From 4e4d6d860b9393c5395ba5920edb5b4c5d43a3a3 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Sun, 18 Dec 2011 20:05:43 -0800 Subject: [PATCH] sysfs: Add s_hash to sysfs_dirent and order directory entries by hash Compute a 31 bit hash of directory entries (that can fit in a signed 32bit off_t) and index the sysfs directory entries by that hash, replacing the per directory indexes by name and by inode. Because we now only use a single rbtree this reduces the size of sysfs_dirent by 2 pointers. Because we have fewer cases to deal with the code is now simpler. For now I use the simple hash that the dcache uses as that is easy to use and seems simple enough. In addition to makeing the code simpler using a hash for the file position in readdir brings sysfs in line with other filesystems that have non-trivial directory structures. Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/dir.c | 219 +++++++++++++++++++++++++---------------------- fs/sysfs/sysfs.h | 9 +- 2 files changed, 120 insertions(+), 108 deletions(-) diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 7fdf6a7b7436..0daf255b7bf9 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -22,76 +22,103 @@ #include #include #include +#include #include "sysfs.h" DEFINE_MUTEX(sysfs_mutex); DEFINE_SPINLOCK(sysfs_assoc_lock); +#define to_sysfs_dirent(X) rb_entry((X), struct sysfs_dirent, s_rb); + static DEFINE_SPINLOCK(sysfs_ino_lock); static DEFINE_IDA(sysfs_ino_ida); /** - * sysfs_link_sibling - link sysfs_dirent into sibling list + * sysfs_name_hash + * @ns: Namespace tag to hash + * @name: Null terminated string to hash + * + * Returns 31 bit hash of ns + name (so it fits in an off_t ) + */ +static unsigned int sysfs_name_hash(const void *ns, const char *name) +{ + unsigned long hash = init_name_hash(); + unsigned int len = strlen(name); + while (len--) + hash = partial_name_hash(*name++, hash); + hash = ( end_name_hash(hash) ^ hash_ptr( (void *)ns, 31 ) ); + hash &= 0x7fffffffU; + /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */ + if (hash < 1) + hash += 2; + if (hash >= INT_MAX) + hash = INT_MAX - 1; + return hash; +} + +static int sysfs_name_compare(unsigned int hash, const void *ns, + const char *name, const struct sysfs_dirent *sd) +{ + if (hash != sd->s_hash) + return hash - sd->s_hash; + if (ns != sd->s_ns) + return ns - sd->s_ns; + return strcmp(name, sd->s_name); +} + +static int sysfs_sd_compare(const struct sysfs_dirent *left, + const struct sysfs_dirent *right) +{ + return sysfs_name_compare(left->s_hash, left->s_ns, left->s_name, + right); +} + +/** + * sysfs_link_subling - link sysfs_dirent into sibling rbtree * @sd: sysfs_dirent of interest * - * Link @sd into its sibling list which starts from + * Link @sd into its sibling rbtree which starts from * sd->s_parent->s_dir.children. * * Locking: * mutex_lock(sysfs_mutex) + * + * RETURNS: + * 0 on susccess -EEXIST on failure. */ -static void sysfs_link_sibling(struct sysfs_dirent *sd) +static int sysfs_link_sibling(struct sysfs_dirent *sd) { - struct sysfs_dirent *parent_sd = sd->s_parent; - - struct rb_node **p; - struct rb_node *parent; + struct rb_node **node = &sd->s_parent->s_dir.children.rb_node; + struct rb_node *parent = NULL; if (sysfs_type(sd) == SYSFS_DIR) - parent_sd->s_dir.subdirs++; - - p = &parent_sd->s_dir.inode_tree.rb_node; - parent = NULL; - while (*p) { - parent = *p; -#define node rb_entry(parent, struct sysfs_dirent, inode_node) - if (sd->s_ino < node->s_ino) { - p = &node->inode_node.rb_left; - } else if (sd->s_ino > node->s_ino) { - p = &node->inode_node.rb_right; - } else { - printk(KERN_CRIT "sysfs: