[Cluster-devel] [GFS2 v4 PATCH 09/25] gfs2: Introduce concept of a pending withdraw

[Bob Peterson <rpeterso@redhat.com>]

File system withdraws can be delayed when inconsistencies are
discovered when we cannot withdraw immediately, for example, when
critical spin_locks are held. But delaying the withdraw can cause
gfs2 to ignore the error and keep running for a short period of time.
For example, an rgrp glock may be dequeued and demoted while there
are still buffers that haven't been properly revoked, due to io
errors writing to the journal.

This patch introduces a new concept of a pending withdraw, which
means an inconsistency has been discovered and we need to withdraw
at the earliest possible opportunity. In these cases, we aren't
quite withdrawn yet, but we still need to not dequeue glocks and
other critical things. If we dequeue the glocks and the withdraw
results in our journal being replayed, the replay could overwrite
data that's been modified by a different node that acquired the
glock in the meantime.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
 fs/gfs2/aops.c       |  4 ++--
 fs/gfs2/file.c       |  2 +-
 fs/gfs2/glock.c      |  7 +++----
 fs/gfs2/glops.c      |  2 +-
 fs/gfs2/incore.h     |  1 +
 fs/gfs2/log.c        | 20 ++++++++------------
 fs/gfs2/meta_io.c    |  6 +++---
 fs/gfs2/ops_fstype.c |  3 +--
 fs/gfs2/quota.c      |  2 +-
 fs/gfs2/super.c      |  6 +++---
 fs/gfs2/sys.c        |  2 +-
 fs/gfs2/util.c       | 14 +++++++-------
 fs/gfs2/util.h       | 12 ++++++++++++
 13 files changed, 44 insertions(+), 37 deletions(-)

diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
index f296d8e67c20..c3c328b782fa 100644
--- a/fs/gfs2/aops.c
+++ b/fs/gfs2/aops.c
@@ -521,7 +521,7 @@ static int __gfs2_readpage(void *file, struct page *page)
 		error = mpage_readpage(page, gfs2_block_map);
 	}
 
-	if (unlikely(test_bit(SDF_WITHDRAWN, &sdp->sd_flags)))
+	if (unlikely(gfs2_withdrawn(sdp)))
 		return -EIO;
 
 	return error;
@@ -638,7 +638,7 @@ static int gfs2_readpages(struct file *file, struct address_space *mapping,
 	gfs2_glock_dq(&gh);
 out_uninit:
 	gfs2_holder_uninit(&gh);
-	if (unlikely(test_bit(SDF_WITHDRAWN, &sdp->sd_flags)))
+	if (unlikely(gfs2_withdrawn(sdp)))
 		ret = -EIO;
 	return ret;
 }
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 699ab831ec65..bba39c73a43c 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -1169,7 +1169,7 @@ static int gfs2_lock(struct file *file, int cmd, struct file_lock *fl)
 		cmd = F_SETLK;
 		fl->fl_type = F_UNLCK;
 	}
-	if (unlikely(test_bit(SDF_WITHDRAWN, &sdp->sd_flags))) {
+	if (unlikely(gfs2_withdrawn(sdp))) {
 		if (fl->fl_type == F_UNLCK)
 			locks_lock_file_wait(file, fl);
 		return -EIO;
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 3663643dc80d..b03f784c982f 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -547,7 +547,7 @@ __acquires(&gl->gl_lockref.lock)
 	unsigned int lck_flags = (unsigned int)(gh ? gh->gh_flags : 0);
 	int ret;
 
-	if (unlikely(test_bit(SDF_WITHDRAWN, &sdp->sd_flags)) &&
+	if (unlikely(gfs2_withdrawn(sdp)) &&
 	    target != LM_ST_UNLOCKED)
 		return;
 	lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
@@ -584,8 +584,7 @@ __acquires(&gl->gl_lockref.lock)
 		}
 		else if (ret) {
 			fs_err(sdp, "lm_lock ret %d\n", ret);
-			GLOCK_BUG_ON(gl, !test_bit(SDF_WITHDRAWN,
-						   &sdp->sd_flags));
+			GLOCK_BUG_ON(gl, !gfs2_withdrawn(sdp));
 		}
 	} else { /* lock_nolock */
 		finish_xmote(gl, target);
@@ -1097,7 +1096,7 @@ int gfs2_glock_nq(struct gfs2_holder *gh)
 	struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 	int error = 0;
 
