linux-kernel - [PATCH v2 3/3] fs/file.c: remove sanity_check from alloc

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Message-ID: <20240622154904.3774273-4-yu.ma@intel.com>
Date: Sat, 22 Jun 2024 11:49:04 -0400
From: Yu Ma <yu.ma@...el.com>
To: viro@...iv.linux.org.uk,
	brauner@...nel.org,
	jack@...e.cz,
	mjguzik@...il.com,
	edumazet@...gle.com
Cc: yu.ma@...el.com,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	pan.deng@...el.com,
	tianyou.li@...el.com,
	tim.c.chen@...el.com,
	tim.c.chen@...ux.intel.com
Subject: [PATCH v2 3/3] fs/file.c: remove sanity_check from alloc_fd()

alloc_fd() has a sanity check inside to make sure the struct file mapping to the
allocated fd is NULL. Remove this sanity check since it can be assured by
exisitng zero initilization and NULL set when recycling fd.

Combined with patch 1 and 2 in series, pts/blogbench-1.1.0 read improved by
32%, write improved by 17% on Intel ICX 160 cores configuration with v6.10-rc4.

Reviewed-by: Tim Chen <tim.c.chen@...ux.intel.com>
Signed-off-by: Yu Ma <yu.ma@...el.com>
---
 fs/file.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/fs/file.c b/fs/file.c
index b4d25f6d4c19..1153b0b7ba3d 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -555,13 +555,6 @@ static int alloc_fd(unsigned start, unsigned end, unsigned flags)
 	else
 		__clear_close_on_exec(fd, fdt);
 	error = fd;
-#if 1
-	/* Sanity check */
-	if (rcu_access_pointer(fdt->fd[fd]) != NULL) {
-		printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd);
-		rcu_assign_pointer(fdt->fd[fd], NULL);
-	}
-#endif
 
 out:
 	spin_unlock(&files->file_lock);
-- 
2.43.0