inserting duplicate inode '%lx'\n", - (unsigned long) sd->s_ino); - BUG(); - } -#undef node - } - rb_link_node(&sd->inode_node, parent, p); - rb_insert_color(&sd->inode_node, &parent_sd->s_dir.inode_tree); - - p = &parent_sd->s_dir.name_tree.rb_node; - parent = NULL; - while (*p) { - int c; - parent = *p; -#define node rb_entry(parent, struct sysfs_dirent, name_node) - c = strcmp(sd->s_name, node->s_name); - if (c < 0) { - p = &node->name_node.rb_left; - } else { - p = &node->name_node.rb_right; - } -#undef node + sd->s_parent->s_dir.subdirs++; + + while (*node) { + struct sysfs_dirent *pos; + int result; + + pos = to_sysfs_dirent(*node); + parent = *node; + result = sysfs_sd_compare(sd, pos); + if (result < 0) + node = &pos->s_rb.rb_left; + else if (result > 0) + node = &pos->s_rb.rb_right; + else + return -EEXIST; } - rb_link_node(&sd->name_node, parent, p); - rb_insert_color(&sd->name_node, &parent_sd->s_dir.name_tree); + /* add new node and rebalance the tree */ + rb_link_node(&sd->s_rb, parent, node); + rb_insert_color(&sd->s_rb, &sd->s_parent->s_dir.children); + return 0; } /** - * sysfs_unlink_sibling - unlink sysfs_dirent from sibling list + * sysfs_unlink_sibling - unlink sysfs_dirent from sibling rbtree * @sd: sysfs_dirent of interest * - * Unlink @sd from its sibling list which starts from + * Unlink @sd from its sibling rbtree which starts from * sd->s_parent->s_dir.children. * * Locking: @@ -102,8 +129,7 @@ static void sysfs_unlink_sibling(struct sysfs_dirent *sd) if (sysfs_type(sd) == SYSFS_DIR) sd->s_parent->s_dir.subdirs--; - rb_erase(&sd->inode_node, &sd->s_parent->s_dir.inode_tree); - rb_erase(&sd->name_node, &sd->s_parent->s_dir.name_tree); + rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children); } /** @@ -402,6 +428,7 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt, int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd) { struct sysfs_inode_attrs *ps_iattr; + int ret; if (!!sysfs_ns_type(acxt->parent_sd) != !!sd->s_ns) { WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n", @@ -410,12 +437,12 @@ int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd) return -EINVAL; } - if (sysfs_find_dirent(acxt->parent_sd, sd->s_ns, sd->s_name)) - return -EEXIST; - + sd->s_hash = sysfs_name_hash(sd->s_ns, sd->s_name); sd->s_parent = sysfs_get(acxt->parent_sd); - sysfs_link_sibling(sd); + ret = sysfs_link_sibling(sd); + if (ret) + return ret; /* Update timestamps on the parent */ ps_iattr = acxt->parent_sd->s_iattr; @@ -565,8 +592,8 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd, const void *ns, const unsigned char *name) { - struct rb_node *p = parent_sd->s_dir.name_tree.rb_node; - struct sysfs_dirent *found = NULL; + struct rb_node *node = parent_sd->s_dir.children.rb_node; + unsigned int hash; if (!!sysfs_ns_type(parent_sd) != !!ns) { WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n", @@ -575,33 +602,21 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd, return NULL; } - while (p) { - int c; -#define node rb_entry(p, struct sysfs_dirent, name_node) - c = strcmp(name, node->s_name); - if (c < 0) { - p = node->name_node.rb_left; - } else if (c > 0) { - p = node->name_node.rb_right; - } else { - found = node; - p = node->name_node.rb_left; - } -#undef node - } - - if (found) { - while (found->s_ns != ns) { - p = rb_next(&found->name_node); - if (!p) - return NULL; - found = rb_entry(p, struct sysfs_dirent, name_node); - if (strcmp(name, found->s_name)) - return NULL; - } + hash = sysfs_name_hash(ns, name); + while (node) { + struct sysfs_dirent *sd; + int result; + + sd = to_sysfs_dirent(node); + result = sysfs_name_compare(hash, ns, name, sd); + if (result < 0) + node = node->rb_left; + else if (result > 0) + node = node->rb_right; + else + return sd; } - - return found; + return NULL; } /** @@ -804,9 +819,9 @@ static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd) pr_debug("sysfs %s: removing dir\n", dir_sd->s_name); sysfs_addrm_start(&acxt, dir_sd); - pos = rb_first(&dir_sd->s_dir.inode_tree); + pos = rb_first(&dir_sd->s_dir.children); while (pos) { - struct sysfs_dirent *sd = rb_entry(pos, struct sysfs_dirent, inode_node); + struct sysfs_dirent *sd = to_sysfs_dirent(pos); pos = rb_next(pos); if (sysfs_type(sd) != SYSFS_DIR) sysfs_remove_one(&acxt, sd); @@ -919,38 +934,36 @@ static int sysfs_dir_release(struct inode *inode, struct file *filp) } static struct sysfs_dirent *sysfs_dir_pos(const void *ns, - struct sysfs_dirent *parent_sd, ino_t ino, struct sysfs_dirent *pos) + struct sysfs_dirent *parent_sd, loff_t hash, struct sysfs_dirent *pos) { if (pos) { int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) && pos->s_parent == parent_sd && - ino == pos->s_ino; + hash == pos->s_hash; sysfs_put(pos); if (!valid) pos = NULL; } - if (!pos && (ino > 1) && (ino < INT_MAX)) { - struct rb_node *p = parent_sd->s_dir.inode_tree.rb_node; - while (p) { -#define node rb_entry(p, struct sysfs_dirent, inode_node) - if (ino < node->s_ino) { - pos = node; - p = node->inode_node.rb_left; - } else if (ino > node->s_ino) { - p = node->inode_node.rb_right; - } else { - pos = node; + if (!pos && (hash > 1) && (hash < INT_MAX)) { + struct rb_node *node = parent_sd->s_dir.children.rb_node; + while (node) { + pos = to_sysfs_dirent(node); + + if (hash < pos->s_hash) + node = node->rb_left; + else if (hash > pos->s_hash) + node = node->rb_right; + else break; - } -#undef node } } + /* Skip over entries in the wrong namespace */ while (pos && pos->s_ns != ns) { - struct rb_node *p = rb_next(&pos->inode_node); - if (!p) + struct rb_node *node = rb_next(&pos->s_rb); + if (!node) pos = NULL; else - pos = rb_entry(p, struct sysfs_dirent, inode_node); + pos = to_sysfs_dirent(node); } return pos; } @@ -960,11 +973,11 @@ static struct sysfs_dirent *sysfs_dir_next_pos(const void *ns, { pos = sysfs_dir_pos(ns, parent_sd, ino, pos); if (pos) do { - struct rb_node *p = rb_next(&pos->inode_node); - if (!p) + struct rb_node *node = rb_next(&pos->s_rb); + if (!node) pos = NULL; else - pos = rb_entry(p, struct sysfs_dirent, inode_node); + pos = to_sysfs_dirent(node); } while (pos && pos->s_ns != ns); return pos; } @@ -1006,7 +1019,7 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir) len = strlen(name); ino = pos->s_ino; type = dt_type(pos); - filp->f_pos = ino; + filp->f_pos = pos->s_hash; filp->private_data = sysfs_get(pos); mutex_unlock(&sysfs_mutex); diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h index 7484a36ee678..2b5c923b4b90 100644 --- a/fs/sysfs/sysfs.h +++ b/fs/sysfs/sysfs.h @@ -20,9 +20,8 @@ struct sysfs_elem_dir { struct kobject *kobj; unsigned long subdirs; - - struct rb_root inode_tree; - struct rb_root name_tree; + /* children rbtree starts here and goes through sd->s_rb */ + struct rb_root children; }; struct sysfs_elem_symlink { @@ -62,8 +61,7 @@ struct sysfs_dirent { struct sysfs_dirent *s_parent; const char *s_name; - struct rb_node inode_node; - struct rb_node name_node; + struct rb_node s_rb; union { struct completion *completion; @@ -71,6 +69,7 @@ struct sysfs_dirent { } u; const void *s_ns; /* namespace tag */ + unsigned int s_hash; /* ns + name hash */ union { struct sysfs_elem_dir s_dir; struct sysfs_elem_symlink s_symlink; -- GitLab