From: Christoph Hellwig In a duplicate of lookup_create in the af_unix code Al commented what's going on nicely, so let's bring that over to lookup_create before the copy is going away (I'll send a patch soon) Signed-off-by: Andrew Morton --- fs/namei.c | 20 ++++++++++++++++++-- 1 files changed, 18 insertions(+), 2 deletions(-) diff -puN fs/namei.c~add-some-comments-to-lookup_create fs/namei.c --- 25/fs/namei.c~add-some-comments-to-lookup_create Tue May 10 12:51:07 2005 +++ 25-akpm/fs/namei.c Tue May 10 12:51:07 2005 @@ -1558,19 +1558,35 @@ do_link: * * Simple function to lookup and return a dentry and create it * if it doesn't exist. Is SMP-safe. + * + * Returns with nd->dentry->d_inode->i_sem locked. */ struct dentry *lookup_create(struct nameidata *nd, int is_dir) { - struct dentry *dentry; + struct dentry *dentry = ERR_PTR(-EEXIST); down(&nd->dentry->d_inode->i_sem); - dentry = ERR_PTR(-EEXIST); + /* + * Yucky last component or no last component at all? + * (foo/., foo/.., /////) + */ if (nd->last_type != LAST_NORM) goto fail; nd->flags &= ~LOOKUP_PARENT; + + /* + * Do the final lookup. + */ dentry = lookup_hash(&nd->last, nd->dentry); if (IS_ERR(dentry)) goto fail; + + /* + * Special case - lookup gave negative, but... we had foo/bar/ + * From the vfs_mknod() POV we just have a negative dentry - + * all is fine. Let's be bastards - you had / on the end, you've + * been asking for (non-existent) directory. -ENOENT for you. + */ if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode) goto enoent; return dentry; _