Do orphaned inode extent freeing in chunks

Fix an issue where the final freeing of extents for unlinked files
could trigger spurious hung task timeout warnings. Instead of holding the
scoutfs inode lock for the entire duration of extent freeing, release and
reacquire the lock every time the transaction sequence number changes.

This is only used in the evict and orphan inode cleanup paths; truncate
and release continue to free during a single lock hold.

Remove the hung_task_timeout_secs workaround from the large-fragmented-free
test script.

Signed-off-by: Chris Kirby <ckirby@versity.com>

kmod/src/data.c

@@ -296,28 +296,39 @@ static s64 truncate_extents(struct super_block *sb, struct inode *inode,
  * and offline blocks.  If it's not provided then the inode is being
  * destroyed and isn't reachable, we don't need to update it.
  *
+ * If 'pause' is set, then we are destroying the inode and we should take
+ * breaks occasionally to allow other nodes access to this inode lock shard.
+ *
  * The caller is in charge of locking the inode and data, but we may
  * have to modify far more items than fit in a transaction so we're in
  * charge of batching updates into transactions.  If the inode is
  * provided then we're responsible for updating its item as we go.
  */
 int scoutfs_data_truncate_items(struct super_block *sb, struct inode *inode,
-				u64 ino, u64 iblock, u64 last, bool offline,
-				struct scoutfs_lock *lock)
+				u64 ino, u64 *iblock, u64 last, bool offline,
+				struct scoutfs_lock *lock, bool pause)
 {
 	struct scoutfs_inode_info *si = NULL;
 	LIST_HEAD(ind_locks);
+	u64 cur_seq;
 	s64 ret = 0;
 
 	WARN_ON_ONCE(inode && !inode_is_locked(inode));
 
+	/*
+	 * If the inode is provided, then we aren't destroying it. So it's not
+	 * safe to pause while removing items- it needs to be done in one chunk.
+	 */
+	if (WARN_ON_ONCE(pause && inode))
+		return -EINVAL;
+
 	/* clamp last to the last possible block? */
 	if (last > SCOUTFS_BLOCK_SM_MAX)
 		last = SCOUTFS_BLOCK_SM_MAX;
 
-	trace_scoutfs_data_truncate_items(sb, iblock, last, offline);
+	trace_scoutfs_data_truncate_items(sb, *iblock, last, offline, pause);
 
-	if (WARN_ON_ONCE(last < iblock))
+	if (WARN_ON_ONCE(last < *iblock))
 		return -EINVAL;
 
 	if (inode) {
@@ -325,7 +336,9 @@ int scoutfs_data_truncate_items(struct super_block *sb, struct inode *inode,
 		down_write(&si->extent_sem);
 	}
 
-	while (iblock <= last) {
+	cur_seq = scoutfs_trans_sample_seq(sb);
+
+	while (*iblock <= last) {
 		if (inode)
 			ret = scoutfs_inode_index_lock_hold(inode, &ind_locks, true, false);
 		else
@@ -339,7 +352,7 @@ int scoutfs_data_truncate_items(struct super_block *sb, struct inode *inode,
 			ret = 0;
 
 		if (ret == 0)
-			ret = truncate_extents(sb, inode, ino, iblock, last,
+			ret = truncate_extents(sb, inode, ino, *iblock, last,
 					       offline, lock);
 
 		if (inode)
@@ -351,8 +364,19 @@ int scoutfs_data_truncate_items(struct super_block *sb, struct inode *inode,
 		if (ret <= 0)
 			break;
 
-		iblock = ret;
+		*iblock = ret;
 		ret = 0;
+
+		/*
+		 * We know there's more to do because truncate_extents()
+		 * pauses every EXTENTS_PER_HOLD extents and it returned the
+		 * next starting block. Our caller might also want us to pause,
+		 * which we will do whenever we cross a transaction boundary.
+		 */
+		if (pause && (cur_seq != scoutfs_trans_sample_seq(sb))) {
+			ret = -EINPROGRESS;
+			break;
+		}
 	}
 
 	if (si)

kmod/src/data.h

@@ -47,8 +47,8 @@ int scoutfs_get_block_write(struct inode *inode, sector_t iblock, struct buffer_
 			    int create);
 
 int scoutfs_data_truncate_items(struct super_block *sb, struct inode *inode,
-				u64 ino, u64 iblock, u64 last, bool offline,
-				struct scoutfs_lock *lock);
+				u64 ino, u64 *iblock, u64 last, bool offline,
+				struct scoutfs_lock *lock, bool pause);
 int scoutfs_data_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 			u64 start, u64 len);
 long scoutfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len);

