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>

/*
 * xfs_sync flushes any pending I/O to file system vfsp.
 *
 * This routine is called by vfs_sync() to make sure that things make it
 * out to disk eventually, on sync() system calls to flush out everything,
 * and when the file system is unmounted.  For the vfs_sync() case, all
 * we really need to do is sync out the log to make all of our meta-data
 * updates permanent (except for timestamps).  For calls from pflushd(),
 * dirty pages are kept moving by calling pdflush() on the inodes
 * containing them.  We also flush the inodes that we can lock without
 * sleeping and the superblock if we can lock it without sleeping from
 * vfs_sync() so that items at the tail of the log are always moving out.
 *
 * Flags:
 *      SYNC_BDFLUSH - We're being called from vfs_sync() so we don't want
 *		       to sleep if we can help it.  All we really need
 *		       to do is ensure that the log is synced at least
 *		       periodically.  We also push the inodes and
 *		       superblock if we can lock them without sleeping
 *			and they are not pinned.
 *      SYNC_ATTR    - We need to flush the inodes.  If SYNC_BDFLUSH is not
 *		       set, then we really want to lock each inode and flush
 *		       it.
 *      SYNC_WAIT    - All the flushes that take place in this call should
 *		       be synchronous.
 *      SYNC_DELWRI  - This tells us to push dirty pages associated with
 *		       inodes.  SYNC_WAIT and SYNC_BDFLUSH are used to
 *		       determine if they should be flushed sync, async, or
 *		       delwri.
 *      SYNC_CLOSE   - This flag is passed when the system is being
 *		       unmounted.  We should sync and invalidate everything.
 *      SYNC_FSDATA  - This indicates that the caller would like to make
 *		       sure the superblock is safe on disk.  We can ensure
 *		       this by simply making sure the log gets flushed
 *		       if SYNC_BDFLUSH is set, and by actually writing it
 *		       out otherwise.
 *	SYNC_IOWAIT  - The caller wants us to wait for all data I/O to complete
 *		       before we return (including direct I/O). Forms the drain
 *		       side of the write barrier needed to safely quiesce the
 *		       filesystem.
 *
 */
int
xfs_sync(
	xfs_mount_t	*mp,
	int		flags)
{
	int		error;

	/*
	 * Get the Quota Manager to flush the dquots.
	 *
	 * If XFS quota support is not enabled or this filesystem
	 * instance does not use quotas XFS_QM_DQSYNC will always
	 * return zero.
	 */
	error = XFS_QM_DQSYNC(mp, flags);
	if (error) {
		/*
		 * If we got an IO error, we will be shutting down.
		 * So, there's nothing more for us to do here.
		 */
		ASSERT(error != EIO || XFS_FORCED_SHUTDOWN(mp));
		if (XFS_FORCED_SHUTDOWN(mp))
			return XFS_ERROR(error);
	}

	if (flags & SYNC_IOWAIT)
		xfs_filestream_flush(mp);

	return xfs_syncsub(mp, flags, NULL);
}

/*
 * xfs sync routine for internal use
 *
 * This routine supports all of the flags defined for the generic vfs_sync
 * interface as explained above under xfs_sync.
 *
 */
int
xfs_sync_inodes(
	xfs_mount_t	*mp,
	int		flags,
	int             *bypassed)
{
	xfs_inode_t	*ip = NULL;
	struct inode	*vp = NULL;
	int		error;
	int		last_error;
	uint64_t	fflag;
	uint		lock_flags;
	uint		base_lock_flags;
	boolean_t	mount_locked;
	boolean_t	vnode_refed;
	int		preempt;
	xfs_iptr_t	*ipointer;
#ifdef DEBUG
	boolean_t	ipointer_in = B_FALSE;

#define IPOINTER_SET	ipointer_in = B_TRUE
#define IPOINTER_CLR	ipointer_in = B_FALSE
#else
#define IPOINTER_SET
#define IPOINTER_CLR
#endif


/* Insert a marker record into the inode list after inode ip. The list
 * must be locked when this is called. After the call the list will no
 * longer be locked.
 */
#define IPOINTER_INSERT(ip, mp)	{ \
		ASSERT(ipointer_in == B_FALSE); \
		ipointer->ip_mnext = ip->i_mnext; \
		ipointer->ip_mprev = ip; \
		ip->i_mnext = (xfs_inode_t *)ipointer; \
		ipointer->ip_mnext->i_mprev = (xfs_inode_t *)ipointer; \
		preempt = 0; \
		XFS_MOUNT_IUNLOCK(mp); \
		mount_locked = B_FALSE; \
		IPOINTER_SET; \
	}

