linux-kernel - [RFC][PATCH 17/27] __shmem_file

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Message-Id: <20180709045417.13988-17-viro@ZenIV.linux.org.uk>
Date:   Mon,  9 Jul 2018 05:54:07 +0100
From:   Al Viro <viro@...IV.linux.org.uk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC][PATCH 17/27] __shmem_file_setup(): reorder allocations

From: Al Viro <viro@...iv.linux.org.uk>

grab inode and reserve memory first.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 mm/shmem.c | 43 ++++++++++++++++++++-----------------------
 1 file changed, 20 insertions(+), 23 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index a76adc3802d1..0aa290f849ee 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -3918,41 +3918,38 @@ static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name, l
 	if (shmem_acct_size(flags, size))
 		return ERR_PTR(-ENOMEM);
 
-	res = ERR_PTR(-ENOMEM);
+	sb = mnt->mnt_sb;
+	inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
+	if (unlikely(!inode)) {
+		shmem_unacct_size(flags, size);
+		return ERR_PTR(-ENOSPC);
+	}
+	inode->i_flags |= i_flags;
+	inode->i_size = size;
+	clear_nlink(inode);	/* It is unlinked */
+	res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
+	if (IS_ERR(res)) {
+		iput(inode);
+		return res;
+	}
+
 	this.name = name;
 	this.len = strlen(name);
 	this.hash = 0; /* will go */
-	sb = mnt->mnt_sb;
 	path.mnt = mntget(mnt);
 	path.dentry = d_alloc_pseudo(sb, &this);
-	if (!path.dentry)
-		goto put_memory;
+	if (!path.dentry) {
+		iput(inode);
+		return ERR_PTR(-ENOMEM);
+	}
 	d_set_d_op(path.dentry, &anon_ops);
 
-	res = ERR_PTR(-ENOSPC);
-	inode = shmem_get_inode(sb, NULL, S_IFREG | 0777, 0, flags);
-	if (!inode)
-		goto put_memory;
-
-	inode->i_flags |= i_flags;
 	d_instantiate(path.dentry, inode);
-	inode->i_size = size;
-	clear_nlink(inode);	/* It is unlinked */
-	res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
-	if (IS_ERR(res))
-		goto put_path;
 
 	res = alloc_file(&path, FMODE_WRITE | FMODE_READ | FMODE_OPENED,
 		  &shmem_file_operations);
 	if (IS_ERR(res))
-		goto put_path;
-
-	return res;
-
-put_memory:
-	shmem_unacct_size(flags, size);
-put_path:
-	path_put(&path);
+		path_put(&path);
 	return res;
 }
 
-- 
2.11.0