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From: Dave Hansen <haveblue@us.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: hch@lst.de, viro@ZenIV.linux.org.uk, viro@ftp.linux.org.uk,
	miklos@szeredi.hu, Dave Hansen <haveblue@us.ibm.com>
Subject: [RFC][PATCH 08/30] r/o bind mounts: create helper to drop file write access
Date: Fri, 08 Feb 2008 14:26:57 -0800	[thread overview]
Message-ID: <20080208222657.0CA60A96@kernel> (raw)
In-Reply-To: <20080208222641.6024A7CC@kernel>


If someone decides to demote a file from r/w to just
r/o, they can use this same code as __fput().

NFS does just that, and will use this in the next
patch.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Cc: Erez Zadok <ezk@cs.sunysb.edu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 linux-2.6.git-dave/fs/file_table.c      |   19 ++++++++++++++++++-
 linux-2.6.git-dave/fs/nfsd/nfs4state.c  |    3 ++-
 linux-2.6.git-dave/include/linux/file.h |    1 +
 3 files changed, 21 insertions(+), 2 deletions(-)

diff -puN fs/file_table.c~create-file_drop_write_access-helper fs/file_table.c
--- linux-2.6.git/fs/file_table.c~create-file_drop_write_access-helper	2008-02-08 13:04:48.000000000 -0800
+++ linux-2.6.git-dave/fs/file_table.c	2008-02-08 13:04:48.000000000 -0800
@@ -211,6 +211,23 @@ void fastcall fput(struct file *file)
 
 EXPORT_SYMBOL(fput);
 
+/**
+ * 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.
+ */
+void drop_file_write_access(struct file *file)
+{
+	struct dentry *dentry = file->f_path.dentry;
+	struct inode *inode = dentry->d_inode;
+
+	put_write_access(inode);
+}
+EXPORT_SYMBOL_GPL(drop_file_write_access);
+
 /* __fput is called from task context when aio completion releases the last
  * last use of a struct file *.  Do not use otherwise.
  */
@@ -237,7 +254,7 @@ void fastcall __fput(struct file *file)
 		cdev_put(inode->i_cdev);
 	fops_put(file->f_op);
 	if (file->f_mode & FMODE_WRITE)
-		put_write_access(inode);
+		drop_file_write_access(file);
 	put_pid(file->f_owner.pid);
 	file_kill(file);
 	file->f_path.dentry = NULL;
diff -puN fs/nfsd/nfs4state.c~create-file_drop_write_access-helper fs/nfsd/nfs4state.c
--- linux-2.6.git/fs/nfsd/nfs4state.c~create-file_drop_write_access-helper	2008-02-08 13:04:48.000000000 -0800
+++ linux-2.6.git-dave/fs/nfsd/nfs4state.c	2008-02-08 13:04:48.000000000 -0800
@@ -41,6 +41,7 @@
 #include <linux/sunrpc/svc.h>
 #include <linux/nfsd/nfsd.h>
 #include <linux/nfsd/cache.h>
+#include <linux/file.h>
 #include <linux/mount.h>
 #include <linux/workqueue.h>
 #include <linux/smp_lock.h>
@@ -1239,7 +1240,7 @@ static inline void
 nfs4_file_downgrade(struct file *filp, unsigned int share_access)
 {
 	if (share_access & NFS4_SHARE_ACCESS_WRITE) {
-		put_write_access(filp->f_path.dentry->d_inode);
+		drop_file_write_access(filp);
 		filp->f_mode = (filp->f_mode | FMODE_READ) & ~FMODE_WRITE;
 	}
 }
diff -puN include/linux/file.h~create-file_drop_write_access-helper include/linux/file.h
--- linux-2.6.git/include/linux/file.h~create-file_drop_write_access-helper	2008-02-08 13:04:48.000000000 -0800
+++ linux-2.6.git-dave/include/linux/file.h	2008-02-08 13:04:48.000000000 -0800
@@ -61,6 +61,7 @@ extern struct kmem_cache *filp_cachep;
 
 extern void FASTCALL(__fput(struct file *));
 extern void FASTCALL(fput(struct file *));
+extern void drop_file_write_access(struct file *file);
 
 struct file_operations;
 struct vfsmount;
_

  parent reply	other threads:[~2008-02-08 22:31 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-08 22:26 [RFC][PATCH 00/30] Read-only bind mounts (-mm resend) Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 01/30] reiserfs: eliminate private use of struct file in xattr Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 02/30] hppfs pass vfsmount to dentry_open() Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 03/30] check for null vfsmount in dentry_open() Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 04/30] fix up new filp allocators Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 05/30] do namei_flags calculation inside open_namei() Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 06/30] make open_namei() return a filp Dave Hansen
2008-02-09  5:09   ` Christoph Hellwig
2008-02-08 22:26 ` [RFC][PATCH 07/30] r/o bind mounts: stub functions Dave Hansen
2008-02-08 22:26 ` Dave Hansen [this message]
2008-02-08 22:26 ` [RFC][PATCH 09/30] r/o bind mounts: drop write during emergency remount Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 10/30] r/o bind mounts: elevate write count for vfs_rmdir() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 11/30] r/o bind mounts: elevate write count for callers of vfs_mkdir() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 12/30] r/o bind mounts: elevate mnt_writers for unlink callers Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 13/30] r/o bind mounts: elevate write count for xattr_permission() callers Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 14/30] r/o bind mounts: elevate write count for ncp_ioctl() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 15/30] r/o bind mounts: write counts for time functions Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 16/30] r/o bind mounts: elevate write count for do_utimes() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 17/30] r/o bind mounts: write count for file_update_time() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 18/30] r/o bind mounts: write counts for link/symlink Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 19/30] r/o bind mounts: elevate write count for ioctls() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 20/30] r/o bind mounts: elevate write count for open()s Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 21/30] r/o bind mounts: get write access for vfs_rename() callers Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 22/30] r/o bind mounts: elevate write count for chmod/chown callers Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 23/30] r/o bind mounts: write counts for truncate() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 24/30] r/o bind mounts: elevate count for xfs timestamp updates Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 25/30] r/o bind mounts: make access() use new r/o helper Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 26/30] r/o bind mounts: check mnt instead of superblock directly Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 27/30] r/o bind mounts: get callers of vfs_mknod/create() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 28/30] r/o bind mounts: track numbers of writers to mounts Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 29/30] r/o bind mounts: honor mount writer counts at remount Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 30/30] r/o bind mounts: debugging for missed calls Dave Hansen
2008-02-09  6:39 ` [RFC][PATCH 00/30] Read-only bind mounts (-mm resend) Christoph Hellwig
2008-02-09  7:57 ` Al Viro
2008-02-12  5:06 ` Christoph Hellwig

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