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From: ebiederm@xmission.com (Eric W. Biederman)
To: Andrew Morton <akpm@linux-foundation.org>
Cc: <linux-kernel@vger.kernel.org>, <linux-pci@vger.kernel.org>,
	<linux-mm@kvack.org>, <linux-fsdevel@vger.kernel.org>,
	Al Viro <viro@ZenIV.linux.org.uk>,
	Hugh Dickins <hugh@veritas.com>, Tejun Heo <tj@kernel.org>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Alan Cox <alan@lxorguk.ukuu.org.uk>,
	Greg Kroah-Hartman <gregkh@suse.de>
Subject: [RFC][PATCH 8/9] vfs: Implement generic revoked file operations
Date: Sat, 11 Apr 2009 05:13:22 -0700
Message-ID: <m1prfj5qxp.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <m1skkf761y.fsf@fess.ebiederm.org> (Eric W. Biederman's message of "Sat\, 11 Apr 2009 05\:01\:29 -0700")


revoked_file_ops is a set of file operations designed to be used
when a files backing store has been removed.

revoked_file_ops return 0 from reads (aka EOF). Tell poll the file is
always ready for I/O and return -EIO from all other operations.

This is designed to allow userspace to gracefully file descriptors
that enter this unusable state.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 fs/Makefile        |    2 +-
 fs/revoked_file.c  |  181 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/fs.h |    2 +
 3 files changed, 184 insertions(+), 1 deletions(-)
 create mode 100644 fs/revoked_file.c

diff --git a/fs/Makefile b/fs/Makefile
index af6d047..7787ddd 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -11,7 +11,7 @@ obj-y :=	open.o read_write.o file_table.o super.o \
 		attr.o bad_inode.o file.o filesystems.o namespace.o \
 		seq_file.o xattr.o libfs.o fs-writeback.o \
 		pnode.o drop_caches.o splice.o sync.o utimes.o \
-		stack.o fs_struct.o
+		stack.o fs_struct.o revoked_file.o
 
