linux-ext4 - [RFC PATCH v2 22/25] ext4: fall back to buffer

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20240102123918.799062-23-yi.zhang@huaweicloud.com>
Date: Tue,  2 Jan 2024 20:39:15 +0800
From: Zhang Yi <yi.zhang@...weicloud.com>
To: linux-ext4@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org,
	tytso@....edu,
	adilger.kernel@...ger.ca,
	jack@...e.cz,
	ritesh.list@...il.com,
	hch@...radead.org,
	djwong@...nel.org,
	willy@...radead.org,
	yi.zhang@...wei.com,
	yi.zhang@...weicloud.com,
	chengzhihao1@...wei.com,
	yukuai3@...wei.com,
	wangkefeng.wang@...wei.com
Subject: [RFC PATCH v2 22/25] ext4: fall back to buffer_head path for defrag

From: Zhang Yi <yi.zhang@...wei.com>

Online defrag doesn't support iomap path yet, so we have to fall back to
buffer_head path for inodes which have been useing iomap. Fall back
active inode is dangerous, we must writeback and drop all dirty pages
under inode lock and mapping->invalidate_lock, those can protect us from
adding new folios into mapping.

Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
---
 fs/ext4/move_extent.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 3aa57376d9c2..7a9ca71d4cac 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -538,6 +538,34 @@ mext_check_arguments(struct inode *orig_inode,
 	return 0;
 }
 
+/*
+ * Disable buffered iomap path for the inode that requiring move extents,
+ * fallback to buffer_head path.
+ */
+static int ext4_disable_buffered_iomap_aops(struct inode *inode)
+{
+	int err;
+
+	/*
+	 * The buffered_head aops don't know how to handle folios
+	 * dirtied by iomap, so before falling back, flush all dirty
+	 * folios the inode has.
+	 */
+	filemap_invalidate_lock(inode->i_mapping);
+	err = filemap_write_and_wait(inode->i_mapping);
+	if (err < 0) {
+		filemap_invalidate_unlock(inode->i_mapping);
+		return err;
+	}
+	truncate_inode_pages(inode->i_mapping, 0);
+
+	ext4_clear_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP);
+	ext4_set_aops(inode);
+	filemap_invalidate_unlock(inode->i_mapping);
+
+	return 0;
+}
+
 /**
  * ext4_move_extents - Exchange the specified range of a file
  *
@@ -609,6 +637,12 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
 	inode_dio_wait(orig_inode);
 	inode_dio_wait(donor_inode);
 
+	/* Fallback to buffer_head aops for inodes with buffered iomap aops */
+	if (ext4_test_inode_state(orig_inode, EXT4_STATE_BUFFERED_IOMAP))
+		ext4_disable_buffered_iomap_aops(orig_inode);
+	if (ext4_test_inode_state(donor_inode, EXT4_STATE_BUFFERED_IOMAP))
+		ext4_disable_buffered_iomap_aops(donor_inode);
+
 	/* Protect extent tree against block allocations via delalloc */
 	ext4_double_down_write_data_sem(orig_inode, donor_inode);
 	/* Check the filesystem environment whether move_extent can be done */
-- 
2.39.2