From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759131AbYGNWGN (ORCPT ); Mon, 14 Jul 2008 18:06:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758250AbYGNWCQ (ORCPT ); Mon, 14 Jul 2008 18:02:16 -0400 Received: from ns.suse.de ([195.135.220.2]:49950 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758243AbYGNWCN (ORCPT ); Mon, 14 Jul 2008 18:02:13 -0400 From: Mark Fasheh To: linux-kernel@vger.kernel.org Cc: Mark Fasheh , ocfs2-devel@oss.oracle.com, Joel Becker , Louis Rilling Subject: [PATCH 10/17] configfs: Introduce configfs_dirent_lock Date: Mon, 14 Jul 2008 15:01:43 -0700 Message-Id: <1216072910-27226-11-git-send-email-mfasheh@suse.com> X-Mailer: git-send-email 1.5.4.1 In-Reply-To: <1216072910-27226-1-git-send-email-mfasheh@suse.com> References: <1216072910-27226-1-git-send-email-mfasheh@suse.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Louis Rilling This patch introduces configfs_dirent_lock spinlock to protect configfs_dirent traversals against linkage mutations (add/del/move). This will allow configfs_detach_prep() to avoid locking i_mutexes. Locking rules for configfs_dirent linkage mutations are the same plus the requirement of taking configfs_dirent_lock. For configfs_dirent walking, one can either take appropriate i_mutex as before, or take configfs_dirent_lock. The spinlock could actually be a mutex, but the critical sections are either O(1) or should not be too long (default groups walking in last patch). ChangeLog: - Clarify the comment on configfs_dirent_lock usage - Move sd->s_element init before linking the new dirent - In lseek(), do not release configfs_dirent_lock before the dirent is relinked. Signed-off-by: Louis Rilling Signed-off-by: Joel Becker --- fs/configfs/configfs_internal.h | 3 +++ fs/configfs/dir.c | 28 +++++++++++++++++++++++++++- fs/configfs/inode.c | 2 ++ fs/configfs/symlink.c | 2 ++ 4 files changed, 34 insertions(+), 1 deletions(-) diff --git a/fs/configfs/configfs_internal.h b/fs/configfs/configfs_internal.h index cca9860..5a33b58 100644 --- a/fs/configfs/configfs_internal.h +++ b/fs/configfs/configfs_internal.h @@ -26,6 +26,7 @@ #include #include +#include struct configfs_dirent { atomic_t s_count; @@ -49,6 +50,8 @@ struct configfs_dirent { #define CONFIGFS_USET_DROPPING 0x0100 #define CONFIGFS_NOT_PINNED (CONFIGFS_ITEM_ATTR) +extern spinlock_t configfs_dirent_lock; + extern struct vfsmount * configfs_mount; extern struct kmem_cache *configfs_dir_cachep; diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c index a48dc7d..2619f48 100644 --- a/fs/configfs/dir.c +++ b/fs/configfs/dir.c @@ -35,6 +35,14 @@ #include "configfs_internal.h" DECLARE_RWSEM(configfs_rename_sem); +/* + * Protects mutations of configfs_dirent linkage together with proper i_mutex + * Mutators of configfs_dirent linkage must *both* have the proper inode locked + * and configfs_dirent_lock locked, in that order. + * This allows one to safely traverse configfs_dirent trees without having to + * lock inodes. + */ +DEFINE_SPINLOCK(configfs_dirent_lock); static void configfs_d_iput(struct dentry * dentry, struct inode * inode) @@ -79,8 +87,10 @@ static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent * pare atomic_set(&sd->s_count, 1); INIT_LIST_HEAD(&sd->s_links); INIT_LIST_HEAD(&sd->s_children); - list_add(&sd->s_sibling, &parent_sd->s_children); sd->s_element = element; + spin_lock(&configfs_dirent_lock); + list_add(&sd->s_sibling, &parent_sd->s_children); + spin_unlock(&configfs_dirent_lock); return sd; } @@ -173,7 +183,9 @@ static