From a4464dbc0ca6a3ab8e9d1206bc05059dae2a559d Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 7 Jul 2011 15:03:58 -0400 Subject: [PATCH] Make ->d_sb assign-once and always non-NULL New helper (non-exported, fs/internal.h-only): __d_alloc(sb, name). Allocates dentry, sets its ->d_sb to given superblock and sets ->d_op accordingly. Old d_alloc(NULL, name) callers are converted to that (all of them know what superblock they want). d_alloc() itself is left only for parent != NULl case; uses __d_alloc(), inserts result into the list of parent's children. Note that now ->d_sb is assign-once and never NULL *and* ->d_parent is never NULL either. Signed-off-by: Al Viro --- fs/dcache.c | 75 ++++++++++++++++++++++++++------------------------- fs/internal.h | 5 ++++ fs/libfs.c | 6 ++--- 3 files changed, 47 insertions(+), 39 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index d3902139b533..c61edd0318c3 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1275,8 +1275,8 @@ static struct shrinker dcache_shrinker = { }; /** - * d_alloc - allocate a dcache entry - * @parent: parent of entry to allocate + * __d_alloc - allocate a dcache entry + * @sb: filesystem it will belong to * @name: qstr of the name * * Allocates a dentry. It returns %NULL if there is insufficient memory @@ -1284,7 +1284,7 @@ static struct shrinker dcache_shrinker = { * copied and the copy passed in may be reused after this call. */ -struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) +struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) { struct dentry *dentry; char *dname; @@ -1314,8 +1314,8 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) spin_lock_init(&dentry->d_lock); seqcount_init(&dentry->d_seq); dentry->d_inode = NULL; - dentry->d_parent = NULL; - dentry->d_sb = NULL; + dentry->d_parent = dentry; + dentry->d_sb = sb; dentry->d_op = NULL; dentry->d_fsdata = NULL; INIT_HLIST_BL_NODE(&dentry->d_hash); @@ -1323,36 +1323,47 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) INIT_LIST_HEAD(&dentry->d_subdirs); INIT_LIST_HEAD(&dentry->d_alias); INIT_LIST_HEAD(&dentry->d_u.d_child); - - if (parent) { - spin_lock(&parent->d_lock); - /* - * don't need child lock because it is not subject - * to concurrency here - */ - __dget_dlock(parent); - dentry->d_parent = parent; - dentry->d_sb = parent->d_sb; - d_set_d_op(dentry, dentry->d_sb->s_d_op); - list_add(&dentry->d_u.d_child, &parent->d_subdirs); - spin_unlock(&parent->d_lock); - } + d_set_d_op(dentry, dentry->d_sb->s_d_op); this_cpu_inc(nr_dentry); return dentry; } + +/** + * d_alloc - allocate a dcache entry + * @parent: parent of entry to allocate + * @name: qstr of the name + * + * Allocates a dentry. It returns %NULL if there is insufficient memory + * available. On a success the dentry is returned. The name passed in is + * copied and the copy passed in may be reused after this call. + */ +struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) +{ + struct dentry *dentry = __d_alloc(parent->d_sb, name); + if (!dentry) + return NULL; + + spin_lock(&parent->d_lock); + /* + * don't need child lock because it is not subject + * to concurrency here + */ + __dget_dlock(parent); + dentry->d_parent = parent; + list_add(&dentry->d_u.d_child, &parent->d_subdirs); + spin_unlock(&parent->d_lock); + + return dentry; +} EXPORT_SYMBOL(d_alloc); struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) { - struct dentry *dentry = d_alloc(NULL, name); - if (dentry) { - dentry->d_sb = sb; - d_set_d_op(dentry, dentry->d_sb->s_d_op); - dentry->d_parent = dentry; + struct dentry *dentry = __d_alloc(sb, name); + if (dentry) dentry->d_flags |= DCACHE_DISCONNECTED; - } return dentry; } EXPORT_SYMBOL(d_alloc_pseudo); @@ -1522,13 +1533,9 @@ struct dentry * d_alloc_root(struct inode * root_inode) if (root_inode) { static const struct qstr name = { .name = "/", .len = 1 }; - res = d_alloc(NULL, &name); - if (res) { - res->d_sb = root_inode->i_sb; - d_set_d_op(res, res->d_sb->s_d_op); - res->d_parent = res; + res = __d_alloc(root_inode->i_sb, &name); + if (res) d_instantiate(res, root_inode); - } } return res; } @@ -1589,13 +1596,11 @@ struct dentry *d_obtain_alias(struct inode *inode) if (res) goto out_iput; - tmp = d_alloc(NULL, &anonstring); + tmp = __d_alloc(inode->i_sb, &anonstring); if (!tmp) { res = ERR_PTR(-ENOMEM); goto out_iput; } - tmp->d_parent = tmp; /* make sure dput doesn't croak */ - spin_lock(&inode->i_lock); res = __d_find_any_alias(inode); @@ -1607,8 +1612,6 @@ struct dentry *d_obtain_alias(struct inode *inode) /* attach a disconnected dentry */ spin_lock(&tmp->d_lock); - tmp->d_sb = inode->i_sb; - d_set_d_op(tmp, tmp->d_sb->s_d_op); tmp->d_inode = inode; tmp->d_flags |= DCACHE_DISCONNECTED; list_add(&tmp->d_alias, &inode->i_dentry); diff --git a/fs/internal.h b/fs/internal.h index b29c46e4e32f..ae47c48bedde 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -135,3 +135,8 @@ extern void inode_wb_list_del(struct inode *inode); extern int get_nr_dirty_inodes(void); extern void evict_inodes(struct super_block *); extern int invalidate_inodes(struct super_block *, bool); + +/* + * dcache.c + */ +extern struct dentry *__d_alloc(struct super_block *, const struct qstr *); diff --git a/fs/libfs.c b/fs/libfs.c index 275ca4749a2e..bd50b11f92da 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -16,6 +16,8 @@ #include +#include "internal.h" + static inline int simple_positive(struct dentry *dentry) { return dentry->d_inode && !d_unhashed(dentry); @@ -246,13 +248,11 @@ struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name, root->i_ino = 1; root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; - dentry = d_alloc(NULL, &d_name); + dentry = __d_alloc(s, &d_name); if (!dentry) { iput(root); goto Enomem; } - dentry->d_sb = s; - dentry->d_parent = dentry; d_instantiate(dentry, root); s->s_root = dentry; s->s_d_op = dops;