 ifeq ($(CONFIG_BLOCK),y)
 obj-y +=	buffer.o bio.o block_dev.o direct-io.o mpage.o ioprio.o
diff --git a/fs/revoked_file.c b/fs/revoked_file.c
new file mode 100644
index 0000000..9936693
--- /dev/null
+++ b/fs/revoked_file.c
@@ -0,0 +1,181 @@
+/*
+ *  linux/fs/revoked_file.c
+ *
+ *  Copyright (C) 1997, Stephen Tweedie
+ *
+ *  Provide stub functions for unreadable inodes
+ *
+ *  Fabian Frederick : August 2003 - All file operations assigned to EIO
+ *
+ *  Eric Biederman : 8 April 2008 - Derivied from bad_inode.c
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/stat.h>
+#include <linux/time.h>
+#include <linux/namei.h>
+#include <linux/poll.h>
+
+static loff_t revoked_file_llseek(struct file *file, loff_t offset, int origin)
+{
+	return -EIO;
+}
+
+static ssize_t revoked_file_read(struct file *filp, char __user *buf,
+			size_t size, loff_t *ppos)
+{
+        return 0;
+}
+
+static ssize_t revoked_file_write(struct file *filp, const char __user *buf,
+			size_t siz, loff_t *ppos)
+{
+        return -EIO;
+}
+
+static ssize_t revoked_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
+			unsigned long nr_segs, loff_t pos)
+{
+	return 0;
+}
+
+static ssize_t revoked_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
+			unsigned long nr_segs, loff_t pos)
+{
+	return -EIO;
+}
+
+static int revoked_file_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+	return -EIO;
+}
+
+static unsigned int revoked_file_poll(struct file *filp, poll_table *wait)
+{
+	return POLLIN | POLLOUT | POLLERR | POLLRDNORM | POLLWRNORM;
+}
+
+static int revoked_file_ioctl (struct inode *inode, struct file *filp,
+			unsigned int cmd, unsigned long arg)
+{
+	return -EIO;
+}
+
+static long revoked_file_unlocked_ioctl(struct file *file, unsigned cmd,
+			unsigned long arg)
+{
+	return -EIO;
+}
+
+static long revoked_file_compat_ioctl(struct file *file, unsigned int cmd,
+			unsigned long arg)
+{
+	return -EIO;
+}
+
+static int revoked_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	return -EIO;
+}
+
+static int revoked_file_open(struct inode *inode, struct file *filp)
+{
+	return -EIO;
+}
+
+static int revoked_file_flush(struct file *file, fl_owner_t id)
+{
+	return 0;
+}
+
+static int revoked_file_release(struct inode *inode, struct file *filp)
+{
+	return 0;
+}
+
+static int revoked_file_fsync(struct file *file, struct dentry *dentry,
+			int datasync)
+{
+	return -EIO;
+}
+
+static int revoked_file_aio_fsync(struct kiocb *iocb, int datasync)
+{
+	return -EIO;
+}
+
+static int revoked_file_fasync(int fd, struct file *filp, int on)
+{
+	return -EIO;
+}
+
+static int revoked_file_lock(struct file *file, int cmd, struct file_lock *fl)
+{
+	return -EIO;
+}
+
+static ssize_t revoked_file_sendpage(struct file *file, struct page *page,
+			int off, size_t len, loff_t *pos, int more)
+{
+	return -EIO;
+}
+
+static unsigned long revoked_file_get_unmapped_area(struct file *file,
+				unsigned long addr, unsigned long len,
+				unsigned long pgoff, unsigned long flags)
+{
+	return -EIO;
+}
+
+static int revoked_file_check_flags(int flags)
+{
+	return -EIO;
+}
+
+static int revoked_file_flock(struct file *filp, int cmd, struct file_lock *fl)
+{
+	return -EIO;
+}
+
+static ssize_t revoked_file_splice_write(struct pipe_inode_info *pipe,
+			struct file *out, loff_t *ppos, size_t len,
+			unsigned int flags)
+{
+	return -EIO;
+}
+
+static ssize_t revoked_file_splice_read(struct file *in, loff_t *ppos,
+			struct pipe_inode_info *pipe, size_t len,
+			unsigned int flags)
+{
+	return -EIO;
+}
+
+const struct file_operations revoked_file_ops =
+{
+	.llseek		= revoked_file_llseek,
+	.read		= revoked_file_read,
+	.write		= revoked_file_write,
+	.aio_read	= revoked_file_aio_read,
+	.aio_write	= revoked_file_aio_write,
+	.readdir	= revoked_file_readdir,
+	.poll		= revoked_file_poll,
+	.ioctl		= revoked_file_ioctl,
+	.unlocked_ioctl	= revoked_file_unlocked_ioctl,
+	.compat_ioctl	= revoked_file_compat_ioctl,
+	.mmap		= revoked_file_mmap,
+	.open		= revoked_file_open,
+	.flush		= revoked_file_flush,
+	.release	= revoked_file_release,
+	.fsync		= revoked_file_fsync,
+	.aio_fsync	= revoked_file_aio_fsync,
+	.fasync		= revoked_file_fasync,
+	.lock		= revoked_file_lock,
+	.sendpage	= revoked_file_sendpage,
+	.get_unmapped_area = revoked_file_get_unmapped_area,
+	.check_flags	= revoked_file_check_flags,
+	.flock		= revoked_file_flock,
+	.splice_write	= revoked_file_splice_write,
+	.splice_read	= revoked_file_splice_read,
+};
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a82a2ea..2fb0871 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -896,6 +896,8 @@ extern int fops_substitute(struct file *file, const struct file_operations *f_op
 extern void inode_fops_substitute(struct inode *inode,
 	const struct file_operations *f_op, struct vm_operations_struct *vm_ops);
 
+extern const struct file_operations revoked_file_ops;
+
 extern struct mutex files_lock;
 #define file_list_lock() mutex_lock(&files_lock);
 #define file_list_unlock() mutex_unlock(&files_lock);
-- 
1.6.1.2.350.g88cc

