linux-ext4 - [PATCH v2] ext4: lost matching-pair of trace in ext4

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Date:   Mon, 29 Jun 2020 20:26:21 +0800
From:   Yi Zhuang <zhuangyi1@...wei.com>
To:     <tytso@....edu>, <adilger.kernel@...ger.ca>
CC:     <linux-ext4@...r.kernel.org>
Subject: [PATCH v2] ext4: lost matching-pair of trace in ext4_unlink

If dquot_initialize() return non-zero and trace of ext4_unlink_enter/exit
enabled then the matching-pair of trace_exit will lost in log.

v2:
Change the new label to be "out_trace:", which makes it more clear that
it is undoing the "trace" part of the code. At the same time, fix other
similar problems in this function:

	bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
	if (IS_ERR(bh))
		return PTR_ERR(bh);
	if (!bh)
		goto end_unlink;

According to Andreas' suggestion, split up the "end_unlink:" label becomes
two separate labels, and then remove the "if (handle)" check, and then
use out_bh: before the handle is started.

Signed-off-by: Yi Zhuang <zhuangyi1@...wei.com>
---
 fs/ext4/namei.c | 38 +++++++++++++++++++++-----------------
 1 file changed, 21 insertions(+), 17 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 56738b538ddf..941f66f417f0 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3193,30 +3193,33 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
 	 * in separate transaction */
 	retval = dquot_initialize(dir);
 	if (retval)
-		return retval;
+		goto out_trace;
 	retval = dquot_initialize(d_inode(dentry));
 	if (retval)
-		return retval;
+		goto out_trace;
 
-	retval = -ENOENT;
 	bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
-	if (IS_ERR(bh))
-		return PTR_ERR(bh);
-	if (!bh)
-		goto end_unlink;
+	if (IS_ERR(bh)) {
+		retval = PTR_ERR(bh);
+		goto out_trace;
+	}
+	if (!bh) {
+		retval = -ENOENT;
+		goto out_trace;
+	}
 
 	inode = d_inode(dentry);
 
-	retval = -EFSCORRUPTED;
-	if (le32_to_cpu(de->inode) != inode->i_ino)
-		goto end_unlink;
+	if (le32_to_cpu(de->inode) != inode->i_ino) {
+		retval = -EFSCORRUPTED;
+		goto out_bh;
+	}
 
 	handle = ext4_journal_start(dir, EXT4_HT_DIR,
 				    EXT4_DATA_TRANS_BLOCKS(dir->i_sb));
 	if (IS_ERR(handle)) {
 		retval = PTR_ERR(handle);
-		handle = NULL;
-		goto end_unlink;
+		goto out_bh;
 	}
 
 	if (IS_DIRSYNC(dir))
@@ -3224,12 +3227,12 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
 
 	retval = ext4_delete_entry(handle, dir, de, bh);
 	if (retval)
-		goto end_unlink;
+		goto out_handle;
 	dir->i_ctime = dir->i_mtime = current_time(dir);
 	ext4_update_dx_flag(dir);
 	retval = ext4_mark_inode_dirty(handle, dir);
 	if (retval)
-		goto end_unlink;
+		goto out_handle;
 	if (inode->i_nlink == 0)
 		ext4_warning_inode(inode, "Deleting file '%.*s' with no links",
 				   dentry->d_name.len, dentry->d_name.name);
@@ -3251,10 +3254,11 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
 		d_invalidate(dentry);
 #endif
 
-end_unlink:
+out_handle:
+	ext4_journal_stop(handle);
+out_bh:
 	brelse(bh);
-	if (handle)
-		ext4_journal_stop(handle);
+out_trace:
 	trace_ext4_unlink_exit(dentry, retval);
 	return retval;
 }
-- 
2.26.0.106.g9fadedd