linux-kernel - [RFC][PATCH v3 35/55] do_last(): rejoing the common path earlier in FMODE

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Message-Id: <20200301215240.873899-35-viro@ZenIV.linux.org.uk>
Date:   Sun,  1 Mar 2020 21:52:20 +0000
From:   Al Viro <viro@...IV.linux.org.uk>
To:     linux-fsdevel@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [RFC][PATCH v3 35/55] do_last(): rejoing the common path earlier in FMODE_{OPENED,CREATED} case

From: Al Viro <viro@...iv.linux.org.uk>

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/namei.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index b4de0994ccee..66c3e2df46b2 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3204,13 +3204,6 @@ static const char *do_last(struct nameidata *nd,
 		return ERR_CAST(dentry);
 
 	if (file->f_mode & FMODE_OPENED) {
-		if (file->f_mode & FMODE_CREATED) {
-			open_flag &= ~O_TRUNC;
-			will_truncate = false;
-			acc_mode = 0;
-		} else if (!S_ISREG(file_inode(file)->i_mode))
-			will_truncate = false;
-
 		audit_inode(nd->name, file->f_path.dentry, 0);
 		dput(nd->path.dentry);
 		nd->path.dentry = dentry;
@@ -3218,10 +3211,6 @@ static const char *do_last(struct nameidata *nd,
 	}
 
 	if (file->f_mode & FMODE_CREATED) {
-		/* Don't check for write permission, don't truncate */
-		open_flag &= ~O_TRUNC;
-		will_truncate = false;
-		acc_mode = 0;
 		dput(nd->path.dentry);
 		nd->path.dentry = dentry;
 		goto finish_open_created;
@@ -3255,10 +3244,16 @@ static const char *do_last(struct nameidata *nd,
 	}
 	if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry))
 		return ERR_PTR(-ENOTDIR);
-	if (!d_is_reg(nd->path.dentry))
-		will_truncate = false;
 
 finish_open_created:
+	if (file->f_mode & FMODE_CREATED) {
+		/* Don't check for write permission, don't truncate */
+		open_flag &= ~O_TRUNC;
+		will_truncate = false;
+		acc_mode = 0;
+	} else if (!d_is_reg(nd->path.dentry)) {
+		will_truncate = false;
+	}
 	if (will_truncate) {
 		error = mnt_want_write(nd->path.mnt);
 		if (error)
-- 
2.11.0