Overlayfs needs lookup without inode_permission() and already has the name
hash (in form of dentry->d_name on overlayfs dentry). It also doesn't
support filesystems with d_op->d_hash() so basically it only needs
__lookup_hash() from lookup_one_len().
Rename __lookup_hash() to lookup_hash() and export to modules.
Signed-off-by: Miklos Szeredi <mszer...@redhat.com>
---
fs/namei.c | 35 ++++++++++++++++++++++++++---------
include/linux/namei.h | 2 ++
2 files changed, 28 insertions(+), 9 deletions(-)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1492,8 +1492,24 @@ static struct dentry *lookup_real(struct
return dentry;
}
-static struct dentry *__lookup_hash(const struct qstr *name,
- struct dentry *base, unsigned int flags)
+/**
+ * lookup_hash - lookup single pathname component on already hashed name
+ * @name: name and hash to lookup
+ * @base: base directory to lookup from
+ * @flags: lookup flags
+ *
+ * The name must have been verified and hashed (see lookup_one_len()). Using
+ * this after just full_name_hash() is unsafe.
+ *
+ * This function also doesn't check for search permission on base directory.
+ *
+ * Use lookup_one_len() or lookup_one_len_unlocked() instead, unless you really
+ * know what you are doing.
+ *
+ * The caller must hold base->i_mutex.
+ */
+struct dentry *lookup_hash(const struct qstr *name,
+ struct dentry *base, unsigned int flags)
{
struct dentry *dentry = lookup_dcache(name, base, flags);
@@ -1506,6 +1522,7 @@ static struct dentry *__lookup_hash(cons
return lookup_real(base->d_inode, dentry, flags);
}
+EXPORT_SYMBOL(lookup_hash);
static int lookup_fast(struct nameidata *nd,
struct path *path, struct inode **inode,
@@ -2229,7 +2246,7 @@ struct dentry *kern_path_locked(const ch
return ERR_PTR(-EINVAL);
}
inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);
- d = __lookup_hash(&last, path->dentry, 0);
+ d = lookup_hash(&last, path->dentry, 0);
if (IS_ERR(d)) {
inode_unlock(path->dentry->d_inode);
path_put(path);
@@ -2313,7 +2330,7 @@ struct dentry *lookup_one_len(const char
if (err)
return ERR_PTR(err);
- return __lookup_hash(&this, base, 0);
+ return lookup_hash(&this, base, 0);
}
EXPORT_SYMBOL(lookup_one_len);
@@ -3476,7 +3493,7 @@ static struct dentry *filename_create(in
*/
lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL;
inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);
- dentry = __lookup_hash(&last, path->dentry, lookup_flags);
+ dentry = lookup_hash(&last, path->dentry, lookup_flags);
if (IS_ERR(dentry))
goto unlock;
@@ -3756,7 +3773,7 @@ static long do_rmdir(int dfd, const char
goto exit1;
inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT);
- dentry = __lookup_hash(&last, path.dentry, lookup_flags);
+ dentry = lookup_hash(&last, path.dentry, lookup_flags);
error = PTR_ERR(dentry);
if (IS_ERR(dentry))
goto exit2;
@@ -3878,7 +3895,7 @@ static long do_unlinkat(int dfd, const c
goto exit1;
retry_deleg:
inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT);
- dentry = __lookup_hash(&last, path.dentry, lookup_flags);
+ dentry = lookup_hash(&last, path.dentry, lookup_flags);
error = PTR_ERR(dentry);
if (!IS_ERR(dentry)) {
/* Why not before? Because we want correct error value */
@@ -4407,7 +4424,7 @@ SYSCALL_DEFINE5(renameat2, int, olddfd,
retry_deleg:
trap = lock_rename(new_path.dentry, old_path.dentry);
- old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags);
+ old_dentry = lookup_hash(&old_last, old_path.dentry, lookup_flags);
error = PTR_ERR(old_dentry);
if (IS_ERR(old_dentry))
goto exit3;
@@ -4415,7 +4432,7 @@ SYSCALL_DEFINE5(renameat2, int, olddfd,
error = -ENOENT;
if (d_is_negative(old_dentry))
goto exit4;
- new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags |
target_flags);
+ new_dentry = lookup_hash(&new_last, new_path.dentry, lookup_flags |
target_flags);
error = PTR_ERR(new_dentry);
if (IS_ERR(new_dentry))
goto exit4;
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -79,6 +79,8 @@ extern int kern_path_mountpoint(int, con
extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *,
int);
+struct qstr;
+extern struct dentry *lookup_hash(const struct qstr *, struct dentry *,
unsigned int);
extern int follow_down_one(struct path *);
extern int follow_down(struct path *);