/* Remove the marker from the inode list. If the marker was the only item
 * in the list then there are no remaining inodes and we should zero out
 * the whole list. If we are the current head of the list then move the head
 * past us.
 */
#define IPOINTER_REMOVE(ip, mp)	{ \
		ASSERT(ipointer_in == B_TRUE); \
		if (ipointer->ip_mnext != (xfs_inode_t *)ipointer) { \
			ip = ipointer->ip_mnext; \
			ip->i_mprev = ipointer->ip_mprev; \
			ipointer->ip_mprev->i_mnext = ip; \
			if (mp->m_inodes == (xfs_inode_t *)ipointer) { \
				mp->m_inodes = ip; \
			} \
		} else { \
			ASSERT(mp->m_inodes == (xfs_inode_t *)ipointer); \
			mp->m_inodes = NULL; \
			ip = NULL; \
		} \
		IPOINTER_CLR; \
	}

#define XFS_PREEMPT_MASK	0x7f

	ASSERT(!(flags & SYNC_BDFLUSH));

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

	/* Allocate a reference marker */
	ipointer = (xfs_iptr_t *)kmem_zalloc(sizeof(xfs_iptr_t), KM_SLEEP);

	fflag = XFS_B_ASYNC;		/* default is don't wait */
	if (flags & SYNC_DELWRI)
		fflag = XFS_B_DELWRI;
	if (flags & SYNC_WAIT)
		fflag = 0;		/* synchronous overrides all */

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

	XFS_MOUNT_ILOCK(mp);

	ip = mp->m_inodes;

	mount_locked = B_TRUE;
	vnode_refed  = B_FALSE;

	IPOINTER_CLR;

	do {
		ASSERT(ipointer_in == B_FALSE);
		ASSERT(vnode_refed == B_FALSE);

		lock_flags = base_lock_flags;

		/*
		 * There were no inodes in the list, just break out
		 * of the loop.
		 */
		if (ip == NULL) {
			break;
		}

		/*
		 * We found another sync thread marker - skip it
		 */
		if (ip->i_mount == NULL) {
			ip = ip->i_mnext;
			continue;
		}

		vp = VFS_I(ip);

		/*
		 * If the vnode is gone then this is being torn down,
		 * call reclaim if it is flushed, else let regular flush
		 * code deal with it later in the loop.
		 */

		if (vp == NULL) {
			/* Skip ones already in reclaim */
			if (ip->i_flags & XFS_IRECLAIM) {
				ip = ip->i_mnext;
				continue;
			}
			if (xfs_ilock_nowait(ip, XFS_ILOCK_EXCL) == 0) {
				ip = ip->i_mnext;
			} else if ((xfs_ipincount(ip) == 0) &&
				    xfs_iflock_nowait(ip)) {
				IPOINTER_INSERT(ip, mp);

				xfs_finish_reclaim(ip, 1,
						XFS_IFLUSH_DELWRI_ELSE_ASYNC);

				XFS_MOUNT_ILOCK(mp);
				mount_locked = B_TRUE;
				IPOINTER_REMOVE(ip, mp);
			} else {
				xfs_iunlock(ip, XFS_ILOCK_EXCL);
				ip = ip->i_mnext;
			}
			continue;
		}

		if (VN_BAD(vp)) {
			ip = ip->i_mnext;
			continue;
		}

		if (XFS_FORCED_SHUTDOWN(mp) && !(flags & SYNC_CLOSE)) {
			XFS_MOUNT_IUNLOCK(mp);
			kmem_free(ipointer);
			return 0;
		}

		/*
		 * Try to lock without sleeping.  We're out of order with
		 * the inode list lock here, so if we fail we need to drop
		 * the mount lock and try again.  If we're called from
		 * bdflush() here, then don't bother.
		 *
		 * The inode lock here actually coordinates with the
		 * almost spurious inode lock in xfs_ireclaim() to prevent
		 * the vnode we handle here without a reference from
		 * being freed while we reference it.  If we lock the inode
		 * while it's on the mount list here, then the spurious inode
		 * lock in xfs_ireclaim() after the inode is pulled from
		 * the mount list will sleep until we release it here.
		 * This keeps the vnode from being freed while we reference
		 * it.
		 */
		if (xfs_ilock_nowait(ip, lock_flags) == 0) {
			if (vp == NULL) {
				ip = ip->i_mnext;
				continue;
			}

			vp = vn_grab(vp);
			if (vp == NULL) {
				ip = ip->i_mnext;
				continue;
			}

			IPOINTER_INSERT(ip, mp);
			xfs_ilock(ip, lock_flags);

