mirror of https://gitee.com/openkylin/linux.git
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 <ebiederm@xmission.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Eric W. Biederman
Greg Kroah-Hartman
parent
dcd6c92267
commit
4e4d6d860b
213
fs/sysfs/dir.c
213
fs/sysfs/dir.c
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@ -22,76 +22,103 @@
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/security.h>
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#include <linux/hash.h>
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#include "sysfs.h"
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DEFINE_MUTEX(sysfs_mutex);
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DEFINE_SPINLOCK(sysfs_assoc_lock);
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#define to_sysfs_dirent(X) rb_entry((X), struct sysfs_dirent, s_rb);
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static DEFINE_SPINLOCK(sysfs_ino_lock);
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static DEFINE_IDA(sysfs_ino_ida);
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/**
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* sysfs_link_sibling - link sysfs_dirent into sibling list
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* sysfs_name_hash
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* @ns: Namespace tag to hash
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* @name: Null terminated string to hash
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*
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* Returns 31 bit hash of ns + name (so it fits in an off_t )
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*/
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static unsigned int sysfs_name_hash(const void *ns, const char *name)
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{
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unsigned long hash = init_name_hash();
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unsigned int len = strlen(name);
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while (len--)
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hash = partial_name_hash(*name++, hash);
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hash = ( end_name_hash(hash) ^ hash_ptr( (void *)ns, 31 ) );
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hash &= 0x7fffffffU;
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/* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
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if (hash < 1)
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hash += 2;
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if (hash >= INT_MAX)
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hash = INT_MAX - 1;
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return hash;
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}
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static int sysfs_name_compare(unsigned int hash, const void *ns,
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const char *name, const struct sysfs_dirent *sd)
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{
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if (hash != sd->s_hash)
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return hash - sd->s_hash;
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if (ns != sd->s_ns)
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return ns - sd->s_ns;
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return strcmp(name, sd->s_name);
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}
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static int sysfs_sd_compare(const struct sysfs_dirent *left,
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const struct sysfs_dirent *right)
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{
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return sysfs_name_compare(left->s_hash, left->s_ns, left->s_name,
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right);
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}
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/**
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* sysfs_link_subling - link sysfs_dirent into sibling rbtree
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* @sd: sysfs_dirent of interest
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*
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* Link @sd into its sibling list which starts from
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* Link @sd into its sibling rbtree which starts from
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* sd->s_parent->s_dir.children.
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*
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* Locking:
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* mutex_lock(sysfs_mutex)
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*
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* RETURNS:
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* 0 on susccess -EEXIST on failure.
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*/
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static void sysfs_link_sibling(struct sysfs_dirent *sd)
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static int sysfs_link_sibling(struct sysfs_dirent *sd)
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{
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struct sysfs_dirent *parent_sd = sd->s_parent;
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struct rb_node **p;
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struct rb_node *parent;
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struct rb_node **node = &sd->s_parent->s_dir.children.rb_node;
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struct rb_node *parent = NULL;
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if (sysfs_type(sd) == SYSFS_DIR)
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parent_sd->s_dir.subdirs++;
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sd->s_parent->s_dir.subdirs++;
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p = &parent_sd->s_dir.inode_tree.rb_node;
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parent = NULL;
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while (*p) {
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parent = *p;
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#define node rb_entry(parent, struct sysfs_dirent, inode_node)
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if (sd->s_ino < node->s_ino) {
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p = &node->inode_node.rb_left;
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} else if (sd->s_ino > node->s_ino) {
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p = &node->inode_node.rb_right;
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} else {
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printk(KERN_CRIT "sysfs: inserting duplicate inode '%lx'\n",
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(unsigned long) sd->s_ino);
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BUG();
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}
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#undef node
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}
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rb_link_node(&sd->inode_node, parent, p);
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rb_insert_color(&sd->inode_node, &parent_sd->s_dir.inode_tree);
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while (*node) {
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struct sysfs_dirent *pos;
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int result;
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p = &parent_sd->s_dir.name_tree.rb_node;
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parent = NULL;
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while (*p) {
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int c;
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parent = *p;
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#define node rb_entry(parent, struct sysfs_dirent, name_node)
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c = strcmp(sd->s_name, node->s_name);
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if (c < 0) {
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p = &node->name_node.rb_left;
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} else {
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p = &node->name_node.rb_right;
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}
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#undef node
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pos = to_sysfs_dirent(*node);
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parent = *node;
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result = sysfs_sd_compare(sd, pos);
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if (result < 0)
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node = &pos->s_rb.rb_left;
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else if (result > 0)
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node = &pos->s_rb.rb_right;
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else
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return -EEXIST;
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}
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rb_link_node(&sd->name_node, parent, p);
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rb_insert_color(&sd->name_node, &parent_sd->s_dir.name_tree);
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/* add new node and rebalance the tree */
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rb_link_node(&sd->s_rb, parent, node);
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rb_insert_color(&sd->s_rb, &sd->s_parent->s_dir.children);
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return 0;
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}
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/**
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* sysfs_unlink_sibling - unlink sysfs_dirent from sibling list
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* sysfs_unlink_sibling - unlink sysfs_dirent from sibling rbtree
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* @sd: sysfs_dirent of interest
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*
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* Unlink @sd from its sibling list which starts from
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* Unlink @sd from its sibling rbtree which starts from
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* sd->s_parent->s_dir.children.