-	if (unlikely(test_bit(SDF_WITHDRAWN, &sdp->sd_flags)))
+	if (unlikely(gfs2_withdrawn(sdp)))
 		return -EIO;
 
 	if (test_bit(GLF_LRU, &gl->gl_flags))
diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c
index 1e5720e50e9c..4825a00b7dfa 100644
--- a/fs/gfs2/glops.c
+++ b/fs/gfs2/glops.c
@@ -543,7 +543,7 @@ static int freeze_go_xmote_bh(struct gfs2_glock *gl, struct gfs2_holder *gh)
 			gfs2_consist(sdp);
 
 		/*  Initialize some head of the log stuff  */
-		if (!test_bit(SDF_WITHDRAWN, &sdp->sd_flags)) {
+		if (!gfs2_withdrawn(sdp)) {
 			sdp->sd_log_sequence = head.lh_sequence + 1;
 			gfs2_log_pointers_init(sdp, head.lh_blkno);
 		}
diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 52c5777289f5..b261168be298 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -622,6 +622,7 @@ enum {
 	SDF_FORCE_AIL_FLUSH     = 9,
 	SDF_AIL1_IO_ERROR	= 10,
 	SDF_FS_FROZEN           = 11,
+	SDF_WITHDRAWING		= 12, /* Will withdraw eventually */
 };
 
 enum gfs2_freeze_state {
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index ed64a3e48a66..6ccc5d01b813 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -92,8 +92,7 @@ static void gfs2_remove_from_ail(struct gfs2_bufdata *bd)
 
 static int gfs2_ail1_start_one(struct gfs2_sbd *sdp,
 			       struct writeback_control *wbc,
-			       struct gfs2_trans *tr,
-			       bool *withdraw)
+			       struct gfs2_trans *tr)
 __releases(&sdp->sd_ail_lock)
 __acquires(&sdp->sd_ail_lock)
 {
@@ -112,7 +111,7 @@ __acquires(&sdp->sd_ail_lock)
 			    !test_and_set_bit(SDF_AIL1_IO_ERROR,
 					      &sdp->sd_flags)) {
 				gfs2_io_error_bh(sdp, bh);
-				*withdraw = true;
+				set_bit(SDF_WITHDRAWING, &sdp->sd_flags);
 			}
 			list_move(&bd->bd_ail_st_list, &tr->tr_ail2_list);
 			continue;
@@ -153,7 +152,6 @@ void gfs2_ail1_flush(struct gfs2_sbd *sdp, struct writeback_control *wbc)
 	struct list_head *head = &sdp->sd_ail1_list;
 	struct gfs2_trans *tr;
 	struct blk_plug plug;
-	bool withdraw = false;
 
 	trace_gfs2_ail_flush(sdp, wbc, 1);
 	blk_start_plug(&plug);
@@ -162,12 +160,12 @@ void gfs2_ail1_flush(struct gfs2_sbd *sdp, struct writeback_control *wbc)
 	list_for_each_entry_reverse(tr, head, tr_list) {
 		if (wbc->nr_to_write <= 0)
 			break;
-		if (gfs2_ail1_start_one(sdp, wbc, tr, &withdraw))
+		if (gfs2_ail1_start_one(sdp, wbc, tr))
 			goto restart;
 	}
 	spin_unlock(&sdp->sd_ail_lock);
 	blk_finish_plug(&plug);
-	if (withdraw)
+	if (test_bit(SDF_WITHDRAWING, &sdp->sd_flags))
 		gfs2_lm_withdraw(sdp, NULL);
 	trace_gfs2_ail_flush(sdp, wbc, 0);
 }
@@ -196,8 +194,7 @@ static void gfs2_ail1_start(struct gfs2_sbd *sdp)
  *
  */
 
