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fsnotify: parent event notification 

inotify and dnotify both use a similar parent notification mechanism.  We
add a generic parent notification mechanism to fsnotify for both of these
to use.  This new machanism also adds the dentry flag optimization which
exists for inotify to dnotify.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Eric Paris 2009-05-21 17:01:29 -04:00
parent 3be25f49b9
commit c28f7e56e9
6 changed files with 205 additions and 10 deletions
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91
fs/notify/fsnotify.c
View File

@ -34,6 +34,97 @@ void __fsnotify_inode_delete(struct inode *inode)
}
EXPORT_SYMBOL_GPL(__fsnotify_inode_delete);
/*
* Given an inode, first check if we care what happens to our children. Inotify
* and dnotify both tell their parents about events. If we care about any event
* on a child we run all of our children and set a dentry flag saying that the
* parent cares. Thus when an event happens on a child it can quickly tell if
* if there is a need to find a parent and send the event to the parent.
*/
void __fsnotify_update_child_dentry_flags(struct inode *inode)
{
struct dentry *alias;
int watched;
if (!S_ISDIR(inode->i_mode))
return;
/* determine if the children should tell inode about their events */
watched = fsnotify_inode_watches_children(inode);
spin_lock(&dcache_lock);
/* run all of the dentries associated with this inode. Since this is a
* directory, there damn well better only be one item on this list */
list_for_each_entry(alias, &inode->i_dentry, d_alias) {
struct dentry *child;
/* run all of the children of the original inode and fix their
* d_flags to indicate parental interest (their parent is the
* original inode) */
list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
if (!child->d_inode)
continue;
spin_lock(&child->d_lock);
if (watched)
child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
else
child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
spin_unlock(&child->d_lock);
}
}
spin_unlock(&dcache_lock);
}
/* Notify this dentry's parent about a child's events. */
void __fsnotify_parent(struct dentry *dentry, __u32 mask)
{
struct dentry *parent;
struct inode *p_inode;
bool send = false;
bool should_update_children = false;
if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
return;
spin_lock(&dentry->d_lock);
parent = dentry->d_parent;
p_inode = parent->d_inode;
if (fsnotify_inode_watches_children(p_inode)) {
if (p_inode->i_fsnotify_mask & mask) {
dget(parent);
send = true;
}
} else {
/*
* The parent doesn't care about events on it's children but
* at least one child thought it did. We need to run all the
* children and update their d_flags to let them know p_inode
* doesn't care about them any more.
*/
dget(parent);
should_update_children = true;
}
spin_unlock(&dentry->d_lock);
if (send) {
/* we are notifying a parent so come up with the new mask which
* specifies these are events which came from a child. */
mask |= FS_EVENT_ON_CHILD;
fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE);
dput(parent);
}
if (unlikely(should_update_children)) {
__fsnotify_update_child_dentry_flags(p_inode);
dput(parent);
}
}
EXPORT_SYMBOL_GPL(__fsnotify_parent);
/*
* 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

5
fs/notify/fsnotify.h
View File

@ -17,4 +17,9 @@ extern __u32 fsnotify_mask;
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);
/*
* update the dentry->d_flags of all of inode's children to indicate if inode cares
* about events that happen to its children.
*/
extern void __fsnotify_update_child_dentry_flags(struct inode *inode);
#endif /* __FS_NOTIFY_FSNOTIFY_H_ */

17
fs/notify/inode_mark.c
View File

@ -131,6 +131,8 @@ void fsnotify_recalc_inode_mask(struct inode *inode)
spin_lock(&inode->i_lock);
fsnotify_recalc_inode_mask_locked(inode);
spin_unlock(&inode->i_lock);
__fsnotify_update_child_dentry_flags(inode);
}
/*
@ -189,6 +191,19 @@ void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry)
*/
group->ops->freeing_mark(entry, 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 entry->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...)
*/
/*
* it's possible that this group tried to destroy itself, but this
* this mark was simultaneously being freed by inode. If that's the
@ -323,6 +338,8 @@ int fsnotify_add_mark(struct fsnotify_mark_entry *entry,
if (lentry) {
ret = -EEXIST;
fsnotify_put_mark(lentry);
} else {
__fsnotify_update_child_dentry_flags(inode);
}
return ret;

4
include/linux/dcache.h
View File

@ -180,10 +180,12 @@ d_iput: no no no yes
#define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */
#define DCACHE_UNHASHED 0x0010
#define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched */
#define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched by inotify */
#define DCACHE_COOKIE 0x0040 /* For use by dcookie subsystem */
#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x0080 /* Parent inode is watched by some fsnotify listener */
extern spinlock_t dcache_lock;
extern seqlock_t rename_lock;

