Commit e1a24bb0 authored Jun 29, 2012 by J. Bruce Fields Committed by Al Viro Nov 09, 2013

dcache: Don't set DISCONNECTED on "pseudo filesystem" dentries



I can't for the life of me see any reason why anyone should care whether
a dentry that is never hooked into the dentry cache would need
DCACHE_DISCONNECTED set.

This originates from 4b936885 "fs:
improve scalability of pseudo filesystems", which probably just made the
false assumption the DCACHE_DISCONNECTED was meant to be set on anything
not connected to a parent somehow.

So this is just confusing.  Ideally the only uses of DCACHE_DISCONNECTED
would be in the filehandle-lookup code, which needs it to ensure
dentries are connected into the dentry tree before use.

I left d_alloc_pseudo there even though it's now equivalent to
__d_alloc(), just on the theory the name is better documentation of its
intended use outside dcache.c.

Cc: Nick Piggin <npiggin@kernel.dk>
Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent 7632e465

fs/dcache.c

+9 −4

Original line number	Diff line number	Diff line
		@@ -1607,12 +1607,17 @@ struct dentry d_alloc(struct dentry parent, const struct qstr *name)
		}
		EXPORT_SYMBOL(d_alloc);

		/**
		* d_alloc_pseudo - allocate a dentry (for lookup-less filesystems)
		* @sb: the superblock
		* @name: qstr of the name
		*
		* For a filesystem that just pins its dentries in memory and never
		* performs lookups at all, return an unhashed IS_ROOT dentry.
		*/
		struct dentry d_alloc_pseudo(struct super_block sb, const struct qstr *name)
		{
		struct dentry *dentry = __d_alloc(sb, name);
		if (dentry)
		dentry->d_flags \|= DCACHE_DISCONNECTED;
		return dentry;
		return __d_alloc(sb, name);
		}
		EXPORT_SYMBOL(d_alloc_pseudo);

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