int create_dir(struct config_item * k, struct dentry * p, } else { struct configfs_dirent *sd = d->d_fsdata; if (sd) { + spin_lock(&configfs_dirent_lock); list_del_init(&sd->s_sibling); + spin_unlock(&configfs_dirent_lock); configfs_put(sd); } } @@ -224,7 +236,9 @@ int configfs_create_link(struct configfs_symlink *sl, else { struct configfs_dirent *sd = dentry->d_fsdata; if (sd) { + spin_lock(&configfs_dirent_lock); list_del_init(&sd->s_sibling); + spin_unlock(&configfs_dirent_lock); configfs_put(sd); } } @@ -238,7 +252,9 @@ static void remove_dir(struct dentry * d) struct configfs_dirent * sd; sd = d->d_fsdata; + spin_lock(&configfs_dirent_lock); list_del_init(&sd->s_sibling); + spin_unlock(&configfs_dirent_lock); configfs_put(sd); if (d->d_inode) simple_rmdir(parent->d_inode,d); @@ -410,7 +426,9 @@ static void detach_attrs(struct config_item * item) list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) { if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED)) continue; + spin_lock(&configfs_dirent_lock); list_del_init(&sd->s_sibling); + spin_unlock(&configfs_dirent_lock); configfs_drop_dentry(sd, dentry); configfs_put(sd); } @@ -1268,7 +1286,9 @@ static int configfs_dir_close(struct inode *inode, struct file *file) struct configfs_dirent * cursor = file->private_data; mutex_lock(&dentry->d_inode->i_mutex); + spin_lock(&configfs_dirent_lock); list_del_init(&cursor->s_sibling); + spin_unlock(&configfs_dirent_lock); mutex_unlock(&dentry->d_inode->i_mutex); release_configfs_dirent(cursor); @@ -1308,7 +1328,9 @@ static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir /* fallthrough */ default: if (filp->f_pos == 2) { + spin_lock(&configfs_dirent_lock); list_move(q, &parent_sd->s_children); + spin_unlock(&configfs_dirent_lock); } for (p=q->next; p!= &parent_sd->s_children; p=p->next) { struct configfs_dirent *next; @@ -1331,7 +1353,9 @@ static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir dt_type(next)) < 0) return 0; + spin_lock(&configfs_dirent_lock); list_move(q, p); + spin_unlock(&configfs_dirent_lock); p = q; filp->f_pos++; } @@ -1362,6 +1386,7 @@ static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin) struct list_head *p; loff_t n = file->f_pos - 2; + spin_lock(&configfs_dirent_lock); list_del(&cursor->s_sibling); p = sd->s_children.next; while (n && p != &sd->s_children) { @@ -1373,6 +1398,7 @@ static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin) p = p->next; } list_add_tail(&cursor->s_sibling, p); + spin_unlock(&configfs_dirent_lock); } } mutex_unlock(&dentry->d_inode->i_mutex); diff --git a/fs/configfs/inode.c b/fs/configfs/inode.c index b9a1d81..4803ccc 100644 --- a/fs/configfs/inode.c +++ b/fs/configfs/inode.c @@ -247,7 +247,9 @@ void configfs_hash_and_remove(struct dentry * dir, const char * name) if (!sd->s_element) continue; if (!strcmp(configfs_get_name(sd), name)) { + spin_lock(&configfs_dirent_lock); list_del_init(&sd->s_sibling); + spin_unlock(&configfs_dirent_lock); configfs_drop_dentry(sd, dir); configfs_put(sd); break; diff --git a/fs/configfs/symlink.c b/fs/configfs/symlink.c index 2a731ef..676c84c 100644 --- a/fs/configfs/symlink.c +++ b/fs/configfs/symlink.c @@ -169,7 +169,9 @@ int configfs_unlink(struct inode *dir, struct dentry *dentry) parent_item = configfs_get_config_item(dentry->d_parent); type = parent_item->ci_type; + spin_lock(&configfs_dirent_lock); list_del_init(&sd->s_sibling); + spin_unlock(&configfs_dirent_lock); configfs_drop_dentry(sd, dentry->d_parent); dput(dentry); configfs_put(sd); -- 1.5.4.1