*/
#include <linux/init.h>
-#include <linux/module.h>
+#include <linux/export.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/namei.h>
char *getname(const char __user * filename)
{
- return getname_flags(filename, 0, 0);
+ return getname_flags(filename, 0, NULL);
}
#ifdef CONFIG_AUDITSYSCALL
cond_resched();
current->total_link_count++;
- touch_atime(link->mnt, dentry);
+ touch_atime(link);
nd_set_link(nd, NULL);
error = security_inode_follow_link(link->dentry, nd);
}
/*
- * 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.
return -ECHILD;
nd->seq = seq;
+ if (unlikely(d_need_lookup(dentry)))
+ goto unlazy;
if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
status = d_revalidate(dentry, nd);
if (unlikely(status <= 0)) {
goto unlazy;
}
}
- if (unlikely(d_need_lookup(dentry)))
- goto unlazy;
path->mnt = mnt;
path->dentry = dentry;
if (unlikely(!__follow_mount_rcu(nd, path, inode)))
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 */
- need_reval = 0;
- 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 */
- need_reval = 0;
- status = 1;
- }
- mutex_unlock(&dir->i_mutex);
+ 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;
- need_reval = 1;
- goto retry;
+ goto need_lookup;
}
}
-
+done:
path->mnt = mnt;
path->dentry = dentry;
err = follow_managed(path, nd->flags);
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)
return 1;
}
+/*
+ * We can do the critical dentry name comparison and hashing
+ * operations one word at a time, but we are limited to:
+ *
+ * - Architectures with fast unaligned word accesses. We could
+ * do a "get_unaligned()" if this helps and is sufficiently
+ * fast.
+ *
+ * - Little-endian machines (so that we can generate the mask
+ * of low bytes efficiently). Again, we *could* do a byte
+ * swapping load on big-endian architectures if that is not
+ * expensive enough to make the optimization worthless.
+ *
+ * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
+ * do not trap on the (extremely unlikely) case of a page
+ * crossing operation.
+ *
+ * - Furthermore, we need an efficient 64-bit compile for the
+ * 64-bit case in order to generate the "number of bytes in
+ * the final mask". Again, that could be replaced with a
+ * efficient population count instruction or similar.
+ */
+#ifdef CONFIG_DCACHE_WORD_ACCESS
+
+#include <asm/word-at-a-time.h>
+
+#ifdef CONFIG_64BIT
+
+static inline unsigned int fold_hash(unsigned long hash)
+{
+ hash += hash >> (8*sizeof(int));
+ return hash;
+}
+
+#else /* 32-bit case */
+
+#define fold_hash(x) (x)
+
+#endif
+
+unsigned int full_name_hash(const unsigned char *name, unsigned int len)
+{
+ unsigned long a, mask;
+ unsigned long hash = 0;
+
+ for (;;) {
+ a = load_unaligned_zeropad(name);
+ if (len < sizeof(unsigned long))
+ break;
+ hash += a;
+ hash *= 9;
+ name += sizeof(unsigned long);
+ len -= sizeof(unsigned long);
+ if (!len)
+ goto done;
+ }
+ mask = ~(~0ul << len*8);
+ hash += mask & a;
+done:
+ return fold_hash(hash);
+}
+EXPORT_SYMBOL(full_name_hash);
+
+/*
+ * Calculate the length and hash of the path component, and
+ * return the length of the component;
+ */
+static inline unsigned long hash_name(const char *name, unsigned int *hashp)
+{
+ unsigned long a, mask, hash, len;
+
+ hash = a = 0;
+ len = -sizeof(unsigned long);
+ do {
+ hash = (hash + a) * 9;
+ len += sizeof(unsigned long);
+ a = load_unaligned_zeropad(name+len);
+ /* Do we have any NUL or '/' bytes in this word? */
+ mask = has_zero(a) | has_zero(a ^ REPEAT_BYTE('/'));
+ } while (!mask);
+
+ /* The mask *below* the first high bit set */
+ mask = (mask - 1) & ~mask;
+ mask >>= 7;
+ hash += a & mask;
+ *hashp = fold_hash(hash);
+
+ return len + count_masked_bytes(mask);
+}
+
+#else
+
unsigned int full_name_hash(const unsigned char *name, unsigned int len)
{
unsigned long hash = init_name_hash();
return len;
}
+#endif
+
/*
* Name resolution.
* This is the basic name resolution function, turning a pathname into
return err;
}
-static struct dentry *__lookup_hash(struct qstr *name,
- struct dentry *base, struct nameidata *nd)
-{
- struct inode *inode = base->d_inode;
- struct dentry *dentry;
- int err;
-
- err = inode_permission(inode, MAY_EXEC);
- if (err)
- return ERR_PTR(err);
-
- /*
- * 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.
- */
- dentry = d_inode_lookup(base, dentry, nd);
- if (IS_ERR(dentry))
- return dentry;
- }
-
- 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.
{
struct qstr this;
unsigned int c;
+ int err;
WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
return ERR_PTR(err);
}
+ err = inode_permission(base->d_inode, MAY_EXEC);
+ if (err)
+ return ERR_PTR(err);
+
return __lookup_hash(&this, base, NULL);
}
int user_path_at(int dfd, const char __user *name, unsigned flags,
struct path *path)
{
- return user_path_at_empty(dfd, name, flags, path, 0);
+ return user_path_at_empty(dfd, name, flags, path, NULL);
}
static int user_path_parent(int dfd, const char __user *path,
/* sayonara */
error = complete_walk(nd);
if (error)
- return ERR_PTR(-ECHILD);
+ return ERR_PTR(error);
error = -ENOTDIR;
if (nd->flags & LOOKUP_DIRECTORY) {
int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
int error = may_create(dir, dentry);
+ unsigned max_links = dir->i_sb->s_max_links;
if (error)
return error;
if (error)
return error;
+ if (max_links && dir->i_nlink >= max_links)
+ return -EMLINK;
+
error = dir->i_op->mkdir(dir, dentry, mode);
if (!error)
fsnotify_mkdir(dir, dentry);
/*
* 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.
*
int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
{
struct inode *inode = old_dentry->d_inode;
+ unsigned max_links = dir->i_sb->s_max_links;
int error;
if (!inode)
/* Make sure we don't allow creating hardlink to an unlinked file */
if (inode->i_nlink == 0)
error = -ENOENT;
+ else if (max_links && inode->i_nlink >= max_links)
+ error = -EMLINK;
else
error = dir->i_op->link(old_dentry, dir, new_dentry);
mutex_unlock(&inode->i_mutex);
{
int error = 0;
struct inode *target = new_dentry->d_inode;
+ unsigned max_links = new_dir->i_sb->s_max_links;
/*
* If we are going to change the parent - check write permissions,
if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry))
goto out;
+ error = -EMLINK;
+ if (max_links && !target && new_dir != old_dir &&
+ new_dir->i_nlink >= max_links)
+ goto out;
+
if (target)
shrink_dcache_parent(new_dentry);
error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
if (err)
goto fail;
- kaddr = kmap_atomic(page, KM_USER0);
+ kaddr = kmap_atomic(page);
memcpy(kaddr, symname, len-1);
- kunmap_atomic(kaddr, KM_USER0);
+ kunmap_atomic(kaddr);
err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
page, fsdata);
Code Review / linux-3.10.git / blobdiff