linux-kernel - [PATCH 05/79] libfs: simple_follow

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Date:	Tue,  5 May 2015 06:21:39 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Neil Brown <neilb@...e.de>, Christoph Hellwig <hch@...radead.org>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH 05/79] libfs: simple_follow_link()

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

let "fast" symlinks store the pointer to the body into ->i_link and
use simple_follow_link for ->follow_link()

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/inode.c         |  1 +
 fs/libfs.c         | 13 +++++++++++++
 include/linux/fs.h |  3 +++
 3 files changed, 17 insertions(+)

diff --git a/fs/inode.c b/fs/inode.c
index ea37cd1..952fb48 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -152,6 +152,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
 	inode->i_pipe = NULL;
 	inode->i_bdev = NULL;
 	inode->i_cdev = NULL;
+	inode->i_link = NULL;
 	inode->i_rdev = 0;
 	inode->dirtied_when = 0;
 
diff --git a/fs/libfs.c b/fs/libfs.c
index cb1fb4b..72e4e01 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1093,3 +1093,16 @@ simple_nosetlease(struct file *filp, long arg, struct file_lock **flp,
 	return -EINVAL;
 }
 EXPORT_SYMBOL(simple_nosetlease);
+
+void *simple_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+	nd_set_link(nd, d_inode(dentry)->i_link);
+	return NULL;
+}
+EXPORT_SYMBOL(simple_follow_link);
+
+const struct inode_operations simple_symlink_inode_operations = {
+	.follow_link = simple_follow_link,
+	.readlink = generic_readlink
+};
+EXPORT_SYMBOL(simple_symlink_inode_operations);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 35ec87e..0ac758f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -656,6 +656,7 @@ struct inode {
 		struct pipe_inode_info	*i_pipe;
 		struct block_device	*i_bdev;
 		struct cdev		*i_cdev;
+		char			*i_link;
 	};
 
 	__u32			i_generation;
@@ -2721,6 +2722,8 @@ void __inode_sub_bytes(struct inode *inode, loff_t bytes);
 void inode_sub_bytes(struct inode *inode, loff_t bytes);
 loff_t inode_get_bytes(struct inode *inode);
 void inode_set_bytes(struct inode *inode, loff_t bytes);
+void *simple_follow_link(struct dentry *, struct nameidata *);
+extern const struct inode_operations simple_symlink_inode_operations;
 
 extern int iterate_dir(struct file *, struct dir_context *);
 
-- 
2.1.4

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