reclaim_inode(
        xfs_inode_t     *ip,
        int             locked,
        int             sync_mode)
{
        xfs_perag_t     *pag = xfs_get_perag(ip->i_mount, ip->i_ino);

        /* The hash lock here protects a thread in xfs_iget_core from
         * racing with us on linking the inode back with a vnode.
         * Once we have the XFS_IRECLAIM flag set it will not touch
         * us.
         */
        write_lock(&pag->pag_ici_lock);
        spin_lock(&ip->i_flags_lock);
        if (__xfs_iflags_test(ip, XFS_IRECLAIM) ||
            !__xfs_iflags_test(ip, XFS_IRECLAIMABLE)) {
                spin_unlock(&ip->i_flags_lock);
                write_unlock(&pag->pag_ici_lock);
                if (locked) {
                        xfs_ifunlock(ip);
                        xfs_iunlock(ip, XFS_ILOCK_EXCL);
                }
                return 1;
        }
        __xfs_iflags_set(ip, XFS_IRECLAIM);
        spin_unlock(&ip->i_flags_lock);
        write_unlock(&pag->pag_ici_lock);
        xfs_put_perag(ip->i_mount, pag);

        /*
         * If the inode is still dirty, then flush it out.  If the inode
         * is not in the AIL, then it will be OK to flush it delwri as
         * long as xfs_iflush() does not keep any references to the inode.
         * We leave that decision up to xfs_iflush() since it has the
         * knowledge of whether it's OK to simply do a delwri flush of
         * the inode or whether we need to wait until the inode is
         * pulled from the AIL.
         * We get the flush lock regardless, though, just to make sure
         * we don't free it while it is being flushed.
         */
        if (!locked) {
                xfs_ilock(ip, XFS_ILOCK_EXCL);
                xfs_iflock(ip);
        }

        /*
         * In the case of a forced shutdown we rely on xfs_iflush() to
         * wait for the inode to be unpinned before returning an error.
         */
        if (!is_bad_inode(VFS_I(ip)) && xfs_iflush(ip, sync_mode) == 0) {
                /* synchronize with xfs_iflush_done */
                xfs_iflock(ip);
                xfs_ifunlock(ip);
        }

        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        xfs_ireclaim(ip);
        return 0;
}

int
xfs_reclaim_inodes(
        xfs_mount_t     *mp,
        int              noblock,
        int             mode)
{
        xfs_inode_t     *ip, *n;

restart:
        XFS_MOUNT_ILOCK(mp);
        list_for_each_entry_safe(ip, n, &mp->m_del_inodes, i_reclaim) {
                if (noblock) {
                        if (xfs_ilock_nowait(ip, XFS_ILOCK_EXCL) == 0)
                                continue;
                        if (xfs_ipincount(ip) ||
                            !xfs_iflock_nowait(ip)) {
                                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                                continue;
                        }
                }
                XFS_MOUNT_IUNLOCK(mp);
                if (xfs_reclaim_inode(ip, noblock, mode))
                        delay(1);
                goto restart;
        }
        XFS_MOUNT_IUNLOCK(mp);
        return 0;
}