Merge tag 'ext4_for_linus-6.5-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 fixes from Ted Ts'o:
 "Bug and regression fixes for 6.5-rc3 for ext4's mballoc and jbd2's
  checkpoint code"

* tag 'ext4_for_linus-6.5-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix rbtree traversal bug in ext4_mb_use_preallocated
  ext4: fix off by one issue in ext4_mb_choose_next_group_best_avail()
  ext4: correct inline offset when handling xattrs in inode body
  jbd2: remove __journal_try_to_free_buffer()
  jbd2: fix a race when checking checkpoint buffer busy
  jbd2: Fix wrongly judgement for buffer head removing while doing checkpoint
  jbd2: remove journal_clean_one_cp_list()
  jbd2: remove t_checkpoint_io_list
  jbd2: recheck chechpointing non-dirty buffer

fs/ext4/mballoc.c

@@ -1006,14 +1006,11 @@ static void ext4_mb_choose_next_group_best_avail(struct ext4_allocation_context
 	 * fls() instead since we need to know the actual length while modifying
 	 * goal length.
 	 */
-	order = fls(ac->ac_g_ex.fe_len);
+	order = fls(ac->ac_g_ex.fe_len) - 1;
 	min_order = order - sbi->s_mb_best_avail_max_trim_order;
 	if (min_order < 0)
 		min_order = 0;
 
-	if (1 << min_order < ac->ac_o_ex.fe_len)
-		min_order = fls(ac->ac_o_ex.fe_len) + 1;
-
 	if (sbi->s_stripe > 0) {
 		/*
 		 * We are assuming that stripe size is always a multiple of
@@ -1021,9 +1018,16 @@ static void ext4_mb_choose_next_group_best_avail(struct ext4_allocation_context
 		 */
 		num_stripe_clusters = EXT4_NUM_B2C(sbi, sbi->s_stripe);
 		if (1 << min_order < num_stripe_clusters)
-			min_order = fls(num_stripe_clusters);
+			/*
+			 * We consider 1 order less because later we round
+			 * up the goal len to num_stripe_clusters
+			 */
+			min_order = fls(num_stripe_clusters) - 1;
 	}
 
+	if (1 << min_order < ac->ac_o_ex.fe_len)
+		min_order = fls(ac->ac_o_ex.fe_len);
+
 	for (i = order; i >= min_order; i--) {
 		int frag_order;
 		/*
@@ -4761,8 +4765,8 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
 	int order, i;
 	struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
 	struct ext4_locality_group *lg;
-	struct ext4_prealloc_space *tmp_pa, *cpa = NULL;
-	ext4_lblk_t tmp_pa_start, tmp_pa_end;
+	struct ext4_prealloc_space *tmp_pa = NULL, *cpa = NULL;
+	loff_t tmp_pa_end;
 	struct rb_node *iter;
 	ext4_fsblk_t goal_block;
 
@@ -4770,47 +4774,151 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
 	if (!(ac->ac_flags & EXT4_MB_HINT_DATA))
 		return false;
 
-	/* first, try per-file preallocation */
+	/*
+	 * first, try per-file preallocation by searching the inode pa rbtree.
+	 *
+	 * Here, we can't do a direct traversal of the tree because
+	 * ext4_mb_discard_group_preallocation() can paralelly mark the pa
+	 * deleted and that can cause direct traversal to skip some entries.
+	 */
 	read_lock(&ei->i_prealloc_lock);
+
+	if (RB_EMPTY_ROOT(&ei->i_prealloc_node)) {
+		goto try_group_pa;
+	}
+
+	/*
+	 * Step 1: Find a pa with logical start immediately adjacent to the
+	 * original logical start. This could be on the left or right.
+	 *
+	 * (tmp_pa->pa_lstart never changes so we can skip locking for it).
+	 */
 	for (iter = ei->i_prealloc_node.rb_node; iter;
 	     iter = ext4_mb_pa_rb_next_iter(ac->ac_o_ex.fe_logical,
-					    tmp_pa_start, iter)) {
+					    tmp_pa->pa_lstart, iter)) {
 		tmp_pa = rb_entry(iter, struct ext4_prealloc_space,
 				  pa_node.inode_node);
+	}
 
