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>

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index e319379..f3af45e 100644 (file)
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -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
@@ -399,47 +393,20 @@ 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);
-               }
-       }
 }
 
 /**
@@ -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);

diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 12ccc07..90b3501 100644 (file)
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -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;
 };
 
 /*