kmod/src/inode.c

@@ -468,8 +468,8 @@ int scoutfs_complete_truncate(struct inode *inode, struct scoutfs_lock *lock)
 	start = (i_size_read(inode) + SCOUTFS_BLOCK_SM_SIZE - 1) >>
 		SCOUTFS_BLOCK_SM_SHIFT;
 	ret = scoutfs_data_truncate_items(inode->i_sb, inode,
-					  scoutfs_ino(inode), start, ~0ULL,
-					  false, lock);
+					  scoutfs_ino(inode), &start, ~0ULL,
+					  false, lock, false);
 	err = clear_truncate_flag(inode, lock);
 
 	return ret ? ret : err;
@@ -1635,7 +1635,8 @@ int scoutfs_inode_orphan_delete(struct super_block *sb, u64 ino, struct scoutfs_
  * partial deletion until all deletion is complete and the orphan item
  * is removed.
  */
-static int delete_inode_items(struct super_block *sb, u64 ino, struct scoutfs_inode *sinode,
+static int delete_inode_items(struct super_block *sb, u64 ino,
+			      struct scoutfs_inode *sinode, u64 *start,
 			      struct scoutfs_lock *lock, struct scoutfs_lock *orph_lock)
 {
 	struct scoutfs_key key;
@@ -1654,8 +1655,8 @@ static int delete_inode_items(struct super_block *sb, u64 ino, struct scoutfs_in
 
 	/* remove data items in their own transactions */
 	if (S_ISREG(mode)) {
-		ret = scoutfs_data_truncate_items(sb, NULL, ino, 0, ~0ULL,
-						  false, lock);
+		ret = scoutfs_data_truncate_items(sb, NULL, ino, start, ~0ULL,
+						  false, lock, true);
 		if (ret)
 			goto out;
 	}
@@ -1803,16 +1804,23 @@ out:
  */
 static int try_delete_inode_items(struct super_block *sb, u64 ino)
 {
-	struct inode_deletion_lock_data *ldata = NULL;
-	struct scoutfs_lock *orph_lock = NULL;
-	struct scoutfs_lock *lock = NULL;
+	struct inode_deletion_lock_data *ldata;
+	struct scoutfs_lock *orph_lock;
+	struct scoutfs_lock *lock;
 	struct scoutfs_inode sinode;
 	struct scoutfs_key key;
 	bool clear_trying = false;
+	bool more = false;
 	u64 group_nr;
+	u64 start = 0;
 	int bit_nr;
 	int ret;
 
+again:
+	ldata = NULL;
+	orph_lock = NULL;
+	lock = NULL;
+
 	ret = scoutfs_lock_ino(sb, SCOUTFS_LOCK_WRITE, 0, ino, &lock);
 	if (ret < 0)
 		goto out;
@@ -1824,11 +1832,12 @@ static int try_delete_inode_items(struct super_block *sb, u64 ino)
 		goto out;
 
 	/* only one local attempt per inode at a time */
-	if (test_and_set_bit(bit_nr, ldata->trying)) {
+	if (!more && test_and_set_bit(bit_nr, ldata->trying)) {
 		ret = 0;
 		goto out;
 	}
 	clear_trying = true;
+	more = false;
 
 	/* can't delete if it's cached in local or remote mounts */
 	if (scoutfs_omap_test(sb, ino) || test_bit_le(bit_nr, ldata->map.bits)) {
@@ -1853,7 +1862,15 @@ static int try_delete_inode_items(struct super_block *sb, u64 ino)
 	if (ret < 0)
 		goto out;
 
-	ret = delete_inode_items(sb, ino, &sinode, lock, orph_lock);
+	ret = delete_inode_items(sb, ino, &sinode, &start, lock, orph_lock);
+
+	if (ret == -EINPROGRESS) {
+		more = true;
+		clear_trying = false;
+	} else {
+		more = false;
+	}
+
 out:
 	if (clear_trying)
 		clear_bit(bit_nr, ldata->trying);
@@ -1861,6 +1878,9 @@ out:
 	scoutfs_unlock(sb, lock, SCOUTFS_LOCK_WRITE);
 	scoutfs_unlock(sb, orph_lock, SCOUTFS_LOCK_WRITE_ONLY);
 
