[Xen-devel] [PATCHv4 1/3] libfs: allow simple_fill_super() to add symlinks

[David Vrabel <david.vrabel@xxxxxxxxxx>]

simple_fill_super() will add symlinks if an entry has mode & S_IFLNK.
The target is provided in the new "link" field.

Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
v4:
- Use switch for file type.

v2:
- simplified.
---
 fs/libfs.c         | 27 ++++++++++++++++++++++++---
 include/linux/fs.h |  2 +-
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/fs/libfs.c b/fs/libfs.c
index 48826d4..8eabcb1 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -509,6 +509,7 @@ int simple_fill_super(struct super_block *s, unsigned long 
magic,
        struct dentry *root;
        struct dentry *dentry;
        int i;
+       int ret = -ENOMEM;
 
        s->s_blocksize = PAGE_SIZE;
        s->s_blocksize_bits = PAGE_SHIFT;
@@ -550,9 +551,29 @@ int simple_fill_super(struct super_block *s, unsigned long 
magic,
                        dput(dentry);
                        goto out;
                }
-               inode->i_mode = S_IFREG | files->mode;
+               switch (files->mode & S_IFMT) {
+               case S_IFLNK:
+                       inode->i_mode = files->mode;
+                       inode->i_op = &simple_symlink_inode_operations;
+                       inode->i_link = kstrdup(files->link, GFP_KERNEL);
+                       if (!inode->i_link) {
+                               iput(inode);
+                               dput(dentry);
+                               goto out;
+                       }
+                       break;
+               case S_IFREG:
+               case 0:
+                       inode->i_mode = S_IFREG | files->mode;
+                       inode->i_fop = files->ops;
+                       break;
+               default:
+                       iput(inode);
+                       dput(dentry);
+                       ret = -EINVAL;
+                       goto out;
+               }
                inode->i_atime = inode->i_mtime = inode->i_ctime = 
current_time(inode);
-               inode->i_fop = files->ops;
                inode->i_ino = i;
                d_add(dentry, inode);
        }
@@ -562,7 +583,7 @@ int simple_fill_super(struct super_block *s, unsigned long 
magic,
        d_genocide(root);
        shrink_dcache_parent(root);
        dput(root);
-       return -ENOMEM;
+       return ret;
 }
 EXPORT_SYMBOL(simple_fill_super);
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 16d2b6e..4b64fbb 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2988,7 +2988,7 @@ extern const struct file_operations simple_dir_operations;
 extern const struct inode_operations simple_dir_inode_operations;
 extern void make_empty_dir_inode(struct inode *inode);
 extern bool is_empty_dir_inode(struct inode *inode);
-struct tree_descr { char *name; const struct file_operations *ops; int mode; };
+struct tree_descr { char *name; const struct file_operations *ops; int mode; 
char *link; };
 struct dentry *d_alloc_name(struct dentry *, const char *);
 extern int simple_fill_super(struct super_block *, unsigned long, struct 
tree_descr *);
 extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, 
int *count);
-- 
2.1.4


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