From 5444e2981c31d0ed7465475e451b8437084337e5 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Thu, 17 Dec 2009 21:24:27 -0500 Subject: fsnotify: split generic and inode specific mark code currently all marking is done by functions in inode-mark.c. Some of this is pretty generic and should be instead done in a generic function and we should only put the inode specific code in inode-mark.c Signed-off-by: Eric Paris --- fs/notify/inode_mark.c | 246 ++++--------------------------------------------- 1 file changed, 19 insertions(+), 227 deletions(-) (limited to 'fs/notify/inode_mark.c') diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c index ba6f9833561b..c925579ba011 100644 --- a/fs/notify/inode_mark.c +++ b/fs/notify/inode_mark.c @@ -16,72 +16,6 @@ * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ -/* - * fsnotify inode mark locking/lifetime/and refcnting - * - * REFCNT: - * The mark->refcnt tells how many "things" in the kernel currently are - * referencing this object. The object typically will live inside the kernel - * with a refcnt of 2, one for each list it is on (i_list, g_list). Any task - * which can find this object holding the appropriete locks, can take a reference - * and the object itself is guarenteed to survive until the reference is dropped. - * - * LOCKING: - * There are 3 spinlocks involved with fsnotify inode marks and they MUST - * be taken in order as follows: - * - * mark->lock - * group->mark_lock - * inode->i_lock - * - * mark->lock protects 2 things, mark->group and mark->inode. You must hold - * that lock to dereference either of these things (they could be NULL even with - * the lock) - * - * group->mark_lock protects the marks_list anchored inside a given group - * and each mark is hooked via the g_list. It also sorta protects the - * free_g_list, which when used is anchored by a private list on the stack of the - * task which held the group->mark_lock. - * - * inode->i_lock protects the i_fsnotify_marks list anchored inside a - * given inode and each mark is hooked via the i_list. (and sorta the - * free_i_list) - * - * - * LIFETIME: - * Inode marks survive between when they are added to an inode and when their - * refcnt==0. - * - * The inode mark can be cleared for a number of different reasons including: - * - The inode is unlinked for the last time. (fsnotify_inode_remove) - * - The inode is being evicted from cache. (fsnotify_inode_delete) - * - The fs the inode is on is unmounted. (fsnotify_inode_delete/fsnotify_unmount_inodes) - * - Something explicitly requests that it be removed. (fsnotify_destroy_mark) - * - The fsnotify_group associated with the mark is going away and all such marks - * need to be cleaned up. (fsnotify_clear_marks_by_group) - * - * Worst case we are given an inode and need to clean up all the marks on that - * inode. We take i_lock and walk the i_fsnotify_marks safely. For each - * mark on the list we take a reference (so the mark can't disappear under us). - * We remove that mark form the inode's list of marks and we add this mark to a - * private list anchored on the stack using i_free_list; At this point we no - * longer fear anything finding the mark using the inode's list of marks. - * - * We can safely and locklessly run the private list on the stack of everything - * we just unattached from the original inode. For each mark on the private list - * we grab the mark-> and can thus dereference mark->group and mark->inode. If - * we see the group and inode are not NULL we take those locks. Now holding all - * 3 locks we can completely remove the mark from other tasks finding it in the - * future. Remember, 10 things might already be referencing this mark, but they - * better be holding a ref. We drop our reference we took before we unhooked it - * from the inode. When the ref hits 0 we can free the mark. - * - * Very similarly for freeing by group, except we use free_g_list. - * - * This has the very interesting property of being able to run concurrently with - * any (or all) other directions. - */ - #include #include #include @@ -95,17 +29,6 @@ #include #include "fsnotify.h" -void fsnotify_get_mark(struct fsnotify_mark *mark) -{ - atomic_inc(&mark->refcnt); -} - -void fsnotify_put_mark(struct fsnotify_mark *mark) -{ - if (atomic_dec_and_test(&mark->refcnt)) - mark->free_mark(mark); -} - /* * Recalculate the mask of events relevant to a given inode locked. */ @@ -135,44 +58,18 @@ void fsnotify_recalc_inode_mask(struct inode *inode) __fsnotify_update_child_dentry_flags(inode); } -/* - * Any time a mark is getting freed we end up here. - * The caller had better be holding a reference to this mark so we don't actually - * do the final put under the mark->lock - */ -void fsnotify_destroy_mark(struct fsnotify_mark *mark) +void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark) { - struct fsnotify_group *group; - struct inode *inode; - - spin_lock(&mark->lock); + struct inode *inode = mark->i.inode; - group = mark->group; - inode = mark->i.inode; + assert_spin_locked(&mark->lock); + assert_spin_locked(&mark->group->mark_lock); - BUG_ON(group && !inode); - BUG_ON(!group && inode); - - /* if !group something else already marked this to die */ - if (!group) { - spin_unlock(&mark->lock); - return; - } - - /* 1 from caller and 1 for being on i_list/g_list */ - BUG_ON(atomic_read(&mark->refcnt) < 2); - - spin_lock(&group->mark_lock); spin_lock(&inode->i_lock); hlist_del_init(&mark->i.i_list); mark->i.inode = NULL; - list_del_init(&mark->g_list); - mark->group = NULL; - - fsnotify_put_mark(mark); /* for i_list and g_list */ - /* * this mark is now off