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[PATCH] dcache: Add helper d_hash_and_lookup

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It is very common to hash a dentry and then to call lookup.  If we take fs
specific hash functions into account the full hash logic can get ugly.
Further full_name_hash as an inline function is almost 100 bytes on x86 so
having a non-inline choice in some cases can measurably decrease code size.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Eric W. Biederman 2006-03-31 02:31:43 -08:00 committed by Linus Torvalds
parent 92476d7fc0
commit 3e7e241f8c
2 changed files with 29 additions and 16 deletions
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44
fs/dcache.c
View file

@ -1100,6 +1100,32 @@ struct dentry * __d_lookup(struct dentry * parent, struct qstr * name)
return found;
}
/**
* d_hash_and_lookup - hash the qstr then search for a dentry
* @dir: Directory to search in
* @name: qstr of name we wish to find
*
* On hash failure or on lookup failure NULL is returned.
*/
struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
{
struct dentry *dentry = NULL;
/*
* Check for a fs-specific hash function. Note that we must
* calculate the standard hash first, as the d_op->d_hash()
* routine may choose to leave the hash value unchanged.
*/
name->hash = full_name_hash(name->name, name->len);
if (dir->d_op && dir->d_op->d_hash) {
if (dir->d_op->d_hash(dir, name) < 0)
goto out;
}
dentry = d_lookup(dir, name);
out:
return dentry;
}
/**
* d_validate - verify dentry provided from insecure source
* @dentry: The dentry alleged to be valid child of @dparent
@ -1616,26 +1642,12 @@ ino_t find_inode_number(struct dentry *dir, struct qstr *name)
struct dentry * dentry;
ino_t ino = 0;
/*
* Check for a fs-specific hash function. Note that we must
* calculate the standard hash first, as the d_op->d_hash()
* routine may choose to leave the hash value unchanged.
*/
name->hash = full_name_hash(name->name, name->len);
if (dir->d_op && dir->d_op->d_hash)
{
if (dir->d_op->d_hash(dir, name) != 0)
goto out;
}
dentry = d_lookup(dir, name);
if (dentry)
{
dentry = d_hash_and_lookup(dir, name);
if (dentry) {
if (dentry->d_inode)
ino = dentry->d_inode->i_ino;
dput(dentry);
}
out:
return ino;
}

1
include/linux/dcache.h
View file

@ -275,6 +275,7 @@ extern void d_move(struct dentry *, struct dentry *);
/* appendix may either be NULL or be used for transname suffixes */
extern struct dentry * d_lookup(struct dentry *, struct qstr *);
extern struct dentry * __d_lookup(struct dentry *, struct qstr *);
extern struct dentry * d_hash_and_lookup(struct dentry *, struct qstr *);
/* validate "insecure" dentry pointer */
extern int d_validate(struct dentry *, struct dentry *);