			ASSERT(vp == VFS_I(ip));
			ASSERT(ip->i_mount == mp);

			vnode_refed = B_TRUE;
		}

		/* From here on in the loop we may have a marker record
		 * in the inode list.
		 */

		/*
		 * 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_CLOSE|SYNC_IOWAIT)) ||
		    ((flags & SYNC_DELWRI) && VN_DIRTY(vp))) {
			if (mount_locked) {
				IPOINTER_INSERT(ip, mp);
			}
			xfs_iunlock(ip, XFS_ILOCK_SHARED);

			if (flags & SYNC_CLOSE) {
				/* Shutdown case. Flush and invalidate. */
				if (XFS_FORCED_SHUTDOWN(mp))
					xfs_tosspages(ip, 0, -1,
							     FI_REMAPF);
				else
					error = xfs_flushinval_pages(ip,
							0, -1, FI_REMAPF);
			} else if ((flags & SYNC_DELWRI) && VN_DIRTY(vp)) {
				error = xfs_flush_pages(ip, 0,
							-1, fflag, FI_NONE);
			}

			/*
			 * When freezing, we need to wait ensure all I/O (including direct
			 * I/O) is complete to ensure no further data modification can take
			 * place after this point
			 */
			if (flags & SYNC_IOWAIT)
				vn_iowait(ip);

			xfs_ilock(ip, XFS_ILOCK_SHARED);
		}

		if ((flags & SYNC_ATTR) &&
		    (ip->i_update_core ||
		     (ip->i_itemp && ip->i_itemp->ili_format.ilf_fields))) {
			if (mount_locked)
				IPOINTER_INSERT(ip, mp);

			if (flags & SYNC_WAIT) {
				xfs_iflock(ip);
				error = xfs_iflush(ip, XFS_IFLUSH_SYNC);

			/*
			 * If we can't acquire the flush lock, then the inode
			 * is already being flushed so don't bother waiting.
			 *
			 * If we can lock it then do a delwri flush so we can
			 * combine multiple inode flushes in each disk write.
			 */
			} else if (xfs_iflock_nowait(ip)) {
				error = xfs_iflush(ip, XFS_IFLUSH_DELWRI);
			} else if (bypassed) {
				(*bypassed)++;
			}
		}

		if (lock_flags != 0) {
			xfs_iunlock(ip, lock_flags);
		}

		if (vnode_refed) {
			/*
			 * If we had to take a reference on the vnode
			 * above, then wait until after we've unlocked
			 * the inode to release the reference.  This is
			 * because we can be already holding the inode
			 * lock when IRELE() calls xfs_inactive().
			 *
			 * Make sure to drop the mount lock before calling
			 * IRELE() so that we don't trip over ourselves if
			 * we have to go for the mount lock again in the
			 * inactive code.
			 */
			if (mount_locked) {
				IPOINTER_INSERT(ip, mp);
			}

			IRELE(ip);

			vnode_refed = B_FALSE;
		}

		if (error) {
			last_error = error;
		}

		/*
		 * bail out if the filesystem is corrupted.
		 */
		if (error == EFSCORRUPTED)  {
			if (!mount_locked) {
				XFS_MOUNT_ILOCK(mp);
				IPOINTER_REMOVE(ip, mp);
			}
			XFS_MOUNT_IUNLOCK(mp);
			ASSERT(ipointer_in == B_FALSE);
			kmem_free(ipointer);
			return XFS_ERROR(error);
		}

		/* Let other threads have a chance at the mount lock
		 * if we have looped many times without dropping the
		 * lock.
		 */
		if ((++preempt & XFS_PREEMPT_MASK) == 0) {
			if (mount_locked) {
				IPOINTER_INSERT(ip, mp);
			}
		}

		if (mount_locked == B_FALSE) {
			XFS_MOUNT_ILOCK(mp);
			mount_locked = B_TRUE;
			IPOINTER_REMOVE(ip, mp);
			continue;
		}

		ASSERT(ipointer_in == B_FALSE);
		ip = ip->i_mnext;

	} while (ip != mp->m_inodes);