the inode->i_fsnotify_marks list and we * hold the inode->i_lock, so this is the perfect time to update the @@ -181,61 +78,6 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark) fsnotify_recalc_inode_mask_locked(inode); spin_unlock(&inode->i_lock); - spin_unlock(&group->mark_lock); - spin_unlock(&mark->lock); - - /* - * Some groups like to know that marks are being freed. This is a - * callback to the group function to let it know that this mark - * is being freed. - */ - if (group->ops->freeing_mark) - group->ops->freeing_mark(mark, group); - - /* - * __fsnotify_update_child_dentry_flags(inode); - * - * I really want to call that, but we can't, we have no idea if the inode - * still exists the second we drop the mark->lock. - * - * The next time an event arrive to this inode from one of it's children - * __fsnotify_parent will see that the inode doesn't care about it's - * children and will update all of these flags then. So really this - * is just a lazy update (and could be a perf win...) - */ - - - iput(inode); - - /* - * it's possible that this group tried to destroy itself, but this - * this mark was simultaneously being freed by inode. If that's the - * case, we finish freeing the group here. - */ - if (unlikely(atomic_dec_and_test(&group->num_marks))) - fsnotify_final_destroy_group(group); -} - -/* - * Given a group, destroy all of the marks associated with that group. - */ -void fsnotify_clear_marks_by_group(struct fsnotify_group *group) -{ - struct fsnotify_mark *lmark, *mark; - LIST_HEAD(free_list); - - spin_lock(&group->mark_lock); - list_for_each_entry_safe(mark, lmark, &group->marks_list, g_list) { - list_add(&mark->free_g_list, &free_list); - list_del_init(&mark->g_list); - fsnotify_get_mark(mark); - } - spin_unlock(&group->mark_lock); - - list_for_each_entry_safe(mark, lmark, &free_list, free_g_list) { - fsnotify_destroy_mark(mark); - fsnotify_put_mark(mark); - } } /* @@ -261,8 +103,12 @@ void fsnotify_clear_marks_by_inode(struct inode *inode) } } -static struct fsnotify_mark *fsnotify_find_mark_locked(struct fsnotify_group *group, - struct inode *inode) +/* + * given a group and inode, find the mark associated with that combination. + * if found take a reference to that mark and return it, else return NULL + */ +struct fsnotify_mark *fsnotify_find_inode_mark_locked(struct fsnotify_group *group, + struct inode *inode) { struct fsnotify_mark *mark; struct hlist_node *pos; @@ -282,50 +128,26 @@ static struct fsnotify_mark *fsnotify_find_mark_locked(struct fsnotify_group *gr * given a group and inode, find the mark associated with that combination. * if found take a reference to that mark and return it, else return NULL */ -struct fsnotify_mark *fsnotify_find_mark(struct fsnotify_group *group, - struct inode *inode) +struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, + struct inode *inode) { struct fsnotify_mark *mark; spin_lock(&inode->i_lock); - mark = fsnotify_find_mark_locked(group, inode); + mark = fsnotify_find_inode_mark_locked(group, inode); spin_unlock(&inode->i_lock); return mark; } -void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old) -{ - assert_spin_locked(&old->lock); - new->i.inode = old->i.inode; - new->group = old->group; - new->mask = old->mask; - new->free_mark = old->free_mark; -} - -/* - * Nothing fancy, just initialize lists and locks and counters. - */ -void fsnotify_init_mark(struct fsnotify_mark *mark, - void (*free_mark)(struct fsnotify_mark *mark)) -{ - spin_lock_init(&mark->lock); - atomic_set(&mark->refcnt, 1); - INIT_HLIST_NODE(&mark->i.i_list); - mark->group = NULL; - mark->mask = 0; - mark->i.inode = NULL; - mark->free_mark = free_mark; -} - /* * Attach an initialized mark mark to a given group and inode. * These marks may be used for the fsnotify backend to determine which * event types should be delivered to which group and for which inodes. */ -int fsnotify_add_mark(struct fsnotify_mark *mark, - struct fsnotify_group *group, struct inode *inode, - int allow_dups) +int fsnotify_add_inode_mark(struct fsnotify_mark *mark, + struct fsnotify_group *group, struct inode *inode, + int allow_dups) { struct fsnotify_mark *lmark = NULL; int ret = 0; @@ -336,56 +158,26 @@ int fsnotify_add_mark(struct fsnotify_mark *mark, mark->flags = FSNOTIFY_MARK_FLAG_INODE; - /* - * if this group isn't being testing for inode type events we need - * to start testing - */ - if (unlikely(list_empty(&group->inode_group_list))) - fsnotify_add_inode_group(group); - /* - * XXX This is where we could also do the fsnotify_add_vfsmount_group - * if we are setting and vfsmount mark.... - - if (unlikely(list_empty(&group->vfsmount_group_list))) - fsnotify_add_vfsmount_group(group); - */ + assert_spin_locked(&mark->lock); + assert_spin_locked(&group->mark_lock); - /* - * LOCKING ORDER!!!! - * mark->lock - * group->mark_lock - * inode->i_lock - */ - spin_lock(&mark->lock); - spin_lock(&group->mark_lock); spin_lock(&inode->i_lock); if (!allow_dups) - lmark = fsnotify_find_mark_locked(group, inode); + lmark = fsnotify_find_inode_mark_locked(group, inode); if (!lmark) { - mark->group = group; mark->i.inode = inode; hlist_add_head(&mark->i.i_list, &inode->i_fsnotify_marks); - list_add(&mark->g_list, &group->marks_list); - - fsnotify_get_mark(mark); /* for i_list and g_list */ - - atomic_inc(&group->num_marks); fsnotify_recalc_inode_mask_locked(inode); } spin_unlock(&inode->i_lock); - spin_unlock(&group->mark_lock); - spin_unlock(&mark->lock); if (lmark) { ret = -EEXIST; iput(inode); - fsnotify_put_mark(lmark); - } else { - __fsnotify_update_child_dentry_flags(inode); } return ret; -- cgit v1.2.3