From 75c1be487a690db43da2c1234fcacd84c982803c Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Wed, 28 Jul 2010 10:18:38 -0400 Subject: fsnotify: srcu to protect read side of inode and vfsmount locks Currently reading the inode->i_fsnotify_marks or vfsmount->mnt_fsnotify_marks lists are protected by a spinlock on both the read and the write side. This patch protects the read side of those lists with a new single srcu. Signed-off-by: Eric Paris --- fs/notify/fsnotify.c | 69 ++++++++++++++++++++++++++++++++++------------------ 1 file changed, 45 insertions(+), 24 deletions(-) (limited to 'fs/notify/fsnotify.c') diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index 4788c866473a..4678b416241e 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -144,14 +144,15 @@ void __fsnotify_flush_ignored_mask(struct inode *inode, void *data, int data_is) { struct fsnotify_mark *mark; struct hlist_node *node; + int idx; + + idx = srcu_read_lock(&fsnotify_mark_srcu); if (!hlist_empty(&inode->i_fsnotify_marks)) { - spin_lock(&inode->i_lock); - hlist_for_each_entry(mark, node, &inode->i_fsnotify_marks, i.i_list) { + hlist_for_each_entry_rcu(mark, node, &inode->i_fsnotify_marks, i.i_list) { if (!(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) mark->ignored_mask = 0; } - spin_unlock(&inode->i_lock); } if (data_is == FSNOTIFY_EVENT_FILE) { @@ -159,14 +160,14 @@ void __fsnotify_flush_ignored_mask(struct inode *inode, void *data, int data_is) mnt = ((struct file *)data)->f_path.mnt; if (mnt && !hlist_empty(&mnt->mnt_fsnotify_marks)) { - spin_lock(&mnt->mnt_root->d_lock); - hlist_for_each_entry(mark, node, &mnt->mnt_fsnotify_marks, m.m_list) { + hlist_for_each_entry_rcu(mark, node, &mnt->mnt_fsnotify_marks, m.m_list) { if (!(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) mark->ignored_mask = 0; } - spin_unlock(&mnt->mnt_root->d_lock); } } + + srcu_read_unlock(&fsnotify_mark_srcu, idx); } static int send_to_group(struct fsnotify_group *group, struct inode *to_tell, @@ -208,8 +209,10 @@ static bool needed_by_vfsmount(__u32 test_mask, struct vfsmount *mnt) int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const unsigned char *file_name, u32 cookie) { + struct fsnotify_mark *mark; struct fsnotify_group *group; struct fsnotify_event *event = NULL; + struct hlist_node *node; struct vfsmount *mnt = NULL; int idx, ret = 0; /* global tests shouldn't care about events on child only the specific event */ @@ -237,35 +240,47 @@ int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, !needed_by_vfsmount(test_mask, mnt)) return 0; - /* - * SRCU!! the groups list is very very much read only and the path is - * very hot. The VAST majority of events are not going to need to do - * anything other than walk the list so it's crazy to pre-allocate. - */ - idx = srcu_read_lock(&fsnotify_grp_srcu); + idx = srcu_read_lock(&fsnotify_mark_srcu); if (test_mask & to_tell->i_fsnotify_mask) { - list_for_each_entry_rcu(group, &fsnotify_inode_groups, inode_group_list) { - if (test_mask & group->mask) { - ret = send_to_group(group, to_tell, NULL, mask, data, data_is, - cookie, file_name, &event); + hlist_for_each_entry_rcu(mark, node, &to_tell->i_fsnotify_marks, i.i_list) { + + pr_debug("%s: inode_loop: mark=%p mark->mask=%x mark->ignored_mask=%x\n", + __func__, mark, mark->mask, mark->ignored_mask); + + if (test_mask & mark->mask & ~mark->ignored_mask) { + group = mark->group; + if (!group) + continue; + ret = send_to_group(group, to_tell, NULL, mask, + data, data_is, cookie, file_name, + &event); if (ret) goto out; } } } - if (needed_by_vfsmount(test_mask, mnt)) { - list_for_each_entry_rcu(group, &fsnotify_vfsmount_groups, vfsmount_group_list) { - if (test_mask & group->mask) { - ret = send_to_group(group, to_tell, mnt, mask, data, data_is, - cookie, file_name, &event); + + if (mnt && (test_mask & mnt->mnt_fsnotify_mask)) { + hlist_for_each_entry_rcu(mark, node, &mnt->mnt_fsnotify_marks, m.m_list) { + + pr_debug("%s: mnt_loop: mark=%p mark->mask=%x mark->ignored_mask=%x\n", + __func__, mark, mark->mask, mark->ignored_mask); + + if (test_mask & mark->mask & ~mark->ignored_mask) { + group = mark->group; + if (!group) + continue; + ret = send_to_group(group, to_tell, mnt, mask, + data, data_is, cookie, file_name, + &event); if (ret) goto out; } } } out: - srcu_read_unlock(&fsnotify_grp_srcu, idx); + srcu_read_unlock(&fsnotify_mark_srcu, idx); /* * fsnotify_create_event() took a reference so the event can't be cleaned * up while we are still trying to add it to lists, drop that one. @@ -279,8 +294,14 @@ EXPORT_SYMBOL_GPL(fsnotify); static __init int fsnotify_init(void) { + int ret; + BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23); - return init_srcu_struct(&fsnotify_grp_srcu); + ret = init_srcu_struct(&fsnotify_mark_srcu); + if (ret) + panic("initializing fsnotify_mark_srcu"); + + return 0; } -subsys_initcall(fsnotify_init); +core_initcall(fsnotify_init); -- cgit