-static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
-				bool *withdraw)
+static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 {
 	struct gfs2_bufdata *bd, *s;
 	struct buffer_head *bh;
@@ -211,7 +208,7 @@ static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
 		if (!buffer_uptodate(bh) &&
 		    !test_and_set_bit(SDF_AIL1_IO_ERROR, &sdp->sd_flags)) {
 			gfs2_io_error_bh(sdp, bh);
-			*withdraw = true;
+			set_bit(SDF_WITHDRAWING, &sdp->sd_flags);
 		}
 		list_move(&bd->bd_ail_st_list, &tr->tr_ail2_list);
 	}
@@ -229,11 +226,10 @@ static int gfs2_ail1_empty(struct gfs2_sbd *sdp)
 	struct gfs2_trans *tr, *s;
 	int oldest_tr = 1;
 	int ret;
-	bool withdraw = false;
 
 	spin_lock(&sdp->sd_ail_lock);
 	list_for_each_entry_safe_reverse(tr, s, &sdp->sd_ail1_list, tr_list) {
-		gfs2_ail1_empty_one(sdp, tr, &withdraw);
+		gfs2_ail1_empty_one(sdp, tr);
 		if (list_empty(&tr->tr_ail1_list) && oldest_tr)
 			list_move(&tr->tr_list, &sdp->sd_ail2_list);
 		else
@@ -242,7 +238,7 @@ static int gfs2_ail1_empty(struct gfs2_sbd *sdp)
 	ret = list_empty(&sdp->sd_ail1_list);
 	spin_unlock(&sdp->sd_ail_lock);
 
-	if (withdraw)
+	if (test_bit(SDF_WITHDRAWING, &sdp->sd_flags))
 		gfs2_lm_withdraw(sdp, "fatal: I/O error(s)\n");
 
 	return ret;
diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index 7768823cdf05..b125008f064f 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -255,7 +255,7 @@ int gfs2_meta_read(struct gfs2_glock *gl, u64 blkno, int flags,
 	struct buffer_head *bh, *bhs[2];
 	int num = 0;
 
-	if (unlikely(test_bit(SDF_WITHDRAWN, &sdp->sd_flags))) {
+	if (unlikely(gfs2_withdrawn(sdp))) {
 		*bhp = NULL;
 		return -EIO;
 	}
@@ -313,7 +313,7 @@ int gfs2_meta_read(struct gfs2_glock *gl, u64 blkno, int flags,
 
 int gfs2_meta_wait(struct gfs2_sbd *sdp, struct buffer_head *bh)
 {
-	if (unlikely(test_bit(SDF_WITHDRAWN, &sdp->sd_flags)))
+	if (unlikely(gfs2_withdrawn(sdp)))
 		return -EIO;
 
 	wait_on_buffer(bh);
@@ -324,7 +324,7 @@ int gfs2_meta_wait(struct gfs2_sbd *sdp, struct buffer_head *bh)
 			gfs2_io_error_bh_wd(sdp, bh);
 		return -EIO;
 	}
-	if (unlikely(test_bit(SDF_WITHDRAWN, &sdp->sd_flags)))
+	if (unlikely(gfs2_withdrawn(sdp)))
 		return -EIO;
 
 	return 0;
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index f836ae4f7fce..56616997ab24 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -999,8 +999,7 @@ static int gfs2_lm_mount(struct gfs2_sbd *sdp, int silent)
 void gfs2_lm_unmount(struct gfs2_sbd *sdp)
 {
 	const struct lm_lockops *lm = sdp->sd_lockstruct.ls_ops;
-	if (likely(!test_bit(SDF_WITHDRAWN, &sdp->sd_flags)) &&
-	    lm->lm_unmount)
+	if (likely(!gfs2_withdrawn(sdp)) && lm->lm_unmount)
 		lm->lm_unmount(sdp);
 }
 
diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index 33d5063e2c7f..a8dfc86fd682 100644
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -1478,7 +1478,7 @@ static void quotad_error(struct gfs2_sbd *sdp, const char *msg, int error)
 {
 	if (error == 0 || error == -EROFS)
 		return;
-	if (!test_bit(SDF_WITHDRAWN, &sdp->sd_flags)) {
+	if (!gfs2_withdrawn(sdp)) {
 		fs_err(sdp, "gfs2_quotad: %s error %d\n", msg, error);
 		sdp->sd_log_error = error;
 		wake_up(&sdp->sd_logd_waitq);
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 62cc451f30d5..5ea8d45e989d 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -808,7 +808,7 @@ static void gfs2_dirty_inode(struct inode *inode, int flags)
 
