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Commit 1a16dbaf authored by Al Viro's avatar Al Viro
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Document d_splice_alias() calling conventions for ->lookup() users. 



Short version: it does the right thing when given NULL or ERR_PTR(...)
and its calling conventions are chosen to have minimal PITA when
used in ->lookup() instances.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 3837d208

Documentation/filesystems/porting

+11 −0
Original line number Diff line number Diff line
@@ -622,3 +622,14 @@ in your dentry operations instead. 
	alloc_file_clone(file, flags, ops) does not affect any caller's references.

	On success you get a new struct file sharing the mount/dentry with the

	original, on failure - ERR_PTR().

--

[recommended]

	->lookup() instances doing an equivalent of

		if (IS_ERR(inode))

			return ERR_CAST(inode);

		return d_splice_alias(inode, dentry);

	don't need to bother with the check - d_splice_alias() will do the

	right thing when given ERR_PTR(...) as inode.  Moreover, passing NULL

	inode to d_splice_alias() will also do the right thing (equivalent of

	d_add(dentry, NULL); return NULL;), so that kind of special cases

	also doesn't need a separate treatment.