-		/* all fields in this condition don't change,
-		 * so we can skip locking for them */
-		tmp_pa_start = tmp_pa->pa_lstart;
-		tmp_pa_end = tmp_pa->pa_lstart + EXT4_C2B(sbi, tmp_pa->pa_len);
+	/*
+	 * Step 2: The adjacent pa might be to the right of logical start, find
+	 * the left adjacent pa. After this step we'd have a valid tmp_pa whose
+	 * logical start is towards the left of original request's logical start
+	 */
+	if (tmp_pa->pa_lstart > ac->ac_o_ex.fe_logical) {
+		struct rb_node *tmp;
+		tmp = rb_prev(&tmp_pa->pa_node.inode_node);
 
-		/* original request start doesn't lie in this PA */
-		if (ac->ac_o_ex.fe_logical < tmp_pa_start ||
-		    ac->ac_o_ex.fe_logical >= tmp_pa_end)
-			continue;
+		if (tmp) {
+			tmp_pa = rb_entry(tmp, struct ext4_prealloc_space,
+					    pa_node.inode_node);
+		} else {
+			/*
+			 * If there is no adjacent pa to the left then finding
+			 * an overlapping pa is not possible hence stop searching
+			 * inode pa tree
+			 */
+			goto try_group_pa;
+		}
+	}
+
+	BUG_ON(!(tmp_pa && tmp_pa->pa_lstart <= ac->ac_o_ex.fe_logical));
+
+	/*
+	 * Step 3: If the left adjacent pa is deleted, keep moving left to find
+	 * the first non deleted adjacent pa. After this step we should have a
+	 * valid tmp_pa which is guaranteed to be non deleted.
+	 */
+	for (iter = &tmp_pa->pa_node.inode_node;; iter = rb_prev(iter)) {
+		if (!iter) {
+			/*
+			 * no non deleted left adjacent pa, so stop searching
+			 * inode pa tree
+			 */
+			goto try_group_pa;
+		}
+		tmp_pa = rb_entry(iter, struct ext4_prealloc_space,
+				  pa_node.inode_node);
+		spin_lock(&tmp_pa->pa_lock);
+		if (tmp_pa->pa_deleted == 0) {
+			/*
+			 * We will keep holding the pa_lock from
+			 * this point on because we don't want group discard
+			 * to delete this pa underneath us. Since group
+			 * discard is anyways an ENOSPC operation it
+			 * should be okay for it to wait a few more cycles.
+			 */
+			break;
+		} else {
+			spin_unlock(&tmp_pa->pa_lock);
+		}
+	}
+
+	BUG_ON(!(tmp_pa && tmp_pa->pa_lstart <= ac->ac_o_ex.fe_logical));
+	BUG_ON(tmp_pa->pa_deleted == 1);
+
+	/*
+	 * Step 4: We now have the non deleted left adjacent pa. Only this
+	 * pa can possibly satisfy the request hence check if it overlaps
+	 * original logical start and stop searching if it doesn't.
+	 */
+	tmp_pa_end = (loff_t)tmp_pa->pa_lstart + EXT4_C2B(sbi, tmp_pa->pa_len);
+
+	if (ac->ac_o_ex.fe_logical >= tmp_pa_end) {
+		spin_unlock(&tmp_pa->pa_lock);
+		goto try_group_pa;
+	}
 
 	/* non-extent files can't have physical blocks past 2^32 */
 	if (!(ext4_test_inode_flag(ac->ac_inode, EXT4_INODE_EXTENTS)) &&
 	    (tmp_pa->pa_pstart + EXT4_C2B(sbi, tmp_pa->pa_len) >
 	     EXT4_MAX_BLOCK_FILE_PHYS)) {
 		/*
-			 * Since PAs don't overlap, we won't find any
-			 * other PA to satisfy this.
+		 * Since PAs don't overlap, we won't find any other PA to
+		 * satisfy this.
 		 */
-			break;
+		spin_unlock(&tmp_pa->pa_lock);
+		goto try_group_pa;
 	}
 
