From 45e0d4b95b65fedd18aa3e1b6571e16a2e6e0aa9 Mon Sep 17 00:00:00 2001
From: Mateusz Guzik <mjguzik@gmail.com>
Date: Fri, 11 Aug 2023 21:48:14 +0200
Subject: [PATCH] vfs: fix up the assert in i_readcount_dec
Drops a race where 2 threads could spot a positive value and both
proceed to dec to -1, without reporting anything.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Message-Id: <20230811194814.1612336-1-mjguzik@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
---
include/linux/fs.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 11055d00fab87..57e2a0a9eea19 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2607,8 +2607,7 @@ static inline bool inode_is_open_for_write(const struct inode *inode)
#if defined(CONFIG_IMA) || defined(CONFIG_FILE_LOCKING)
static inline void i_readcount_dec(struct inode *inode)
{
- BUG_ON(!atomic_read(&inode->i_readcount));
- atomic_dec(&inode->i_readcount);
+ BUG_ON(atomic_dec_return(&inode->i_readcount) < 0);
}
static inline void i_readcount_inc(struct inode *inode)
{
--
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