Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull second vfs pile from Al Viro:
 "The stuff in there: fsfreeze deadlock fixes by Jan (essentially, the
  deadlock reproduced by xfstests 068), symlink and hardlink restriction
  patches, plus assorted cleanups and fixes.

  Note that another fsfreeze deadlock (emergency thaw one) is *not*
  dealt with - the series by Fernando conflicts a lot with Jan's, breaks
  userland ABI (FIFREEZE semantics gets changed) and trades the deadlock
  for massive vfsmount leak; this is going to be handled next cycle.
  There probably will be another pull request, but that stuff won't be
  in it."

Fix up trivial conflicts due to unrelated changes next to each other in
drivers/{staging/gdm72xx/usb_boot.c, usb/gadget/storage_common.c}

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (54 commits)
  delousing target_core_file a bit
  Documentation: Correct s_umount state for freeze_fs/unfreeze_fs
  fs: Remove old freezing mechanism
  ext2: Implement freezing
  btrfs: Convert to new freezing mechanism
  nilfs2: Convert to new freezing mechanism
  ntfs: Convert to new freezing mechanism
  fuse: Convert to new freezing mechanism
  gfs2: Convert to new freezing mechanism
  ocfs2: Convert to new freezing mechanism
  xfs: Convert to new freezing code
  ext4: Convert to new freezing mechanism
  fs: Protect write paths by sb_start_write - sb_end_write
  fs: Skip atime update on frozen filesystem
  fs: Add freezing handling to mnt_want_write() / mnt_drop_write()
  fs: Improve filesystem freezing handling
  switch the protection of percpu_counter list to spinlock
  nfsd: Push mnt_want_write() outside of i_mutex
  btrfs: Push mnt_want_write() outside of i_mutex
  fat: Push mnt_want_write() outside of i_mutex
  ...

5 files changed, 63 insertions, 46 deletions

diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 5ff0b7b9fc0..43295d45cc2 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -154,6 +154,10 @@ nfsd4_create_clid_dir(struct nfs4_client *clp)
 	if (status < 0)
 		return;
 
+	status = mnt_want_write_file(rec_file);
+	if (status)
+		return;
+
 	dir = rec_file->f_path.dentry;
 	/* lock the parent */
 	mutex_lock(&dir->d_inode->i_mutex);
@@ -173,11 +177,7 @@ nfsd4_create_clid_dir(struct nfs4_client *clp)
 		 * as well be forgiving and just succeed silently.
 		 */
 		goto out_put;
-	status = mnt_want_write_file(rec_file);
-	if (status)
-		goto out_put;
 	status = vfs_mkdir(dir->d_inode, dentry, S_IRWXU);
-	mnt_drop_write_file(rec_file);
 out_put:
 	dput(dentry);
 out_unlock:
@@ -189,6 +189,7 @@ out_unlock:
 				" (err %d); please check that %s exists"
 				" and is writeable", status,
 				user_recovery_dirname);
+	mnt_drop_write_file(rec_file);
 	nfs4_reset_creds(original_cred);
 }
 
diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index cc793005a87..032af381b3a 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -635,6 +635,7 @@ fh_put(struct svc_fh *fhp)
 		fhp->fh_post_saved = 0;
 #endif
 	}
+	fh_drop_write(fhp);
 	if (exp) {
 		exp_put(exp);
 		fhp->fh_export = NULL;
diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index e15dc45fc5e..aad6d457b9e 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -196,6 +196,7 @@ nfsd_proc_create(struct svc_rqst *rqstp, struct nfsd_createargs *argp,
 	struct dentry	*dchild;
 	int		type, mode;
 	__be32		nfserr;
+	int		hosterr;
 	dev_t		rdev = 0, wanted = new_decode_dev(attr->ia_size);
 
