Messages in this thread Patch in this message | | | From | Eric Paris <> | Subject | [PATCH -v2 07/16] fanotify: fastpath to ignore certain in core inodes | Date | Tue, 14 Oct 2008 16:52:07 -0400 |
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Allows a process to ignore certain events for the given in core inodes. This does not preclude the need to keep a userspace or xattr based cache if a fanotifier listener wants something with a different lifetime than in core inode.
Signed-off-by: Eric Paris <eparis@redhat.com> ---
fs/inode.c | 6 + fs/notify/Makefile | 2 fs/notify/fanotify.c | 19 ++++ fs/notify/fanotify.h | 34 +++++++ fs/notify/fastpath.c | 230 ++++++++++++++++++++++++++++++++++++++++++++++ fs/notify/group.c | 3 + include/linux/fanotify.h | 17 +++ include/linux/fs.h | 5 + include/linux/fsnotify.h | 8 ++ 9 files changed, 323 insertions(+), 1 deletions(-) create mode 100644 fs/notify/fastpath.c
diff --git a/fs/inode.c b/fs/inode.c index 0487ddb..cc802ae 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -21,6 +21,7 @@ #include <linux/cdev.h> #include <linux/bootmem.h> #include <linux/inotify.h> +#include <linux/fsnotify.h> #include <linux/mount.h> /* @@ -183,6 +184,10 @@ static struct inode *alloc_inode(struct super_block *sb) } inode->i_private = NULL; inode->i_mapping = mapping; +#ifdef CONFIG_FANOTIFY + INIT_LIST_HEAD(&inode->fastpath_entries); + rwlock_init(&inode->fastpath_rwlock); +#endif } return inode; } @@ -191,6 +196,7 @@ void destroy_inode(struct inode *inode) { BUG_ON(inode_has_buffers(inode)); security_inode_free(inode); + fsnotify_inode_delete(inode); if (inode->i_sb->s_op->destroy_inode) inode->i_sb->s_op->destroy_inode(inode); else diff --git a/fs/notify/Makefile b/fs/notify/Makefile index c467c97..90cb910 100644 --- a/fs/notify/Makefile +++ b/fs/notify/Makefile @@ -3,4 +3,4 @@ obj-$(CONFIG_INOTIFY_USER) += inotify_user.o obj-$(CONFIG_DNOTIFY) += dnotify.o -obj-$(CONFIG_FANOTIFY) += fanotify.o notification.o group.o +obj-$(CONFIG_FANOTIFY) += fanotify.o notification.o group.o fastpath.o diff --git a/fs/notify/fanotify.c b/fs/notify/fanotify.c index e2a338e..aa12e91 100644 --- a/fs/notify/fanotify.c +++ b/fs/notify/fanotify.c @@ -35,6 +35,15 @@ struct dentry *fanotify_fs_root; +void fanotify_inode_delete(struct inode *inode) +{ + if (likely(list_empty(&fanotify_groups))) + return; + + fanotify_fastpath_clear(inode); +} +EXPORT_SYMBOL_GPL(fanotify_inode_delete); + void fanotify(struct file *file, unsigned int mask) { struct fanotify_group *group; @@ -52,6 +61,8 @@ void fanotify(struct file *file, unsigned int mask) if (!S_ISREG(inode->i_mode)) return; + if (mask & FAN_MODIFY) + fanotify_fastpath_clear(inode); /* * SRCU!! the groups list is very very much read only and the path is * very hot (assuming something is using fanotify) Not blocking while @@ -67,6 +78,8 @@ void fanotify(struct file *file, unsigned int mask) idx = srcu_read_lock(&fanotify_grp_srcu_struct); list_for_each_entry_rcu(group, &fanotify_groups, group_list) { if (mask & group->mask) { + if (fanotify_is_fastpath(file, mask, group)) + continue; if (!event) { event = create_event(file, mask); /* shit, we OOM'd and now we can't tell, lets hope something else blows up */ @@ -94,6 +107,12 @@ static __init int fanotify_init(void) if (ret) return ret; + ret = fanotify_fastpath_init(); + if (ret) { + fanotify_notification_uninit(); + return ret; + } + return init_srcu_struct(&fanotify_grp_srcu_struct); } __initcall(fanotify_init); diff --git a/fs/notify/fanotify.h b/fs/notify/fanotify.h index 5b0253e..091ea5e 100644 --- a/fs/notify/fanotify.h +++ b/fs/notify/fanotify.h @@ -46,6 +46,31 @@ struct fanotify_event { atomic_t refcnt; /* how many groups still are using/need to send this event */ }; +/* + * a fastpath is simply an entry attached to an in core inode which allows an + * fanotify listener to indicate they are no longer interested in events of + * a type matching mask. + * + * these are flushed when an inode is evicted from core or when the inode is + * modified (as seen by fsnotify_access) + */ +struct fanotify_fastpath_entry { + struct fanotify_group *group; /* group this fastpath entry is for */ + unsigned int mask; /* mask this fastpath entry is for */ + struct inode *inode; /* inode this entry is associated with */ + /* + * killcnt starts at 0 and is incremented when this entry will be killed + * since multiple processes my try to kill it at the same time. + * One might try to kill it from walking the i_list when an inode is being + * kicked out of cache and one might try to kill it when an fanotify group + * is being unregistered. The last one to finish cleaning everything up + * and decrement it to 0 will do the actual killing + */ + atomic_t killcnt; + struct list_head i_list; /* list of fastpath_entries by inode->fastpath_entries */ + struct list_head g_list; /* list of fastpath_entries by group->fastpath_entries */ +}; + extern struct mutex fanotify_grp_mutex; extern struct srcu_struct fanotify_grp_srcu_struct; extern struct list_head fanotify_groups; @@ -61,4 +86,13 @@ extern struct fanotify_event_holder *alloc_event_holder(void); extern void fanotify_destroy_event_holder(struct fanotify_event_holder *holder); extern __init int fanotify_notification_init(void); extern __init int fanotify_notification_uninit(void); + +extern void fanotify_fastpath_get(struct fanotify_fastpath_entry *entry); +extern void fanotify_fastpath_put(struct fanotify_fastpath_entry *entry); +extern int fanotify_is_fastpath(struct file *file, unsigned int mask, struct fanotify_group *group); +extern void fanotify_fastpath_clear_group(struct fanotify_group *group); +extern void fanotify_fastpath_clear(struct inode *inode); +extern __init int fanotify_fastpath_init(void); +extern __init int fanotify_fastpath_uninit(void); + #endif /* _LINUX_FANOTIFY_PRIVATE_H */ diff --git a/fs/notify/fastpath.c b/fs/notify/fastpath.c new file mode 100644 index 0000000..c4114af --- /dev/null +++ b/fs/notify/fastpath.c @@ -0,0 +1,230 @@ +/* + * 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. + */ + +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/namei.h> +#include <linux/poll.h> +#include <linux/rculist.h> +#include <linux/rcupdate.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/security.h> +#include <linux/uaccess.h> +#include <linux/writeback.h> + +#include <linux/fanotify.h> +#include "fanotify.h" + +static struct kmem_cache *fastpath_kmem_cache; + +static void fanotify_fastpath_kill(struct fanotify_fastpath_entry *entry) +{ + entry->group = NULL; + entry->inode = NULL; + entry->mask = 0; + entry->i_list.next = NULL; + entry->g_list.next = NULL; + kmem_cache_free(fastpath_kmem_cache, entry); +} + +static struct fanotify_fastpath_entry *fanotify_fastpath_alloc(void) +{ + struct fanotify_fastpath_entry *entry; + + entry = kmem_cache_alloc(fastpath_kmem_cache, GFP_KERNEL); + + return entry; +} + +void fanotify_fastpath_get(struct fanotify_fastpath_entry *entry) +{ + atomic_inc(&entry->killcnt); +} + +void fanotify_fastpath_put(struct fanotify_fastpath_entry *entry) +{ + if (atomic_dec_and_test(&entry->killcnt)) + fanotify_fastpath_kill(entry); +} + +int fanotify_is_fastpath(struct file *file, unsigned int mask, struct fanotify_group *group) +{ + struct inode *inode = file->f_path.dentry->d_inode; + struct