 	if (!(flags & I_DIRTY_INODE))
 		return;
-	if (unlikely(test_bit(SDF_WITHDRAWN, &sdp->sd_flags)))
+	if (unlikely(gfs2_withdrawn(sdp)))
 		return;
 	if (!gfs2_glock_is_locked_by_me(ip->i_gl)) {
 		ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
@@ -857,7 +857,7 @@ static int gfs2_make_fs_ro(struct gfs2_sbd *sdp)
 
 	error = gfs2_glock_nq_init(sdp->sd_freeze_gl, LM_ST_SHARED, GL_NOCACHE,
 				   &freeze_gh);
-	if (error && !test_bit(SDF_WITHDRAWN, &sdp->sd_flags))
+	if (error && !gfs2_withdrawn(sdp))
 		return error;
 
 	flush_workqueue(gfs2_delete_workqueue);
@@ -1016,7 +1016,7 @@ static int gfs2_freeze(struct super_block *sb)
 	if (atomic_read(&sdp->sd_freeze_state) != SFS_UNFROZEN)
 		goto out;
 
-	if (test_bit(SDF_WITHDRAWN, &sdp->sd_flags)) {
+	if (gfs2_withdrawn(sdp)) {
 		error = -EINVAL;
 		goto out;
 	}
diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c
index c28439475e62..b772ff5509bb 100644
--- a/fs/gfs2/sys.c
+++ b/fs/gfs2/sys.c
@@ -121,7 +121,7 @@ static ssize_t freeze_store(struct gfs2_sbd *sdp, const char *buf, size_t len)
 
 static ssize_t withdraw_show(struct gfs2_sbd *sdp, char *buf)
 {
-	unsigned int b = test_bit(SDF_WITHDRAWN, &sdp->sd_flags);
+	unsigned int b = gfs2_withdrawn(sdp);
 	return snprintf(buf, PAGE_SIZE, "%u\n", b);
 }
 
diff --git a/fs/gfs2/util.c b/fs/gfs2/util.c
index 084a76ffaf65..bd3c91fa446b 100644
--- a/fs/gfs2/util.c
+++ b/fs/gfs2/util.c
@@ -261,13 +261,13 @@ void gfs2_io_error_bh_i(struct gfs2_sbd *sdp, struct buffer_head *bh,
 			const char *function, char *file, unsigned int line,
 			bool withdraw)
 {
-	if (!test_bit(SDF_WITHDRAWN, &sdp->sd_flags))
-		fs_err(sdp,
-		       "fatal: I/O error\n"
-		       "  block = %llu\n"
-		       "  function = %s, file = %s, line = %u\n",
-		       (unsigned long long)bh->b_blocknr,
-		       function, file, line);
+	if (gfs2_withdrawn(sdp))
+		return;
+
+	fs_err(sdp, "fatal: I/O error\n"
+	       "  block = %llu\n"
+	       "  function = %s, file = %s, line = %u\n",
+	       (unsigned long long)bh->b_blocknr, function, file, line);
 	if (withdraw)
 		gfs2_lm_withdraw(sdp, NULL);
 }
diff --git a/fs/gfs2/util.h b/fs/gfs2/util.h
index 9278fecba632..8d9085c0ecde 100644
--- a/fs/gfs2/util.h
+++ b/fs/gfs2/util.h
@@ -167,6 +167,18 @@ static inline unsigned int gfs2_tune_get_i(struct gfs2_tune *gt,
 	return x;
 }
 
+/**
+ * gfs2_withdrawn - test whether the file system is withdrawing or withdrawn
+ * @sdp: the superblock
+ */
+static inline bool gfs2_withdrawn(struct gfs2_sbd *sdp)
+{
+	if (test_bit(SDF_WITHDRAWN, &sdp->sd_flags) ||
+	    test_bit(SDF_WITHDRAWING, &sdp->sd_flags))
+		return true;
+	return false;
+}
+
 #define gfs2_tune_get(sdp, field) \
 gfs2_tune_get_i(&(sdp)->sd_tune, &(sdp)->sd_tune.field)
 
-- 
2.20.1