linux-ext4 - [PATCH 1/2] ext4: use handle to mark fc as ineligible in __track_dentry

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Message-ID: <20240919093848.2330-2-luis.henriques@linux.dev>
Date: Thu, 19 Sep 2024 10:38:47 +0100
From: "Luis Henriques (SUSE)" <luis.henriques@...ux.dev>
To: Theodore Ts'o <tytso@....edu>,
	Andreas Dilger <adilger@...ger.ca>,
	Jan Kara <jack@...e.cz>,
	Harshad Shirwadkar <harshadshirwadkar@...il.com>
Cc: linux-ext4@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Luis Henriques (SUSE)" <luis.henriques@...ux.dev>
Subject: [PATCH 1/2] ext4: use handle to mark fc as ineligible in __track_dentry_update()

Calling ext4_fc_mark_ineligible() with a NULL handle is racy and may result
in a fast-commit being done before the filesystem is effectively marked as
ineligible.  This patch fixes the calls to this function in
__track_dentry_update() by adding an extra parameter to the callback used in
ext4_fc_track_template().

Suggested-by: Jan Kara <jack@...e.cz>
Signed-off-by: Luis Henriques (SUSE) <luis.henriques@...ux.dev>
---
 fs/ext4/fast_commit.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
index 3926a05eceee..c330efd771d1 100644
--- a/fs/ext4/fast_commit.c
+++ b/fs/ext4/fast_commit.c
@@ -372,7 +372,7 @@ void ext4_fc_mark_ineligible(struct super_block *sb, int reason, handle_t *handl
  */
 static int ext4_fc_track_template(
 	handle_t *handle, struct inode *inode,
-	int (*__fc_track_fn)(struct inode *, void *, bool),
+	int (*__fc_track_fn)(handle_t *handle, struct inode *, void *, bool),
 	void *args, int enqueue)
 {
 	bool update = false;
@@ -389,7 +389,7 @@ static int ext4_fc_track_template(
 		ext4_fc_reset_inode(inode);
 		ei->i_sync_tid = tid;
 	}
-	ret = __fc_track_fn(inode, args, update);
+	ret = __fc_track_fn(handle, inode, args, update);
 	mutex_unlock(&ei->i_fc_lock);
 
 	if (!enqueue)
@@ -413,7 +413,8 @@ struct __track_dentry_update_args {
 };
 
 /* __track_fn for directory entry updates. Called with ei->i_fc_lock. */
-static int __track_dentry_update(struct inode *inode, void *arg, bool update)
+static int __track_dentry_update(handle_t *handle, struct inode *inode,
+				 void *arg, bool update)
 {
 	struct ext4_fc_dentry_update *node;
 	struct ext4_inode_info *ei = EXT4_I(inode);
@@ -428,14 +429,14 @@ static int __track_dentry_update(struct inode *inode, void *arg, bool update)
 
 	if (IS_ENCRYPTED(dir)) {
 		ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_ENCRYPTED_FILENAME,
-					NULL);
+					handle);
 		mutex_lock(&ei->i_fc_lock);
 		return -EOPNOTSUPP;
 	}
 
 	node = kmem_cache_alloc(ext4_fc_dentry_cachep, GFP_NOFS);
 	if (!node) {
-		ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM, NULL);
+		ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM, handle);
 		mutex_lock(&ei->i_fc_lock);
 		return -ENOMEM;
 	}
@@ -447,7 +448,7 @@ static int __track_dentry_update(struct inode *inode, void *arg, bool update)
 		node->fcd_name.name = kmalloc(dentry->d_name.len, GFP_NOFS);
 		if (!node->fcd_name.name) {
 			kmem_cache_free(ext4_fc_dentry_cachep, node);
-			ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM, NULL);
+			ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_NOMEM, handle);
 			mutex_lock(&ei->i_fc_lock);
 			return -ENOMEM;
 		}
@@ -569,7 +570,8 @@ void ext4_fc_track_create(handle_t *handle, struct dentry *dentry)
 }
 
 /* __track_fn for inode tracking */
-static int __track_inode(struct inode *inode, void *arg, bool update)
+static int __track_inode(handle_t *handle, struct inode *inode, void *arg,
+			 bool update)
 {
 	if (update)
 		return -EEXIST;
@@ -607,7 +609,8 @@ struct __track_range_args {
 };
 
 /* __track_fn for tracking data updates */
-static int __track_range(struct inode *inode, void *arg, bool update)
+static int __track_range(handle_t *handle, struct inode *inode, void *arg,
+			 bool update)
 {
 	struct ext4_inode_info *ei = EXT4_I(inode);
 	ext4_lblk_t oldstart;