-		/* found preallocated blocks, use them */
-		spin_lock(&tmp_pa->pa_lock);
-		if (tmp_pa->pa_deleted == 0 && tmp_pa->pa_free &&
-		    likely(ext4_mb_pa_goal_check(ac, tmp_pa))) {
+	if (tmp_pa->pa_free && likely(ext4_mb_pa_goal_check(ac, tmp_pa))) {
 		atomic_inc(&tmp_pa->pa_count);
 		ext4_mb_use_inode_pa(ac, tmp_pa);
 		spin_unlock(&tmp_pa->pa_lock);
 		read_unlock(&ei->i_prealloc_lock);
 		return true;
+	} else {
+		/*
+		 * We found a valid overlapping pa but couldn't use it because
+		 * it had no free blocks. This should ideally never happen
+		 * because:
+		 *
+		 * 1. When a new inode pa is added to rbtree it must have
+		 *    pa_free > 0 since otherwise we won't actually need
+		 *    preallocation.
+		 *
+		 * 2. An inode pa that is in the rbtree can only have it's
+		 *    pa_free become zero when another thread calls:
+		 *      ext4_mb_new_blocks
+		 *       ext4_mb_use_preallocated
+		 *        ext4_mb_use_inode_pa
+		 *
+		 * 3. Further, after the above calls make pa_free == 0, we will
+		 *    immediately remove it from the rbtree in:
+		 *      ext4_mb_new_blocks
+		 *       ext4_mb_release_context
+		 *        ext4_mb_put_pa
+		 *
+		 * 4. Since the pa_free becoming 0 and pa_free getting removed
+		 * from tree both happen in ext4_mb_new_blocks, which is always
+		 * called with i_data_sem held for data allocations, we can be
+		 * sure that another process will never see a pa in rbtree with
+		 * pa_free == 0.
+		 */
+		WARN_ON_ONCE(tmp_pa->pa_free == 0);
 	}
 	spin_unlock(&tmp_pa->pa_lock);
-	}
+try_group_pa:
 	read_unlock(&ei->i_prealloc_lock);
 
 	/* can we use group allocation? */

fs/ext4/xattr.c

@@ -1782,6 +1782,20 @@ static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
 		memmove(here, (void *)here + size,
 			(void *)last - (void *)here + sizeof(__u32));
 		memset(last, 0, size);
+
+		/*
+		 * Update i_inline_off - moved ibody region might contain
+		 * system.data attribute.  Handling a failure here won't
+		 * cause other complications for setting an xattr.
+		 */
+		if (!is_block && ext4_has_inline_data(inode)) {
+			ret = ext4_find_inline_data_nolock(inode);
+			if (ret) {
+				ext4_warning_inode(inode,
+					"unable to update i_inline_off");
+				goto out;
+			}
+		}
 	} else if (s->not_found) {
 		/* Insert new name. */
 		size_t size = EXT4_XATTR_LEN(name_len);

fs/jbd2/checkpoint.c

@@ -27,7 +27,7 @@
  *
  * Called with j_list_lock held.
  */
-static inline void __buffer_unlink_first(struct journal_head *jh)
+static inline void __buffer_unlink(struct journal_head *jh)
 {
 	transaction_t *transaction = jh->b_cp_transaction;
 
@@ -40,45 +40,6 @@ static inline void __buffer_unlink_first(struct journal_head *jh)
 	}
 }
 
