From c32ccd87bfd1414b0aabfcd8dbc7539ad23bcbaa Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Sat, 25 Mar 2006 03:07:09 -0800 Subject: [PATCH] inotify: lock avoidance with parent watch status in dentry Previous inotify work avoidance is good when inotify is completely unused, but it breaks down if even a single watch is in place anywhere in the system. Robin Holt notices that udev is one such culprit - it slows down a 512-thread application on a 512 CPU system from 6 seconds to 22 minutes. Solve this by adding a flag in the dentry that tells inotify whether or not its parent inode has a watch on it. Event queueing to parent will skip taking locks if this flag is cleared. Setting and clearing of this flag on all child dentries versus event delivery: this is no in terms of race cases, and that was shown to be equivalent to always performing the check. The essential behaviour is that activity occuring _after_ a watch has been added and _before_ it has been removed, will generate events. Signed-off-by: Nick Piggin Cc: Robert Love Cc: John McCutchan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/dcache.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index 139e5fd22fa..0f7ec12d65f 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -802,6 +802,7 @@ void d_instantiate(struct dentry *entry, struct inode * inode) if (inode) list_add(&entry->d_alias, &inode->i_dentry); entry->d_inode = inode; + fsnotify_d_instantiate(entry, inode); spin_unlock(&dcache_lock); security_d_instantiate(entry, inode); } @@ -853,6 +854,7 @@ struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) list_add(&entry->d_alias, &inode->i_dentry); do_negative: entry->d_inode = inode; + fsnotify_d_instantiate(entry, inode); spin_unlock(&dcache_lock); security_d_instantiate(entry, inode); return NULL; @@ -983,6 +985,7 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) new = __d_find_alias(inode, 1); if (new) { BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); + fsnotify_d_instantiate(new, inode); spin_unlock(&dcache_lock); security_d_instantiate(new, inode); d_rehash(dentry); @@ -992,6 +995,7 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) /* d_instantiate takes dcache_lock, so we do it by hand */ list_add(&dentry->d_alias, &inode->i_dentry); dentry->d_inode = inode; + fsnotify_d_instantiate(dentry, inode); spin_unlock(&dcache_lock); security_d_instantiate(dentry, inode); d_rehash(dentry); @@ -1176,6 +1180,9 @@ void d_delete(struct dentry * dentry) spin_lock(&dentry->d_lock); isdir = S_ISDIR(dentry->d_inode->i_mode); if (atomic_read(&dentry->d_count) == 1) { + /* remove this and other inotify debug checks after 2.6.18 */ + dentry->d_flags &= ~DCACHE_INOTIFY_PARENT_WATCHED; + dentry_iput(dentry); fsnotify_nameremove(dentry, isdir); return; @@ -1342,6 +1349,7 @@ already_unhashed: list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); spin_unlock(&target->d_lock); + fsnotify_d_move(dentry); spin_unlock(&dentry->d_lock); write_sequnlock(&rename_lock); spin_unlock(&dcache_lock); -- cgit