34
include/linux/fsnotify.h
View File

@ -23,15 +23,31 @@
static inline void fsnotify_d_instantiate(struct dentry *entry,
struct inode *inode)
{
__fsnotify_d_instantiate(entry, inode);
inotify_d_instantiate(entry, inode);
}
/* Notify this dentry's parent about a child's events. */
static inline void fsnotify_parent(struct dentry *dentry, __u32 mask)
{
__fsnotify_parent(dentry, mask);
inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
}
/*
* fsnotify_d_move - entry has been moved
* Called with dcache_lock and entry->d_lock held.
*/
static inline void fsnotify_d_move(struct dentry *entry)
{
/*
* On move we need to update entry->d_flags to indicate if the new parent
* cares about events from this entry.
*/
__fsnotify_update_dcache_flags(entry);
inotify_d_move(entry);
}
@ -117,7 +133,8 @@ static inline void fsnotify_nameremove(struct dentry *dentry, int isdir)
if (isdir)
mask |= FS_IN_ISDIR;
dnotify_parent(dentry, DN_DELETE);
inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
fsnotify_parent(dentry, mask);
}
/*
@ -188,9 +205,9 @@ static inline void fsnotify_access(struct dentry *dentry)
mask |= FS_IN_ISDIR;
dnotify_parent(dentry, DN_ACCESS);
inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
inotify_inode_queue_event(inode, mask, 0, NULL, NULL);
fsnotify_parent(dentry, mask);
fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE);
}
@ -206,9 +223,9 @@ static inline void fsnotify_modify(struct dentry *dentry)
mask |= FS_IN_ISDIR;
dnotify_parent(dentry, DN_MODIFY);
inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
inotify_inode_queue_event(inode, mask, 0, NULL, NULL);
fsnotify_parent(dentry, mask);
fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE);
}
@ -223,9 +240,9 @@ static inline void fsnotify_open(struct dentry *dentry)
if (S_ISDIR(inode->i_mode))
mask |= FS_IN_ISDIR;
inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
inotify_inode_queue_event(inode, mask, 0, NULL, NULL);
fsnotify_parent(dentry, mask);
fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE);
}
@ -236,16 +253,15 @@ static inline void fsnotify_close(struct file *file)
{
struct dentry *dentry = file->f_path.dentry;
struct inode *inode = dentry->d_inode;
const char *name = dentry->d_name.name;
fmode_t mode = file->f_mode;
__u32 mask = (mode & FMODE_WRITE) ? FS_CLOSE_WRITE : FS_CLOSE_NOWRITE;
if (S_ISDIR(inode->i_mode))
mask |= FS_IN_ISDIR;
inotify_dentry_parent_queue_event(dentry, mask, 0, name);
inotify_inode_queue_event(inode, mask, 0, NULL, NULL);
fsnotify_parent(dentry, mask);
fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE);
}
@ -260,9 +276,9 @@ static inline void fsnotify_xattr(struct dentry *dentry)
if (S_ISDIR(inode->i_mode))
mask |= FS_IN_ISDIR;
inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
inotify_inode_queue_event(inode, mask, 0, NULL, NULL);
fsnotify_parent(dentry, mask);
fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE);
}
@ -311,8 +327,8 @@ static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
if (S_ISDIR(inode->i_mode))
in_mask |= FS_IN_ISDIR;
inotify_inode_queue_event(inode, in_mask, 0, NULL, NULL);
inotify_dentry_parent_queue_event(dentry, in_mask, 0,
dentry->d_name.name);
fsnotify_parent(dentry, in_mask);
fsnotify(inode, in_mask, inode, FSNOTIFY_EVENT_INODE);
}
}

64
include/linux/fsnotify_backend.h
View File

@ -46,6 +46,17 @@
#define FS_DN_RENAME 0x10000000 /* file renamed */
#define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
/* This inode cares about things that happen to its children. Always set for
* dnotify and inotify. */
#define FS_EVENT_ON_CHILD 0x08000000
/* This is a list of all events that may get sent to a parernt based on fs event
* happening to inodes inside that directory */
#define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\
FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\
FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
FS_DELETE)
struct fsnotify_group;
struct fsnotify_event;
struct fsnotify_mark_entry;
@ -183,8 +194,52 @@ struct fsnotify_mark_entry {
/* main fsnotify call to send events */
extern void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is);
extern void __fsnotify_parent(struct dentry *dentry, __u32 mask);
extern void __fsnotify_inode_delete(struct inode *inode);
static inline int fsnotify_inode_watches_children(struct inode *inode)
{
/* FS_EVENT_ON_CHILD is set if the inode may care */
if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
return 0;
/* this inode might care about child events, does it care about the
* specific set of events that can happen on a child? */
return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
}
/*
* Update the dentry with a flag indicating the interest of its parent to receive
* filesystem events when those events happens to this dentry->d_inode.
*/
static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
{
struct dentry *parent;
assert_spin_locked(&dcache_lock);
assert_spin_locked(&dentry->d_lock);
parent = dentry->d_parent;
if (fsnotify_inode_watches_children(parent->d_inode))
dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
else
dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
}
/*
* fsnotify_d_instantiate - instantiate a dentry for inode
* Called with dcache_lock held.
*/
static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
{
if (!inode)
return;
assert_spin_locked(&dcache_lock);
spin_lock(&dentry->d_lock);
__fsnotify_update_dcache_flags(dentry);
spin_unlock(&dentry->d_lock);
}
/* called from fsnotify listeners, such as fanotify or dnotify */
@ -230,9 +285,18 @@ extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32
static inline void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is)
{}
static inline void __fsnotify_parent(struct dentry *dentry, __u32 mask)
{}
static inline void __fsnotify_inode_delete(struct inode *inode)
{}
static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
{}
static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
{}
#endif /* CONFIG_FSNOTIFY */
#endif /* __KERNEL __ */