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*
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* Locking:
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@ -102,8 +129,7 @@ static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
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if (sysfs_type(sd) == SYSFS_DIR)
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sd->s_parent->s_dir.subdirs--;
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rb_erase(&sd->inode_node, &sd->s_parent->s_dir.inode_tree);
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rb_erase(&sd->name_node, &sd->s_parent->s_dir.name_tree);
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rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children);
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}
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/**
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@ -402,6 +428,7 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
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int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
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{
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struct sysfs_inode_attrs *ps_iattr;
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int ret;
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if (!!sysfs_ns_type(acxt->parent_sd) != !!sd->s_ns) {
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WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
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@ -410,12 +437,12 @@ int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
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return -EINVAL;
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}
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if (sysfs_find_dirent(acxt->parent_sd, sd->s_ns, sd->s_name))
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return -EEXIST;
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sd->s_hash = sysfs_name_hash(sd->s_ns, sd->s_name);
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sd->s_parent = sysfs_get(acxt->parent_sd);
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sysfs_link_sibling(sd);
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ret = sysfs_link_sibling(sd);
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if (ret)
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return ret;
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/* Update timestamps on the parent */
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ps_iattr = acxt->parent_sd->s_iattr;
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@ -565,8 +592,8 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
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const void *ns,
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const unsigned char *name)
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{
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struct rb_node *p = parent_sd->s_dir.name_tree.rb_node;
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struct sysfs_dirent *found = NULL;
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struct rb_node *node = parent_sd->s_dir.children.rb_node;
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unsigned int hash;
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if (!!sysfs_ns_type(parent_sd) != !!ns) {
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WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
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@ -575,33 +602,21 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
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return NULL;
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}
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while (p) {
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int c;
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#define node rb_entry(p, struct sysfs_dirent, name_node)
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c = strcmp(name, node->s_name);
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if (c < 0) {
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p = node->name_node.rb_left;
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} else if (c > 0) {
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p = node->name_node.rb_right;
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} else {
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found = node;
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p = node->name_node.rb_left;
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}
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#undef node
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}
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hash = sysfs_name_hash(ns, name);
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while (node) {
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struct sysfs_dirent *sd;
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int result;
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if (found) {
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while (found->s_ns != ns) {
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p = rb_next(&found->name_node);
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if (!p)
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return NULL;
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found = rb_entry(p, struct sysfs_dirent, name_node);
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if (strcmp(name, found->s_name))
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return NULL;
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}
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sd = to_sysfs_dirent(node);
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result = sysfs_name_compare(hash, ns, name, sd);
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if (result < 0)
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node = node->rb_left;
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else if (result > 0)
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node = node->rb_right;
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else
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return sd;
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}
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return found;
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return NULL;
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}
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/**
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@ -804,9 +819,9 @@ static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
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pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);
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sysfs_addrm_start(&acxt, dir_sd);
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pos = rb_first(&dir_sd->s_dir.inode_tree);
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pos = rb_first(&dir_sd->s_dir.children);
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while (pos) {
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struct sysfs_dirent *sd = rb_entry(pos, struct sysfs_dirent, inode_node);
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struct sysfs_dirent *sd = to_sysfs_dirent(pos);
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pos = rb_next(pos);
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if (sysfs_type(sd) != SYSFS_DIR)
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sysfs_remove_one(&acxt, sd);
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@ -919,38 +934,36 @@ static int sysfs_dir_release(struct inode *inode, struct file *filp)
