[PATCH] r/o bind mounts: elevate write count for rmdir and unlink.

Elevate the write count during the vfs_rmdir() and vfs_unlink().

[AV: merged rmdir and unlink parts, added missing pieces in nfsd]

Acked-by: Serge Hallyn <serue@us.ibm.com>
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>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 11 insertions, 1 deletions

diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 1ff90625860f..4e77a1a3bd73 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -46,6 +46,7 @@
 #include <linux/scatterlist.h>
 #include <linux/crypto.h>
 #include <linux/sched.h>
+#include <linux/mount.h>
 
 #define NFSDDBG_FACILITY                NFSDDBG_PROC
 
@@ -313,12 +314,17 @@ nfsd4_remove_clid_dir(struct nfs4_client *clp)
         if (!rec_dir_init || !clp->cl_firststate)
                 return;
 
+        status = mnt_want_write(rec_dir.path.mnt);
+        if (status)
+                goto out;
         clp->cl_firststate = 0;
         nfs4_save_user(&uid, &gid);
         status = nfsd4_unlink_clid_dir(clp->cl_recdir, HEXDIR_LEN-1);
         nfs4_reset_user(uid, gid);
         if (status == 0)
                 nfsd4_sync_rec_dir();
+        mnt_drop_write(rec_dir.path.mnt);
+out:
         if (status)
                 printk("NFSD: Failed to remove expired client state directory"
                                 " %.*s\n", HEXDIR_LEN, clp->cl_recdir);
@@ -347,13 +353,17 @@ nfsd4_recdir_purge_old(void) {
 
         if (!rec_dir_init)
                 return;
+        status = mnt_want_write(rec_dir.path.mnt);
+        if (status)
+                goto out;
         status = nfsd4_list_rec_dir(rec_dir.path.dentry, purge_old);
         if (status == 0)
                 nfsd4_sync_rec_dir();
+        mnt_drop_write(rec_dir.path.mnt);
+out:
         if (status)
                 printk("nfsd4: failed to purge old clients from recovery"
                         " directory %s\n", rec_dir.path.dentry->d_name.name);
-        return;
 }
 
 static int