}
/*
- * Allocate a dentry with name and parent, and perform a parent
- * directory ->lookup on it. Returns the new dentry, or ERR_PTR
- * on error. parent->d_inode->i_mutex must be held. d_lookup must
- * have verified that no child exists while under i_mutex.
+ * This looks up the name in dcache, possibly revalidates the old dentry and
+ * allocates a new one if not found or not valid. In the need_lookup argument
+ * returns whether i_op->lookup is necessary.
+ *
+ * dir->d_inode->i_mutex must be held
*/
-static struct dentry *d_alloc_and_lookup(struct dentry *parent,
- struct qstr *name, struct nameidata *nd)
+static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir,
+ struct nameidata *nd, bool *need_lookup)
{
- struct inode *inode = parent->d_inode;
struct dentry *dentry;
- struct dentry *old;
+ int error;
- /* Don't create child dentry for a dead directory. */
- if (unlikely(IS_DEADDIR(inode)))
- return ERR_PTR(-ENOENT);
+ *need_lookup = false;
+ dentry = d_lookup(dir, name);
+ if (dentry) {
+ if (d_need_lookup(dentry)) {
+ *need_lookup = true;
+ } else if (dentry->d_flags & DCACHE_OP_REVALIDATE) {
+ error = d_revalidate(dentry, nd);
+ if (unlikely(error <= 0)) {
+ if (error < 0) {
+ dput(dentry);
+ return ERR_PTR(error);
+ } else if (!d_invalidate(dentry)) {
+ dput(dentry);
+ dentry = NULL;
+ }
+ }
+ }
+ }
- dentry = d_alloc(parent, name);
- if (unlikely(!dentry))
- return ERR_PTR(-ENOMEM);
+ if (!dentry) {
+ dentry = d_alloc(dir, name);
+ if (unlikely(!dentry))
+ return ERR_PTR(-ENOMEM);
- old = inode->i_op->lookup(inode, dentry, nd);
- if (unlikely(old)) {
- dput(dentry);
- dentry = old;
+ *need_lookup = true;
}
return dentry;
}
/*
- * We already have a dentry, but require a lookup to be performed on the parent
- * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error.
- * parent->d_inode->i_mutex must be held. d_lookup must have verified that no
- * child exists while under i_mutex.
+ * Call i_op->lookup on the dentry. The dentry must be negative but may be
+ * hashed if it was pouplated with DCACHE_NEED_LOOKUP.
+ *
+ * dir->d_inode->i_mutex must be held
*/
-static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry,
- struct nameidata *nd)
+static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry,
+ struct nameidata *nd)
{
- struct inode *inode = parent->d_inode;
struct dentry *old;
/* Don't create child dentry for a dead directory. */
- if (unlikely(IS_DEADDIR(inode))) {
+ if (unlikely(IS_DEADDIR(dir))) {
dput(dentry);
return ERR_PTR(-ENOENT);
}
- old = inode->i_op->lookup(inode, dentry, nd);
+ old = dir->i_op->lookup(dir, dentry, nd);
if (unlikely(old)) {
dput(dentry);
dentry = old;
return dentry;
}
+static struct dentry *__lookup_hash(struct qstr *name,
+ struct dentry *base, struct nameidata *nd)
+{
+ bool need_lookup;
+ struct dentry *dentry;
+
+ dentry = lookup_dcache(name, base, nd, &need_lookup);
+ if (!need_lookup)
+ return dentry;
+
+ return lookup_real(base->d_inode, dentry, nd);
+}
+
/*
* It's more convoluted than I'd like it to be, but... it's still fairly
* small and for now I'd prefer to have fast path as straight as possible.
