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[PATCH 21/30] r/o bind mounts: get write access for vfs_rename() callers

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From: Dave Hansen <haveblue@...>
To: <linux-kernel@...>
Cc: <hch@...>, <miklos@...>, <akpm@...>, Dave Hansen <haveblue@...>
Subject: [PATCH 21/30] r/o bind mounts: get write access for vfs_rename() callers
Date: Friday, February 15, 2008 - 6:37 pm

This also uses the little helper in the NFS code to make an if() a little bit
less ugly.  We introduced the helper at the beginning of the series.

Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 linux-2.6.git-dave/fs/namei.c    |    4 ++++
 linux-2.6.git-dave/fs/nfsd/vfs.c |   17 +++++++++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)

diff -puN fs/namei.c~r-o-bind-mounts-elevate-write-count-over-calls-to-vfs_rename fs/namei.c
--- linux-2.6.git/fs/namei.c~r-o-bind-mounts-elevate-write-count-over-calls-to-vfs_rename	2008-02-15 13:25:54.000000000 -0800
+++ linux-2.6.git-dave/fs/namei.c	2008-02-15 13:25:54.000000000 -0800
@@ -2751,8 +2751,12 @@ static int do_rename(int olddfd, const c
 	if (new_dentry == trap)
 		goto exit5;
 
+	error = mnt_want_write(oldnd.path.mnt);
+	if (error)
+		goto exit5;
 	error = vfs_rename(old_dir->d_inode, old_dentry,
 				   new_dir->d_inode, new_dentry);
+	mnt_drop_write(oldnd.path.mnt);
 exit5:
 	dput(new_dentry);
 exit4:
diff -puN fs/nfsd/vfs.c~r-o-bind-mounts-elevate-write-count-over-calls-to-vfs_rename fs/nfsd/vfs.c
--- linux-2.6.git/fs/nfsd/vfs.c~r-o-bind-mounts-elevate-write-count-over-calls-to-vfs_rename	2008-02-15 13:25:54.000000000 -0800
+++ linux-2.6.git-dave/fs/nfsd/vfs.c	2008-02-15 13:25:54.000000000 -0800
@@ -1678,13 +1678,20 @@ nfsd_rename(struct svc_rqst *rqstp, stru
 	if (ndentry == trap)
 		goto out_dput_new;
 
-#ifdef MSNFS
-	if ((ffhp->fh_export->ex_flags & NFSEXP_MSNFS) &&
+	if (svc_msnfs(ffhp) &&
 		((atomic_read(&odentry->d_count) > 1)
 		 || (atomic_read(&ndentry->d_count) > 1))) {
 			host_err = -EPERM;
-	} else
-#endif
+			goto out_dput_new;
+	}
+
+	host_err = -EXDEV;
+	if (ffhp->fh_export->ex_mnt != tfhp->fh_export->ex_mnt)
+		goto out_dput_new;
+	host_err = mnt_want_write(ffhp->fh_export->ex_mnt);
+	if (host_err)
+		goto out_dput_new;
+
 	host_err = vfs_rename(fdir, odentry, tdir, ndentry);
 	if (!host_err && EX_ISSYNC(tfhp->fh_export)) {
 		host_err = nfsd_sync_dir(tdentry);
@@ -1692,6 +1699,8 @@ nfsd_rename(struct svc_rqst *rqstp, stru
 			host_err = nfsd_sync_dir(fdentry);
 	}
 
+	mnt_drop_write(ffhp->fh_export->ex_mnt);
+
  out_dput_new:
 	dput(ndentry);
  out_dput_old:
_
--
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Messages in current thread:
[PATCH 00/30] Read-only bind mounts (-mm resend), Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH] r/o bind mounts: stub functions, Dave Hansen, (Fri Feb 15, 9:32 pm)
[PATCH 30/30] r/o bind mounts: debugging for missed calls, Dave Hansen, (Fri Feb 15, 6:38 pm)
[PATCH 29/30] r/o bind mounts: honor mount writer counts at ..., Dave Hansen, (Fri Feb 15, 6:38 pm)
[PATCH 28/30] r/o bind mounts: track numbers of writers to m..., Dave Hansen, (Fri Feb 15, 6:37 pm)
Re: [PATCH 28/30] r/o bind mounts: track numbers of writers ..., Miklos Szeredi, (Mon Feb 18, 12:10 pm)
Re: [PATCH 28/30] r/o bind mounts: track numbers of writers ..., Dave Hansen, (Wed Feb 20, 5:12 pm)
[PATCH 27/30] r/o bind mounts: get callers of vfs_mknod/crea..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 26/30] r/o bind mounts: check mnt instead of superblo..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 22/30] r/o bind mounts: elevate write count for chmod..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 25/30] r/o bind mounts: make access() use new r/o hel..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 24/30] r/o bind mounts: elevate count for xfs timesta..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 23/30] r/o bind mounts: write counts for truncate(), Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 21/30] r/o bind mounts: get write access for vfs_rena..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 20/30] r/o bind mounts: elevate write count for open()s, Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 19/30] r/o bind mounts: elevate write count for ioctl..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 18/30] r/o bind mounts: write counts for link/symlink, Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 17/30] r/o bind mounts: write count for file_update_t..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 06/30] merge open_namei() and do_filp_open(), Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 16/30] r/o bind mounts: elevate write count for do_ut..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 15/30] r/o bind mounts: write counts for time functions, Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 14/30] r/o bind mounts: elevate write count for ncp_i..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 13/30] r/o bind mounts: elevate write count for xattr..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 12/30] r/o bind mounts: elevate mnt_writers for unlin..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 11/30] r/o bind mounts: elevate write count for calle..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 10/30] r/o bind mounts: elevate write count for vfs_r..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 08/30] r/o bind mounts: create helper to drop file wr..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 05/30] do namei_flags calculation inside open_namei(), Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 03/30] check for null vfsmount in dentry_open(), Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 07/30] r/o bind mounts: stub functions, Dave Hansen, (Fri Feb 15, 6:37 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Theodore Tso, (Fri Feb 15, 8:32 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Dave Hansen, (Fri Feb 15, 8:49 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Theodore Tso, (Fri Feb 15, 9:00 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Andrew Morton, (Fri Feb 15, 9:11 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Christoph Hellwig, (Sat Feb 16, 2:31 am)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Dave Hansen, (Wed Feb 20, 6:25 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Christoph Hellwig, (Wed Feb 20, 6:58 pm)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Andrew Morton, (Sat Feb 16, 2:46 am)
Re: [PATCH 07/30] r/o bind mounts: stub functions, Dave Hansen, (Mon Feb 18, 3:06 am)
[PATCH 09/30] r/o bind mounts: drop write during emergency r..., Dave Hansen, (Fri Feb 15, 6:37 pm)
Re: [PATCH 09/30] r/o bind mounts: drop write during emergen..., Miklos Szeredi, (Mon Feb 18, 12:29 pm)
Re: [PATCH 09/30] r/o bind mounts: drop write during emergen..., Al Viro, (Sat Feb 23, 9:38 am)
[PATCH 01/30] reiserfs: eliminate private use of struct file..., Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 04/30] fix up new filp allocators, Dave Hansen, (Fri Feb 15, 6:37 pm)
[PATCH 02/30] hppfs pass vfsmount to dentry_open(), Dave Hansen, (Fri Feb 15, 6:37 pm)