From d5446cfc528262ae3a41da31a8524c9d2e793f45 Mon Sep 17 00:00:00 2001
From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Thu, 20 Dec 2012 09:55:47 -0800
Subject: [PATCH] Revert "Remove TSD zfs_fsyncer_key"

This reverts commit 31f2b5abdf95d8426d8bfd66ca7f62ec70215e3c back
to the original code until the fsync(2) performance regression
can be addressed.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
---
 include/sys/zfs_vfsops.h | 2 ++
 module/zfs/zfs_ioctl.c   | 3 +++
 module/zfs/zfs_log.c     | 8 +++++++-
 module/zfs/zfs_vnops.c   | 4 ++++
 4 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/include/sys/zfs_vfsops.h b/include/sys/zfs_vfsops.h
index 5b11c93128..4dd46710f7 100644
--- a/include/sys/zfs_vfsops.h
+++ b/include/sys/zfs_vfsops.h
@@ -150,6 +150,8 @@ typedef struct zfid_long {
 #define	SHORT_FID_LEN	(sizeof (zfid_short_t) - sizeof (uint16_t))
 #define	LONG_FID_LEN	(sizeof (zfid_long_t) - sizeof (uint16_t))
 
+extern uint_t zfs_fsyncer_key;
+
 extern int zfs_suspend_fs(zfs_sb_t *zsb);
 extern int zfs_resume_fs(zfs_sb_t *zsb, const char *osname);
 extern int zfs_userspace_one(zfs_sb_t *zsb, zfs_userquota_prop_t type,
diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
index d8e823427b..c609203ea4 100644
--- a/module/zfs/zfs_ioctl.c
+++ b/module/zfs/zfs_ioctl.c
@@ -5187,6 +5187,7 @@ zfs_detach(void)
 	list_destroy(&zfsdev_state_list);
 }
 
+uint_t zfs_fsyncer_key;
 extern uint_t rrw_tsd_key;
 
 #ifdef DEBUG
@@ -5209,6 +5210,7 @@ _init(void)
 	if ((error = zfs_attach()) != 0)
 		goto out2;
 
+	tsd_create(&zfs_fsyncer_key, NULL);
 	tsd_create(&rrw_tsd_key, NULL);
 
 	printk(KERN_NOTICE "ZFS: Loaded module v%s-%s%s, "
@@ -5238,6 +5240,7 @@ _fini(void)
 	zfs_fini();
 	spa_fini();
 
+	tsd_destroy(&zfs_fsyncer_key);
 	tsd_destroy(&rrw_tsd_key);
 
 	printk(KERN_NOTICE "ZFS: Unloaded module v%s-%s%s\n",
diff --git a/module/zfs/zfs_log.c b/module/zfs/zfs_log.c
index 4f144d553e..cbd6f1cb41 100644
--- a/module/zfs/zfs_log.c
+++ b/module/zfs/zfs_log.c
@@ -457,6 +457,7 @@ zfs_log_write(zilog_t *zilog, dmu_tx_t *tx, int txtype,
 {
 	itx_wr_state_t write_state;
 	boolean_t slogging;
+	uintptr_t fsync_cnt;
 	ssize_t immediate_write_sz;
 
 	if (zil_replaying(zilog, tx) || zp->z_unlinked)
@@ -474,6 +475,10 @@ zfs_log_write(zilog_t *zilog, dmu_tx_t *tx, int txtype,
 	else
 		write_state = WR_NEED_COPY;
 
+	if ((fsync_cnt = (uintptr_t)tsd_get(zfs_fsyncer_key)) != 0) {
+		(void) tsd_set(zfs_fsyncer_key, (void *)(fsync_cnt - 1));
+	}
+
 	while (resid) {
 		itx_t *itx;
 		lr_write_t *lr;
@@ -509,7 +514,8 @@ zfs_log_write(zilog_t *zilog, dmu_tx_t *tx, int txtype,
 
 		itx->itx_private = ZTOZSB(zp);
 
-		if (!(ioflag & (FSYNC | FDSYNC)) && (zp->z_sync_cnt == 0))
+		if (!(ioflag & (FSYNC | FDSYNC)) && (zp->z_sync_cnt == 0) &&
+		    (fsync_cnt == 0))
 			itx->itx_sync = B_FALSE;
 
 		zil_itx_assign(zilog, itx, tx);
diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c
index 38f04e5c25..8ec4db26f3 100644
--- a/module/zfs/zfs_vnops.c
+++ b/module/zfs/zfs_vnops.c
@@ -2070,12 +2070,16 @@ out:
 }
 EXPORT_SYMBOL(zfs_readdir);
 
+ulong_t zfs_fsync_sync_cnt = 4;
+
 int
 zfs_fsync(struct inode *ip, int syncflag, cred_t *cr)
 {
 	znode_t	*zp = ITOZ(ip);
 	zfs_sb_t *zsb = ITOZSB(ip);
 
+	(void) tsd_set(zfs_fsyncer_key, (void *)zfs_fsync_sync_cnt);
+
 	if (zsb->z_os->os_sync != ZFS_SYNC_DISABLED) {
 		ZFS_ENTER(zsb);
 		ZFS_VERIFY_ZP(zp);