-/*
- * Unlink a buffer from a transaction checkpoint(io) list.
- *
- * Called with j_list_lock held.
- */
-static inline void __buffer_unlink(struct journal_head *jh)
-{
-	transaction_t *transaction = jh->b_cp_transaction;
-
-	__buffer_unlink_first(jh);
-	if (transaction->t_checkpoint_io_list == jh) {
-		transaction->t_checkpoint_io_list = jh->b_cpnext;
-		if (transaction->t_checkpoint_io_list == jh)
-			transaction->t_checkpoint_io_list = NULL;
-	}
-}
-
-/*
- * Move a buffer from the checkpoint list to the checkpoint io list
- *
- * Called with j_list_lock held
- */
-static inline void __buffer_relink_io(struct journal_head *jh)
-{
-	transaction_t *transaction = jh->b_cp_transaction;
-
-	__buffer_unlink_first(jh);
-
-	if (!transaction->t_checkpoint_io_list) {
-		jh->b_cpnext = jh->b_cpprev = jh;
-	} else {
-		jh->b_cpnext = transaction->t_checkpoint_io_list;
-		jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;
-		jh->b_cpprev->b_cpnext = jh;
-		jh->b_cpnext->b_cpprev = jh;
-	}
-	transaction->t_checkpoint_io_list = jh;
-}
-
 /*
  * Check a checkpoint buffer could be release or not.
  *
@@ -183,6 +144,7 @@ __flush_batch(journal_t *journal, int *batch_count)
 		struct buffer_head *bh = journal->j_chkpt_bhs[i];
 		BUFFER_TRACE(bh, "brelse");
 		__brelse(bh);
+		journal->j_chkpt_bhs[i] = NULL;
 	}
 	*batch_count = 0;
 }
@@ -242,15 +204,6 @@ int jbd2_log_do_checkpoint(journal_t *journal)
 		jh = transaction->t_checkpoint_list;
 		bh = jh2bh(jh);
 
-		if (buffer_locked(bh)) {
-			get_bh(bh);
-			spin_unlock(&journal->j_list_lock);
-			wait_on_buffer(bh);
-			/* the journal_head may have gone by now */
-			BUFFER_TRACE(bh, "brelse");
-			__brelse(bh);
-			goto retry;
-		}
 		if (jh->b_transaction != NULL) {
 			transaction_t *t = jh->b_transaction;
 			tid_t tid = t->t_tid;
@@ -285,30 +238,50 @@ int jbd2_log_do_checkpoint(journal_t *journal)
 			spin_lock(&journal->j_list_lock);
 			goto restart;
 		}
-		if (!buffer_dirty(bh)) {
+		if (!trylock_buffer(bh)) {
+			/*
+			 * The buffer is locked, it may be writing back, or
+			 * flushing out in the last couple of cycles, or
+			 * re-adding into a new transaction, need to check
+			 * it again until it's unlocked.
+			 */
+			get_bh(bh);
+			spin_unlock(&journal->j_list_lock);
+			wait_on_buffer(bh);
+			/* the journal_head may have gone by now */
+			BUFFER_TRACE(bh, "brelse");
+			__brelse(bh);
+			goto retry;
+		} else if (!buffer_dirty(bh)) {
+			unlock_buffer(bh);
 			BUFFER_TRACE(bh, "remove from checkpoint");
-			if (__jbd2_journal_remove_checkpoint(jh))
-				/* The transaction was released; we're done */
+			/*
+			 * If the transaction was released or the checkpoint
+			 * list was empty, we're done.
+			 */
+			if (__jbd2_journal_remove_checkpoint(jh) ||
+			    !transaction->t_checkpoint_list)
 				goto out;
-			continue;
-		}
+		} else {
+			unlock_buffer(bh);
 			/*
-		 * Important: we are about to write the buffer, and
-		 * possibly block, while still holding the journal
-		 * lock.  We cannot afford to let the transaction
-		 * logic start messing around with this buffer before
-		 * we write it to disk, as that would break
-		 * recoverability.
+			 * We are about to write the buffer, it could be
+			 * raced by some other transaction shrink or buffer
+			 * re-log logic once we release the j_list_lock,
+			 * leave it on the checkpoint list and check status
+			 * again to make sure it's clean.
 			 */
 			BUFFER_TRACE(bh, "queue");
 			get_bh(bh);
 			J_ASSERT_BH(bh, !buffer_jwrite(bh));
 			journal->j_chkpt_bhs[batch_count++] = bh;
-		__buffer_relink_io(jh);
 			transaction->t_chp_stats.cs_written++;
+			transaction->t_checkpoint_list = jh->b_cpnext;
+		}
+
 		if ((batch_count == JBD2_NR_BATCH) ||
-		    need_resched() ||
-		    spin_needbreak(&journal->j_list_lock))
+		    need_resched() || spin_needbreak(&journal->j_list_lock) ||
+		    jh2bh(transaction->t_checkpoint_list) == journal->j_chkpt_bhs[0])
 			goto unlock_and_flush;
 	}
 
