linux-kernel - [RFC][PATCH 13/42] introduce FMODE

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Message-Id: <20180711022206.12571-13-viro@ZenIV.linux.org.uk>
Date:   Wed, 11 Jul 2018 03:21:37 +0100
From:   Al Viro <viro@...IV.linux.org.uk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Miklos Szeredi <mszeredi@...hat.com>
Subject: [RFC][PATCH 13/42] introduce FMODE_OPENED

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

basically, "is that instance set up enough for regular fput(), or
do we want put_filp() for that one".

NOTE: the only alloc_file() caller that could be followed by put_filp()
is in arch/ia64/kernel/perfmon.c, which is (Kconfig-level) broken.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/file_table.c    | 2 +-
 fs/open.c          | 3 ++-
 include/linux/fs.h | 2 ++
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/file_table.c b/fs/file_table.c
index d7a03a47b702..eaee481295de 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -174,7 +174,7 @@ struct file *alloc_file(const struct path *path, fmode_t mode,
 	if ((mode & FMODE_WRITE) &&
 	     likely(fop->write || fop->write_iter))
 		mode |= FMODE_CAN_WRITE;
-	file->f_mode = mode;
+	file->f_mode = mode | FMODE_OPENED;
 	file->f_op = fop;
 	if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
 		i_readcount_inc(path->dentry->d_inode);
diff --git a/fs/open.c b/fs/open.c
index 008a65e82de5..ce092dda5472 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -752,7 +752,7 @@ static int do_dentry_open(struct file *f,
 	f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
 
 	if (unlikely(f->f_flags & O_PATH)) {
-		f->f_mode = FMODE_PATH;
+		f->f_mode = FMODE_PATH | FMODE_OPENED;
 		f->f_op = &empty_fops;
 		return 0;
 	}
@@ -794,6 +794,7 @@ static int do_dentry_open(struct file *f,
 		if (error)
 			goto cleanup_all;
 	}
+	f->f_mode |= FMODE_OPENED;
 	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
 		i_readcount_inc(inode);
 	if ((f->f_mode & FMODE_READ) &&
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c4ca4c9c1130..05f34726e29c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -148,6 +148,8 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 /* Has write method(s) */
 #define FMODE_CAN_WRITE         ((__force fmode_t)0x40000)
 
+#define FMODE_OPENED		((__force fmode_t)0x80000)
+
 /* File was opened by fanotify and shouldn't generate fanotify events */
 #define FMODE_NONOTIFY		((__force fmode_t)0x4000000)
 
-- 
2.11.0