diff options
Diffstat (limited to 'fs/notify')
| -rw-r--r-- | fs/notify/Makefile | 2 | ||||
| -rw-r--r-- | fs/notify/fsnotify.c | 13 | ||||
| -rw-r--r-- | fs/notify/fsnotify.h | 5 | ||||
| -rw-r--r-- | fs/notify/group.c | 49 | ||||
| -rw-r--r-- | fs/notify/inode_mark.c | 329 |
5 files changed, 396 insertions, 2 deletions
diff --git a/fs/notify/Makefile b/fs/notify/Makefile index db5467b5b58d..0922cc826c46 100644 --- a/fs/notify/Makefile +++ b/fs/notify/Makefile @@ -1,4 +1,4 @@ -obj-$(CONFIG_FSNOTIFY) += fsnotify.o notification.o group.o +obj-$(CONFIG_FSNOTIFY) += fsnotify.o notification.o group.o inode_mark.o obj-y += dnotify/ obj-y += inotify/ diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index 56bee0f10c38..d5654629c659 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -26,6 +26,15 @@ #include "fsnotify.h" /* + * Clear all of the marks on an inode when it is being evicted from core + */ +void __fsnotify_inode_delete(struct inode *inode) +{ + fsnotify_clear_marks_by_inode(inode); +} +EXPORT_SYMBOL_GPL(__fsnotify_inode_delete); + +/* * This is the main call to fsnotify. The VFS calls into hook specific functions * in linux/fsnotify.h. Those functions then in turn call here. Here will call * out to all of the registered fsnotify_group. Those groups can then use the @@ -43,6 +52,8 @@ void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is) if (!(mask & fsnotify_mask)) return; + if (!(mask & to_tell->i_fsnotify_mask)) + return; /* * 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 @@ -51,6 +62,8 @@ void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is) idx = srcu_read_lock(&fsnotify_grp_srcu); list_for_each_entry_rcu(group, &fsnotify_groups, group_list) { if (mask & group->mask) { + if (!group->ops->should_send_event(group, to_tell, mask)) + continue; if (!event) { event = fsnotify_create_event(to_tell, mask, data, data_is); /* shit, we OOM'd and now we can't tell, maybe diff --git a/fs/notify/fsnotify.h b/fs/notify/fsnotify.h index c6a8bd476572..8ebcbe893c91 100644 --- a/fs/notify/fsnotify.h +++ b/fs/notify/fsnotify.h @@ -12,4 +12,9 @@ extern struct srcu_struct fsnotify_grp_srcu; extern struct list_head fsnotify_groups; /* all bitwise OR of all event types (FS_*) for all fsnotify_groups */ extern __u32 fsnotify_mask; + +/* final kfree of a group */ +extern void fsnotify_final_destroy_group(struct fsnotify_group *group); +/* run the list of all marks associated with inode and flag them to be freed */ +extern void fsnotify_clear_marks_by_inode(struct inode *inode); #endif /* __FS_NOTIFY_FSNOTIFY_H_ */ diff --git a/fs/notify/group.c b/fs/notify/group.c index c6812953b968..a29d2fa67927 100644 --- a/fs/notify/group.c +++ b/fs/notify/group.c @@ -55,6 +55,29 @@ void fsnotify_recalc_global_mask(void) } /* + * Update the group->mask by running all of the marks associated with this + * group and finding the bitwise | of all of the mark->mask. If we change + * the group->mask we need to update the global mask of events interesting + * to the system. + */ +void fsnotify_recalc_group_mask(struct fsnotify_group *group) +{ + __u32 mask = 0; + __u32 old_mask = group->mask; + struct fsnotify_mark_entry *entry; + + spin_lock(&group->mark_lock); + list_for_each_entry(entry, &group->mark_entries, g_list) + mask |= entry->mask; + spin_unlock(&group->mark_lock); + + group->mask = mask; + + if (old_mask != mask) + fsnotify_recalc_global_mask(); +} + +/* * Take a reference to a group so things found under the fsnotify_grp_mutex * can't get freed under us */ @@ -66,7 +89,7 @@ static void fsnotify_get_group(struct fsnotify_group *group) /* * Final freeing of a group */ -static void fsnotify_destroy_group(struct fsnotify_group *group) +void fsnotify_final_destroy_group(struct fsnotify_group *group) { if (group->ops->free_group_priv) group->ops->free_group_priv(group); @@ -75,6 +98,24 @@ static void