 	dprintk("nfsd: CREATE   %s %.*s\n",
@@ -214,6 +215,12 @@ nfsd_proc_create(struct svc_rqst *rqstp, struct nfsd_createargs *argp,
 	nfserr = nfserr_exist;
 	if (isdotent(argp->name, argp->len))
 		goto done;
+	hosterr = fh_want_write(dirfhp);
+	if (hosterr) {
+		nfserr = nfserrno(hosterr);
+		goto done;
+	}
+
 	fh_lock_nested(dirfhp, I_MUTEX_PARENT);
 	dchild = lookup_one_len(argp->name, dirfhp->fh_dentry, argp->len);
 	if (IS_ERR(dchild)) {
@@ -330,7 +337,7 @@ nfsd_proc_create(struct svc_rqst *rqstp, struct nfsd_createargs *argp,
 out_unlock:
 	/* We don't really need to unlock, as fh_put does it. */
 	fh_unlock(dirfhp);
-
+	fh_drop_write(dirfhp);
 done:
 	fh_put(dirfhp);
 	return nfsd_return_dirop(nfserr, resp);
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 702f64e820c..a9269f142cc 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1284,6 +1284,10 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	 * If it has, the parent directory should already be locked.
 	 */
 	if (!resfhp->fh_dentry) {
+		host_err = fh_want_write(fhp);
+		if (host_err)
+			goto out_nfserr;
+
 		/* called from nfsd_proc_mkdir, or possibly nfsd3_proc_create */
 		fh_lock_nested(fhp, I_MUTEX_PARENT);
 		dchild = lookup_one_len(fname, dentry, flen);
@@ -1327,14 +1331,11 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		goto out;
 	}
 
-	host_err = fh_want_write(fhp);
-	if (host_err)
-		goto out_nfserr;
-
 	/*
 	 * Get the dir op function pointer.
 	 */
 	err = 0;
+	host_err = 0;
 	switch (type) {
 	case S_IFREG:
 		host_err = vfs_create(dirp, dchild, iap->ia_mode, true);
@@ -1351,10 +1352,8 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		host_err = vfs_mknod(dirp, dchild, iap->ia_mode, rdev);
 		break;
 	}
-	if (host_err < 0) {
-		fh_drop_write(fhp);
+	if (host_err < 0)
 		goto out_nfserr;
-	}
 
 	err = nfsd_create_setattr(rqstp, resfhp, iap);
 
@@ -1366,7 +1365,6 @@ nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	err2 = nfserrno(commit_metadata(fhp));
 	if (err2)
 		err = err2;
-	fh_drop_write(fhp);
 	/*
 	 * Update the file handle to get the new inode info.
 	 */
@@ -1425,6 +1423,11 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	err = nfserr_notdir;
 	if (!dirp->i_op->lookup)
 		goto out;
+
+	host_err = fh_want_write(fhp);
+	if (host_err)
+		goto out_nfserr;
+
 	fh_lock_nested(fhp, I_MUTEX_PARENT);
 
 	/*
@@ -1457,9 +1460,6 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		v_atime = verifier[1]&0x7fffffff;
 	}
 	
-	host_err = fh_want_write(fhp);
-	if (host_err)
-		goto out_nfserr;
 	if (dchild->d_inode) {
 		err = 0;
 
@@ -1530,7 +1530,6 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	if (!err)
 		err = nfserrno(commit_metadata(fhp));
 
-	fh_drop_write(fhp);
 	/*
 	 * Update the filehandle to get the new inode info.
 	 */
@@ -1541,6 +1540,7 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	fh_unlock(fhp);
 	if (dchild && !IS_ERR(dchild))
 		dput(dchild);
+	fh_drop_write(fhp);
  	return err;
  
  out_nfserr:
@@ -1621,6 +1621,11 @@ nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
 	if (err)
 		goto out;
+
+	host_err = fh_want_write(fhp);
+	if (host_err)
+		goto out_nfserr;
+
 	fh_lock(fhp);
 	dentry = fhp->fh_dentry;
 	dnew = lookup_one_len(fname, dentry, flen);
@@ -1628,10 +1633,6 @@ nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	if (IS_ERR(dnew))
 		goto out_nfserr;
 
-	host_err = fh_want_write(fhp);
-	if (host_err)
-		goto out_nfserr;
-
 	if (unlikely(path[plen] != 0)) {
 		char *path_alloced = kmalloc(plen+1, GFP_KERNEL);
 		if (path_alloced == NULL)
@@ -1691,6 +1692,12 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
 	if (isdotent(name, len))
 		goto out;
 
+	host_err = fh_want_write(tfhp);
+	if (host_err) {
+		err = nfserrno(host_err);
+		goto out;
+	}
+
 	fh_lock_nested(ffhp, I_MUTEX_PARENT);
 	ddir = ffhp->fh_dentry;
 	dirp = ddir->d_inode;
@@ -1702,18 +1709,13 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
 
 	dold = tfhp->fh_dentry;
 
