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Commit 83f936c7 authored by Al Viro's avatar Al Viro
Browse files

mark struct file that had write access grabbed by open() 



new flag in ->f_mode - FMODE_WRITER.  Set by do_dentry_open() in case
when it has grabbed write access, checked by __fput() to decide whether
it wants to drop the sucker.  Allows to stop bothering with mnt_clone_write()
in alloc_file(), along with fewer special_file() checks.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 0ccb2863

fs/file_table.c

+4 −33
Original line number Diff line number Diff line
@@ -177,43 +177,12 @@ struct file *alloc_file(struct path *path, fmode_t mode, 
	file->f_mapping = path->dentry->d_inode->i_mapping;

	file->f_mode = mode;

	file->f_op = fop;



	/*

	 * These mounts don't really matter in practice

	 * for r/o bind mounts.  They aren't userspace-

	 * visible.  We do this for consistency, and so

	 * that we can do debugging checks at __fput()

	 */

	if ((mode & FMODE_WRITE) && !special_file(path->dentry->d_inode->i_mode)) {

		WARN_ON(mnt_clone_write(path->mnt));

	}

	if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)

		i_readcount_inc(path->dentry->d_inode);

	return file;

}

EXPORT_SYMBOL(alloc_file);



/**

 * drop_file_write_access - give up ability to write to a file

 * @file: the file to which we will stop writing

 *

 * This is a central place which will give up the ability

 * to write to @file, along with access to write through

 * its vfsmount.

 */

static void drop_file_write_access(struct file *file)

{

	struct vfsmount *mnt = file->f_path.mnt;

	struct dentry *dentry = file->f_path.dentry;

	struct inode *inode = dentry->d_inode;



	if (special_file(inode->i_mode))

		return;



	put_write_access(inode);

	__mnt_drop_write(mnt);

}



/* the real guts of fput() - releasing the last reference to file

 */

static void __fput(struct file *file)
@@ -248,8 +217,10 @@ static void __fput(struct file *file) 
	put_pid(file->f_owner.pid);

	if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)

		i_readcount_dec(inode);

	if (file->f_mode & FMODE_WRITE)

		drop_file_write_access(file);

	if (file->f_mode & FMODE_WRITER) {

		put_write_access(inode);

		__mnt_drop_write(mnt);

	}

	file->f_path.dentry = NULL;

	file->f_path.mnt = NULL;

	file->f_inode = NULL;

fs/namespace.c

+1 −3
Original line number Diff line number Diff line
@@ -414,9 +414,7 @@ EXPORT_SYMBOL_GPL(mnt_clone_write); 
 */

int __mnt_want_write_file(struct file *file)

{

	struct inode *inode = file_inode(file);



	if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode))

	if (!(file->f_mode & FMODE_WRITER))

		return __mnt_want_write(file->f_path.mnt);

	else

		return mnt_clone_write(file->f_path.mnt);

fs/open.c

+4 −5
Original line number Diff line number Diff line
@@ -670,6 +670,7 @@ static int do_dentry_open(struct file *f, 
			put_write_access(inode);

			goto cleanup_file;

		}

		f->f_mode |= FMODE_WRITER;

	}



	f->f_mapping = inode->i_mapping;
@@ -715,12 +716,10 @@ static int do_dentry_open(struct file *f, 


cleanup_all:

	fops_put(f->f_op);

	if (f->f_mode & FMODE_WRITE) {

		if (!special_file(inode->i_mode)) {

	if (f->f_mode & FMODE_WRITER) {

		put_write_access(inode);

		__mnt_drop_write(f->f_path.mnt);

	}

	}

cleanup_file:

	path_put(&f->f_path);

	f->f_path.mnt = NULL;

include/linux/fs.h

+2 −0
Original line number Diff line number Diff line
@@ -125,6 +125,8 @@ typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset, 


/* File needs atomic accesses to f_pos */

#define FMODE_ATOMIC_POS	((__force fmode_t)0x8000)

/* Write access to underlying fs */

#define FMODE_WRITER		((__force fmode_t)0x10000)



/* File was opened by fanotify and shouldn't generate fanotify events */

#define FMODE_NONOTIFY		((__force fmode_t)0x1000000)