[XFS] move sync code to its own file

The sync code in XFS is spread around several files. While it used to make
sense to have such a distribution, the code is about to be cleaned up and
so centralising it in one spot as the first step makes sense.

SGI-PV: 988139

SGI-Modid: xfs-linux-melb:xfs-kern:32282a

Signed-off-by: David Chinner <david@fromorbit.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>

3 files changed, 613 insertions, 0 deletions

diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 0c71c215853..727d0e47e80 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -59,6 +59,7 @@
 #include "xfs_extfree_item.h"
 #include "xfs_mru_cache.h"
 #include "xfs_inode_item.h"
+#include "xfs_sync.h"
 
 #include <linux/namei.h>
 #include <linux/init.h>
diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
new file mode 100644
index 00000000000..c765eb2a8dc
--- /dev/null
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -0,0 +1,605 @@
+/*
+ * 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"
+
+/*
+ * 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);
+}
diff --git a/fs/xfs/linux-2.6/xfs_sync.h b/fs/xfs/linux-2.6/xfs_sync.h
new file mode 100644
index 00000000000..f4c3b1ea64c
--- /dev/null
+++ b/fs/xfs/linux-2.6/xfs_sync.h
@@ -0,0 +1,7 @@
+#ifndef XFS_SYNC_H
+#define XFS_SYNC_H 1
+
+int xfs_sync(struct xfs_mount *mp, int flags);
+int xfs_syncsub(struct xfs_mount *mp, int flags, int *bypassed);
+
+#endif