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Commit a16bbc34 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Greg Kroah-Hartman
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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: default avatarSerge Hallyn <serue@us.ibm.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarEric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 06fc0d66

fs/sysfs/dir.c

+4 −87
Original line number Diff line number Diff line
@@ -386,12 +386,6 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type) 
	return NULL;

}



static int sysfs_ilookup_test(struct inode *inode, void *arg)

{

	struct sysfs_dirent *sd = arg;

	return inode->i_ino == sd->s_ino;

}



/**

 *	sysfs_addrm_start - prepare for sysfs_dirent add/remove

 *	@acxt: pointer to sysfs_addrm_cxt to be used
@@ -399,48 +393,21 @@ static int sysfs_ilookup_test(struct inode *inode, void *arg) 
 *

 *	This function is called when the caller is about to add or

 *	remove sysfs_dirent under @parent_sd.  This function acquires

 *	sysfs_mutex, grabs inode for @parent_sd if available and lock

 *	i_mutex of it.  @acxt is used to keep and pass context to

 *	sysfs_mutex.  @acxt is used to keep and pass context to

 *	other addrm functions.

 *

 *	LOCKING:

 *	Kernel thread context (may sleep).  sysfs_mutex is locked on

 *	return.  i_mutex of parent inode is locked on return if

 *	available.

 *	return.

 */

void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,

		       struct sysfs_dirent *parent_sd)

{

	struct inode *inode;



	memset(acxt, 0, sizeof(*acxt));

	acxt->parent_sd = parent_sd;



	/* Lookup parent inode.  inode initialization is protected by

	 * sysfs_mutex, so inode existence can be determined by

	 * looking up inode while holding sysfs_mutex.

	 */

	mutex_lock(&sysfs_mutex);



	inode = ilookup5(sysfs_sb, parent_sd->s_ino, sysfs_ilookup_test,

			 parent_sd);

	if (inode) {

		WARN_ON(inode->i_state & I_NEW);



		/* parent inode available */

		acxt->parent_inode = inode;



		/* sysfs_mutex is below i_mutex in lock hierarchy.

		 * First, trylock i_mutex.  If fails, unlock

		 * sysfs_mutex and lock them in order.

		 */

		if (!mutex_trylock(&inode->i_mutex)) {

			mutex_unlock(&sysfs_mutex);

			mutex_lock(&inode->i_mutex);

	mutex_lock(&sysfs_mutex);

}

	}

}



/**

 *	__sysfs_add_one - add sysfs_dirent to parent without warning
@@ -471,11 +438,6 @@ int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd) 


	sd->s_parent = sysfs_get(acxt->parent_sd);



	if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)

		inc_nlink(acxt->parent_inode);



	acxt->cnt++;



	sysfs_link_sibling(sd);



	/* Update timestamps on the parent */
@@ -579,40 +541,6 @@ void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd) 
	sd->s_flags |= SYSFS_FLAG_REMOVED;

	sd->s_sibling = acxt->removed;

	acxt->removed = sd;



	if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)

		drop_nlink(acxt->parent_inode);



	acxt->cnt++;

}



/**

 *	sysfs_dec_nlink - Decrement link count for the specified sysfs_dirent

 *	@sd: target sysfs_dirent

 *

 *	Decrement nlink for @sd.  @sd must have been unlinked from its

 *	parent on entry to this function such that it can't be looked

 *	up anymore.

 */

static void sysfs_dec_nlink(struct sysfs_dirent *sd)

{

	struct inode *inode;



	inode = ilookup(sysfs_sb, sd->s_ino);

	if (!inode)

		return;



	/* adjust nlink and update timestamp */

	mutex_lock(&inode->i_mutex);



	inode->i_ctime = CURRENT_TIME;

	drop_nlink(inode);

	if (sysfs_type(sd) == SYSFS_DIR)

		drop_nlink(inode);



	mutex_unlock(&inode->i_mutex);



	iput(inode);

}



/**
@@ -621,25 +549,15 @@ static void sysfs_dec_nlink(struct sysfs_dirent *sd) 
 *

 *	Finish up sysfs_dirent add/remove.  Resources acquired by

 *	sysfs_addrm_start() are released and removed sysfs_dirents are

 *	cleaned up.  Timestamps on the parent inode are updated.

 *	cleaned up.

 *

 *	LOCKING:

 *	All mutexes acquired by sysfs_addrm_start() are released.

 *	sysfs_mutex is released.

 */

void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)

{

	/* release resources acquired by sysfs_addrm_start() */

	mutex_unlock(&sysfs_mutex);

	if (acxt->parent_inode) {

		struct inode *inode = acxt->parent_inode;



		/* if added/removed, update timestamps on the parent */

		if (acxt->cnt)

			inode->i_ctime = inode->i_mtime = CURRENT_TIME;



		mutex_unlock(&inode->i_mutex);

		iput(inode);

	}



	/* kill removed sysfs_dirents */

	while (acxt->removed) {
@@ -648,7 +566,6 @@ void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt) 
		acxt->removed = sd->s_sibling;

		sd->s_sibling = NULL;



		sysfs_dec_nlink(sd);

		sysfs_deactivate(sd);

		unmap_bin_file(sd);

		sysfs_put(sd);

fs/sysfs/sysfs.h

+0 −2
Original line number Diff line number Diff line
@@ -89,9 +89,7 @@ static inline unsigned int sysfs_type(struct sysfs_dirent *sd) 
 */

struct sysfs_addrm_cxt {

	struct sysfs_dirent	*parent_sd;

	struct inode		*parent_inode;

	struct sysfs_dirent	*removed;

	int			cnt;

};



/*