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  parent reply index

Thread overview: 99+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-11 12:01 [RFC][PATCH 0/9] File descriptor hot-unplug support Eric W. Biederman
2009-04-11 12:03 ` [RFC][PATCH 1/9] mm: Introduce remap_file_mappings Eric W. Biederman
2009-04-11 12:05 ` [RFC][PATCH 2/9] mm: Implement generic support for revoking a mapping Eric W. Biederman
2009-04-11 12:06 ` [RFC][PATCH 3/9] sysfs: Use remap_file_mappings Eric W. Biederman
2009-04-11 12:07 ` [RFC][PATCH 4/9] vfs: Generalize the file_list Eric W. Biederman
2009-04-11 12:08 ` [RFC][PATCH 5/9] vfs: Introduce basic infrastructure for revoking a file Eric W. Biederman
2009-04-14 22:12   ` Jonathan Corbet
2009-04-15  2:55     ` Eric W. Biederman
2009-04-11 12:10 ` [RFC][PATCH 6/9] vfs: Utilize fops_read_lock where appropriate Eric W. Biederman
2009-04-11 12:11 ` [RFC][PATCH 7/9] vfs: Optimize fops_read_lock Eric W. Biederman
2009-04-11 12:13 ` Eric W. Biederman [this message]
2009-04-12 18:56   ` [RFC][PATCH 8/9] vfs: Implement generic revoked file operations Jamie Lokier
2009-04-12 20:04     ` Eric W. Biederman
2009-04-12 20:31       ` Jamie Lokier
2009-04-12 21:53         ` Eric W. Biederman
2009-04-12 20:54       ` Eric W. Biederman
2009-04-12 21:02         ` Jamie Lokier
2009-04-12 23:06           ` Eric W. Biederman
2009-04-11 12:14 ` [RFC][PATCH 9/9] proc: Use the generic vfs revoke facility that now exists Eric W. Biederman
2009-04-11 15:58 ` [RFC][PATCH 0/9] File descriptor hot-unplug support Al Viro
2009-04-11 16:49   ` Eric W. Biederman
2009-04-11 16:56     ` Al Viro
2009-04-11 23:57       ` Eric W. Biederman
2009-04-12 20:21       ` Eric W. Biederman
2009-04-14  3:16 ` Tejun Heo
2009-04-14  7:39   ` Eric W. Biederman
2009-04-14  7:45     ` Tejun Heo
2009-04-14  8:27       ` Eric W. Biederman
2009-04-14  8:49         ` Tejun Heo
2009-04-14 15:07         ` Jamie Lokier
2009-04-14 19:09           ` Eric W. Biederman
2009-06-01 21:45 ` [PATCH 0/23] File descriptor hot-unplug support v2 Eric W. Biederman
2009-06-01 21:50   ` [PATCH 01/23] mm: Introduce revoke_file_mappings Eric W. Biederman
2009-06-01 22:25     ` Andrew Morton
2009-06-02  0:12       ` Eric W. Biederman
2009-06-01 21:50   ` [PATCH 02/23] vfs: Implement unpoll_file Eric W. Biederman
2009-06-06  8:08     ` Al Viro
2009-06-01 21:50   ` [PATCH 03/23] vfs: Generalize the file_list Eric W. Biederman
2009-06-02  7:06     ` Nick Piggin
2009-06-05 19:33       ` Eric W. Biederman
2009-06-09 10:38         ` Nick Piggin
2009-06-09 18:38           ` Eric W. Biederman
2009-06-10  6:05             ` Nick Piggin
2009-06-01 21:50   ` [PATCH 04/23] vfs: Introduce infrastructure for revoking a file Eric W. Biederman
2009-06-02  5:16     ` Pekka Enberg
2009-06-02  6:51       ` Eric W. Biederman
2009-06-02  7:08         ` Pekka Enberg
2009-06-02  7:14     ` Nick Piggin
2009-06-02 17:06       ` Linus Torvalds
2009-06-02 20:52         ` Eric W. Biederman
2009-06-03  6:37           ` Nick Piggin