@@ -322,38 +295,6 @@ int jbd2_log_do_checkpoint(journal_t *journal)
 			goto restart;
 	}
 
-	/*
-	 * Now we issued all of the transaction's buffers, let's deal
-	 * with the buffers that are out for I/O.
-	 */
-restart2:
-	/* Did somebody clean up the transaction in the meanwhile? */
-	if (journal->j_checkpoint_transactions != transaction ||
-	    transaction->t_tid != this_tid)
-		goto out;
-
-	while (transaction->t_checkpoint_io_list) {
-		jh = transaction->t_checkpoint_io_list;
-		bh = jh2bh(jh);
-		if (buffer_locked(bh)) {
-			get_bh(bh);
-			spin_unlock(&journal->j_list_lock);
-			wait_on_buffer(bh);
-			/* the journal_head may have gone by now */
-			BUFFER_TRACE(bh, "brelse");
-			__brelse(bh);
-			spin_lock(&journal->j_list_lock);
-			goto restart2;
-		}
-
-		/*
-		 * Now in whatever state the buffer currently is, we
-		 * know that it has been written out and so we can
-		 * drop it from the list
-		 */
-		if (__jbd2_journal_remove_checkpoint(jh))
-			break;
-	}
 out:
 	spin_unlock(&journal->j_list_lock);
 	result = jbd2_cleanup_journal_tail(journal);
@@ -408,50 +349,10 @@ int jbd2_cleanup_journal_tail(journal_t *journal)
 
 /* Checkpoint list management */
 
-/*
- * journal_clean_one_cp_list
- *
- * Find all the written-back checkpoint buffers in the given list and
- * release them. If 'destroy' is set, clean all buffers unconditionally.
- *
- * Called with j_list_lock held.
- * Returns 1 if we freed the transaction, 0 otherwise.
- */
-static int journal_clean_one_cp_list(struct journal_head *jh, bool destroy)
-{
-	struct journal_head *last_jh;
-	struct journal_head *next_jh = jh;
-
-	if (!jh)
-		return 0;
-
-	last_jh = jh->b_cpprev;
-	do {
-		jh = next_jh;
-		next_jh = jh->b_cpnext;
-
-		if (!destroy && __cp_buffer_busy(jh))
-			return 0;
-
-		if (__jbd2_journal_remove_checkpoint(jh))
-			return 1;
-		/*
-		 * This function only frees up some memory
-		 * if possible so we dont have an obligation
-		 * to finish processing. Bail out if preemption
-		 * requested:
-		 */
-		if (need_resched())
-			return 0;
-	} while (jh != last_jh);
-
-	return 0;
-}
-
 /*
  * journal_shrink_one_cp_list
  *
- * Find 'nr_to_scan' written-back checkpoint buffers in the given list
+ * Find all the written-back checkpoint buffers in the given list
  * and try to release them. If the whole transaction is released, set
  * the 'released' parameter. Return the number of released checkpointed
  * buffers.
@@ -459,15 +360,15 @@ static int journal_clean_one_cp_list(struct journal_head *jh, bool destroy)
  * Called with j_list_lock held.
  */
 static unsigned long journal_shrink_one_cp_list(struct journal_head *jh,
-						unsigned long *nr_to_scan,
-						bool *released)
+						bool destroy, bool *released)
 {
 	struct journal_head *last_jh;
 	struct journal_head *next_jh = jh;
 	unsigned long nr_freed = 0;
 	int ret;
 
-	if (!jh || *nr_to_scan == 0)
+	*released = false;
+	if (!jh)
 		return 0;
 
 	last_jh = jh->b_cpprev;
@@ -475,12 +376,15 @@ static unsigned long journal_shrink_one_cp_list(struct journal_head *jh,
 		jh = next_jh;
 		next_jh = jh->b_cpnext;
 
