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Date:   Fri, 20 Aug 2021 23:54:27 -0400
From:   "Theodore Ts'o" <>
To:     Ext4 Developers List <>
Cc:, "Theodore Ts'o" <>,,
Subject: [PATCH] ext4: fix race writing to an inline_data file while its xattrs are changing

The location of the extended attribute can change whenever
xattr_sem is not taken.  So we need to recalculate the i_inline_off
field since it mgiht have changed between ext4_write_begin() and

This means that caching i_inline_off is probably not helpful, so in
the long run we should probably get rid of it and shrink the in-memory
ext4 inode slightly, but let's fix the race the simple way for now.

Fixes: f19d5870cbf72 ("ext4: add normal write support for inline data")
Signed-off-by: Theodore Ts'o <>
 fs/ext4/inline.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 70cb64db33f7..24e994e75f5c 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -750,6 +750,12 @@ int ext4_write_inline_data_end(struct inode *inode, loff_t pos, unsigned len,
 	ext4_write_lock_xattr(inode, &no_expand);
+	/*
+	 * ei->i_inline_off may have changed since ext4_write_begin()
+	 * called ext4_try_to_write_inline_data()
+	 */
+	(void) ext4_find_inline_data_nolock(inode);
 	kaddr = kmap_atomic(page);
 	ext4_write_inline_data(inode, &iloc, kaddr, pos, len);

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