+	if (more)
+		goto again;
+
 	return ret;
 }
 

kmod/src/ioctl.c

@@ -372,9 +372,9 @@ static long scoutfs_ioc_release(struct file *file, unsigned long arg)
 	sblock = args.offset >> SCOUTFS_BLOCK_SM_SHIFT;
 	eblock = (args.offset + args.length - 1) >> SCOUTFS_BLOCK_SM_SHIFT;
 	ret = scoutfs_data_truncate_items(sb, inode, scoutfs_ino(inode),
-					  sblock,
+					  &sblock,
 					  eblock, true,
-					  lock);
+					  lock, false);
 	if (ret == 0) {
 		scoutfs_inode_get_onoff(inode, &online, &offline);
 		isize = i_size_read(inode);
@@ -383,8 +383,8 @@ static long scoutfs_ioc_release(struct file *file, unsigned long arg)
 					>> SCOUTFS_BLOCK_SM_SHIFT;
 			ret = scoutfs_data_truncate_items(sb, inode,
 							  scoutfs_ino(inode),
-							  sblock, U64_MAX,
-							  false, lock);
+							  &sblock, U64_MAX,
+							  false, lock, false);
 		}
 	}
 

kmod/src/scoutfs_trace.h

@@ -378,15 +378,16 @@ DEFINE_EVENT(scoutfs_data_file_extent_class, scoutfs_data_fiemap_extent,
 );
 
 TRACE_EVENT(scoutfs_data_truncate_items,
-	TP_PROTO(struct super_block *sb, __u64 iblock, __u64 last, int offline),
+	TP_PROTO(struct super_block *sb, __u64 iblock, __u64 last, int offline, bool pause),
 
-	TP_ARGS(sb, iblock, last, offline),
+	TP_ARGS(sb, iblock, last, offline, pause),
 
 	TP_STRUCT__entry(
 		SCSB_TRACE_FIELDS
 		__field(__u64, iblock)
 		__field(__u64, last)
 		__field(int, offline)
+		__field(bool, pause)
 	),
 
 	TP_fast_assign(
@@ -394,10 +395,12 @@ TRACE_EVENT(scoutfs_data_truncate_items,
 		__entry->iblock = iblock;
 		__entry->last = last;
 		__entry->offline = offline;
+		__entry->pause = pause;
 	),
 
-	TP_printk(SCSBF" iblock %llu last %llu offline %u", SCSB_TRACE_ARGS,
-		  __entry->iblock, __entry->last, __entry->offline)
+	TP_printk(SCSBF" iblock %llu last %llu offline %u pause %d",
+		  SCSB_TRACE_ARGS, __entry->iblock, __entry->last,
+		  __entry->offline, __entry->pause)
 );
 
 TRACE_EVENT(scoutfs_data_wait_check,

tests/golden/large-fragmented-free

@@ -1,4 +1,3 @@
-== setting longer hung task timeout
 == creating fragmented extents
 == unlink file with moved extents to free extents per block
 == cleanup

tests/tests/large-fragmented-free.sh

@@ -10,30 +10,6 @@ EXTENTS_PER_BTREE_BLOCK=600
 EXTENTS_PER_LIST_BLOCK=8192
 FREED_EXTENTS=$((EXTENTS_PER_BTREE_BLOCK * EXTENTS_PER_LIST_BLOCK))
 
-#
-# This test specifically creates a pathologically sparse file that will
-# be as expensive as possible to free.  This is usually fine on
-# dedicated or reasonable hardware, but trying to run this in
-# virtualized debug kernels can take a very long time.  This test is
-# about making sure that the server doesn't fail, not that the platform
-# can handle the scale of work that our btree formats happen to require
-# while execution is bogged down with use-after-free memory reference
-# tracking.  So we give the test a lot more breathing room before
-# deciding that its hung.
-#
-echo "== setting longer hung task timeout"
-if [ -w /proc/sys/kernel/hung_task_timeout_secs ]; then
-	secs=$(cat /proc/sys/kernel/hung_task_timeout_secs)
-	test "$secs" -gt 0 || \
-		t_fail "confusing value '$secs' from /proc/sys/kernel/hung_task_timeout_secs"
-	restore_hung_task_timeout()
-	{
-		echo "$secs" > /proc/sys/kernel/hung_task_timeout_secs
-	}
-	trap restore_hung_task_timeout EXIT
-	echo "$((secs * 5))" > /proc/sys/kernel/hung_task_timeout_secs
-fi
-
 echo "== creating fragmented extents"
 fragmented_data_extents $FREED_EXTENTS $EXTENTS_PER_BTREE_BLOCK "$T_D0/alloc" "$T_D0/move"