Commit 8966be90 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

vfs: trivial __d_lookup_rcu() cleanups 



These don't change any semantics, but they clean up the code a bit and
mark some arguments appropriately 'const'.

They came up as I was doing the word-at-a-time dcache name accessor
code, and cleaning this up now allows me to send out a smaller relevant
interesting patch for the experimental stuff.

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2273d5cc

fs/dcache.c

+8 −5
Original line number Diff line number Diff line
@@ -104,7 +104,7 @@ static unsigned int d_hash_shift __read_mostly; 


static struct hlist_bl_head *dentry_hashtable __read_mostly;



static inline struct hlist_bl_head *d_hash(struct dentry *parent,

static inline struct hlist_bl_head *d_hash(const struct dentry *parent,

					unsigned long hash)

{

	hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES;
@@ -1717,8 +1717,9 @@ EXPORT_SYMBOL(d_add_ci); 
 * child is looked up. Thus, an interlocking stepping of sequence lock checks

 * is formed, giving integrity down the path walk.

 */

struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,

				unsigned *seq, struct inode **inode)

struct dentry *__d_lookup_rcu(const struct dentry *parent,

				const struct qstr *name,

				unsigned *seqp, struct inode **inode)

{

	unsigned int len = name->len;

	unsigned int hash = name->hash;
@@ -1748,6 +1749,7 @@ struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name, 
	 * See Documentation/filesystems/path-lookup.txt for more details.

	 */

	hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {

		unsigned seq;

		struct inode *i;

		const char *tname;

		int tlen;
@@ -1756,7 +1758,7 @@ struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name, 
			continue;



seqretry:

		*seq = read_seqcount_begin(&dentry->d_seq);

		seq = read_seqcount_begin(&dentry->d_seq);

		if (dentry->d_parent != parent)

			continue;

		if (d_unhashed(dentry))
@@ -1771,7 +1773,7 @@ seqretry: 
		 * edge of memory when walking. If we could load this

		 * atomically some other way, we could drop this check.

		 */

		if (read_seqcount_retry(&dentry->d_seq, *seq))

		if (read_seqcount_retry(&dentry->d_seq, seq))

			goto seqretry;

		if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {

			if (parent->d_op->d_compare(parent, *inode,
@@ -1788,6 +1790,7 @@ seqretry: 
		 * order to do anything useful with the returned dentry

		 * anyway.

		 */

		*seqp = seq;

		*inode = i;

		return dentry;

	}

include/linux/dcache.h

+2 −1
Original line number Diff line number Diff line
@@ -309,7 +309,8 @@ extern struct dentry *d_ancestor(struct dentry *, struct dentry *); 
extern struct dentry *d_lookup(struct dentry *, struct qstr *);

extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);

extern struct dentry *__d_lookup(struct dentry *, struct qstr *);

extern struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,

extern struct dentry *__d_lookup_rcu(const struct dentry *parent,

				const struct qstr *name,

				unsigned *seq, struct inode **inode);



/**

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