linux-kernel - [PATCH 3/6] fs: clear FMODE

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Message-Id: <20220624165631.2124632-4-Jason@zx2c4.com>
Date:   Fri, 24 Jun 2022 18:56:28 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk,
        Jens Axboe <axboe@...nel.dk>, linux-fsdevel@...r.kernel.org
Cc:     "Jason A. Donenfeld" <Jason@...c4.com>
Subject: [PATCH 3/6] fs: clear FMODE_LSEEK if no llseek function

This helps unify a longstanding wart where FMODE_LSEEK hasn't been
uniformly unset when it should be.

Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
 fs/file_table.c | 2 ++
 fs/open.c       | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/fs/file_table.c b/fs/file_table.c
index 5424e3a8df5f..15700b2e1b53 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -241,6 +241,8 @@ static struct file *alloc_file(const struct path *path, int flags,
 	if ((file->f_mode & FMODE_WRITE) &&
 	     likely(fop->write || fop->write_iter))
 		file->f_mode |= FMODE_CAN_WRITE;
+	if ((file->f_mode & FMODE_LSEEK) && !file->f_op->llseek)
+		file->f_mode &= ~FMODE_LSEEK;
 	file->f_mode |= FMODE_OPENED;
 	file->f_op = fop;
 	if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
diff --git a/fs/open.c b/fs/open.c
index 1d57fbde2feb..07c332753a36 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -858,6 +858,8 @@ static int do_dentry_open(struct file *f,
 	if ((f->f_mode & FMODE_WRITE) &&
 	     likely(f->f_op->write || f->f_op->write_iter))
 		f->f_mode |= FMODE_CAN_WRITE;
+	if ((f->f_mode & FMODE_LSEEK) && !f->f_op->llseek)
+		f->f_mode &= ~FMODE_LSEEK;
 	if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO)
 		f->f_mode |= FMODE_CAN_ODIRECT;
 
-- 
2.35.1