-		(*nr_to_scan)--;
-		if (__cp_buffer_busy(jh))
+		if (destroy) {
+			ret = __jbd2_journal_remove_checkpoint(jh);
+		} else {
+			ret = jbd2_journal_try_remove_checkpoint(jh);
+			if (ret < 0)
 				continue;
+		}
 
 		nr_freed++;
-		ret = __jbd2_journal_remove_checkpoint(jh);
 		if (ret) {
 			*released = true;
 			break;
@@ -488,7 +392,7 @@ static unsigned long journal_shrink_one_cp_list(struct journal_head *jh,
 
 		if (need_resched())
 			break;
-	} while (jh != last_jh && *nr_to_scan);
+	} while (jh != last_jh);
 
 	return nr_freed;
 }
@@ -506,11 +410,11 @@ unsigned long jbd2_journal_shrink_checkpoint_list(journal_t *journal,
 						  unsigned long *nr_to_scan)
 {
 	transaction_t *transaction, *last_transaction, *next_transaction;
-	bool released;
+	bool __maybe_unused released;
 	tid_t first_tid = 0, last_tid = 0, next_tid = 0;
 	tid_t tid = 0;
 	unsigned long nr_freed = 0;
-	unsigned long nr_scanned = *nr_to_scan;
+	unsigned long freed;
 
 again:
 	spin_lock(&journal->j_list_lock);
@@ -539,19 +443,11 @@ unsigned long jbd2_journal_shrink_checkpoint_list(journal_t *journal,
 		transaction = next_transaction;
 		next_transaction = transaction->t_cpnext;
 		tid = transaction->t_tid;
-		released = false;
 
-		nr_freed += journal_shrink_one_cp_list(transaction->t_checkpoint_list,
-						       nr_to_scan, &released);
-		if (*nr_to_scan == 0)
-			break;
-		if (need_resched() || spin_needbreak(&journal->j_list_lock))
-			break;
-		if (released)
-			continue;
-
-		nr_freed += journal_shrink_one_cp_list(transaction->t_checkpoint_io_list,
-						       nr_to_scan, &released);
+		freed = journal_shrink_one_cp_list(transaction->t_checkpoint_list,
+						   false, &released);
+		nr_freed += freed;
+		(*nr_to_scan) -= min(*nr_to_scan, freed);
 		if (*nr_to_scan == 0)
 			break;
 		if (need_resched() || spin_needbreak(&journal->j_list_lock))
@@ -572,9 +468,8 @@ unsigned long jbd2_journal_shrink_checkpoint_list(journal_t *journal,
 	if (*nr_to_scan && next_tid)
 		goto again;
 out:
-	nr_scanned -= *nr_to_scan;
 	trace_jbd2_shrink_checkpoint_list(journal, first_tid, tid, last_tid,
-					  nr_freed, nr_scanned, next_tid);
+					  nr_freed, next_tid);
 
 	return nr_freed;
 }
@@ -590,7 +485,7 @@ unsigned long jbd2_journal_shrink_checkpoint_list(journal_t *journal,
 void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy)
 {
 	transaction_t *transaction, *last_transaction, *next_transaction;
-	int ret;
+	bool released;
 
 	transaction = journal->j_checkpoint_transactions;
 	if (!transaction)
@@ -601,8 +496,8 @@ void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy)
 	do {
 		transaction = next_transaction;
 		next_transaction = transaction->t_cpnext;
-		ret = journal_clean_one_cp_list(transaction->t_checkpoint_list,
-						destroy);
+		journal_shrink_one_cp_list(transaction->t_checkpoint_list,
+					   destroy, &released);
 		/*
 		 * This function only frees up some memory if possible so we
 		 * dont have an obligation to finish processing. Bail out if
@@ -610,23 +505,12 @@ void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy)
 		 */
 		if (need_resched())
 			return;
-		if (ret)
-			continue;
-		/*
-		 * It is essential that we are as careful as in the case of
-		 * t_checkpoint_list with removing the buffer from the list as
-		 * we can possibly see not yet submitted buffers on io_list
-		 */
-		ret = journal_clean_one_cp_list(transaction->
-				t_checkpoint_io_list, destroy);
-		if (need_resched())
-			return;
 		/*
 		 * Stop scanning if we couldn't free the transaction. This
 		 * avoids pointless scanning of transactions which still
 		 * weren't checkpointed.
 		 */
-		if (!ret)
+		if (!released)
 			return;
 	} while (transaction != last_transaction);
 }
@@ -705,7 +589,7 @@ int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
 	jbd2_journal_put_journal_head(jh);
 