-	host_err = fh_want_write(tfhp);
-	if (host_err) {
-		err = nfserrno(host_err);
-		goto out_dput;
-	}
 	err = nfserr_noent;
 	if (!dold->d_inode)
-		goto out_drop_write;
+		goto out_dput;
 	host_err = nfsd_break_lease(dold->d_inode);
 	if (host_err) {
 		err = nfserrno(host_err);
-		goto out_drop_write;
+		goto out_dput;
 	}
 	host_err = vfs_link(dold, dirp, dnew);
 	if (!host_err) {
@@ -1726,12 +1728,11 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
 		else
 			err = nfserrno(host_err);
 	}
-out_drop_write:
-	fh_drop_write(tfhp);
 out_dput:
 	dput(dnew);
 out_unlock:
 	fh_unlock(ffhp);
+	fh_drop_write(tfhp);
 out:
 	return err;
 
@@ -1774,6 +1775,12 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
 	if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
 		goto out;
 
+	host_err = fh_want_write(ffhp);
+	if (host_err) {
+		err = nfserrno(host_err);
+		goto out;
+	}
+
 	/* cannot use fh_lock as we need deadlock protective ordering
 	 * so do it by hand */
 	trap = lock_rename(tdentry, fdentry);
@@ -1804,17 +1811,14 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
 	host_err = -EXDEV;
 	if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
 		goto out_dput_new;
-	host_err = fh_want_write(ffhp);
-	if (host_err)
-		goto out_dput_new;
 
 	host_err = nfsd_break_lease(odentry->d_inode);
 	if (host_err)
-		goto out_drop_write;
+		goto out_dput_new;
 	if (ndentry->d_inode) {
 		host_err = nfsd_break_lease(ndentry->d_inode);
 		if (host_err)
-			goto out_drop_write;
+			goto out_dput_new;
 	}
 	host_err = vfs_rename(fdir, odentry, tdir, ndentry);
 	if (!host_err) {
@@ -1822,8 +1826,6 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
 		if (!host_err)
 			host_err = commit_metadata(ffhp);
 	}
-out_drop_write:
-	fh_drop_write(ffhp);
  out_dput_new:
 	dput(ndentry);
  out_dput_old:
@@ -1839,6 +1841,7 @@ out_drop_write:
 	fill_post_wcc(tfhp);
 	unlock_rename(tdentry, fdentry);
 	ffhp->fh_locked = tfhp->fh_locked = 0;
+	fh_drop_write(ffhp);
 
 out:
 	return err;
@@ -1864,6 +1867,10 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
 	if (err)
 		goto out;
 
+	host_err = fh_want_write(fhp);
+	if (host_err)
+		goto out_nfserr;
+
 	fh_lock_nested(fhp, I_MUTEX_PARENT);
 	dentry = fhp->fh_dentry;
 	dirp = dentry->d_inode;
@@ -1882,21 +1889,15 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
 	if (!type)
 		type = rdentry->d_inode->i_mode & S_IFMT;
 
-	host_err = fh_want_write(fhp);
-	if (host_err)
-		goto out_put;
-
 	host_err = nfsd_break_lease(rdentry->d_inode);
 	if (host_err)
-		goto out_drop_write;
+		goto out_put;
 	if (type != S_IFDIR)
 		host_err = vfs_unlink(dirp, rdentry);
 	else
 		host_err = vfs_rmdir(dirp, rdentry);
 	if (!host_err)
 		host_err = commit_metadata(fhp);
-out_drop_write:
-	fh_drop_write(fhp);
 out_put:
 	dput(rdentry);
 
diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index ec0611b2b73..359594c393d 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -110,12 +110,19 @@ int nfsd_set_posix_acl(struct svc_fh *, int, struct posix_acl *);
 
 static inline int fh_want_write(struct svc_fh *fh)
 {
-	return mnt_want_write(fh->fh_export->ex_path.mnt);
+	int ret = mnt_want_write(fh->fh_export->ex_path.mnt);
+
+	if (!ret)
+		fh->fh_want_write = 1;
+	return ret;
 }
 
 static inline void fh_drop_write(struct svc_fh *fh)
 {
-	mnt_drop_write(fh->fh_export->ex_path.mnt);
+	if (fh->fh_want_write) {
+		fh->fh_want_write = 0;
+		mnt_drop_write(fh->fh_export->ex_path.mnt);
+	}
 }
 
 #endif /* LINUX_NFSD_VFS_H */