[RFC][PATCH 17/27] elevate write count over calls to vfs_rename()

From: Dave Hansen
Date: Wed Jul 12 2006 - 14:16:42 EST



This does create a little helper in the NFS code to
make an if() a little bit less ugly.

Signed-off-by: Dave Hansen <haveblue@xxxxxxxxxx>
---

lxc-dave/fs/namei.c | 4 ++++
lxc-dave/fs/nfsd/vfs.c | 25 ++++++++++++++++++++-----
2 files changed, 24 insertions(+), 5 deletions(-)

diff -puN fs/namei.c~C-elevate-writers-vfs_rename-part1 fs/namei.c
--- lxc/fs/namei.c~C-elevate-writers-vfs_rename-part1 2006-07-12 11:09:31.000000000 -0700
+++ lxc-dave/fs/namei.c 2006-07-12 11:09:34.000000000 -0700
@@ -2544,8 +2544,12 @@ static int do_rename(int olddfd, const c
if (new_dentry == trap)
goto exit5;

+ error = mnt_want_write(oldnd.mnt);
+ if (error)
+ goto exit5;
error = vfs_rename(old_dir->d_inode, old_dentry,
new_dir->d_inode, new_dentry);
+ mnt_drop_write(oldnd.mnt);
exit5:
dput(new_dentry);
exit4:
diff -puN fs/nfsd/vfs.c~C-elevate-writers-vfs_rename-part1 fs/nfsd/vfs.c
--- lxc/fs/nfsd/vfs.c~C-elevate-writers-vfs_rename-part1 2006-07-12 11:09:12.000000000 -0700
+++ lxc-dave/fs/nfsd/vfs.c 2006-07-12 11:09:34.000000000 -0700
@@ -1533,6 +1533,14 @@ out_nfserr:
goto out_unlock;
}

+static inline int svc_msnfs(struct svc_fh *ffhp)
+{
+#ifdef MSNFS
+ return (ffhp->fh_export->ex_flags & NFSEXP_MSNFS);
+#else
+ return 0;
+#endif
+}
/*
* Rename a file
* N.B. After this call _both_ ffhp and tfhp need an fh_put
@@ -1593,20 +1601,27 @@ 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))) {
err = -EPERM;
- } else
-#endif
+ goto out_dput_new;
+ }
+
+ err = -EXDEV;
+ if (ffhp->fh_export->ex_mnt != tfhp->fh_export->ex_mnt)
+ goto out_dput_new;
+ err = mnt_want_write(ffhp->fh_export->ex_mnt);
+ if (err)
+ goto out_dput_new;
+
err = vfs_rename(fdir, odentry, tdir, ndentry);
if (!err && EX_ISSYNC(tfhp->fh_export)) {
err = nfsd_sync_dir(tdentry);
if (!err)
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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