fsnotify_destroy_group(struct fsnotify_group *group) } /* + * Trying to get rid of a group. We need to first get rid of any outstanding + * allocations and then free the group. Remember that fsnotify_clear_marks_by_group + * could miss marks that are being freed by inode and those marks could still + * hold a reference to this group (via group->num_marks) If we get into that + * situtation, the fsnotify_final_destroy_group will get called when that final + * mark is freed. + */ +static void fsnotify_destroy_group(struct fsnotify_group *group) +{ + /* clear all inode mark entries for this group */ + fsnotify_clear_marks_by_group(group); + + /* past the point of no return, matches the initial value of 1 */ + if (atomic_dec_and_test(&group->num_marks)) + fsnotify_final_destroy_group(group); +} + +/* * Remove this group from the global list of groups that will get events * this can be done even if there are still references and things still using * this group. This just stops the group from getting new events. @@ -173,6 +214,10 @@ struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num, __u32 mask, group->group_num = group_num; group->mask = mask; + spin_lock_init(&group->mark_lock); + atomic_set(&group->num_marks, 0); + INIT_LIST_HEAD(&group->mark_entries); + group->ops = ops; mutex_lock(&fsnotify_grp_mutex); @@ -188,6 +233,8 @@ struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num, __u32 mask, /* group not found, add a new one */ list_add_rcu(&group->group_list, &fsnotify_groups); group->on_group_list = 1; + /* being on the fsnotify_groups list holds one num_marks */ + atomic_inc(&group->num_marks); mutex_unlock(&fsnotify_grp_mutex); diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c new file mode 100644 index 000000000000..cdc154146974 --- /dev/null +++ b/fs/notify/inode_mark.c @@ -0,0 +1,329 @@ +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; see the file COPYING. If not, write to + * 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: + * + * entry->lock + * group->mark_lock + * inode->i_lock + * + * entry->lock protects 2 things, entry->group and entry->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 mark_entries list anchored inside a given group + * and each entry 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_mark_entries list anchored inside a + * given inode and each entry 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_by_entry) + * - 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_mark_entries 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 <linux/fs.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/slab.h> +#include <linux/spinlock.h> + +#include <asm/atomic.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" + +void fsnotify_get_mark(struct fsnotify_mark_entry *entry) +{ + atomic_inc(&entry->refcnt); +} + +void fsnotify_put_mark(struct fsnotify_mark_entry *entry) +{ + if (atomic_dec_and_test(&entry->refcnt)) + entry->free_mark(entry); +} + +/* + * Recalculate the mask of events relevant to a given inode locked. + */ +static void fsnotify_recalc_inode_mask_locked(struct inode *inode) +{ + struct fsnotify_mark_entry *entry; + struct hlist_node *pos; + __u32 new_mask = 0; + + assert_spin_locked(&inode->i_lock); + + hlist_for_each_entry(entry, pos, &inode->i_fsnotify_mark_entries, i_list) + new_mask |= entry->mask; + inode->i_fsnotify_mask = new_mask; +} + +/* + * Recalculate the inode->i_fsnotify_mask, or the mask of all FS_* event types + * any notifier is interested in hearing for this inode. + */ +void fsnotify_recalc_inode_mask(struct inode *inode) +{ + spin_lock(&inode->i_lock); + fsnotify_recalc_inode_mask_locked(inode); + spin_unlock(&inode->i_lock); +} + +/* + * 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 entry->lock + */ +void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry) +{ + struct fsnotify_group *group; + struct