 	/* Is this transaction empty? */
-	if (transaction->t_checkpoint_list || transaction->t_checkpoint_io_list)
+	if (transaction->t_checkpoint_list)
 		return 0;
 
 	/*
@@ -736,6 +620,34 @@ int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
 	return 1;
 }
 
+/*
+ * Check the checkpoint buffer and try to remove it from the checkpoint
+ * list if it's clean. Returns -EBUSY if it is not clean, returns 1 if
+ * it frees the transaction, 0 otherwise.
+ *
+ * This function is called with j_list_lock held.
+ */
+int jbd2_journal_try_remove_checkpoint(struct journal_head *jh)
+{
+	struct buffer_head *bh = jh2bh(jh);
+
+	if (!trylock_buffer(bh))
+		return -EBUSY;
+	if (buffer_dirty(bh)) {
+		unlock_buffer(bh);
+		return -EBUSY;
+	}
+	unlock_buffer(bh);
+
+	/*
+	 * Buffer is clean and the IO has finished (we held the buffer
+	 * lock) so the checkpoint is done. We can safely remove the
+	 * buffer from this transaction.
+	 */
+	JBUFFER_TRACE(jh, "remove from checkpoint list");
+	return __jbd2_journal_remove_checkpoint(jh);
+}
+
 /*
  * journal_insert_checkpoint: put a committed buffer onto a checkpoint
  * list so that we know when it is safe to clean the transaction out of
@@ -797,7 +709,6 @@ void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transact
 	J_ASSERT(transaction->t_forget == NULL);
 	J_ASSERT(transaction->t_shadow_list == NULL);
 	J_ASSERT(transaction->t_checkpoint_list == NULL);
-	J_ASSERT(transaction->t_checkpoint_io_list == NULL);
 	J_ASSERT(atomic_read(&transaction->t_updates) == 0);
 	J_ASSERT(journal->j_committing_transaction != transaction);
 	J_ASSERT(journal->j_running_transaction != transaction);

fs/jbd2/commit.c

@@ -1141,8 +1141,7 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	spin_lock(&journal->j_list_lock);
 	commit_transaction->t_state = T_FINISHED;
 	/* Check if the transaction can be dropped now that we are finished */
-	if (commit_transaction->t_checkpoint_list == NULL &&
-	    commit_transaction->t_checkpoint_io_list == NULL) {
+	if (commit_transaction->t_checkpoint_list == NULL) {
 		__jbd2_journal_drop_transaction(journal, commit_transaction);
 		jbd2_journal_free_transaction(commit_transaction);
 	}

fs/jbd2/transaction.c

@@ -1784,8 +1784,7 @@ int jbd2_journal_forget(handle_t *handle, struct buffer_head *bh)
 		 * Otherwise, if the buffer has been written to disk,
 		 * it is safe to remove the checkpoint and drop it.
 		 */
-		if (!buffer_dirty(bh)) {
-			__jbd2_journal_remove_checkpoint(jh);
+		if (jbd2_journal_try_remove_checkpoint(jh) >= 0) {
 			spin_unlock(&journal->j_list_lock);
 			goto drop;
 		}
@@ -2100,35 +2099,6 @@ void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
 	__brelse(bh);
 }
 
