[RFC,v4,38/69] do_last(): simplify the liveness analysis past finish_open_created
diff mbox series

Message ID 20200313235357.2646756-38-viro@ZenIV.linux.org.uk
State New
Headers show
Series
  • [RFC,v4,01/69] do_add_mount(): lift lock_mount/unlock_mount into callers
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Commit Message

Al Viro March 13, 2020, 11:53 p.m. UTC
From: Al Viro <viro@zeniv.linux.org.uk>

Don't mess with got_write there - it is guaranteed to be false on
entry and it will be set true if and only if we decide to go for
truncation and manage to get write access for that.

Don't carry acc_mode through the entire thing - it's only used
in that part.  And don't bother with gotos in there - compiler is
quite capable of optimizing that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/namei.c | 28 +++++++++++-----------------
 1 file changed, 11 insertions(+), 17 deletions(-)

Patch
diff mbox series

diff --git a/fs/namei.c b/fs/namei.c
index c85fdfd6b33d..8cdf8ef41194 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3122,9 +3122,9 @@  static const char *do_last(struct nameidata *nd,
 	kuid_t dir_uid = nd->inode->i_uid;
 	umode_t dir_mode = nd->inode->i_mode;
 	int open_flag = op->open_flag;
-	bool will_truncate = (open_flag & O_TRUNC) != 0;
+	bool do_truncate;
 	bool got_write = false;
-	int acc_mode = op->acc_mode;
+	int acc_mode;
 	unsigned seq;
 	struct inode *inode;
 	struct dentry *dentry;
@@ -3243,36 +3243,30 @@  static const char *do_last(struct nameidata *nd,
 		return ERR_PTR(-ENOTDIR);
 
 finish_open_created:
+	do_truncate = false;
+	acc_mode = op->acc_mode;
 	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) {
+	} else if (d_is_reg(nd->path.dentry) && open_flag & O_TRUNC) {
 		error = mnt_want_write(nd->path.mnt);
 		if (error)
 			return ERR_PTR(error);
-		got_write = true;
+		do_truncate = true;
 	}
 	error = may_open(&nd->path, acc_mode, open_flag);
-	if (error)
-		goto out;
-	if (!(file->f_mode & FMODE_OPENED))
+	if (!error && !(file->f_mode & FMODE_OPENED))
 		error = vfs_open(&nd->path, file);
-	if (error)
-		goto out;
-	error = ima_file_check(file, op->acc_mode);
-	if (!error && will_truncate)
+	if (!error)
+		error = ima_file_check(file, op->acc_mode);
+	if (!error && do_truncate)
 		error = handle_truncate(file);
-out:
 	if (unlikely(error > 0)) {
 		WARN_ON(1);
 		error = -EINVAL;
 	}
-	if (got_write)
+	if (do_truncate)
 		mnt_drop_write(nd->path.mnt);
 	return ERR_PTR(error);
 }