fanotify_fastpath_entry *entry; + int found = 0; + + read_lock(&inode->fastpath_rwlock); + list_for_each_entry(entry, &inode->fastpath_entries, i_list) { + /* is the entry for this group and is the entry->mask a superset of this event mask? */ + if ((entry->group == group) && ((entry->mask & mask) == mask)) { + found = 1; + break; + } + } + read_unlock(&inode->fastpath_rwlock); + + return found; +} + +void fanotify_fastpath_clear_group(struct fanotify_group *group) +{ + struct fanotify_fastpath_entry *entry; + struct inode *inode; + + mutex_lock(&group->fastpath_mutex); + while (!list_empty(&group->fastpath_entries)) { + entry = list_first_entry(&group->fastpath_entries, struct fanotify_fastpath_entry, g_list); + + /* make sure the entry survives until it is off both lists */ + fanotify_fastpath_get(entry); + + /* remove from g_list */ + list_del_init(&entry->g_list); + mutex_unlock(&group->fastpath_mutex); + + inode = entry->inode; + + /* remove from i_list */ + write_lock(&inode->fastpath_rwlock); + if (!list_empty(&entry->i_list)) + list_del_init(&entry->i_list); + write_unlock(&inode->fastpath_rwlock); + + /* off both lists, may free now */ + fanotify_fastpath_put(entry); + + mutex_lock(&group->fastpath_mutex); + } + mutex_unlock(&group->fastpath_mutex); +} + +void fanotify_fastpath_clear(struct inode *inode) +{ + struct fanotify_fastpath_entry *entry; + struct fanotify_group *group; + + write_lock(&inode->fastpath_rwlock); + while (!list_empty(&inode->fastpath_entries)) { + entry = list_first_entry(&inode->fastpath_entries, struct fanotify_fastpath_entry, i_list); + + /* make sure the entry survives until off both lists */ + fanotify_fastpath_get(entry); + list_del_init(&entry->i_list); + + group = entry->group; + + write_unlock(&inode->fastpath_rwlock); + + mutex_lock(&group->fastpath_mutex); + if (!list_empty(&entry->g_list)) + list_del_init(&entry->g_list); + mutex_unlock(&group->fastpath_mutex); + + /* off both lists, may kill now */ + fanotify_fastpath_put(entry); + + write_lock(&inode->fastpath_rwlock); + } + write_unlock(&inode->fastpath_rwlock); +} + +/* + * add the fastpath entry to the in core inode referenced by fd + */ +int fanotify_fastpath_add(struct fanotify_group *group, int fd, unsigned int mask) +{ + struct file *file; + int fput_needed; + int ret = 0; + /* we initialize entry to shut up the compiler in case we just to out... */ + struct fanotify_fastpath_entry *entry = NULL, *lentry; + struct inode *inode; + bool used = true; + + file = fget_light(fd, &fput_needed); + if (!file) + return -EBADF; + + inode = file->f_path.dentry->d_inode; + + if (!S_ISREG(inode->i_mode)) { + ret = -EINVAL; + goto out; + } + + /* pre allocate an entry so we can hold the writelock */ + entry = fanotify_fastpath_alloc(); + if (!entry) { + ret = -ENOMEM; + /* be sure that used==TRUE here so it doens't try to free */ + goto out; + } + + /* + * this is the only place we hold both the group and the inode lock + * we could take them in either order, but we take the mutex first + * so we don't sleep holding the rwlock + */ + mutex_lock(&group->fastpath_mutex); + write_lock(&inode->fastpath_rwlock); + list_for_each_entry(lentry, &inode->fastpath_entries, i_list) { + if (lentry->group == group) { + lentry->mask |= mask; + used = false; + goto out_unlock; + } + } + + atomic_set(&entry->killcnt, 0); + entry->group = group; + entry->mask = mask; + entry->inode = inode; + + list_add(&entry->i_list, &inode->fastpath_entries); + list_add(&entry->g_list, &group->fastpath_entries); + +out_unlock: + write_unlock(&inode->fastpath_rwlock); + mutex_unlock(&group->fastpath_mutex); +out: + fput_light(file, fput_needed); + if (!used) + fanotify_fastpath_kill(entry); + return ret; +} + + +__init int fanotify_fastpath_uninit(void) +{ + kmem_cache_destroy(fastpath_kmem_cache); + fastpath_kmem_cache = NULL; + + return 0; +} + +__init int fanotify_fastpath_init(void) +{ + fastpath_kmem_cache = kmem_cache_create("fanotify_fastpath_entry", sizeof(struct fanotify_fastpath_entry), 0, SLAB_PANIC, NULL); + + return 0; +} diff --git a/fs/notify/group.c b/fs/notify/group.c index fc3d736..ff9b5ef 100644 --- a/fs/notify/group.c +++ b/fs/notify/group.c @@ -87,6 +87,9 @@ void fanotify_kill_group(struct fanotify_group *group) /* clear the notification queue of all events */ fanotify_notification_clear_group(group); + /* clear all fastpath entries for this group */ + fanotify_fastpath_clear_group(group); + kfree(group); } diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h index 5add54f..015cfea 100644 --- a/include/linux/fanotify.h +++ b/include/linux/fanotify.h @@ -76,17 +76,25 @@ struct fanotify_group { struct mutex notification_mutex;/* protect the notification_list */ struct list_head notification_list; /* list of event_holder this group needs to send to userspace */ wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */ + + /* stores all fastapth entries assoc with this group so they can be cleaned on unregister */ + struct mutex fastpath_mutex; /* protect fastpath_entries list */ + struct list_head fastpath_entries; /* all fastpath entries for this group */ }; #ifdef CONFIG_FANOTIFY extern void fanotify(struct file *file, unsigned int mask); +extern void fanotify_inode_delete(struct inode *inode); extern void fanotify_get_group(struct fanotify_group *group); extern struct fanotify_group *fanotify_find_group(unsigned int group_num, unsigned int mask); extern void fanotify_put_group(struct fanotify_group *group); +/* things called from the socket */ extern int fanotify_create_event_fd(struct fanotify_group *group, struct fanotify_event_metadata *data, int nonblock); +extern int fanotify_fastpath_add(struct fanotify_group *group, int fd, unsigned int mask); + #else static inline void fanotify(struct file *file, unsigned int mask) @@ -108,6 +116,15 @@ static inline int fanotify_create_event_fd(struct fanotify_group *group, struct memset(data, 0, sizeof(struct fanotify_event_metadata)); return 0; } + +static inline int fanotify_fastpath_add(struct fanotify_group *group, int fd, unsigned int mask) +{ + return 0; +} + +static inline void fanotify_inode_delete(struct inode *inode) +{} + #endif /* CONFIG_FANOTIFY */ #endif /* __KERNEL __ */ diff --git a/include/linux/fs.h b/include/linux/fs.h index 44e3cb2..3d877e3 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -676,6 +676,11 @@ struct inode { struct mutex inotify_mutex; /* protects the watches list */ #endif +#ifdef CONFIG_FANOTIFY + struct list_head fastpath_entries; /* fanotify fastpath entries protected by group */ + rwlock_t fastpath_rwlock; /* protect the fastpath entries list */ +#endif + unsigned long i_state; unsigned long dirtied_when; /* jiffies of first dirtying */ diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h index ccee5ea..5af4225 100644 --- a/include/linux/fsnotify.h +++ b/include/linux/fsnotify.h @@ -82,6 +82,14 @@ static inline void fsnotify_nameremove(struct dentry *dentry, int isdir) } /* + * fsnotify_inode_delete - and inode is being evicted from cache, clean up is needed + */ +static inline void fsnotify_inode_delete(struct inode *inode) +{ + fanotify_inode_delete(inode); +} + +/* * fsnotify_inoderemove - an inode is going away */ static inline void fsnotify_inoderemove(struct inode *inode)
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