sysfs: Gut sysfs_addrm_start and sysfs_addrm_finish
With lazy inode updates and dentry operations bringing everything into sync on demand there is no longer any need to immediately update the vfs or grab i_mutex to protect those updates as we make changes to sysfs. Acked-by: Serge Hallyn <serue@us.ibm.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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@ -386,12 +386,6 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
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return NULL;
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return NULL;
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}
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}
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static int sysfs_ilookup_test(struct inode *inode, void *arg)
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{
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struct sysfs_dirent *sd = arg;
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return inode->i_ino == sd->s_ino;
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}
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/**
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/**
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* sysfs_addrm_start - prepare for sysfs_dirent add/remove
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* sysfs_addrm_start - prepare for sysfs_dirent add/remove
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* @acxt: pointer to sysfs_addrm_cxt to be used
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* @acxt: pointer to sysfs_addrm_cxt to be used
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@ -399,47 +393,20 @@ static int sysfs_ilookup_test(struct inode *inode, void *arg)
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*
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*
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* This function is called when the caller is about to add or
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* This function is called when the caller is about to add or
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* remove sysfs_dirent under @parent_sd. This function acquires
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* remove sysfs_dirent under @parent_sd. This function acquires
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* sysfs_mutex, grabs inode for @parent_sd if available and lock
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* sysfs_mutex. @acxt is used to keep and pass context to
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* i_mutex of it. @acxt is used to keep and pass context to
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* other addrm functions.
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* other addrm functions.
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*
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*
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* LOCKING:
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* LOCKING:
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* Kernel thread context (may sleep). sysfs_mutex is locked on
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* Kernel thread context (may sleep). sysfs_mutex is locked on
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* return. i_mutex of parent inode is locked on return if
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* return.
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* available.
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*/
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*/
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void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
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void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
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struct sysfs_dirent *parent_sd)
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struct sysfs_dirent *parent_sd)
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{
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{
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struct inode *inode;
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memset(acxt, 0, sizeof(*acxt));
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memset(acxt, 0, sizeof(*acxt));
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acxt->parent_sd = parent_sd;
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acxt->parent_sd = parent_sd;
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/* Lookup parent inode. inode initialization is protected by
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* sysfs_mutex, so inode existence can be determined by
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* looking up inode while holding sysfs_mutex.
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*/
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mutex_lock(&sysfs_mutex);
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mutex_lock(&sysfs_mutex);
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inode = ilookup5(sysfs_sb, parent_sd->s_ino, sysfs_ilookup_test,
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parent_sd);
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if (inode) {
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WARN_ON(inode->i_state & I_NEW);
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/* parent inode available */
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acxt->parent_inode = inode;
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/* sysfs_mutex is below i_mutex in lock hierarchy.
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* First, trylock i_mutex. If fails, unlock
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* sysfs_mutex and lock them in order.
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*/
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if (!mutex_trylock(&inode->i_mutex)) {
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mutex_unlock(&sysfs_mutex);
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mutex_lock(&inode->i_mutex);
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mutex_lock(&sysfs_mutex);
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}
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}
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}
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}
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/**
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/**
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@ -471,11 +438,6 @@ int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
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sd->s_parent = sysfs_get(acxt->parent_sd);
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sd->s_parent = sysfs_get(acxt->parent_sd);
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if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
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inc_nlink(acxt->parent_inode);
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acxt->cnt++;
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sysfs_link_sibling(sd);
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sysfs_link_sibling(sd);
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/* Update timestamps on the parent */
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/* Update timestamps on the parent */
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@ -579,40 +541,6 @@ void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
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sd->s_flags |= SYSFS_FLAG_REMOVED;
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sd->s_flags |= SYSFS_FLAG_REMOVED;
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sd->s_sibling = acxt->removed;
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sd->s_sibling = acxt->removed;
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acxt->removed = sd;
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acxt->removed = sd;
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if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
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drop_nlink(acxt->parent_inode);
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acxt->cnt++;
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}
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/**
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* sysfs_dec_nlink - Decrement link count for the specified sysfs_dirent
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* @sd: target sysfs_dirent
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*
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* Decrement nlink for @sd. @sd must have been unlinked from its
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* parent on entry to this function such that it can't be looked
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* up anymore.
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*/
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static void sysfs_dec_nlink(struct sysfs_dirent *sd)
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{
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struct inode *inode;
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inode = ilookup(sysfs_sb, sd->s_ino);
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if (!inode)
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return;
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/* adjust nlink and update timestamp */
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mutex_lock(&inode->i_mutex);
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inode->i_ctime = CURRENT_TIME;
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drop_nlink(inode);
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if (sysfs_type(sd) == SYSFS_DIR)
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drop_nlink(inode);
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mutex_unlock(&inode->i_mutex);
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iput(inode);
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}
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}
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/**
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/**
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@ -621,25 +549,15 @@ static void sysfs_dec_nlink(struct sysfs_dirent *sd)
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*
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*
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* Finish up sysfs_dirent add/remove. Resources acquired by
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* Finish up sysfs_dirent add/remove. Resources acquired by
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* sysfs_addrm_start() are released and removed sysfs_dirents are
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* sysfs_addrm_start() are released and removed sysfs_dirents are
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* cleaned up. Timestamps on the parent inode are updated.
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* cleaned up.
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*
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*
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* LOCKING:
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* LOCKING:
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* All mutexes acquired by sysfs_addrm_start() are released.
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* sysfs_mutex is released.
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*/
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*/
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void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
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void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
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{
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{
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/* release resources acquired by sysfs_addrm_start() */
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/* release resources acquired by sysfs_addrm_start() */
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mutex_unlock(&sysfs_mutex);
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mutex_unlock(&sysfs_mutex);
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if (acxt->parent_inode) {
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struct inode *inode = acxt->parent_inode;
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/* if added/removed, update timestamps on the parent */
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if (acxt->cnt)
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inode->i_ctime = inode->i_mtime = CURRENT_TIME;
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mutex_unlock(&inode->i_mutex);
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iput(inode);
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}
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/* kill removed sysfs_dirents */
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/* kill removed sysfs_dirents */
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while (acxt->removed) {
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while (acxt->removed) {
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@ -648,7 +566,6 @@ void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
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acxt->removed = sd->s_sibling;
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acxt->removed = sd->s_sibling;
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sd->s_sibling = NULL;
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sd->s_sibling = NULL;
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sysfs_dec_nlink(sd);
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sysfs_deactivate(sd);
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sysfs_deactivate(sd);
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unmap_bin_file(sd);
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unmap_bin_file(sd);
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sysfs_put(sd);
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sysfs_put(sd);
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@ -89,9 +89,7 @@ static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
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*/
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*/
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struct sysfs_addrm_cxt {
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struct sysfs_addrm_cxt {
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struct sysfs_dirent *parent_sd;
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struct sysfs_dirent *parent_sd;
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struct inode *parent_inode;
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struct sysfs_dirent *removed;
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struct sysfs_dirent *removed;
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int cnt;
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};
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};
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/*
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/*
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