dentry = __d_lookup(parent, name);
}
- if (dentry && unlikely(d_need_lookup(dentry))) {
+ if (unlikely(!dentry))
+ goto need_lookup;
+
+ if (unlikely(d_need_lookup(dentry))) {
dput(dentry);
- dentry = NULL;
- }
-retry:
- if (unlikely(!dentry)) {
- struct inode *dir = parent->d_inode;
- BUG_ON(nd->inode != dir);
-
- mutex_lock(&dir->i_mutex);
- dentry = d_lookup(parent, name);
- if (likely(!dentry)) {
- dentry = d_alloc_and_lookup(parent, name, nd);
- if (IS_ERR(dentry)) {
- mutex_unlock(&dir->i_mutex);
- return PTR_ERR(dentry);
- }
- /* known good */
- status = 1;
- } else if (unlikely(d_need_lookup(dentry))) {
- dentry = d_inode_lookup(parent, dentry, nd);
- if (IS_ERR(dentry)) {
- mutex_unlock(&dir->i_mutex);
- return PTR_ERR(dentry);
- }
- /* known good */
- status = 1;
- } else if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE))
- status = d_revalidate(dentry, nd);
- if (unlikely(status <= 0)) {
- if (status < 0) {
- mutex_unlock(&dir->i_mutex);
- dput(dentry);
- return status;
- }
- if (!d_invalidate(dentry)) {
- dput(dentry);
- dentry = d_alloc_and_lookup(parent, name, nd);
- if (IS_ERR(dentry)) {
- mutex_unlock(&dir->i_mutex);
- return PTR_ERR(dentry);
- }
- /* known good */
- status = 1;
- }
- }
- mutex_unlock(&dir->i_mutex);
- goto done;
+ goto need_lookup;
}
+
if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval)
status = d_revalidate(dentry, nd);
if (unlikely(status <= 0)) {
}
if (!d_invalidate(dentry)) {
dput(dentry);
- dentry = NULL;
- goto retry;
+ goto need_lookup;
}
}
done:
nd->flags |= LOOKUP_JUMPED;
*inode = path->dentry->d_inode;
return 0;
+
+need_lookup:
+ BUG_ON(nd->inode != parent->d_inode);
+
+ mutex_lock(&parent->d_inode->i_mutex);
+ dentry = __lookup_hash(name, parent, nd);
+ mutex_unlock(&parent->d_inode->i_mutex);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+ goto done;
}
static inline int may_lookup(struct nameidata *nd)
*/
#ifdef CONFIG_DCACHE_WORD_ACCESS
-#ifdef CONFIG_64BIT
+#include <asm/word-at-a-time.h>
-/*
- * Jan Achrenius on G+: microoptimized version of
- * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
- * that works for the bytemasks without having to
- * mask them first.
- */
-static inline long count_masked_bytes(unsigned long mask)
-{
- return mask*0x0001020304050608ul >> 56;
-}
+#ifdef CONFIG_64BIT
static inline unsigned int fold_hash(unsigned long hash)
{
#else /* 32-bit case */
-/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
-static inline long count_masked_bytes(long mask)
-{
- /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
- long a = (0x0ff0001+mask) >> 23;
- /* Fix the 1 for 00 case */
- return a & mask;
-}
-
#define fold_hash(x) (x)
#endif
unsigned long hash = 0;
for (;;) {
- a = *(unsigned long *)name;
+ a = load_unaligned_zeropad(name);
if (len < sizeof(unsigned long))
break;
hash += a;
}
EXPORT_SYMBOL(full_name_hash);
-#define REPEAT_BYTE(x) ((~0ul / 0xff) * (x))
-#define ONEBYTES REPEAT_BYTE(0x01)
-#define SLASHBYTES REPEAT_BYTE('/')
-#define HIGHBITS REPEAT_BYTE(0x80)
-
-/* Return the high bit set in the first byte that is a zero */
-static inline unsigned long has_zero(unsigned long a)
-{
- return ((a - ONEBYTES) & ~a) & HIGHBITS;
-}
-
/*
* Calculate the length and hash of the path component, and
* return the length of the component;
do {
hash = (hash + a) * 9;
len += sizeof(unsigned long);
- a = *(unsigned long *)(name+len);
+ a = load_unaligned_zeropad(name+len);
/* Do we have any NUL or '/' bytes in this word? */
- mask = has_zero(a) | has_zero(a ^ SLASHBYTES);
+ mask = has_zero(a) | has_zero(a ^ REPEAT_BYTE('/'));
} while (!mask);
/* The mask *below* the first high bit set */
return err;
}
-static struct dentry *__lookup_hash(struct qstr *name,
- struct dentry *base, struct nameidata *nd)
-{
- struct dentry *dentry;
-
- /*
- * Don't bother with __d_lookup: callers are for creat as
- * well as unlink, so a lot of the time it would cost
- * a double lookup.
- */
- dentry = d_lookup(base, name);
-
- if (dentry && d_need_lookup(dentry)) {
- /*
- * __lookup_hash is called with the parent dir's i_mutex already
- * held, so we are good to go here.
- */
- return d_inode_lookup(base, dentry, nd);
- }
-
- if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) {
- int status = d_revalidate(dentry, nd);
- if (unlikely(status <= 0)) {
- /*
- * The dentry failed validation.
- * If d_revalidate returned 0 attempt to invalidate
- * the dentry otherwise d_revalidate is asking us
- * to return a fail status.
- */
- if (status < 0) {
- dput(dentry);
- return ERR_PTR(status);
- } else if (!d_invalidate(dentry)) {
- dput(dentry);
- dentry = NULL;
- }
- }
- }
-
- if (!dentry)
- dentry = d_alloc_and_lookup(base, name, nd);
-
- return dentry;
-}
-
/*
* Restricted form of lookup. Doesn't follow links, single-component only,
* needs parent already locked. Doesn't follow mounts.
/*
* The dentry_unhash() helper will try to drop the dentry early: we
- * should have a usage count of 2 if we're the only user of this
+ * should have a usage count of 1 if we're the only user of this
* dentry, and if that is true (possibly after pruning the dcache),
* then we drop the dentry now.
*
projects / linux-flexiantxendom0-3.2.10.git / blobdiff