inode *inode; + + spin_lock(&entry->lock); + + group = entry->group; + inode = entry->inode; + + BUG_ON(group && !inode); + BUG_ON(!group && inode); + + /* if !group something else already marked this to die */ + if (!group) { + spin_unlock(&entry->lock); + return; + } + + /* 1 from caller and 1 for being on i_list/g_list */ + BUG_ON(atomic_read(&entry->refcnt) < 2); + + spin_lock(&group->mark_lock); + spin_lock(&inode->i_lock); + + hlist_del_init(&entry->i_list); + entry->inode = NULL; + + list_del_init(&entry->g_list); + entry->group = NULL; + + fsnotify_put_mark(entry); /* for i_list and g_list */ + + /* + * this mark is now off the inode->i_fsnotify_mark_entries list and we + * hold the inode->i_lock, so this is the perfect time to update the + * inode->i_fsnotify_mask + */ + fsnotify_recalc_inode_mask_locked(inode); + + spin_unlock(&inode->i_lock); + spin_unlock(&group->mark_lock); + spin_unlock(&entry->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 entry + * is being freed. + */ + group->ops->freeing_mark(entry, group); + + /* + * 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_entry *lentry, *entry; + LIST_HEAD(free_list); + + spin_lock(&group->mark_lock); + list_for_each_entry_safe(entry, lentry, &group->mark_entries, g_list) { + list_add(&entry->free_g_list, &free_list); + list_del_init(&entry->g_list); + fsnotify_get_mark(entry); + } + spin_unlock(&group->mark_lock); + + list_for_each_entry_safe(entry, lentry, &free_list, free_g_list) { + fsnotify_destroy_mark_by_entry(entry); + fsnotify_put_mark(entry); + } +} + +/* + * Given an inode, destroy all of the marks associated with that inode. + */ +void fsnotify_clear_marks_by_inode(struct inode *inode) +{ + struct fsnotify_mark_entry *entry, *lentry; + struct hlist_node *pos, *n; + LIST_HEAD(free_list); + + spin_lock(&inode->i_lock); + hlist_for_each_entry_safe(entry, pos, n, &inode->i_fsnotify_mark_entries, i_list) { + list_add(&entry->free_i_list, &free_list); + hlist_del_init(&entry->i_list); + fsnotify_get_mark(entry); + } + spin_unlock(&inode->i_lock); + + list_for_each_entry_safe(entry, lentry, &free_list, free_i_list) { + fsnotify_destroy_mark_by_entry(entry); + fsnotify_put_mark(entry); + } +} + +/* + * 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_entry *fsnotify_find_mark_entry(struct fsnotify_group *group, + struct inode *inode) +{ + struct fsnotify_mark_entry *entry; + struct hlist_node *pos; + + assert_spin_locked(&inode->i_lock); + + hlist_for_each_entry(entry, pos, &inode->i_fsnotify_mark_entries, i_list) { + if (entry->group == group) { + fsnotify_get_mark(entry); + return entry; + } + } + return NULL; +} + +/* + * Nothing fancy, just initialize lists and locks and counters. + */ +void fsnotify_init_mark(struct fsnotify_mark_entry *entry, + void (*free_mark)(struct fsnotify_mark_entry *entry)) + +{ + spin_lock_init(&entry->lock); + atomic_set(&entry->refcnt, 1); + INIT_HLIST_NODE(&entry->i_list); + entry->group = NULL; + entry->mask = 0; + entry->inode = NULL; + entry->free_mark = free_mark; +} + +/* + * Attach an initialized mark entry 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_entry *entry, + struct fsnotify_group *group, struct inode *inode) +{ + struct fsnotify_mark_entry *lentry; + int ret = 0; + + /* + * LOCKING ORDER!!!! + * entry->lock + * group->mark_lock + * inode->i_lock + */ + spin_lock(&entry->lock); + spin_lock(&group->mark_lock); + spin_lock(&inode->i_lock); + + entry->group = group; + entry->inode = inode; + + lentry = fsnotify_find_mark_entry(group, inode); + if (!lentry) { + hlist_add_head(&entry->i_list, &inode->i_fsnotify_mark_entries); + list_add(&entry->g_list, &group->mark_entries); + + fsnotify_get_mark(entry); /* 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(&entry->lock); + + if (lentry) { + ret = -EEXIST; + fsnotify_put_mark(lentry); + } + + return ret; +} |