	XFS_MOUNT_IUNLOCK(mp);

	ASSERT(ipointer_in == B_FALSE);

	kmem_free(ipointer);
	return XFS_ERROR(last_error);
}

/*
 * xfs sync routine for internal use
 *
 * This routine supports all of the flags defined for the generic vfs_sync
 * interface as explained above under xfs_sync.
 *
 */
int
xfs_syncsub(
	xfs_mount_t	*mp,
	int		flags,
	int             *bypassed)
{
	int		error = 0;
	int		last_error = 0;
	uint		log_flags = XFS_LOG_FORCE;
	xfs_buf_t	*bp;
	xfs_buf_log_item_t	*bip;

	/*
	 * Sync out the log.  This ensures that the log is periodically
	 * flushed even if there is not enough activity to fill it up.
	 */
	if (flags & SYNC_WAIT)
		log_flags |= XFS_LOG_SYNC;

	xfs_log_force(mp, (xfs_lsn_t)0, log_flags);

	if (flags & (SYNC_ATTR|SYNC_DELWRI)) {
		if (flags & SYNC_BDFLUSH)
			xfs_finish_reclaim_all(mp, 1);
		else
			error = xfs_sync_inodes(mp, flags, bypassed);
	}

	/*
	 * Flushing out dirty data above probably generated more
	 * log activity, so if this isn't vfs_sync() then flush
	 * the log again.
	 */
	if (flags & SYNC_DELWRI) {
		xfs_log_force(mp, (xfs_lsn_t)0, log_flags);
	}

	if (flags & SYNC_FSDATA) {
		/*
		 * If this is vfs_sync() then only sync the superblock
		 * if we can lock it without sleeping and it is not pinned.
		 */
		if (flags & SYNC_BDFLUSH) {
			bp = xfs_getsb(mp, XFS_BUF_TRYLOCK);
			if (bp != NULL) {
				bip = XFS_BUF_FSPRIVATE(bp,xfs_buf_log_item_t*);
				if ((bip != NULL) &&
				    xfs_buf_item_dirty(bip)) {
					if (!(XFS_BUF_ISPINNED(bp))) {
						XFS_BUF_ASYNC(bp);
						error = xfs_bwrite(mp, bp);
					} else {
						xfs_buf_relse(bp);
					}
				} else {
					xfs_buf_relse(bp);
				}
			}
		} 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, (xfs_lsn_t)0, XFS_LOG_FORCE);
			if (flags & SYNC_WAIT)
				XFS_BUF_UNASYNC(bp);
			else
				XFS_BUF_ASYNC(bp);
			error = xfs_bwrite(mp, bp);
		}
		if (error) {
			last_error = error;
		}
	}

	/*
	 * Now check to see if the log needs a "dummy" transaction.
	 */
	if (!(flags & SYNC_REMOUNT) && xfs_log_need_covered(mp)) {
		xfs_trans_t *tp;
		xfs_inode_t *ip;

		/*
		 * Put a dummy transaction in the log to tell
		 * recovery that all others are OK.
		 */
		tp = xfs_trans_alloc(mp, XFS_TRANS_DUMMY1);
		if ((error = xfs_trans_reserve(tp, 0,
				XFS_ICHANGE_LOG_RES(mp),
				0, 0, 0)))  {
			xfs_trans_cancel(tp, 0);
			return error;
		}

		ip = mp->m_rootip;
		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);
		error = xfs_trans_commit(tp, 0);
		xfs_iunlock(ip, XFS_ILOCK_EXCL);
		xfs_log_force(mp, (xfs_lsn_t)0, log_flags);
	}

	/*
	 * When shutting down, we need to insure that the AIL is pushed
	 * to disk or the filesystem can appear corrupt from the PROM.
	 */
	if ((flags & (SYNC_CLOSE|SYNC_WAIT)) == (SYNC_CLOSE|SYNC_WAIT)) {
		XFS_bflush(mp->m_ddev_targp);
		if (mp->m_rtdev_targp) {
			XFS_bflush(mp->m_rtdev_targp);
		}
	}

	return XFS_ERROR(last_error);
}

/*
 * 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);
}

STATIC void
xfs_sync_worker(
	struct xfs_mount *mp,
	void		*unused)
{
	int		error;

	if (!(mp->m_flags & XFS_MOUNT_RDONLY))
		error = xfs_sync(mp, SYNC_FSDATA | SYNC_BDFLUSH | SYNC_ATTR);
	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);
}