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}
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static struct sysfs_dirent *sysfs_dir_pos(const void *ns,
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struct sysfs_dirent *parent_sd, ino_t ino, struct sysfs_dirent *pos)
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struct sysfs_dirent *parent_sd, loff_t hash, struct sysfs_dirent *pos)
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{
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if (pos) {
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int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) &&
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pos->s_parent == parent_sd &&
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ino == pos->s_ino;
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hash == pos->s_hash;
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sysfs_put(pos);
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if (!valid)
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pos = NULL;
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}
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if (!pos && (ino > 1) && (ino < INT_MAX)) {
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struct rb_node *p = parent_sd->s_dir.inode_tree.rb_node;
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while (p) {
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#define node rb_entry(p, struct sysfs_dirent, inode_node)
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if (ino < node->s_ino) {
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pos = node;
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p = node->inode_node.rb_left;
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} else if (ino > node->s_ino) {
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p = node->inode_node.rb_right;
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} else {
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pos = node;
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if (!pos && (hash > 1) && (hash < INT_MAX)) {
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struct rb_node *node = parent_sd->s_dir.children.rb_node;
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while (node) {
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pos = to_sysfs_dirent(node);
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if (hash < pos->s_hash)
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node = node->rb_left;
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else if (hash > pos->s_hash)
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node = node->rb_right;
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else
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break;
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}
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#undef node
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}
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}
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/* Skip over entries in the wrong namespace */
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while (pos && pos->s_ns != ns) {
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struct rb_node *p = rb_next(&pos->inode_node);
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if (!p)
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struct rb_node *node = rb_next(&pos->s_rb);
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if (!node)
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pos = NULL;
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else
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pos = rb_entry(p, struct sysfs_dirent, inode_node);
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pos = to_sysfs_dirent(node);
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}
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return pos;
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}
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@ -960,11 +973,11 @@ static struct sysfs_dirent *sysfs_dir_next_pos(const void *ns,
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{
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pos = sysfs_dir_pos(ns, parent_sd, ino, pos);
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if (pos) do {
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struct rb_node *p = rb_next(&pos->inode_node);
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if (!p)
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struct rb_node *node = rb_next(&pos->s_rb);
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if (!node)
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pos = NULL;
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else
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pos = rb_entry(p, struct sysfs_dirent, inode_node);
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pos = to_sysfs_dirent(node);
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} while (pos && pos->s_ns != ns);
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return pos;
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}
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@ -1006,7 +1019,7 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
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len = strlen(name);
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ino = pos->s_ino;
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type = dt_type(pos);
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filp->f_pos = ino;
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filp->f_pos = pos->s_hash;
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filp->private_data = sysfs_get(pos);
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mutex_unlock(&sysfs_mutex);
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@ -20,9 +20,8 @@ struct sysfs_elem_dir {
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struct kobject *kobj;
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unsigned long subdirs;
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struct rb_root inode_tree;
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struct rb_root name_tree;
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/* children rbtree starts here and goes through sd->s_rb */
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struct rb_root children;
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};
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struct sysfs_elem_symlink {
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@ -62,8 +61,7 @@ struct sysfs_dirent {
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struct sysfs_dirent *s_parent;
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const char *s_name;
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struct rb_node inode_node;
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struct rb_node name_node;
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struct rb_node s_rb;
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union {
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struct completion *completion;
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@ -71,6 +69,7 @@ struct sysfs_dirent {
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} u;
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const void *s_ns; /* namespace tag */
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unsigned int s_hash; /* ns + name hash */
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union {
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struct sysfs_elem_dir s_dir;
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struct sysfs_elem_symlink s_symlink;
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