2009-06-02 22:56       ` Eric W. Biederman
2009-06-03  6:38         ` Nick Piggin
2009-06-05  9:03     ` Miklos Szeredi
2009-06-05 19:06       ` Eric W. Biederman
2009-06-01 21:50   ` [PATCH 05/23] vfs: Teach lseek to use file_hotplug_lock Eric W. Biederman
2009-06-01 21:50   ` [PATCH 06/23] vfs: Teach read/write to use file_hotplug_read_lock Eric W. Biederman
2009-06-01 21:50   ` [PATCH 07/23] vfs: Teach sendfile,splice,tee,and vmsplice to use file_hotplug_lock Eric W. Biederman
2009-06-03 23:39     ` Badari Pulavarty
2009-06-05 19:37       ` Eric W. Biederman
2009-06-01 21:50   ` [PATCH 08/23] vfs: Teach readdir " Eric W. Biederman
2009-06-01 21:50   ` [PATCH 09/23] vfs: Teach poll and select " Eric W. Biederman
2009-06-01 21:50   ` [PATCH 10/23] vfs: Teach do_path_lookup " Eric W. Biederman
2009-06-01 21:50   ` [PATCH 11/23] mm: Teach mmap " Eric W. Biederman
2009-06-01 21:50   ` [PATCH 12/23] vfs: Teach fcntl " Eric W. Biederman
2009-06-01 21:50   ` [PATCH 13/23] vfs: Teach ioctl " Eric W. Biederman
2009-06-01 21:50   ` [PATCH 14/23] vfs: Teach flock " Eric W. Biederman
2009-06-01 21:50   ` [PATCH 15/23] vfs: Teach fallocate, and filp_close " Eric W. Biederman
2009-06-01 21:50   ` [PATCH 16/23] vfs: Teach fstatfs, fstatfs64, ftruncate, fchdir, fchmod, fchown " Eric W. Biederman
2009-06-01 21:50   ` [PATCH 17/23] proc: Teach /proc/<pid>/fd " Eric W. Biederman
2009-06-01 21:50   ` [PATCH 18/23] vfs: Teach epoll " Eric W. Biederman
2009-06-02 16:51     ` Davide Libenzi
2009-06-02 21:23       ` Eric W. Biederman
2009-06-02 21:52         ` Davide Libenzi
2009-06-02 22:51           ` Eric W. Biederman
2009-06-03 14:57             ` Davide Libenzi
2009-06-03 20:53               ` Eric W. Biederman
2009-06-04  0:50                 ` Davide Libenzi
2009-06-04  1:42                   ` Eric W. Biederman
2009-06-01 21:50   ` [PATCH 19/23] eventpoll: Fix comment Eric W. Biederman
2009-06-01 21:50   ` [PATCH 20/23] vfs: Teach aio to use file_hotplug_lock Eric W. Biederman
2009-06-01 21:50   ` [PATCH 21/23] vfs: Teach fsync " Eric W. Biederman
2009-06-01 21:50   ` [PATCH 22/23] vfs: Teach fadvice to file_hotplug_lock Eric W. Biederman
2009-06-01 21:50   ` [PATCH 23/23] vfs: Teach readahead to use the file_hotplug_lock Eric W. Biederman
2009-06-03 23:25     ` Badari Pulavarty
2009-06-06  8:03   ` [PATCH 0/23] File descriptor hot-unplug support v2 Al Viro
2009-06-08  9:41     ` Miklos Szeredi
2009-06-08 10:24       ` Jamie Lokier
2009-06-08 16:29       ` Al Viro
2009-06-08 16:44         ` Miklos Szeredi
2009-06-08 17:50           ` Al Viro
2009-06-08 18:01             ` Linus Torvalds
2009-06-08 18:50               ` Al Viro
2009-06-08 19:18                 ` Linus Torvalds
2009-06-09  6:42                   ` Eric W. Biederman
2009-06-09 10:52                     ` Nick Piggin
2009-06-09  5:50             ` Miklos Szeredi
2009-06-09  6:31               ` Eric W. Biederman
2009-06-09  6:22     ` Eric W. Biederman

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