-/*
- * Called from jbd2_journal_try_to_free_buffers().
- *
- * Called under jh->b_state_lock
- */
-static void
-__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
-{
-	struct journal_head *jh;
-
-	jh = bh2jh(bh);
-
-	if (buffer_locked(bh) || buffer_dirty(bh))
-		goto out;
-
-	if (jh->b_next_transaction != NULL || jh->b_transaction != NULL)
-		goto out;
-
-	spin_lock(&journal->j_list_lock);
-	if (jh->b_cp_transaction != NULL) {
-		/* written-back checkpointed metadata buffer */
-		JBUFFER_TRACE(jh, "remove from checkpoint list");
-		__jbd2_journal_remove_checkpoint(jh);
-	}
-	spin_unlock(&journal->j_list_lock);
-out:
-	return;
-}
-
 /**
  * jbd2_journal_try_to_free_buffers() - try to free page buffers.
  * @journal: journal for operation
@@ -2186,7 +2156,13 @@ bool jbd2_journal_try_to_free_buffers(journal_t *journal, struct folio *folio)
 			continue;
 
 		spin_lock(&jh->b_state_lock);
-		__journal_try_to_free_buffer(journal, bh);
+		if (!jh->b_transaction && !jh->b_next_transaction) {
+			spin_lock(&journal->j_list_lock);
+			/* Remove written-back checkpointed metadata buffer */
+			if (jh->b_cp_transaction != NULL)
+				jbd2_journal_try_remove_checkpoint(jh);
+			spin_unlock(&journal->j_list_lock);
+		}
 		spin_unlock(&jh->b_state_lock);
 		jbd2_journal_put_journal_head(jh);
 		if (buffer_jbd(bh))

include/linux/jbd2.h

@@ -613,12 +613,6 @@ struct transaction_s
 	 */
 	struct journal_head	*t_checkpoint_list;
 
-	/*
-	 * Doubly-linked circular list of all buffers submitted for IO while
-	 * checkpointing. [j_list_lock]
-	 */
-	struct journal_head	*t_checkpoint_io_list;
-
 	/*
 	 * Doubly-linked circular list of metadata buffers being
 	 * shadowed by log IO.  The IO buffers on the iobuf list and
@@ -1449,6 +1443,7 @@ extern void jbd2_journal_commit_transaction(journal_t *);
 void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy);
 unsigned long jbd2_journal_shrink_checkpoint_list(journal_t *journal, unsigned long *nr_to_scan);
 int __jbd2_journal_remove_checkpoint(struct journal_head *);
+int jbd2_journal_try_remove_checkpoint(struct journal_head *jh);
 void jbd2_journal_destroy_checkpoint(journal_t *journal);
 void __jbd2_journal_insert_checkpoint(struct journal_head *, transaction_t *);
 

include/trace/events/jbd2.h

@@ -462,11 +462,9 @@ TRACE_EVENT(jbd2_shrink_scan_exit,
 TRACE_EVENT(jbd2_shrink_checkpoint_list,
 
 	TP_PROTO(journal_t *journal, tid_t first_tid, tid_t tid, tid_t last_tid,
-		 unsigned long nr_freed, unsigned long nr_scanned,
-		 tid_t next_tid),
+		 unsigned long nr_freed, tid_t next_tid),
 
-	TP_ARGS(journal, first_tid, tid, last_tid, nr_freed,
-		nr_scanned, next_tid),
+	TP_ARGS(journal, first_tid, tid, last_tid, nr_freed, next_tid),
 
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
@@ -474,7 +472,6 @@ TRACE_EVENT(jbd2_shrink_checkpoint_list,
 		__field(tid_t, tid)
 		__field(tid_t, last_tid)
 		__field(unsigned long, nr_freed)
-		__field(unsigned long, nr_scanned)
 		__field(tid_t, next_tid)
 	),
 
@@ -484,15 +481,14 @@ TRACE_EVENT(jbd2_shrink_checkpoint_list,
 		__entry->tid		= tid;
 		__entry->last_tid	= last_tid;
 		__entry->nr_freed	= nr_freed;
-		__entry->nr_scanned	= nr_scanned;
 		__entry->next_tid	= next_tid;
 	),
 
 	TP_printk("dev %d,%d shrink transaction %u-%u(%u) freed %lu "
-		  "scanned %lu next transaction %u",
+		  "next transaction %u",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  __entry->first_tid, __entry->tid, __entry->last_tid,
-		  __entry->nr_freed, __entry->nr_scanned, __entry->next_tid)
+		  __entry->nr_freed, __entry->next_tid)
 );
 
 #endif /* _TRACE_JBD2_H */